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Urban greenspace plays an important role in buffering the threat of urbanization to biodiversity. Biodiversity research in urban greenspace is essential for understanding the impacts of human activities on biodiversity and the associated ecosystem functioning and services in urban ecosystems. However, we lack large‐scale biodiversity datasets in urban greenspace for macroecological studies. In this paper, we provided a comprehensive biodiversity dataset of vascular plant and bird species in 286 university campuses and 118 urban parks in 143 cities in China, covering a wide range with different levels of urbanization (20–50°N in latitude and 81–130°E in longitude). Plant species were classified into different growth forms, and bird species were identified as resident or migrant. In total, the dataset contains 46,558 occurrence records for 5,915 plant species (about 18% of all Chinese vascular plant species) and 6,423 records for 546 bird species (around 40% of all recorded bird species in China). This dataset provides an important data source for evaluating the anthropogenic effects of biodiversity changes and advancing urban ecology. The complete data set for this abstract published in the Data Paper section of the journal is available in electronic format in MetaCat in JaLTER at http://db.cger.nies.go.jp/JaLTER/metacat/metacat/ERDP-2021-02.1/jalter-en. [ABSTRACT FROM AUTHOR]

Fertile islands are created and maintained by a combination of physical and biologically mediated processes. Plants have been shown to be very important in the formation of fertile islands, and recent research indicates that the activities of burrowing animals have a significant influence on the physiochemical properties of soil that can promote the development of fertile islands. In this paper, we chose tamarisk ( Tamarix spp.)-a constructive species that grows in the oasis-desert ecotone, and the great gerbil ( Rhombomys opimus)-a widely distributed rodent in Central Asia to study the influence of great gerbils on soil nutrient dynamics in tamarisk mounds. Results indicate that fertile islands exist in tamarisk mounds without burrows of the great gerbil. However, the great gerbil's burrowing activities promote the fertile island effect in tamarisk mounds: soil nutrients under shrubs with great gerbil activity were significantly higher than inter-mound areas in both surface soil and deep soil from 15 to 50 cm. Available nitrogen in mounds with rodent burrows was over twice as high as in tamarisk mounds without burrows at the same depth. The great gerbil's burrowing activities promote the concentration of soil nutrients in the tamarisk mounds. [ABSTRACT FROM AUTHOR]

The wetland ecosystem is particularly vulnerable to hydrological and climate changes. The Great Xing'an Mountain is such a region in China that has a large area of wetlands with rare human disturbance. The predictions of the global circulation model CGCM3 (the third-generation coupled global climate model from the Canadian Centre for Climate Modeling and Analysis) indicated that the temperature in The Great Xing'an Mountain will rise by 2-4°C over the next 100 years. This paper predicts the potential distributions of wetlands in this area under the current and warming climate conditions. This predication was performed by the Random Forests model, with 18 environmental variables, which will reflect the climate and topography conditions. The model has been proven to have a great prediction ability. The wetland distributions are primarily topography-driven in the Great Xing'an Mountains. Mean annual temperature, warmness index, and potential evapotranspiration ratio are the most important climatic factors in wetland distributions. The model predictions for three future climate scenarios show that the wetland area tends to decrease, and higher emission will also cause more drastic shrinkage of wetland distributions. About 30% of the wetland area will disappear by 2050. The area will decrease 62.47, 76.90, and 85.83%, respectively, under CGCM3-B1, CGCM3-A1B, and CGCM3-A2 by 2100. As for spatial allocation, wetlands may begin to disappear from the sides to the center and south to north under a warming climate. Under CGCM3-B1, the loss of wetlands may mainly occur in the south hills with flatter terrain, and some may occur in the north hills and intermontane plains. Under CGCM3-A1B, severe vanish of wetlands is predicted. Under CGCM3-A2, only a small area of wetlands may remain in the north of the high mountains. [ABSTRACT FROM AUTHOR]

Compared to conventional approaches, the integration of population size analysis with habitat suitability assessment on a large scale can provide more evidence to explain the mechanisms of habitat isolation and fragmentation, and thus make regional conservation plans. In this paper, we analyzed the habitat suitability for giant pandas in the Minshan Mountains, China, using the ecological-niche factor analysis (ENFA) method, and then evaluated the current conservation status of this endangered species. The results showed that (1) giant pandas were distributed in a narrow altitudinal range in which vegetation cover was dominated by coniferous forest, mixed coniferous and deciduous broadleaf forest, and deciduous broadleaf forest with scattered bamboo understory, and (2) roads and human settlements had strong negative effects on the panda habitat selection. According to habitat analysis, the total habitat area of giant panda in the Minshan Mountains was 953,173 ha, which was fragmented into 12 habitat units by major roads, rivers, and human settlements. The habitat of the mid-Minshan was less fragmentized, but was seriously fragmented in the north. The panda population size estimation showed that 676 individuals inhabited the study area, and 94.53% of them were in the mid-Minshan, but small panda populations less than 30 individuals inhabited the isolated and fragmented habitat patches in the north. The nature reserves in the Minshan Mountains have formed three conservation groups, which covered 41.26% of panda habitat and protected 70.71% of panda population of the study area, but there still exists two conservation gaps, and the connectivity among these reserves is still weak. Due to habitat isolation and extensive human disturbances, giant pandas in the north (i.e., Diebu, Zhouqu, and Wudou) are facing threats of local extinction. In order to protect pandas and their habitats in this area, some effective conservation approaches, such as establishing new reserves in gap areas, creating corridors among patches, and seasonally controlling traffic flux in key roads, should be implemented in the future to link these isolated habitats together. [ABSTRACT FROM AUTHOR]

