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Understanding the drivers of community assembly is critical for predicting the future of biodiversity and ecosystem services. Ecological selection ubiquitously shapes communities by selecting for individuals with the most suitable trait combinations. Detecting selection types on key traits across environmental gradients and over time has the potential to reveal the underlying abiotic and biotic drivers of community dynamics. Here, we present a model‐based predictive framework to quantify the multidimensional trait distributions of communities (community trait spaces), which we use to identify ecological selection types shaping communities along environmental gradients. We apply the framework to over 3600 boreal forest understory plant communities with results indicating that directional, stabilizing, and divergent selection all modify community trait distributions and that the selection type acting on individual traits may change over time. Our results provide novel and rare empirical evidence for divergent selection within a natural system. Our approach provides a framework for identifying key traits under selection and facilitates the detection of processes underlying community dynamics. [ABSTRACT FROM AUTHOR]

Warming associated with climate change will advance the onset of spring phenology for many forest plants across the Eastern United States. Understory forbs and spring ephemerals that fix a disproportionate amount of carbon during early spring may be negatively affected by earlier canopy closure; however, information on the spatial patterns of phenological change for these communities is still lacking. To assess the potential for changes in spring phenological windows, we synthesized observations from the Appalachian Mountain Club's (AMCs) Mountain Watch (MW) project, the National Phenology Network (NPN), and AMC's iNaturalist projects between 2004 and 2022 (n = 118,250) across the length of the Appalachian Trail (AT) Corridor (34° N–46° N latitude). We used hierarchical Bayesian modeling to examine the sensitivity of spring flowering and leaf‐out for 11 understory species and 14 canopy tree species to mean spring temperature (April–June). We conducted analyses across the AT Corridor, partitioned by regions of 4° latitude (south, mid‐Atlantic, and north). Spring phenologies for both understory plants and canopy trees advanced with warming (~6 and ~3 days/°C, respectively). However, the sensitivity of each group varied by latitude, with the phenology of trees and understory plants advancing to a greater degree in the mid‐Atlantic region (~10 days/°C) than in the southern or northern regions (~5 days/°C). While we find evidence that phenological windows remain stable in the southern and mid‐Atlantic portions of the AT, we observed an expansion of the spring phenological window in the north where there was greater understory forb temperature sensitivity compared with trees (~2.7 days/°C). Our analyses indicate the differential sensitivity of forest plant phenology to potential warming across a large latitudinal gradient in the Eastern United States. Further, evidence for a temperature‐driven expansion of the spring phenological window suggests a potential beneficial effect for understory plants in the northern AT, although phenological mismatch with potential pollinators and increased vulnerability to late winter frosts are possible. Using extensive citizen‐science datasets allows us to synthesize regional‐ and continental‐scale data to explore spatial and temporal trends in spring phenology related to warming. Such data can help to standardize approaches in phenological research and its application to forest climate resiliency. [ABSTRACT FROM AUTHOR]

Altered fire regimes, combined with a warmer and drier climate, have been eroding the resilience of temperate rainforests and peatlands worldwide and leading to alternative post-fire vegetation communities. Chronic anthropogenic burning of temperate rainforests at the forest-peatland ecotone in western Patagonia appears to have shifted vegetation communities in poorly-drained sites from forests dominated by the threatened conifer, Pilgerodendron uviferum, to peat-accumulating wetlands covered by Sphagnum mosses. We collected and modeled post-reburn field data using ordinations and hierarchical Bayesian regressions to examine mechanisms through which P. uviferum forests may recover following fire or become locked into alternative development pathways by comparing biophysical factors of a reburned ecotone to those of an unburned (control) ecotone. We found that, (1) the significantly higher densities of P. uviferum trees and seedlings in the forested patches at both the reburned and control sites were associated with significantly lower seasonal water tables, lower cover of Sphagnum mosses and higher cover of other mosses (i.e., not in the Sphagnum or Dicranaloma genera); (2) despite abrupt boundaries in vegetation at both sites, successive fires homogenized the environment at the reburned site; and (3) the distinct life forms and individual species that characterized the understory plant communities across the ecotones affected seedling abundance by shaping microtopography and the substrates available for establishment. Together, our results suggest that fire can push edaphically wet P. uviferum-dominated sites towards a non-forested state by reducing the diversity of microsite structure and composition, thereby placing P. uviferum seedlings in direct competition with Sphagnum mosses and potentially limiting the availability of microsites that are protected from both seasonal inundation and seasonal drought. If wildfires continue under increasingly warmer and drier conditions, the forestpeatland ecotone of western Patagonia may be susceptible to large-scale transformation towards a non-forested state. [ABSTRACT FROM AUTHOR]

Introduction: The Indian Himalayan forests are remarkable landforms experiencing tremendous climatic variation, constituting complex and diversified ecosystems with prominent vegetation zones. Despite their global significance and substantial research efforts focused on plant diversity in the temperate Himalayan region, only a few studies have explicitly assessed the distribution patterns of understory vegetation in relation to forest compositional types along altitudinal gradients. Methods: To cover a wide range of altitudes and diverse overstory compositions, stands were sampled across four altitudinal ranges from 1500 to 3500 meters above mean sea level with increments of 500 meters in elevation steps. The overstory compositions were classified on the basis of dominant tree species in each stand on the similar sites. Vegetation in the shrub and ground layers was surveyed by visually estimating the percentage coverage within circular plots. Results: A total of 99 understory species including 37 species each in the shrub layer, 62 species in the herb layer vegetation were recorded. The abundance, species diversity and composition of understory vegetation differed significantly along the altitudinal gradient and dominant overstory composition types. Moreover, distinct understory vegetation communities were observed at lower elevations compared to higher elevations, with middle elevations exhibiting intermediate vegetation characteristics. The study also highlighted the importance of dominant overstory composition types in shaping the pattern of understory vegetation abundance, species diversity and composition in the temperate Himalayan region. The higher resource conditions associated with broadleaved stands supported higher understory species abundance at lower elevations, while the heterogeneous conditions induced by the mixedwood stands promoted higher understory species diversity. Conclusion: The hump shaped pattern along the altitudinal gradient appeared to be the most dominant pattern of plant abundance and species diversity and call for more conservation concern towards the middle elevation zones in the temperate Himalayan region. Furthermore, the management interventions should aim at maintaining diverse range of overstory composition types for conserving biodiversity and their ecological functions in the temperate Himalayan region. [ABSTRACT FROM AUTHOR]

Although the effects of invasive alien plants on natural ecosystems are well known, the effects of specific plant species can vary across habitat types and disturbance intensity. This study was carried out to analyze the effects of Lantana camara on associated vegetation and soil physico-chemical properties at invaded and non-invaded sites across three different habitat types (forest edge, fallow land, and roadside) in central Nepal. We sampled 50 pairs of 5 m × 5 m (for shrub species) and 1 m × 1 m (for herbs species) plots at invaded and non-invaded sites in each habitat and recorded community variables for each species within the sampling plots for both wet (monsoon) and dry (pre-monsoon) seasons. Further, we collected soil samples from each quadrat and determined the soil physico-chemical properties. We recorded 137 species of flowering plants (119 from non-invaded and 97 from invaded plots) and classified them in accordance with life form/habit. In invaded sites, we found a significant decline in species diversity as indicated by the Simpson and Shannon diversity indices. Specifically, L. camara reduced the species richness, Simpson index, and Shannon diversity index by 36.84%, 11.84%, and 40.21%, respectively. Soil nutrients such as total nitrogen, soil organic carbon, and available phosphorus were significantly higher in invaded sites than non-invaded ones except for available potassium and soil pH. This study provided evidence that Lantana L. camara has a substantial impact on the understory plant community assemblage and the physico-chemical properties of soil. The results suggest that the protection of native plant community requires management of L. camara by implementing appropriate measures. [ABSTRACT FROM AUTHOR]