Spatial dispersion patterns of trees at different life stages are an important aspect to investigate in understanding the mechanisms that facilitate species co-existence. In this paper, Ripley’s univariate L( r) and bivariate L12( r) functions were used to analyze spatial distribution patterns and spatial associations across different life stages of 131 tree species in a 20-ha plot of a tropical rainforest in Xishuangbanna, southwest China. Our results show that: (1) Saplings of 109 (83.2%) species have a significant clumped distribution, which confirms the ubiquity of clumped spatial distributions among tropical tree species. (2) Adults of 126 (96.2%) species have a random distribution suggesting that density-dependent mortality can make the spatial pattern of tropical trees more regular with time. (3) At small scales (0–10 m), 95 (72.5%) species have a neutral or negative sapling-adult association, implying that there is recruitment limitation within the vicinity of their conspecific adults. The reduction in spatial clumping in going from younger to older life stages and the neutral or negative sapling-adult association imply density-dependent mortality in the vicinity of adult trees. In accordance with the Janzen–Connell hypothesis, such density-dependent mortality can free up space for other species to colonize, contributing to the maintenance of species diversity. [ABSTRACT FROM AUTHOR]

The Ordos plateau is a unique ecotone and is a focal region for the campaign to reduce or reverse desertification in China. This paper explores the relationship between vegetation and environmental gradients on the Ordos plateau based on a field survey of species distribution, vegetation distribution patterns, plant community structure, ecophysiological properties, and soil water content along an environmental gradient. The vegetation on the Ordos plateau may be divided into three types from east to west: steppe (eastern part), desert steppe (middle part) and steppe desert (western part). From east to west, precipitation declines significantly (from 400 mm to 150 mm). The spatial distribution pattern of vegetation at different sites was random. The density of shrub islands decreased from east to west, and their height and diameter were negatively correlated with precipitation. From east to west, the transpiration rate increased as temperature increased. Stomatal conductance was positively correlated with percentage of sunshine hours and negatively correlated with temperature. Water-use efficiency was positively correlated with average annual precipitation but negatively correlated with increasing percentage of sunshine hours. The results suggest that for effective revegetation, highly drought-tolerant species, such as Caragana tibetica and C. stenophylla, should be used and a lower percentage of vegetation cover expected (30–40%) in the western half of the Ordos plateau. In the eastern half, moderately drought-tolerant species, such as Artemisia ordosica and C. korshinskii, could be used and a higher percentage vegetation cover expected (40–50%). [ABSTRACT FROM AUTHOR]

Vegetation and land-use mosaics of shrub land, grassland, farmland and reforested land are characteristic for residential areas of the Wolong nature reserve in Sichuan province, southwest China. The patterns represent a stage in long-term human disturbance and natural secondary succession since deforestation. The aim of this paper was to elucidate the soil-land cover types, soil-slope position relationships on a typical disturbed slope in the humid mountainous region. Soils were taken from four typical land cover types (shrub land, grassland, farmland and reforested land) under four slope positions (upper slope, middle slope, lower slope, foot slope) to study the distribution of soil nutrients and moisture on the transect scales of the slope. To elucidate the influence of land-use and slope position on soil quality, two integrated quantitative indexes were developed to compare soil quality under different land-use types ( QI) and under different slope positions ( PI). The results showed shrub land had the highest QI value, while the QI of reforested land and farmland had lower values. Foot slopes and upper slopes had higher soil quality levels compared to middle slopes and lower slopes. The results indicated that on the slope scale shrub land had high soil quality levels. The results also suggested that in the area of China where the climate favors secondary succession, ‘leave nature as it is’ is a better choice than the policy ‘change farmland to forest land’. [ABSTRACT FROM AUTHOR]

Greenspace or green cover is one of the major factors affecting urban avian diversity. In China, small farmlands producing vegetables are relatively common in cities. Although these farmlands could be a part of greenspaces, their habitat value for birds is rarely known. I investigated how these farmlands influenced winter bird community in two cities of southern China, using the multivariate latent variable model. I considered three green cover types: crop (mostly vegetables), weed (pioneer spontaneous vegetation), and wood (tree/shrub). I calculated the percentage of each green cover at local (50 m radius circular area) and landscape (500 m radius circular area) scales. Of 30 bird species, the abundance of 13 species decreased as crop cover decreased with increasing woody cover at the local scale, whereas the abundance of only two bird species increased with decreasing crop cover. Habitat preference of species mediated these responses, leading to a strong association between the open habit trait and the negative responses. Open habitat bird species richness was also negatively affected by decreasing local crop cover. Tree/shrub bird species richness showed a positive response to decreasing crop cover but the explanatory power of the local scale model was low. Variables at the landscape scale were rarely associated with species abundance or richness. These results suggest that small vegetable‐dominant farmlands can serve as open habitat for birds in urban areas where greenspace largely consists of tree/shrub vegetation. The results also indicate that urban bird diversity is more influenced by local habitat features than landscape‐scale features. [ABSTRACT FROM AUTHOR]

Litter plays an important role in plant invasion. Our previous studies have found that litter had two opposite effects as Spartina alterniflora invading native plant Phragmites australis community. Litter stimulated the growth of S. alterniflora on the edge of the community, while it inhibited the growth in the old community. Accordingly, we hypothesized that litter may play different roles in different stages of plant invasions. We selected three types of communities: P. australis monoculture (PAM), S. alterniflora monoculture (SAM), S. alterniflora–P. australis mixture (SPM) and conducted a comparative study by keeping and removing litter at Chongming Dongtan in the Yangtze River estuary, China. Our results revealed that litter removal significantly increased light intensity in SAM, and enhanced it in SPM, but had no significant influence on it in PAM. The effect of litter on light intensity resulted in a higher chlorophyll content and higher plant height of S. alterniflora monoculture after litter removal, which eventually led to a higher single weight and aboveground biomass for PAM and SAM after litter removal, and to a higher aboveground biomass for S. alterniflora in SPM. Litter removal significantly enhanced the dominance of S. alterniflora relative to P. australis in SPM. We concluded that the effects of invasive plants' litter on the invasion processes depend on the stem density of invasive plants relative to native plants. If an invasive species had a higher plant density, its litter may not have a shelter effect on native species, but could restrict its own growth. [ABSTRACT FROM AUTHOR]

To understand the growth and nutritional strategies of two alien Asteraceae species in both nutrient‐rich and nutrient‐poor environments by measuring the stoichiometric characteristics of plants and soil nutrients, two alien species Bidens pilosa and Mikania micrantha from subtropical zone of southeast China was studied. The two species grow in P‐rich environments and/or have a strong capacity for absorption and utilization of P. The two invasive alien species studied used diverse nutrition and growth strategies under different habitats. For B. pilosa under low‐N environments, leaves showed lower N:P and C:P than in other habitats. In contrast, roots showed greater N:P, C:P and C:N ratios, suggesting a "resource conservative strategy," whereas under high‐N and high‐P, or high‐N and low‐P environments, B. pilosa roots had lower N:P and C:P ratios, suggesting a "growth competitive strategy." Conversely, M. micrantha did not match either strategy in high‐ or low‐resource habitats. The growth of B. pilosa is resource‐dependent, mainly driven by C and N content, and C:N ratio in the soil, as well as allocation of P within the plant. The growth of M. micrantha is less limited by soil resources, but mainly by tradeoffs between allocation to leaves versus roots. There are various growth and nutrient strategies under different resource environments (e.g., resource conservative strategy, and/or growth competitive strategy), as well as fundamental trade‐offs between life history traits, which all contribute to the successful invasion by alien species. [ABSTRACT FROM AUTHOR]

Modeling the impacts of urbanization on carbon storage has become a critical and hot topic in the fields of mitigating global warming. This study coupled urban expansion and land use change simulation and prediction model (SLEUTH‐3r model) and ecosystem service evaluation model (InVEST model) to analyze and predict the impacts of urbanization on carbon storage in Shizuishan, a city located in the northwestern of China. Scenarios analysis was used to compare the effects of different policies on carbon storage, while the policies concern about urban growth pattern, ecological protection and socioeconomic development. The results suggested that (1) the coupled model can predict carbon storage change with urbanization in a high accuracy (relative error within ±5% for 94.6% of the whole area); (2) carbon storage of Shizuishan experienced a loss of 2.70 Tg in 1989–2015, and would continue to experience a loss of 6.18 Tg, 5.27 Tg, 3.76 Tg and 2.47 Tg under historical growth scenario (HGS), decrease socioeconomic scenario (DSS), compact growth scenario (CGS) and ecological protection scenario (EPS) in 2015–2035, respectively; (3) compact urban growth pattern and ecological protection policy can both decrease the negative effects of urbanization on carbon storage. Multiple ecosystem services should be integrated into urban planning to achieve a balance of socioeconomic development and environment protection. [ABSTRACT FROM AUTHOR]

Natural wetlands in coastal areas have been reclaimed in China and other regions of Asia. The reclaimed lands have been used for large‐scale industrial farming, replacing traditional farming methods, especially in rice fields. To understand the impact of land‐use conversion on biodiversity, particularly of coastal migratory waterbirds, we selected two study sites in Chongming Island, China, representing traditional rice fields versus industrial rice farms. At each site, we carried out waterbird population surveys, measured the environmental factors hypothesized to be important in determining waterbird abundance, and analyzed the effects of the different farming patterns on waterbird populations. Over two annual cycles (from August 2013 to May 2015), 39 waterbird species were observed, with a mean density of 29.3 ± 5.4/ha, on traditional rice fields, compared with 16 species with a mean density of 2.8 ± 0.4/ha on large‐scale industrial rice farms. Our results demonstrated that waterbird diversity was higher on traditional rice fields than on industrial rice farms. Analyses of habitat characteristics and waterbird populations showed that traditional rice fields had more preferred habitats for waterbirds, such as more open‐water cover areas, lower bare mud cover areas, lower rice plant density, no concrete‐covered areas and flooding in the winter. The results suggested that the replacement of traditional rice fields with large‐scale industrial rice farms has had a significantly negative impact on migratory waterbirds using the East Asian–Australasian Flyway; such a change could also have detrimental effects on waterbird conservation efforts in China and other countries along this important migration route. The article suggested that the replacement of traditional rice fields with large‐scale industrial rice farms has had a significantly negative impact on migratory waterbirds using the East Asian‐Australasian Flyway; such a change could also have detrimental effects on waterbird conservation efforts in China and other countries along this important migration route. [ABSTRACT FROM AUTHOR]

Forest conversion influences soil organic carbon (SOC) decomposition through cascading effects on forest structure, soil properties, and soil microbial communities. However, interactive effects of these drivers and the key pathways that mediate forest SOC decomposition remain relatively unexplored. In this study, we compared relative importance of variables describing forest structure, soil properties, and soil microbial community on affecting SOC decomposition response to the conversion of a broadleaved Korean pine mixed forest into three other forests in the Changbai Mountains of China. We quantified SOC decomposition rate of these four forest types by measuring incubation soil respiration (SR). We then employed univariate regressions to quantify effect size of individual factor on SOC decomposition rate. A structural equation model (SEM) was developed to analyze pathways, relative importance, and interactive effects of these factors on SR. Our results showed strong marginal effects of dissolved organic carbon (DOC) content, fungal Phospholipid fatty acids (PLFAs) to bacterial PLFAs ratio (F/B), broadleaved to conifer ratio (B/C), and total PLFAs content (TPC) on SR. Measured SOC decomposition rate was most closely related to F/B, which was in turn influenced primarily by soil C/N ratio and fraction of non-oxidized carbon (NOC%). Our study identified 'Aboveground forest composition → SOC chemistry → Soil microbial composition → SOC decomposition' as the key pathway by which forest conversion affected SOC decomposition. This research work highlights the critical role of soil microbial community composition in altering SOC decomposition response to forest conversion. [ABSTRACT FROM AUTHOR]