Overstory trees serve multiple functions in grassy savannas. Past research has shown that understory species can vary along gradients of canopy cover and basal area in savannas. This variation is frequently associated with light availability but could also be related to other mechanisms, such as heterogeneity in soil and litter depth and fire intensity. Several savanna studies have found differences in understory plant functional groups within the local environment near trees versus away from them in canopy openings. Although small‐scale variation is known to be high in southeastern U.S. pine savannas, patterns in understory species diversity have not been examined at the scale of individual overstory pine trees in this system. We conducted an observational study of the relationship between understory plant communities and proximity to individual pine trees in xeric and mesic pine savannas in frequently burned sites (1–3 year intervals). We recorded the plant community composition in plots adjacent to tree boles (basal) or outside crown driplines (open). Within each environment, raw species richness was significantly greater in open locations, where light transmittance was greater. In contrast, rarified species richness did not differ. Multivariate analyses showed that community composition differed significantly between basal and open plots. One native, woody species in each environment, Serenoa repens (W. Bartram) Small in mesic and Diospyros virginiana L. in xeric, was more abundant in basal plots. In mesic environments, eight species had greater occurrence in open plots. In xeric environments, four understory forbs were more abundant in open plots. Our results support previous research indicating that individual pine trees are associated with significant variation in understory vegetation in pine savannas. [ABSTRACT FROM AUTHOR]

Trade‐offs are crucial for species divergence and reproductive isolation. Trade‐offs between investment in growth versus defense against herbivores are implicated in tropical forest diversity. Empirically exploring the role of growth–defense trade‐offs in closely related species' reproductive isolation can clarify the eco‐evolutionary dynamics through which growth–defense trade‐offs contribute to diversity. Costus villosissimus and C. allenii are recently diverged, interfertile, and partially sympatric neotropical understory plant species primarily isolated by divergent habitat adaptation. This divergent adaptation involves differences in growth rate, which may constrain investment in defense. Here, we investigate growth–defense trade‐offs and how they relate to the divergent habitat adaptation that isolates these species. We characterize leaf toughness and chemistry, evaluate the feeding preferences of primary beetle herbivores in controlled trials and field‐based experiments, and investigate natural herbivory patterns. We find clear trade‐offs between growth and defense: slower‐growing C. allenii has tougher leaves and higher defensive chemical concentrations than faster‐growing C. villosissimus. Costus villosissimus has rapid growth‐based drought avoidance, enabling growth in drier habitats with few specialist herbivores. Therefore, growth–defense trade‐offs mediate synergistic biotic and abiotic selection, causing the divergent habitat adaptation that prevents most interspecific mating between C. villosissimus and C. allenii. Our findings advance understanding of ecological speciation by highlighting the interplay of biotic and abiotic selection that dictates the outcome of trade‐offs. [ABSTRACT FROM AUTHOR]

Understory forest plants are often limited by shade from the canopy above them. Many such species therefore make use of a shade avoidance strategy referred to as "phenological escape" to access ephemeral light availability during periods when the canopy above them is open (e.g., in early spring). In this primer, we review past literature on phenological escape and related topics. We discuss (1) the physiological importance of this shade avoidance strategy, (2) the effects that climate change may have on species performance via changes in phenological escape, (3) the potential for climate change to result in phenological mismatch related to shade avoidance, and (4) the potential avenues of future research in this area of study. Phenological escape is an important strategy used by spring-active plant species ranging from spring ephemeral wildflowers to deciduous tree seedlings, allowing them to assimilate 50%–100% of their annual carbon budgets before the canopy closes above them. Access to spring light, and thus success of this shade avoidance strategy, is projected to change in response to climate change. Change in access to light, and therefore change in spring performance, likely depends on functional group (woody vs. nonwoody plants), continent, and other geographic and environmental drivers. [ABSTRACT FROM AUTHOR]

Extreme droughts are globally increasing in frequency and severity. Most research on drought in forests focuses on the response of trees, while less is known about the impacts of drought on forest understory species and how these effects are moderated by the local environment. We assessed the impacts of a 45‐day experimental summer drought on the performance of six boreal forest understory plants, using a transplant experiment with rainout shelters replicated across 25 sites. We recorded growth, vitality and reproduction immediately, 2 months, and 1 year after the simulated drought, and examined how differences in ambient soil moisture and canopy cover among sites influenced the effects of drought on the performance of each species. Drought negatively affected the growth and/or vitality of all species, but the effects were stronger and more persistent in the bryophytes than in the vascular plants. The two species associated with older forests, the moss Hylocomiastrum umbratum and the orchid Goodyera repens, suffered larger effects than the more generalist species included in the experiment. The drought reduced reproductive output in the moss Hylocomium splendens in the next growing season, but increased reproduction in the graminoid Luzula pilosa. Higher ambient soil moisture reduced some negative effects of drought on vascular plants. Both denser canopy cover and higher soil moisture alleviated drought effects on bryophytes, likely through alleviating cellular damage. Our experiment shows that boreal understory species can be adversely affected by drought and that effects might be stronger for bryophytes and species associated with older forests. Our results indicate that the effects of drought can vary over small spatial scales and that forest landscapes can be actively managed to alleviate drought effects on boreal forest biodiversity. For example, by managing the tree canopy and protecting hydrological networks. [ABSTRACT FROM AUTHOR]

Herbicides are commonly used in forestry to enhance conifer tree growth by reducing the abundance of competitive, undesired, early successional species. Reducing the abundance of understory species could also lead to changes in community composition that need to be documented to aid the understanding of any downstream ecosystem changes. We examined the effects of glyphosate-based herbicides on the abundance, diversity, and community composition of the understory vegetation community of forests located in the temperate-boreal transition zone. We sampled 37 blocks in two ecoregions of the Acadian Forest in eastern Canada that were harvested over the last 15 years. Species richness, Shannon's diversity, or evenness did not differ among blocks with different herbicide history. However, community composition differed between the non-herbicide and herbicide blocks in both ecoregions. Overall, 26.5% of the plant community variation was explained by the factors herbicide use (10.6%), Biomass Growth Index/site quality (8.6%), time since harvest (3.6%), and ecoregion (1.7%). We found 16 indicator species that differentiated the non-herbicide (9 species) and herbicide blocks (7 species). Indicator species for non-herbicide blocks included two blueberry species, three shrubs (two flowering), and two ferns, whereas indicator species for herbicide blocks were largely perennial forbs. Together, our results indicate that herbicide use does not alter species richness but does reduce shrub abundance, a change that persists throughout the 10 years post-herbicide application captured in our study. The reduced shrub layer likely leads to other changes in the plant community. Herbicide use is associated with subtle changes to the understory plant community, and these changes are missed when only alpha diversity is used to examine the effects of herbicides use on community composition. [ABSTRACT FROM AUTHOR]

Cardamine diphylla is an understory herb of rich forests that exhibits a wintergreen life history strategy in western North Carolina. Unlike many forest floor plants, C. diphylla is able to persist under the evergreen shrub Rhododendron maximum, which is known to inhibit the growth of woody and herbaceous plants. We compared morphological and chemical characteristics of C. diphylla leaves in areas of a mesic cove forest with and without R. maximum during the winter. We also compared soil properties and the taxonomic richness of co-occurring herbaceous and woody plants. Results showed that C. diphylla growing under R. maximum produced significantly less foliar biomass but had significantly higher levels of foliar nitrogen and sulfur. Plants under R. maximum also had a higher proportion of green (rather than purple) abaxial leaf surfaces. Soils under R. maximum contained significantly less total nitrogen and humic matter, but cation exchange capacity and pH did not differ between the two areas. Compared to the surrounding forest, plots in R. maximum thickets supported 35% fewer woody taxa and 41% fewer herbaceous taxa, demonstrating the challenges of this microhabitat to understory plants. The ability of C. diphylla to persist under R. maximum may be advantageous if R. maximum continues its opportunistic expansion in southern Appalachian forests. [ABSTRACT FROM AUTHOR]