Salix psammophila and Caragana korshinskii are two common shrubs in the southern Mu Us Desert, China. Their hydraulic strategies for adapting to this harsh, dry desert environment are not yet clear. This study examined the hydraulic transport efficiency, vulnerability to cavitation, and daily embolism refilling in the leaves and stems of these two shrubs during the dry season. In order to gain insight into water use strategies of whole plants, other related traits were also considered, including daily changes in stomatal conductance, leaf mass per area, leaf pressure-volume parameters, wood density and the Huber value. The leaves and stems of S. psammophila had greater hydraulic efficiency, but were more vulnerable to drought-induced hydraulic dysfunction than C. korshinskii. The difference between leaf and stem water potential at 50 % loss of conductivity was 0.12 MPa for S. psammophila and 0.81 MPa for C. korshinskii. Midday stomatal conductance decreased by 74 % compared to that at 8:30 in S. psammophila, whereas no change occurred in C. korshinskii. Daily embolism and refilling occurred in the stems of S. psammophila and leaves of C. korshinskii. These results suggest that a stricter stomatal regulation, daily embolism repair in stems, and a higher stem water capacitance could be partially compensating for the greater susceptibility to xylem embolism in S. psammophila, whereas higher leaf elastic modulus, greater embolism resistance in stems, larger difference between leaf and stem hydraulic safety, and drought-induced leaf shedding in C. korshinskii were largely responsible for its more extensive distribution in arid and desert steppes. [ABSTRACT FROM AUTHOR]

In almost all dryland systems, biological soil crusts (biocrusts) coexist alongside herbaceous and woody vegetation, creating landscape mosaics of vegetated and biocrusted patches. Results from past studies on the interaction between biocrusts and vascular plants have been contradictory. In the Gurbantunggut desert, a large temperate desert in northwestern China, well-developed lichen-dominated crusts dominate the areas at the base and between the sand dunes. We examined the influence of these lichen-dominated biocrusts on the germination, growth, biomass accumulation, and elemental content of five common plants in this desert: two shrubs ( Haloxylon persicum, Ephedra distachya) and three herbaceous plants ( Ceratocarpus arenarius, Malcolmia africana and Lappula semiglabra) under greenhouse conditions. The influence of biocrusts on seed germination was species-specific. Biocrusts did not affect percent germination in plants with smooth seeds, but inhibited germination of seeds with appendages that reduced or eliminated contact with the soil surface or prevented seeds from slipping into soil cracks. Once seeds had germinated, biocrusts had different influences on growth of shrub and herbaceous plants. The presence of biocrusts increased concentrations of nitrogen but did not affect phosphorus or potassium in tissue of all tested species, while the uptake of the other tested nutrients was species-specific. Our study showed that biocrusts can serve as a biological filter during seed germination and also can influence growth and elemental uptake. Therefore, they may be an important trigger for determining desert plant diversity and community composition in deserts. [ABSTRACT FROM AUTHOR]

Arsenic (As) concentration was analyzed in four sediment-inhabiting animals ( Pearsonia of Mollusca Gastropoda, Enchytraeus of Annelida Lumbricidae, Cybister japonicus Sharp of Hexapoda Dytiscidae and Chipangopaludina chinensis of Mollusca Gastropoda) from 19 sampling sites and eight carcasses of red-crowned crane ( Grus japonensis) to examine As transfer along the typical food chain in Wuyur catchments, northeastern China. Results indicated that As concentration in the prey of the red-crowned cranes was elevated via the food chain. Geo-accumulation indices at all sites were less than 0, which suggests that this region contained background As concentration. The four aquatic animal families containing As were land snail < water snail < beetle < earthworm. The highest As concentration was found in the liver of the red-crowned cranes (145-441 ppb) followed by the kidneys (116-258 ppb) and muscles (36-94 ppb). The eggshells of red-crowned cranes contained relatively high As concentration, which varied from 35 to 235 ppb, whereas the feathers had the lowest concentration, with an average of 25 ppb. The dietary exposure level to As of the red-crowned crane population in Zhalong Wetland, Northeastern China was lower than the As toxicity threshold concentration. This study reported that eggshells are suitable indicators of As risk levels in red-crowned crane. [ABSTRACT FROM AUTHOR]

In plants, silicon (Si) accumulates in phytoliths, which can contain 0.1-6.0 % occluded organic carbon (phytolith-occluded organic carbon, PhytOC). Globally, phytolith formation has implications for the long-term terrestrial carbon balance, and thus, global climate change. In this study, we analyzed the Si contents of 108 species of plants from Inner Mongolia and Hebei, China, to demonstrate the relationships between plant Si content and various phylogenetic and ecological characteristics, and to estimate PhytOC production in the forests of north China. Variations in Si content were related to the plant's higher-level phylogenetic position, according to the Angiosperm Phylogeny Group III classification. In angiosperms, the commelinoid monocot orders accumulated substantially more Si than did the other monocot orders, and the asteroid dicot orders accumulated more Si than did the other dicot orders. In an ecological context, herbs had the highest Si content (0.47 ± 0.26 % dry weight), followed by trees (0.33 ± 0.13 % dry weight) and shrubs (0.24 ± 0.09 % dry weight). The total PhytOC production rate in the forests of north China corresponded to 0.48 ± 0.20 × 10 t CO year, approximately 44 % of which was contributed by the understory vegetation comprising herbs and shrubs. This finding indicates that the phytolith carbon sequestration potential of the forests may be further enhanced by afforestation/reforestation, preserving the understory vegetation, and maximizing the aboveground net primary productivity of all forest layers, especially herbs that accumulate high Si contents. [ABSTRACT FROM AUTHOR]

In recent years, the importance of microbial diversity and function to ecosystem restoration has been recognized. The aim of this work was to investigate the diversity and composition of bacterial communities in response to reclamation of a soil subsidence area affected by mining activities. Soil samples were taken in two seasons (December 2012 and July 2013) from a mining reclamation region at the Liuxin national reclamation demonstration area in China and an adjacent coal-excavated subsidence region. 454 high-throughput sequencing technology was used to compare the composition and diversity of bacterial communities in reclaimed soil to that in subsided soil. Predominant phyla in soils were Proteobacteria, Actinobacteria, Acidobacteria, and Planctomycetes, with Proteobacteria making up the majority of the community. Long-term reclamation was found to have significant influences on bacterial communities, and the bacterial community diversity and composition varied between reclaimed and subsided soil. Seasonal fluctuations also contributed to variation in soil bacterial diversity and community composition, but were minor in comparison to effects of reclamation. Differences observed in bacterial community structure and diversity were related to both fertilizer treatment and vegetation, likely through the effects of soil attributes. Soil organic matter and total nitrogen and available potassium were important factors shaping the microbial communities. The reclaimed soil had higher community diversity of bacteria than subsided soil, which suggests that long-term applications of organic amendments and vegetation mixed sowing had significant impacts on soil remediation and microbial diversity. [ABSTRACT FROM AUTHOR]

Nutrient resorption from senescing leaves is a key nutrient conservation strategy in many ecosystems. In evergreen broad-leaved forests, nutrient resorption occurs with concomitant defoliation almost year-round. However, it is unclear whether nutrient resorption efficiency (NuRE) varies in different defoliation seasons for evergreen broad-leaved trees and how it may relate to soil nutrient availability. Castanopsis eyrei is a dominant tree species in evergreen broad-leaved forests in southern China, with distinct bimodal patterns of defoliation in spring and autumn. We investigated seasonal variation of the resorption efficiency of nitrogen (N) and phosphorus (P) of C. eyrei leaf and its relationship with soil mineral N by measuring the concentrations in leaf, leaf litter, and soil for two consecutive years. We hypothesized that leaf NuRE should be higher in seasons with low soil nutrient availability. We found that on average, soil mineral N content was 38.5 % lower during the autumn defoliation peak than in spring, and N and P concentrations in leaf litter at the spring defoliation peak were 10.0 and 26.7 % higher than at the autumn peak. Nitrogen NuRE at the autumnal defoliation peak was 5.1 % higher than that at the spring peak (49.3 vs 44.2 %), and the phosphorus NuRE in autumn was 6.8 % higher than that in spring (77.6 vs 69.8 %). Our findings suggest an inverse relationship between soil nutrient availability and NuRE and that the dynamics in NuRE should be incorporated into modeling of biogeochemical cycling in evergreen forest ecosystems with a bimodal defoliation pattern. [ABSTRACT FROM AUTHOR]

We examined environmental and anthropogenic factors drive range loss in large mammals, using presence data of Amur tigers opportunistically collected between 2000 and 2012, and anthropogenic and environmental variables to model the distribution of the Amur tiger in northeastern China. Our results suggested that population distribution models of different subregions showed different habitat factors determining tiger population distribution patterns. Where farmland cover was over 50 km per pixel (196 km), distance was within 15 km to the railway in Changbaishan and road density (length per pixel) increased in Wandashan, the relative probability of Amur tiger occurrence exhibited monotonic avoidance responses; however, where distance was within 150 km of the Sino-Russia border, the occurrence probability of Amur tiger was relatively high. We analyzed the avoidance or preference responses of Amur tiger distribution to elevation, snow depth and Viewshed. Furthermore, different subregional models detected a variety of spatial autocorrelation distances due to different population clustering patterns. We found that spatial models significantly improved model fits for non-spatial models and made more robust habitat suitability predications than that of non-spatial models. Consequently, these findings provide useful guidance for habitat conservation and management. [ABSTRACT FROM AUTHOR]

Soil organic carbon (SOC) stock in mountain ecosystems is highly heterogeneous because of differences in soil, climate, and vegetation with elevation. Little is known about the spatial distribution and chemical composition of SOC along altitude gradients in subtropical mountain regions, and the controlling factors remain unclear. In this study, we investigated the changes in SOC stock and chemical composition along an elevation gradient (219, 405, 780, and 1268 m a.s.l.) on Lushan Mountain, subtropical China. The results suggested that SOC stocks were significantly higher at high altitude sites (1268 m) than at low altitude ones (219, 405, and 780 m), but the lower altitude sites did not differ significantly. SOC stocks correlated positively with mean annual precipitation but negatively with mean annual temperature and litter C/N ratio. The variations in SOC stocks were related mainly to decreasing temperature and increasing precipitation with altitude, which resulted in decreased litter decomposition at high altitude sites. This effect was also demonstrated by the chemical composition of SOC, which showed lower alkyl C and higher O-alkyl C contents at high altitude sites. These results will improve the understanding of soil C dynamics and enhance predictions of the responses of mountain ecosystem to global warming under climate change. [ABSTRACT FROM AUTHOR]

Tree survival is a critical driver of stand dynamics, influencing forest structure and composition. Many local-scale drivers (tree size, abiotic and biotic factors) have been proposed as being important in explaining patterns of tree survival, but their contributions are still unknown. We examined the relative importance of these local drivers on tree survival using generalized linear mixed models in an old-growth sub-tropical forest in south China at three levels (community, guild, and species). Among the variables tested, tree size was typically the most important driver of tree survival, followed by abiotic and then biotic variables. Tree size has a strongly positive effect on tree survival for small trees (10-30 cm dbh) and shade-tolerant tree species. Of the abiotic factors tested, elevation tended to be more important in affecting tree survival than other topographic variables. Abiotic factors generally influenced survival of species with relatively high abundances, for individuals in smaller size classes and for mid-tolerant species. Among biotic factors, we found that the mortality of tree species was not driven by density- and frequency-dependent effects in this sub-tropical forest, as indicated by the results of both total basal area of neighbors and the proportion of conspecific neighbors in our study. We conclude that the relative importance of variables driving patterns of tree survival varied greatly among tree size classes, species guilds, shade tolerance, density, and abundance classes in this sub-tropical forest. These results also provide critical information for future studies of forest dynamics and offer insight into forest management in this region. [ABSTRACT FROM AUTHOR]