Global warming is leading understory and canopy plant communities of temperate deciduous forests to grow leaves earlier in spring and drop them later in autumn. If understory species extend their leafy seasons less than canopy trees, they will intercept less light. We look for mismatched phenological shifts between canopy and understory in 28 years (1995–2022) of weekly data from Trelease Woods, Urbana, IL, USA. The observations cover 31 herb species of contrasting seasonality (for 1995–2017), three sapling species, and the 15 most dominant canopy tree species for all years, combined with solar radiation, temperature and canopy light transmittance data. We estimate how understory phenology, cold temperatures, canopy phenology, and solar radiation have individually limited understory plants' potential light interception over >2 decades. Understory and canopy phenology were the two factors most limiting to understory light availability, but which was more limiting varied greatly among species and among/within seasonality groups; solar radiation ranked third and cold fourth. Understory and canopy phenology shifts usually occurred in the same direction; either both strata were early or both were late, offsetting each other's effects. The four light-limiting factors combined showed significant temporal trends for six understory species, five toward less light interception. Warmer springs were significantly associated with shifts toward more light interception in three sapling species and 19 herb species. Canopy phenology became more limiting in warmer years for all three saplings species and 31 herb species. However, in aggregate, these variables mostly offset one another; only one sapling and seven herb species showed overall significant (and negative) relationships between light interception and spring temperature. The few understory species mismatched with canopy phenology due to changing climate are likely to intercept less light in future warmer years. The few species with data for carbon assimilation show broadly similar patterns to light interception. [ABSTRACT FROM AUTHOR]

We address the concerns that managed forest plantations may cause reductions of diversity of understory vegetation. We performed inventories of two mature ponderosa pine plantations in which multiple treatments were applied during plantation establishment. At stand age 35, we measured tree heights and diameters, understory plant cover and diversity, soil nutrients and chemical properties, and soil microbial biomass and diversity with phospholipid fatty acid. We found a significant, positive effect from both herbicide (H) and fertilizer (F) applications on subsequent overstory tree growth and development (P < 0.05); insecticide (I) effect was minimal. We observed negative effects on understory plant diversity decades later when herbicide was applied during stand establishment. However, lower plant diversity and ground cover appeared to have been caused primarily from overstory canopy closure, supported by the increased understory cover and diversity observed in the HI and HFI plots that had been thinned at age 12. Similarly, while fertilizer increased tree growth at both sites, it only negatively affected understory plants at the higher quality site. We did not find significant influence of treatment effects on soil nutrients and microbial communities. Therefore, to mitigate the potential loss of understory biodiversity in plantations, foresters can manage overstory trees with traditional pre-commercial thinning techniques and early tending. [ABSTRACT FROM AUTHOR]

Introduction: Touch by neighboring plants is a common but overlooked environmental variable for plants, especially in dense vegetation. In addition, shade is inevitable for understory plants. The growth performance of clonal plant to the interaction between thigmomorphogenesis and shade response, and their impact on light adaptability is still unknown. Methods: At the present study, parental ramets of Glechoma longituba were exposed to two conditions (neighboring touch and shade), and their offspring ramets were in ambient or shaded environment. The phenotype and growth of parental and offspring ramets were analyzed. Results: The results showed that neighboring touch of parental ramets regulated the performance of offspring ramets, while the effect depended on the light environment. The parental neighboring touch occurring in ambient environment suppressed the expansion of leaf organ, showed as a shorter petiole and smaller leaf area. Moreover, G. longituba exhibited both shade avoidance and shade tolerance characters to shaded environment, such as increased leaf area ratio and leaf mass ratio, longer specific petiole length and specific stolon length. It was notable that these characters of shade response could be promoted by parental neighboring touch to some extent. Additionally, parental light environment plays an important role in offspring growth, parent with ambient light always had wellgrown offspring whatever the light condition of offspring, but the growth of offspring whose parent in shaded environment was inhibited. Finally, for the offspring with shaded environment, the touch between parental ramets in shade environment showed a disadvantage on their growth, but the influence of the touch between parental ramets in ambient environment was slight. Discussion: Overall, the interaction of parental neighboring touch and shade environment complicate the growth of understory plants, the performance of plants is the integrated effect of both. These findings are conducive to an indepth understanding of the environmental adaptation of plants. [ABSTRACT FROM AUTHOR]

Research on understory plant diversity and its response to environmental factors helps in the sustainable development of plantation forests. We investigated the characteristics of understory plant diversity in Eucalyptus plantation forests located in Dongfang, Ding'an, Tunchang, and Lingao on Hainan Island by leveraging the plot survey method, and analyzing how the understory plant diversity in these Eucalyptus plantation forests responds to environmental factors. The results showed that a total of 124 plant species belonging to 62 families and 112 genera were recorded in the sampled plots of the Dongfang, Ding'an, Tunchang, and Lingao regional sites on Hainan Island, among which species of Fabaceae and Poaceae comprised the largest number of plants. The number of species and plant diversity indices of the shrub layer and herb layer in Eucalyptus plantation forests varied at different sites, The richest understory vegetation in Tunchang, located in the center of Hainan Island, and the highest a-diversity whether gauged by species or phylogenetically. The similarity of the understory plant community species was greatest between Ding'an and Tunchang, whereas the difference in composition was largest between Dongfang and the other three sites. Phylogenetically, the understory plant community at Ding'an had the most distant affinities among species, whereas that at Tunchang had the closest affinities among species. The results of the Mantel test and redundancy analysis revealed differing correlations between plant diversity in the shrub layer versus herb layer and various environmental factors. In particular, elevation and annual average temperature are the two main factors influencing plant diversity in the shrub layer, and soil available nitrogen and annual average sunshine duration are the two main factors influencing plant diversity in the herb layer. Variance decomposition showed that the combined effect of soil, climate, and topography factors is the main driver shaping plant diversity in the shrub layer of the understory in Eucalyptus plantation forests, while the combined effect of climate and soil factors is the main one determining plant diversity in their herb layer. [ABSTRACT FROM AUTHOR]

Due to the loss of photosynthetic ability during evolution, some plant species rely on mycorrhizal fungi for their carbon source, and this nutritional strategy is known as mycoheterotrophy. Mycoheterotrophic plants forming Paris-type arbuscular mycorrhizas (AM) exhibit two distinctive mycorrhizal features: degeneration of fungal materials and specialization towards particular fungal lineages. To explore the possibility that some understory AM plants show partial mycoheterotrophy, i.e., both photosynthetic and mycoheterotrophic nutritional strategies, we investigated 13 green herbaceous plant species collected from five Japanese temperate forests. Following microscopic observation, degenerated hyphal coils were observed in four species: two Colchicaceae species, Disporum sessile and Disporum smilacinum, and two Gentianaceae species, Gentiana scabra and Swertia japonica. Through amplicon sequencing, however, we found that all examined plant species exhibited no specificity toward AM fungi. Several AM fungi were consistently found across most sites and all plant species studied. Because previous studies reported the detection of these AM fungi from various tree species in Japanese temperate forests, our findings suggest the presence of ubiquitous AM fungi in forest ecosystems. If the understory plants showing fungal degeneration exhibit partial mycoheterotrophy, they may obtain carbon compounds indirectly from a wide range of surrounding plants utilizing such ubiquitous AM fungi. [ABSTRACT FROM AUTHOR]

Overstory and understory vegetation play a vital role in forest ecosystem functionality. However, it is necessary to enhance the knowledge of their diversity and compositional dynamics following cessation of disturbance, which is required to inform restoration approaches and the mechanisms required for maintaining disturbance cessation. We conducted a chronosequence spanning 0–1, 5–6, 11–12, 20–24, and 28–34 years since disturbance cessation, and old-growth forests to investigate the dynamic changes in overstory and understory vegetation diversity and composition, as well as maintenance mechanisms following the cessation of anthropogenic disturbances in subtropical regions of Eastern China. The current study results indicated a decrease in understory cover and periodic fluctuations in the diversity of overstorey and understory vegetation following disturbance cessation efforts. Specifically, the shrub layer exhibited the highest richness in 28–34 years, while the herb layer showed the lowest evenness. Multivariate analysis using multiple-response permutation procedures indicated that the species composition and interspecific quantity ratio of understory plants in the forest at 28–34 years significantly differ from those in the early closure stage. An indicator species analysis revealed that more support was given to sun-loving plants after 0–1 years of the enclosure, while species with shade tolerance and low nutrient requirements were supported after 28–34 years. The structural equation model results show that 38.8% of the impact on herb evenness was related to light and substrate diversity. The ecological restoration time mainly indirectly affects understory vegetation by influencing the upper vegetation, light availability, and substrate heterogeneity. Overall, this study revealed that cessation of anthropogenic disturbance can maintain and care for understorey plant diversity and contribute to the sustainable management of forests. [ABSTRACT FROM AUTHOR]

Projections of spatial biodiversity dynamics under climate warming are often based on models including only climate variables, and when non-climatic factors (e.g. soil) are included, data are often at much coarser spatial resolutions than those experienced by plants. Field studies along elevation gradients permit the gathering of detailed soil data, while still covering a wide climatic gradient. Here, an intensive field survey of four spring forest herbs along an elevation gradient showed that soil properties had substantial impacts on the occurrence/abundance of all species, and that soil effects were more pronounced at higher elevations. For Trillium erectum and Claytonia caroliniana, very infrequent occurrences at high elevation were strongly associated with rare microsites with high pH or nutrients. In a seven-year transplant experiment with T. erectum, we found that individuals grew to much smaller sizes at high than low elevation, suggesting that environmental factors rather than dispersal limitation constrain the species' upper range limit, despite substantial warming in recent decades. Our study demonstrates that soil factors interact strongly with climate to determine plant range limits along climatic gradients. Unsuitable soils for plants at high elevations or latitudes may represent an important constraint on future plant migration and biodiversity change. This article is part of the theme issue 'Ecological novelty and planetary stewardship: biodiversity dynamics in a transforming biosphere'. [ABSTRACT FROM AUTHOR]

Background: The globose scale (GS), Sphaerolecanium prunastri (Boyer de Fonscolombe) (Hemiptera: Coccoidea), has invaded wild apricot forests in their native range in Central Eurasia threatening the ancestral germplasm resource. Biological control efficacy of the harlequin ladybird, Harmonia axyridis (Pallas, 1773) (Coleoptera: Coccinellidae) against the globose scale was assessed in laboratory and field experiments. Results: In the laboratory, Harmonia axyridis has a high feeding capacity on GS with numbers consumed daily increasing with temperature (15, 20, 25, 30, 35 °C), reaching an upper asymptote of 160–200 scales per day. In field cage experiments, efficacy of biological control (EBC) against first instar (49–99%) and second instar nymphs (20–80%) increased with GS density. When ants were present, control efficiency was reduced by 10–15%. In open-field experiments without cages, EBC was comparatively lower regardless of duration and how H. axyridis were released whether as adults, eggs cards or a mixture of adults and eggs cards. Conclusions: In the long term, biological control with this ladybird predator could be considered as part of an IPM program package that includes banning or delaying mowing grass and understory plants in the forests that offer pollen and nectar for natural enemies. [ABSTRACT FROM AUTHOR]

The response of plants to increasing atmospheric CO2 depends on the ecological context where the plants are found. Several experiments with elevated CO2 (eCO2) have been done worldwide, but the Amazonian forest understory has been neglected. As the central Amazon is limited by light and phosphorus, understanding how understory responds to eCO2 is important for foreseeing how the forest will function in the future. In the understory of a natural forest in the Central Amazon, we installed four open‐top chambers as control replicates and another four under eCO2 (+250 ppm above ambient levels). Under eCO2, we observed increases in carbon assimilation rate (67%), maximum electron transport rate (19%), quantum yield (56%), and water use efficiency (78%). We also detected an increase in leaf area (51%) and stem diameter increment (65%). Central Amazon understory responded positively to eCO2 by increasing their ability to capture and use light and the extra primary productivity was allocated to supporting more leaf and conducting tissues. The increment in leaf area while maintaining transpiration rates suggests that the understory will increase its contribution to evapotranspiration. Therefore, this forest might be less resistant in the future to extreme drought, as no reduction in transpiration rates were detected. Summary statement: The Amazonian understory plants demonstrate a remarkable response to elevated CO2, including an increase in leaf area and a higher investment in the maximum electron transport rate. These findings suggest enhanced carbon storage and water flux, stressing the important role of the understory in the overall functioning of the forest ecosystem. [ABSTRACT FROM AUTHOR]

Forests appeared during the Middle to Late Devonian, but Devonian forests and their compositions are still rarely known. Xinhang forest was reported as the largest Devonian forest, with lycopsid trees of Guangdedendron micrum Wang et al. A fern-like plant Xinhangia spina Yang and Wang with shoots and anatomy, was previously described from this forest, but its habit and ecology remain unclear. From Xinhang forest, we now report more specimens of fern-like plants including X. spina and some unnamed plants in several beds. Prominent adventitious roots, spines and secondary xylem indicate that the stems of X. spina are largely procumbent to function as anchorage, absorption and support. Other fern-like plants with distinct roots or multiple slender branches also suggest procumbent habits. Xinhang forest is thus reconsidered as multispecific with a canopy of lycopsid trees and understory of diverse fern-like plants, which are adapted to the disturbed coastal environment. The composition of Xinhang forest may indicate a structural transition of the early forests' dominator from fern-like plants to lycopsids. [ABSTRACT FROM AUTHOR]

Understory small trees and shrubs play a crucial role in the biogeochemical cycles in forest ecosystems. However, their biomass in northeastern China is still uncertain and has been heavily disregarded due to the limited number of available allometric equations. For this study, 782 plants from 33 species obtained by the destructive method were used to develop species-specific and generalized aboveground allometric biomass equations based on collar diameter (D) and height (H) using weighted nonlinear seemingly unrelated regression. Each biomass component was shown to be well predicted by D alone, with R2 adj. values mostly greater than 0.80. The majority of species performed better in the models for wood and aboveground biomass when H was included as D2H. Furthermore, generalized equations for the two components showed a comparatively large coefficient of variation but comparable Bias to species-specific equations, especially for small trees. It is recommended to estimate biomass using generalized equations for mixed species only when species-specific equations are unavailable at a given site. However, in the event when precision is not the primary concern, generalized equations are also suggested. The developed equations will help to improve the accuracy of biomass assessment of understory woody plants in northeastern China forest ecosystems. [ABSTRACT FROM AUTHOR]

Black locust (Robinia pseudoacacia L.) plantations on the Loess Plateau have become multigenerational sprouting forests with an obvious trend toward degradation. The species composition and vertical distribution pattern of understory woody plants were investigated in mature stands located at the top (T_GS) and bottom (B_GS) of a slope in the gully region to explore whether there may be replacement species for black locust. The species composition of T_GS and B_GS clearly differed, and species diversity indices in B_GS were significantly greater than those in T_GS. These differences in species composition were mainly attributed to elevation, leaf area index, and basal area of total canopy trees. In T_GS, Rubus corchorifolius and Rosa xanthina had an absolute advantage in terms of the number of individuals in the vertical space of (0, 100] cm and (100, 300] cm, respectively. In B_GS, Acanthopanax senticosus was dominant at (0, 200] cm, and Broussonetia papyrifera and Celtis sinensis began to dominate at >200 cm. These results suggest that shrub species (Rubus corchorifolius and Rosa xanthina) and tree species (Broussonetia papyrifera and Celtis sinensis) should be prioritized when mixed with black locust in T_GS and B_GS, respectively, to gradually replace black locust on the Loess Plateau. [ABSTRACT FROM AUTHOR]