Phenology controls the seasonal activities of vegetation on land surfaces and thus plays a fundamental role in regulating photosynthesis and other ecosystem processes. Therefore, accurately simulating phenology and soil processes is critical to ecosystem and climate modeling. In this study, we present an integrated ecosystem model of plant productivity, plant phenology, and the soil freeze-thaw process to (1) improve the quality of simulations of soil thermal regimes and (2) estimate the seasonal variability of plant phenology and its effects on plant productivity in high-altitude seasonal frozen regions. We tested different model configurations and parameterizations, including a refined soil stratification scheme that included unfrozen water in frozen soil, a remotely sensed diagnostic phenology scheme, and a modified prognostic phenology scheme, to describe the seasonal variation in vegetation. After refined soil layering resolution and the inclusion of unfrozen water in frozen soil, the results show that the model adequately reproduced the soil thermal regimes and their interactions observed at the site. The inclusion of unfrozen water in frozen soil was found to have a significant effect on soil moisture simulation during the spring but only a small effect on soil temperature simulation at this site. Moreover, the performance of improved phenology schemes was good. The phenology model accurately predicted the start and end of phenology, and its precise prediction of phenology variation allows an improved simulation of vegetation production. [ABSTRACT FROM AUTHOR]

The subtropical evergreen broad-leaved forests of Yunnan and Taiwan were compared along environmental and successional gradients with the aim of identifying important taxon and species diversity as well as the drivers of mountain biodiversity patterns. A detrended correspondence analysis of an exhaustive set of data collected from 105 and 223 plots for Yunnan and Taiwan, respectively, was applied to classify natural mature forest types. Additional data from 72 and 68 plots for Yunnan and Taiwan, respectively, were used for analyses of secondary succession. The floristic richness and diversity index were calculated for each type of forest. In Yunnan, the monsoon forests in mesic-humid sites had more taxa and tended to show higher species diversity than the other two forest types. In Taiwan, species diversity values were significantly higher in the Machilus- Castanopsis zone in the middle altitudes (500-1500 m) than for the other three forest zones. For both Yunnan and Taiwan, the forests at the middle successional stage showed significantly higher species diversity than those at the early successional stage. Differences in diversity between the middle and late stages were not significant. These findings highlight the high species diversity of the natural mature evergreen broad-leaved forests of both Yunnan and Taiwan. In the secondary forests, as succession proceeds, species diversity comes to resemble that of the natural mature forests. In both ecosystems, the drivers of species diversity patterns are moisture, altitude, and succession/disturbance. [ABSTRACT FROM AUTHOR]

Human-induced nitrogen (N) enrichment is impacting the structure and function of grassland ecosystems, although few studies have been conducted in arid and semi-arid ecosystems under field conditions. Here, a 4-year multi-level N addition experiment under ambient precipitation in a typical temperate desert steppe in arid regions of China was designed to evaluate the impact of N enrichment on the herbaceous vegetation community in desert ecosystems. The results showed that species richness declined in response to N addition during all 4 years, while aboveground biomass increased in the relatively wet year (2007) and decreased in the relatively dry years (2008-2010) according to N addition level, as compared to the control. Plant community composition differed among plant functional groups (PFGs) based on added N. Perennial grasses (PG) benefited more compared with annuals and perennial forbs (PF) from N enrichment in terms of biomass production under conditions of high precipitation in 2007. In relatively dry years, biomass production of all PFGs was strictly dependent on inter- and intra-annual precipitation, which led PG to dominate in 2008 (with a dry spring) and PF to dominate in 2009 and 2010. Our results demonstrate that the impact of N enrichment on the herbaceous vegetation community in desert steppes may be strongly dependent on natural precipitation patterns characterized by shifts in plant community composition, particularly in terms of biomass production. [ABSTRACT FROM AUTHOR]

Defining and quantifying biomass-density relationships in dense plant stands has been a long-standing issue in both theoretical and empirical studies. Most existing/traditional studies focus on whole plant individuals, without considering different plant components (e.g., stem, branch and leaf). However, the analysis of biomass-density relationships for different plant parts is linked to those for whole plants, and thus important for understanding plant strategies for utilizing resources and community dynamics. In our study, we investigated standing stem ( M), branch ( M) and leaf ( M) biomass-density relationships, across a range of forest communities in China. The results showed that there was no constant predicted value (e.g., −1/2 or −1/3 for M; −1/2, −1/3 or 0 for M and M) that can describe all the relationships, and that the scaling exponents for stem, branch and leaf biomass varied across different forest types. In particular, standing leaf biomass (leaf biomass per unit area) was not constant in these forest communities. Furthermore, stem biomass-density lines were steeper than corresponding branch and leaf lines across most of these forest communities. [ABSTRACT FROM AUTHOR]