Subtropical forests, recognized for their intricate vertical canopy stratification, exhibit high resistance to extreme drought. However, the response of leaf phenology to drought in the species‐rich understory remains poorly understood. In this study, we constructed a digital camera system, amassing over 360,000 images through a 70% throughfall exclusion experiment, to explore the drought response of understory leaf phenology. The results revealed a significant advancement in understory leaf senescence phenology under drought, with 11.75 and 15.76 days for the start and end of the leaf‐falling event, respectively. Pre‐season temperature primarily regulated leaf development phenology, whereas soil water dominated the variability in leaf senescence phenology. Under drought conditions, temperature sensitivities for the end of leaf emergence decreased from −13.72 to −11.06 days °C−1, with insignificance observed for the start of leaf emergence. Consequently, drought treatment shortened both the length of the growing season (15.69 days) and the peak growth season (9.80 days) for understory plants. Moreover, this study identified diverse responses among intraspecies and interspecies to drought, particularly during the leaf development phase. These findings underscore the pivotal role of water availability in shaping understory phenology patterns, especially in subtropical forests. [ABSTRACT FROM AUTHOR]

Working pine (Pinus spp.) forests in the southern United States rely on herbicides to remove competing vegetation and improve productivity. We conducted a review of the effects of herbicides on understory plants in southern working forests. We also discuss the impacts of herbicides on insect taxa associated with understory vegetation and its litter layer, including Coleoptera (carabid beetles), Hemiptera (true bugs), Hymenoptera (bees/ants), Lepidoptera (moths/butterflies), and Orthoptera (grasshoppers). Herbicides have few reported long-term impacts on understory herbaceous cover and species richness/diversity when applied according to labeled uses and application rates. However, the method of chemical treatment (e.g. broadcast spray or banded application) may influence understory plant structure and composition. Responses of insects to herbicides were species- and taxa-specific and highly variable given their forage/habitat requirements and life histories. Long-term research is needed to evaluate the effects of herbicides on vegetation-associated insects to provide a comprehensive profile of herbicide nontarget impacts. Study Implications: Land managers rely on herbicides to remove competing vegetation and increase working forest productivity. Given the objective of sustainable forest management to conserve biodiversity, it is important to understand how biological communities respond to chemical applications in intensively managed forest ecosystems. Our review indicated that herbicides have few reported long-term impacts on understory plant communities when applied appropriately. Despite their taxonomic diversity, invertebrates were rarely included in assessments of forest herbicides. Further research is needed to assess the potential nontarget impacts of herbicide applications on forest insect communities. [ABSTRACT FROM AUTHOR]

Lowland tropical forest needs to be studied for its composition and structure because it has high biodiversity. This forest has experienced a lot of degradation so it is vulnerable to loss of genetic resources. This study aims to analyze plant diversity, structure and composition of vegetation in Kemal Muluq Forest, Lombok Island, Indonesia. The composition of the vegetation in Kemal Muluq Forest consists of 36 families, 58 genera and 62 species. The vegetation structure in Kemal Muluq Forest includes: seedling and understory, sapling, pole, and trees with varying densities. The species with the highest density was Schleichera oleosa (Lour.) Oken, followed by Schoutenia ovata Korth., and Streblus asper Lour. Plants at the seedling and understory levels are included in high diversity. Meanwhile, plants at the sapling, pole, and tree levels have diversity is included in moderate category. Plants at the seedling and understory, sapling, pole, and tree levels have low dominance value. Based on the regression analysis, there is soil temperature and soil pH have a significant influence on the plant diversity index in Kemal Muluq Forest, Lombok Island, Indonesia. [ABSTRACT FROM AUTHOR]

The response of plants to increasing atmospheric CO2 depends on the ecological context where the plants are found. Several experiments with elevated CO2 (eCO2) have been done worldwide, but the Amazonian forest understory has been neglected. As the central Amazon is limited by light and phosphorus, understanding how understory responds to eCO2 is important for foreseeing how the forest will function in the future. In the understory of a natural forest in the Central Amazon, we installed four open‐top chambers as control replicates and another four under eCO2 (+250 ppm above ambient levels). Under eCO2, we observed increases in carbon assimilation rate (67%), maximum electron transport rate (19%), quantum yield (56%), and water use efficiency (78%). We also detected an increase in leaf area (51%) and stem diameter increment (65%). Central Amazon understory responded positively to eCO2 by increasing their ability to capture and use light and the extra primary productivity was allocated to supporting more leaf and conducting tissues. The increment in leaf area while maintaining transpiration rates suggests that the understory will increase its contribution to evapotranspiration. Therefore, this forest might be less resistant in the future to extreme drought, as no reduction in transpiration rates were detected. Summary statement: The Amazonian understory plants demonstrate a remarkable response to elevated CO2, including an increase in leaf area and a higher investment in the maximum electron transport rate. These findings suggest enhanced carbon storage and water flux, stressing the important role of the understory in the overall functioning of the forest ecosystem. [ABSTRACT FROM AUTHOR]

Afforestation with nature‐based solutions is beneficial for restoring biodiversity. On the Loess Plateau of China, numerous monocultures have been converted to mixed plantations following nature‐based solutions. However, the effect of plant mixture on understory plant species diversity remains largely unknown. Here, we investigated the understory plant species diversity of different Hippophae rhamnoides mixed plantations resulting from nature‐based solutions and assessed the relative importance of associated factors driving their changes. The results showed that the response of understory plant species diversity to plant mixture was nonsignificant, except for Armeniaca sibirica, which significantly reduced the understory plant species diversity. However, mixed plantations had higher variability in plant species diversity and environmental factors among individual plots than monocultures. In mixed plantations, understory plant species diversity was mainly affected by shrub stratum, followed by overstory stratum, soil nutrients, herbaceous stratum, and topography. Specifically, understory plant species diversity was positively associated with stand density and herb biomass but negatively associated with elevation and soil nitrogen. In particular, soil nitrogen also had negative impacts on herb biomass but was beneficial for the growth of trees and shrubs, indicating that trees and shrubs outperformed herbs in exploiting soil nutrients, a consequence of intense interspecific competition. In addition, the impacts of canopy cover and slope aspects on understory plant species diversity were nonsignificant. Overall, in mixed plantations on the Loess Plateau, understory plant species diversity was primarily affected by interspecific competition for preempting soil nitrogen. [ABSTRACT FROM AUTHOR]

In the world's leading palm oil‐producing countries (Indonesia and Malaysia), smallholders make up about 40 per cent of total oil palm plantation area. Management in smallholdings can be highly variable, ranging from intensive monoculture to polyculture systems, especially in the earlier years of cultivation when open canopies allow a variety of understorey crop types to be grown alongside oil palm. Currently, many plantations in the region are mature and due to be replanted, which is likely to have substantial impacts on the ecosystems within them, but studies investigating the impacts of alternative post‐replanting management strategies in smallholder plantations are lacking.We investigated the impacts of replanting and choice of crop management following replanting (growing oil palm as a monoculture or polyculture) on habitat structure and complexity, and on the abundance, richness and composition of butterfly assemblages in smallholding oil palm plantations in Banting, Selangor, Malaysia. We also assessed the direct effects of habitat structure and complexity on butterfly assemblages. Butterflies are likely to be a valuable indicator group for monitoring the impacts of management practices on biodiversity as butterfly species also show a range of sensitivities to habitat disturbance, with some being vulnerable to change, but others being common in plantations. They are also a functionally important group that pollinate wild plants, are prey for larger species and are common in tropical systems.Across 27 plantations, we recorded 1227 butterflies from 5 families, 46 genera and 56 species. Habitat structure and complexity differed between management decisions (mature monoculture, immature monoculture, immature polyculture), although many environmental parameters overlapped. We found no significant differences in species richness, density and assemblage composition of butterflies between management decisions. However, changes in local environmental conditions, such as an increase in the coverage of understorey vegetation, increased the abundance of butterflies.Synthesis and applications. Our findings suggest that replanting oil palm and choice of mono or polyculture have relatively few effects on butterflies, but management for specific features in plantations could benefit butterfly assemblages. [ABSTRACT FROM AUTHOR]

The genus Hydrangea s.l. (Hydrangeaceae), a favorite among gardeners, comprises more than 80 species that are important understory plants in natural temperate and subtropical forests of the Northern Hemisphere. These species are hypervariable in morphology, especially in indumentum and floral characters, warranting a thorough exploration of the complex evolutionary history of morphological characters of the genus. Ideally, this is done within a robust phylogenetic framework with extensive taxon sampling. In this study, we propose a comprehensive taxonomic reassessment of Hydrangea based on a reconstruction of its molecular phylogeny based mainly on the chloroplast genome (plastome) and the most representative taxon sampling reported to date. Phylogenomic reconstruction yielded five well‐resolved major clades and three newly recognized subclades. Inspection of the 28 characters employed in traditional taxonomic revisions revealed homoplasy in many of these traits. Our results show that characters such as growth habit, woody stem type, number of enlarged marginal sepals, style and stamen number, fruit shape, and ovary position are useful for circumscribing infrageneric divisions. Unique synapomorphies are limited. For example, herb and subshrub growth habits are associated with all the species in H. sect. Deinanthe and sect. Cardiandra, respectively. Character state combinations are proposed for distinguishing infrageneric taxa. Based on a robust phylogenetic framework, our findings suggest a complex evolutionary history of Hydrangea morphological characters. Following the criterion of monophyly and considering the morphological consistency and synapomorphy of single and combined characters to diagnose relevant lineages, we update the classification of Hydrangea into 5 subgenera and 19 sections. Our proposed taxonomic scheme, based on a robust phylogenetic framework and in‐depth character study, provides an updated perspective on the infrageneric subdivision of Hydrangea s.l. [ABSTRACT FROM AUTHOR]

Precommercial thinning and tree pruning are frequently used together to improve timber quality and wildlife habitat in even-aged Sitka spruce (Picea sitchensis) and western hemlock (Tsuga heterophylla) stands. Thinning enhances crop tree growth and understory plant production; however, the benefits and drawbacks of tree pruning have received less attention. Tree pruning was investigated in two long-term experiments on the Tongass National Forest, Alaska, USA. Experiment 1 tracked four uniformly thinned sites for ~30 years that received 2.4, 3.6, and 5.2 m lift, and no pruning treatments. Experiment 2 tracked 11 sites for 16 years that received thinning/no pruning, thinning plus pruning (25% of trees), thinning plus pruning (50% of trees), and no thinning/no pruning treatments. We investigated (i) how pruning lift height affects tree form and understory production and (ii) how pruning density affects canopy closure and understory production. In Experiment 1, pruning reduced butt log taper and did not adversely affect diameter or height in either species. Pruning lift was visible in height-to-live crown measurements. Crown recession occurred first in low lift treatments and later in all treatments until crown form was similar after 28–31 years. Epicormic branching rates in Sitka spruce peaked 6–9 years after treatment before falling sharply. Deer forage declined through time and did not differ between lift treatments. In Experiment 2, canopy closure was lower shortly after thinning and pruning, but did not differ from the control after 16 years. Epicormic branching rates were greater shortly after thinning and pruning but did not differ from the control after 16 years. Deer forage declined with canopy closure and thinned and pruned treatments exhibited greater forage than the control. We conclude that pruning can improve log quality for timber applications but does not enhance understory plant biomass and deer forage over thinning treatment alone. [ABSTRACT FROM AUTHOR]

The comparison of ecological, phenological, morphological and developmental traits between exotic invasive species and coexisting native species contributes to understand the driving mechanisms of successful invasions. This study aimed to examine which of these traits are related to the invasion of woody plants in the understory of deciduous North Patagonian forests of Argentina.We compared the phenology, shoot growth rate, number of leaves, biomass allocation, leaf herbivory, and recruitment type of two exotic deciduous trees, Crataegus monogyna and Sorbus aucuparia, with those of four coexisting native woody species (one deciduous, one semi‐deciduous, and two evergreen species).Spring shoot growth took place several weeks earlier in both exotic species and in the deciduous native species than in the other native species; growth rates were higher in the exotics. Compared to coexisting native species, both exotic species developed shoots that were as long as or longer, had lower biomass allocation to leaves and higher allocation to roots, suffered lower leaf damage by herbivores and exhibited higher seed than vegetative recruitment.This study supports the idea that a combination of phenological, growth rate and mass allocation traits allow exotic species to preempt resources, thus favouring invasion processes. [ABSTRACT FROM AUTHOR]

Alien woody species are successful invaders, frequently used for afforestation in regions like semi-arid lands. Shrubs and trees create important microhabitats in arid areas. Understorey vegetation in these habitats has unique species composition and coexistence. However, the impact of solitary woody species on understorey vegetation is less understood. This study evaluated the effect of native (Juniperus communis) and invasive solitary conifers (Pinus nigra) on surrounding vegetation, where individuals were relatively isolated (referred to as solitary conifers). The field study conducted in Pannonic dry sand grassland in 2018 recorded plant and lichen species presence around six selected solitary conifers. Composition and pattern of understorey vegetation were assessed using 26 m belt transects with 520 units of 5 cm × 5 cm contiguous microquadrats. Compositional diversity (CD) and the number of realized species combinations (NRC) were calculated from the circular transects. Results showed native conifer J. communis created more complex, organized microhabitats compared to alien P. nigra. CD and NRC values were significantly higher under native conifers than invasive ones (p = 0.045 and p = 0.026, respectively). Native species also had more species with a homogeneous pattern than the alien species. Alien conifers negatively affected understorey vegetation composition and pattern: some species exhibited significant gaps and clusters of occurrences along the transects under P. nigra. Based on our study, the removal of invasive woody species is necessary to sustain habitat diversity. [ABSTRACT FROM AUTHOR]

Although ecological impacts of overabundant white‐tailed deer (Odocoileus virginianus) are well documented in eastern North America, few studies have evaluated the long‐term effects of adaptive deer population suppression after a period of overabundance. We examined vegetation community changes over a period of 30 years (1992–2021) on the Long Point Peninsula, Ontario, Canada following a >85% reduction of a previously overabundant white‐tailed deer population. We documented a significant increase in species diversity and shifts in the species composition of understory plants and woody vegetation. We then evaluated several hypotheses to explain these patterns. Our results provide support for the all‐you‐can‐browse hypothesis, in which the abundance of woody stems above the browse layer did not increase within the first 3 years of sampling but, consistent within an expected period of recruitment, increased by >1,500% from 1995–2021. We also found support for both the lawn maintenance hypothesis, with a significant decline in the proportional abundance of non‐preferred species relative to preferred species, and for the seed bank hypothesis, with native species accounting for nearly 80% of new species observed over the sampling period. We conclude that the effective, long‐term management and continued suppression of an previously overabundant white‐tailed deer population can lead to increased vegetation community heterogeneity and diversity, which is likely one of the most important steps for the regeneration of woody stems and native vegetation communities. [ABSTRACT FROM AUTHOR]

Forests restored passively or by tree planting can take many decades to be recolonized by native forest understory plant species, if at all. Our study tested (1) the ability of forest topsoil transfer to accelerate the recovery of native forest plant communities in post‐agricultural reforestation sites after tree‐planting and without previous topsoil removal and (2) the effect of adding combinations of woody debris (WD), shrub plantings, and shade shelters (SS) on top of the transferred topsoil. Five 12.5 × 10 m treatment blocks were established in each of three recipient sites, which included two post‐agricultural reforestation sites, and one abandoned gravel pit site. Each treatment blocks received forest topsoil and a combination of additional treatments. Treatment and control plots were sampled for all vascular species in spring and summer. Native forest plant species richness in topsoil recipient plots was similar (p > 0.05) to that of mature donor forest sites, and significantly higher (p < 0.05) than that of passive control plots in the recipient sites. The plant community composition of all topsoil recipient plots had also become more like the donor forests and less like recipient site controls. Only the unplanted gravel pit‐site increased in non‐native ruderal plant species after topsoil transfer. The addition of WD, shrub plantings, or SS had no significant effect after two growing seasons. We recommend that topsoil should when possible be added where trees have already been planted, allowing for shorter time to canopy closure and thereby higher survival of shade‐adapted understory species. [ABSTRACT FROM AUTHOR]