The responses of aboveground parts of the forest to changes in environmental factors and stand age is well studied, but the same is not true for the belowground parts of the forest. Two plantation black locust ( Robinia pseudoacacia L.) forest sites were taken in the Loess Plateau of China, one in the drier, infertile, more sandy area of the middle Loess Plateau, and another in the wetter, fertile, more clay-filled area of the southern Loess Plateau. At each site, both a younger (8-year-old) plantation stand and an older (30-year-old) plantation stand were included to study the effects of soil physicochemical properties and stand age on the fine root (<2 mm) biomass and vertical distribution of black locust forests. Root samples were taken with soil cores to a depth of 100 cm. The fine root biomass decreased from the middle site to the southern site for both stand ages, as expected, and the decrease could be due to a higher fine root N concentration associated with a higher fine root turnover rate at the southern site. There was a similar rooting pattern, though not deeper, in the drier, sandy site as predicted based on soil water infiltration and evaporation demands. The different effects of stand characters (e.g., tree density, tree height) on the fine root distribution as compared with the environmental properties may contribute partly to the similar pattern found in the two sites. The fine root biomass increased with stand age in both sites. In contrast to the evident difference in fine root biomass, there was no clear trend in the fine root vertical distribution pattern with stand age. Our results indicate that fine roots are likely to respond to changes in soil physicochemical properties and stand age by changing fine root biomass rather than by varying rooting pattern. [ABSTRACT FROM AUTHOR]

Light quantity and quality strongly influence plant growth. However, different ecosystems have different capabilities to assimilate solar radiation. In this study, the effects of cloudiness intensity on the net ecosystem exchange of carbon dioxide (NEE) were compared between an alpine grassland (with lower leaf area index) at A'Rou and an oasis maize cropland (with higher leaf area index) at Yingke, using flux data obtained during the middle of the growing season (July-August) in 2008 and 2009. The results showed that the response of NEE to photosynthetically active radiation (PAR) was more negative (carbon uptake) under cloudy than under clear skies at both sites. The maximum NEE occurred when the clearness index (CI) ranged from 0.4 to 0.7 under cloudy skies. The maximum enhancements were 11.9% for solar elevation angles of 60-65° in the grassland, and 34.9% for solar elevation angles of 60-65° and 10.3% for angles of 35-40° in the maize cropland before the irrigation period. The response of NEE to CI changed slightly with solar elevation angle in the grassland compared to the maize cropland. The results indicate that enhanced NEE under cloudy skies can be attributed to increasingly diffuse PAR and interactions with environmental factors (air temperature and vapor pressure deficit). [ABSTRACT FROM AUTHOR]

Indigenous ecological knowledge (IEK) can contribute to the management of local ecosystems and landscapes. Cultural landscapes are produced by and reflect the long-term interactions between humans and nature in indigenous societies. Yunnan Province, located in southwestern China, is the homeland of many ethnic groups, and is also a refuge for numerous species of wild plants and animals. Indigenous people in Yunnan, who have rich ecological knowledge, play an important role in the conservation of local biodiversity and the region's unique terraced agricultural landscapes. We used the Hani people and their outstanding cultural landscape of rice terraces in Yuanyang County of Yunnan Province as a case study to describe their worldview and discuss their formation of IEK; their roles in the preservation of rice landraces and in pest regulation; their management of water, forest, and soil resources; and the vertical landscape pattern and resource-circulation system that has evolved in the areas managed by the Hani. We also discuss the challenges and threats facing the Hani, their IEK, and their cultural landscape, as well as discuss the potential for integration of the Hani's IEK with modern conservation efforts. [ABSTRACT FROM AUTHOR]

This study was carried out to improve our understanding of the diversity and decomposition potential of endophytes in the leaves of Cinnamomum camphora trees grown in a subtropical region of China. We isolated and identified endophytic fungi from senescent leaves of C. camphora and tested their role in decomposition through pure-culture and pre-colonization. A total of 2,861 endophytic fungi isolated from 69 leaves of C. camphora were grouped into 39 taxa comprising 36 Ascomycetes and 3 Basidiomycetes based on sporulation and ITS sequence analysis. Of these, Colletotrichum gloeosporioides was the most common species (69% relative abundance and 96% colonization frequency), followed by Cladosporium sp.1, Colletotrichum sp. and Chaetomium sp. All 39 endophytes had the ability to decompose C. camphora leaf litter in pure culture, and a few exhibited >20% litter mass loss in 2 months. In most cases, single endopyhytic species showed lower mass loss than mixed microbial groups from active soil after 60 or 120 days. In pre-inoculation, endophytic fungi like Chaetomium sp., Cladosporium sp.1, C. gloeosporioides, Colletotrichum sp. and Guignardia sp. exhibited higher abundance and caused greater mass loss, indicating the potential of these groups to enter and significantly accelerate the process of decomposition. This study concludes that, after entering the decomposition process, selected endophytic fungi with high abundance could influence significantly the decomposition process and thus probably affect carbon and nutrient cycling in C. camphora plantations. [ABSTRACT FROM AUTHOR]

Desert plants have unique strategies for survival and growth to cope with the limited water availability in arid regions. The stable carbon isotope ( δC) provides an integrated measurement of internal plant physiological and external environmental properties affecting photosynthetic gas exchange and water use efficiency. The δC values of 84 species in the Junggar Basin were categorized into two groups (ranged from −30.1 to −23.3‰ for C and −14.9 to −9.9‰ for C species, respectively). No life form differences in δC values were detected in C ( p = 0.78) and C plants ( p = 0.63). Small differences among life forms were observed in δC values in C species with shrubs slightly depleted (−13.3‰) relative to perennials (−13.1‰) and annuals (−12.5‰). These differences suggested that δC value could not represent a plant functional group classification based on life forms in C plants in extremely arid regions. Ephemerals are all using C photosynthetic pathway and no significant differences ( p = 0.92) in δC values were observed between annuals (−26.5‰) and perennials (−26.4‰). The δC values of Tulipa iliensis (an important ephemeral species distributed widely in the Junggar Basin) among nine natural populations were positively correlated with leaf ( r = 0.46, p = 0.046) and soil ( r = 0.67, p = 0.007) total nitrogen content, and negatively correlated with leaf ( r = 0.48, p = 0.039) and soil ( r = 0.79, p = 0.001) water content. This indicated that the variation in δC values of T. iliensis was probably caused by both water availability associated stomatal openness and nitrogen availability associated photosynthetic capacity. T. iliensis is very sensitive to water and nitrogen availability in soil. [ABSTRACT FROM AUTHOR]