Anthropogenic influences are altering fire regimes worldwide, resulting in an increase in the size and severity of wildfires. Simultaneously, throughout western North America, there is increasing recognition of the important role of Indigenous fire stewardship in shaping historical fire regimes and fire‐adapted ecosystems. However, there is limited understanding of how ecosystems are affected by or recover from contemporary "megafires," particularly in terms of understory plant communities that are critical to both biodiversity and Indigenous cultures. To address this gap, our collaborative study, in partnership with Secwépemc First Nations, examined understory community recovery following a large, mixed‐severity wildfire that burned in the dry and mesic conifer forests of British Columbia, Canada, with a focus on plants of high cultural significance to Secwépemc communities. To measure the effect of a continuous gradient of fire severity across forest types, we conducted field assessments of fire severity and sampled understory plants 4 years postfire. We found that native species richness and richness of species of high cultural significance were lowest in areas that burned at high severity, with distinct compositional differences between unburned areas and those that burned at high severity. These findings were consistent across forest types characterized by distinct historical fire regimes. In contrast, richness of exotic species increased with increasing fire severity in the dominant montane interior Douglas‐fir forests, with exotic species closely associated with areas that burned at high severity. Our study indicates that recent megafires may be pushing ecosystems outside their historical range of variability, with negative implications for ecosystem recovery and cultural use across these fire‐affected landscapes. We also found consistently higher plant diversity, and both native and cultural species richness, in subalpine forests. Collectively, our results provide strong evidence of the ecological and cultural significance of low‐ to moderate‐severity fire and subalpine forests, and the longstanding and ongoing role of Indigenous peoples in shaping these landscapes. As wildfires continue to impact ecosystems and human communities, this study offers novel insights into the recovery of important ecological and cultural values, while highlighting the need to support ethical research collaborations with Indigenous communities and Indigenous‐led revitalization of fire and plant stewardship. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to understand the above- and belowground community assembly in subtropical plantations, and to detect the relationship with understory plant communities, soil microbial communities and stocks of soil organic carbon, nitrogen and phosphorus. Methods: We compared the composition and diversity of understory plants and microbial communities among exotic monocultures versus native conifer and broadleaved mixtures, and tested the co-structure between understory plant communities, soil microbial communities and soil characteristics. Results: The two native mixtures compared to exotic monocultures had greater understory plant cover (except for the herbaceous cover that was lower) and diversity, but lower community weighted mean of shrub and herbaceous leaf carbon content. Exotic monocultures and native broadleaved mixtures had a higher biomass of each microbial group than native conifer mixtures based on phospholipid fatty acids (PLFAs) extractions. Based on high throughput sequencing, we found higher bacterial and fungal richness in native mixtures than in exotic monocultures, but lower bacterial Shannon diversity. In terms of soil nutrients, only the soil phosphorus stocks were significantly higher in native mixtures than in exotic monocultures. Moreover, in the two native mixtures there was a strong co-structure between understory plants, soil microbes and soil nutrients. Yet, fungal phyla did not have any co-structure with other taxa. Conclusion: Our study highlights the important yet inconsistent roles of different plantation types in affecting the patterns of above- and belowground diversity, soil nutrients, and the maintenance of their relationships. Long-term monitoring is suggested to determine whether the main findings change with plantation restoration over time. [ABSTRACT FROM AUTHOR]

[Objective] This study evaluated diversity characteristics of Robinia pseudoacacia plantations with different stand densities and analyzed their differences to provide theoretical basis for determining reasonable stand density of Robinia pseudoacacia plantations and their healthy and sustainable management. [Method] Robinia pseudoacacia plantations with densities of 675, 1 025, 1 575, 2 175 and 2 500 plants/hm² in loess areas of Western Shanxi were investigated. Species, number and cover of understory shrubs and herbs plants, and plant diversity indices were analyzed, 10 evaluation indicators were identified, and plant diversity was evaluated using principal component analysis. [Result] (1) The plants of Robinia pseudoacacia forests were mainly from Asteraceae, Rosaceae and Gramineae, and plants with high importance values included Rosa xanthina, Periploca sepium, Rubus parvifolius and Artemisia argyi. (2) With he increase of the density of Robinia pseudoacacia plantations, the plant diversity index of stands tended o increase first and then decrease, with the greatest diversity index at moderate densities of 1 575 and 2 175 plants/hm². There were significant differences between Shannon-Wiener index and Pielou index of hrub layer of 1 575 plants/hm² Robinia pseudoacacia plantations and 675 and 2 500 plants/hm² (P < 0.05). The Simpson index and Shannon-Wiener index of 1 575 plants/hm² were significantly different from hose of 675 and 2 500 plants/hm² (P<0.05). (3) The evaluation of plant diversity in different stand densities showed that the density of 1 575 plants/hm² had the highest overall plant diversity assessment value. [Conclusion] The density of 1 185-1 785 plants/hm² with high diversity of understory plants was suggested for Robinia pseudoacacia plantations in the loess area of Western Shanxi. [ABSTRACT FROM AUTHOR]

Carbon (C) sequestrated in the boreal forest ecosystems plays an important role in climate regulation. This study's objectives were to quantify the differences in the components of the forest C cycle along a 1000 km latitudinal gradient within the boreal region and between dominant coniferous species in Fennoscandia. The study included seven xeric–sub-xeric and eight mesic–herb-rich heath forests dominated by Scots pine and Norway spruce, respectively. The total site carbon stock (CS) ranged from 81 to 260 Mg ha−1. The largest ecosystem component CSs were tree stems, mineral soil, and humus layer, representing 30 ± 2%, 28 ± 2%, and 13 ± 1% of total CS, respectively. On average, the spruce sites had 40% more C than the pine sites, and CS stored in most compartments was higher on spruce than on pine sites. As exceptions, understorey vegetation and litter layer had a larger CS on pine than on spruce sites. The northern sites had an average of 58% less C than the southern sites. Humus layer CS was the only compartment showing no latitudinal trends. Northern sites had a significantly larger fine and small root CS and understorey CS than southern sites. Most CS compartments were significantly correlated with litterfall C transfer components. Dissolved organic carbon (DOC) flux in throughfall was positively correlated with the aboveground tree compartment CS. Our study revealed patterns of C distribution in major boreal forest ecosystems along latitudinal and fertility gradients, which may serve as a reference for Earth system models and in the evaluation of their projections. [ABSTRACT FROM AUTHOR]

Questions: Forests are highly fragmented across the globe. For urban forests in particular, fragmentation increases the exposure to local warming caused by the urban heat island (UHI) effect. We here aim to quantify edge effects on herbaceous understorey vegetation in urban forests, and test whether these effects interact with forest structural complexity. Location: We set up a pan‐European study at the continental scale including six urban forests in Zurich, Paris, Katowice, Brussels, Bremen, and Stockholm. Methods: We recorded understorey plant communities from the edge towards the interior of urban forests. Within each urban forest, we studied edge‐to‐interior gradients in paired stands with differing forest structural complexity. Community composition was analysed based on species specialism, life form, light, nutrient, acidity and disturbance indicator values and species' thermal niches. Results: We found that herbaceous communities at urban forest edges supported more generalists and forbs but fewer ferns than in forests' interiors. A buffered summer microclimate proved crucial for the presence of fern species. The edge communities contained more thermophilous, disturbance‐tolerant, nutrient‐demanding and basiphilous plant species, a pattern strongly confirmed by corresponding edge‐to‐interior gradients in microclimate, soil and light conditions in the understorey. Additionally, plots with a lower canopy cover and higher light availability supported higher numbers of both generalists and forest specialists. Even though no significant interactions were found between the edge distance and forest structural complexity, opposing additive effects indicated that a dense canopy can be used to buffer negative edge effects. Conclusion: The urban environment poses a multifaceted filter on understorey plant communities which contributes to significant differences in community composition between urban forest edges and interiors. For urban biodiversity conservation and the buffering of edge effects, it will be key to maintain dense canopies near urban forest edges. [ABSTRACT FROM AUTHOR]

A combination of forest thinning followed by prescribed burning is widely applied in the western United States to increase ecosystem resistance and resilience to disturbances. Understory plant community responses may be driven by both management treatments and climatic factors. Thus, responses to treatments during a 20‐year megadrought have implications for the role of management in fostering adaptive capacity to climate change.We used a network of five sites (600 plots) spanning an environmental gradient in ponderosa pine (Pinus ponderosa) forests of the American Southwest, an ecosystem that is broadly distributed and actively managed throughout the western United States. We used repeated long‐term monitoring data to quantify plant community responses to treatment 1–5‐, 6–10‐ and >10‐year post‐implementation. Specifically, we focussed on the effects of treatment and abiotic conditions on native and non‐native plant cover and species richness and the proportion of native species with northern (cool‐mesic) biogeographic affinities.Overall, thinning and prescribed burning nearly doubled native cover and increased native species richness by about 50% relative to untreated controls. These effects persisted for over a decade after treatment, even under the influence of significant and persistent drought. Cover and richness were also greater on intermediate to wet sites. Finally, native species with northern biogeographic affinities were reduced for up to 5 years after treatment relative to those with southern (warm‐xeric) affinities, and in dry years, indicating that both management and interannual climate variability may foster shifts to plant communities that are more resilient to a warming climate.Synthesis and applications. In ponderosa pine forests of the American Southwest, tree thinning followed by prescribed burning will generally promote restoration goals of increasing resilience to climate change by enhancing the diversity and abundance of native understory plant species, even during a persistent 20‐year megadrought. [ABSTRACT FROM AUTHOR]

Climate change is pushing species towards and potentially beyond their critical thermal limits. The extent to which species can cope with temperatures exceeding their critical thermal limits is still uncertain. To better assess species' responses to warming, we compute the warming tolerance (ΔTniche) as a thermal vulnerability index, using species' upper thermal limits (the temperature at the warm limit of their distribution range) minus the local habitat temperature actually experienced at a given location. This metric is useful to predict how much more warming species can tolerate before negative impacts are expected to occur. Here we set up a cross‐continental transplant experiment involving five regions distributed along a latitudinal gradient across Europe (43° N–61° N). Transplant sites were located in dense and open forests stands, and at forest edges and in interiors. We estimated the warming tolerance for 12 understory plant species common in European temperate forests. During 3 years, we examined the effects of the warming tolerance of each species across all transplanted locations on local plant performance, in terms of survival, height, ground cover, flowering probabilities and flower number. We found that the warming tolerance (ΔTniche) of the 12 studied understory species was significantly different across Europe and varied by up to 8°C. In general, ΔTniche were smaller (less positive) towards the forest edge and in open stands. Plant performance (growth and reproduction) increased with increasing ΔTniche across all 12 species. Our study demonstrated that ΔTniche of understory plant species varied with macroclimatic differences among regions across Europe, as well as in response to forest microclimates, albeit to a lesser extent. Our findings support the hypothesis that plant performance across species decreases in terms of growth and reproduction as local temperature conditions reach or exceed the warm limit of the focal species. [ABSTRACT FROM AUTHOR]

The study was designed to quantify the soil total nitrogen (STN) storage (SNS) and its controlling factors in Acacia hybrid (Acacia auriculiformis × A. mangium) plantations in five different ages (2-, 4-, 6-, 8-, and 10-years-old) in Langa - Dongnai Forestry Company, Southern Vietnam. A total of 75 soil samples were taken at five different soil depths from 0-100 cm. The STN concentration, SNS, soil properties, and plant biomass features (i.e., understorey vegetation biomass and litter biomass) were estimated. The STN concentration significantly increased with increasing forest stand age, whereas significantly decreased with increasing soil depth in all stand ages. The SNS in the uppermost 1 m soil layer in 2-, 4-, 6-, 8, and 10-yearold stands was 6.83, 9.50, 12.30, 17.15, and 19.41 Mg. ha-1, respectively. The SNS was focused mainly on the topsoil layers (0-40 cm). The SNS in the upper 0-40 cm soil layer accounted for over 50% of the total soil N stocks and the accumulation revealed decreasing tendencies with an increase of soil depth in all five stands. The soil organic carbon concentration and soil particle size fractions (i.e., soil silt concentration) were detected as the leading environmental parameters modulating the SNS variance. Our findings illustrate that considerations of N sequestration potential in Acacia hybrid plantations must take stand age into account and offer significant information for a better comprehension of the key environmental parameters driving SNS in Southern Vietnam. [ABSTRACT FROM AUTHOR]

This article discusses the importance of light in the growth and metabolism of plants, specifically in horticultural crops. It highlights nine original research articles that examine the effects of different lighting environments on the growth and nutritional quality of fruits, vegetables, and herbs. The studies explore topics such as the interaction between far-red light and light intensity in lettuce and cucumber plants, the impact of light intensity and spectrum on anthocyanin accumulation in purple sweet peppers, and the influence of supplemental blue and red LED lighting on flavor volatiles in basil. The findings emphasize the significance of selecting appropriate light conditions for cultivating high-quality vegetable seedlings. [Extracted from the article]

The rotation lengths of intensively managed production forests may be altered to achieve a variety of goals, with correspondingly implications for biodiversity. Here we consider the potential implications of shortened rotation times for biodiversity in planted monocultures of the two most common production tree species in Sweden, Scots pine (Pinus sylvestris) and Norway spruce (Picea abies). To do so we surveyed bird, bryophyte, epiphytic lichen and vascular plant diversity in 80 and 55-year-old stands; stand ages which approximate present-day and potential future rotation lengths in this region respectively. We found clear differences in the species communities of the 55 compared to the 80-year-old stands for both understory species and epiphytes, but not for birds. Nevertheless, bird species richness was still highest in the 80-year-old Norway spruce dominated stands. Dead wood amount was also highest the 80-year-old Norway spruce stands. Highest species richness of epiphytic lichens was found in 80-year-old Scots pine stands. However, 55-year-old Scots pine stands had a higher understory species richness and diversity than the older Scots pine stands, including a larger number of open land species. The 80-year-old forest stands examined may be considered old with respect to production forest rotation lengths in Sweden but are relatively young when comparing stand ages of unmanaged natural forest stands. Nevertheless, our results indicate that shortening the rotation time of Scots pine and Norway spruce, in this part of Sweden from 80 to 55 years, could have important consequences for forest biodiversity. These consequences are primarily inferred from the likely implications from shortened rotations for lichens community composition and diversity in both Norway spruce and Scots pine stands, as well as impacts on understory plant species in Norway spruce stands. [ABSTRACT FROM AUTHOR]

Understory planting affects the growth environment of tea plants, regulating the tea plant growth and the formation of secondary metabolites, which in turn affects the flavor of Xiaobai white tea. The present research adopted biochemical composition determination, widely targeted volatilities (WTV) analysis, multivariate statistical analysis, and odor activity value (OAV) analysis to analyze the characteristics in the macro-composition and volatile compounds of understory white tea. The sensory evaluation results indicated that understory Xiaobai white tea (LWTs) was stronger than ordinary Xiaobai white tea (PWTs) in terms of the taste of smoothness, sweetness, and thickness as well as the aromas of the flower and sweet. Understory planting reduced light intensity and air temperature, increased air humidity, organic matter, total nitrogen, and available nitrogen contents, which improved the growth environment of tea plants. The phytochemical analysis showed that the water-extractable substances, caffeine, flavonoids, and soluble sugar contents of understory tea fresh-leaf (LF) were higher than those of ordinary fresh-leaf (PF). The phytochemical analysis showed that the free amino acids, theaflavins, thearubigins, water-extractable substances, and tea polyphenols contents of LWTs were significantly higher than those of PWTs, which may explain the higher smoothness, sweetness, and thickness scores of LWTs than those of PWTs. The 2-heptanol, 2-decane, damasone, and cedar alcohol contents were significantly higher in LWTs than in PWTs, which may result in stronger flowery and sweet aromas in LWTs than in PWTs. These results provide a firm experimental basis for the observed differences in the flavor of LWTs and PWTs. [ABSTRACT FROM AUTHOR]