Quantifying the self-thinning process in various plant communities has been a long-standing issue in both theoretical and empirical studies. Most studies on plant self-thinning have centered only on aboveground parts, and rarely on belowground parts. There is still a general lack of comparison between above- and belowground self-thinning processes, especially for forest communities. The fundamental mechanistic difference and the functional association between above- and belowground competition indicate that the self-thinning process of belowground parts may be different from that of aboveground parts. We investigated the self-thinning lines for above-ground ( M), below-ground ( M), and total biomass ( M), respectively, across forest communities in China. The results showed that neither the classical self-thinning rule (−3/2 exponent) nor the universal scaling rule (−4/3 exponent) can apply to all the self-thinning relationships across these forest communities and that the self-thinning lines for belowground biomass were flatter and lower than those for aboveground biomass across most of these forest communities. [ABSTRACT FROM AUTHOR]

This study investigated the taxonomic identities and diversity of fungal endophytes isolated from four Rhizophoraceae mangrove plant species, Ceriops tagal, Rhizophora apiculata, R. stylosa and Bruguiera sexangula var. rhynchopetala, using a combination of morphological and molecular approaches. Two hundred ninety-five isolates were classified into 38 taxa by morphological characteristics. The representative 38 isolates from each taxa were selected for further molecular identification using nuclear ribosomal DNA sequences, including both the internal transcribed spacers (ITS1 and ITS2) and the 5.8S gene region. The 38 representative endophytes were identified to various taxonomic levels. These results suggest that Pestalotiopsis and Phomopsis were the most frequent endophytes in the four host species. Some of the endophytes exhibit host and tissue specificity. The colonization frequencies of endophytic fungi in the stems of the four host plants are evidently higher than in the roots. The four Rhizophoraceae mangrove species have low similarities of endophyte communities. [ABSTRACT FROM AUTHOR]

Most Cypripedium species are specialized orchids pollinated by, in a broad sense, bees or flies. Here we present the first evidence that a slipper orchid, Cypripedium flavum, is pollinated by both bees and flies, i.e., bumblebees and blowflies. Artificial pollination experiments demonstrated that the flowers of C. flavum are self-compatible, but need pollen vectors for successful reproduction. Field observations detected 25 insects visiting the flowers, and 14 of these insects entered into the labellum of the flowers, but only female bumblebees, Bombus hypnorum, B. remotus, and the blowfly Calliphora vomitoria exited of the labellum with pollen smears of C. flavum. The floral functional morphology of C. flavum appears to be more suited to bumblebees than to blowflies . The bumblebees are more efficient pollinators of the orchid, but blowflies are more frequent visitors, so they pollinated more flowers despite being less efficient. [ABSTRACT FROM AUTHOR]

Three methods were used to distinguish the characteristics of changes in climate variability and normalized difference vegetation index (NDVI) during the period from 1982 to 2000 in China. Great changes in climate variability and an increased trend in NDVI were observed. The changes in precipitation variability were greater than the changes in temperature variability in each month, which is attributed to changes in the monsoon system in East Asia. The abrupt changes in climate and NDVI were more significant in 1983 than in the other years due to the impacts of El Niño/Southern Oscillation (ENSO). Using these results, the influences of changes in climate variability on vegetation were studied in the whole nation, and eight regions were defined according to the vegetation division map of China. The results show that abrupt climate changes at a small scale cannot cause abrupt NDVI changes directly. At a nationwide level, over a longer time scale the persistence of above/below average temperature determines the changes in NDVI; at a shorter time scale, changes in the magnitude of precipitation influence NDVI significantly. Such regional climate variability affects vegetation in different ways owing to the diversity of vegetation types, climatic conditions and topography of the land. [ABSTRACT FROM AUTHOR]

Ostracod shells in surface sediments from Ulungur Lake (Xinjiang, China) belong mainly to Limnocythere inopinata as the dominant species, and Candona neglecta and Darwinula stevensoni as accompanying, less abundant taxa. Shells of an additional nine species were recorded only sporadically. The three most abundant ostracods have wide tolerance ranges in terms of salinity, substrate and water depth. The similarly recorded bivalve Pisidium subtruncatum, and the gastropods Gyraulus chinensis and Radix auricularia belong to the most tolerant representatives of the genera. The bivalve and gastropods, in addition to the ostracod assemblage, reflect the fact that Ulungur Lake has experienced strong lake level and salinity variations due to water withdrawal in the catchment and the counteracting diversion of river waters to the lake in recent decades. The substrate in Ulungur Lake is typically fine-grained, apart from the delta region of the Ulungur River channel, which is marked by relatively coarse-grained detrital sediments barren of ostracod shells. This channel was created 40 years ago to divert water to Ulungur Lake and support its local fisheries and recreational facilities. A reassessed Holocene ostracod record from the lake shows that a significantly higher salinity and lower lake level existed in the early Holocene before 6.0 ka in response to the regional climate. In contrast, a higher lake level and lowest salinity is inferred for the late Holocene period between ca. 3.6 and 1.3 ka before present. Afterwards, the lake level declined and salinity increased in response to regional moisture reduction, although conditions similar to the early Holocene lake status were not re-established. Our surface-sediment-derived data provide a baseline for analysis of future environmental variations due to global climate change and regional water management. [ABSTRACT FROM AUTHOR]

llelopathy is an important process in plant communities, but the role of seed allelopathy in natural ecosystems remains poorly understood. In the present study, we examined the potential allelopathic effects of Ligularia virgaurea (a dominant species in degraded Tibetan grasslands) seeds on the germination of four native grass species ( Festuca sinensis, Agrostis gigantean, Bromus inermis, and Elymus nutans). The results showed that L. virgaurea seeds can have potential allelopathic effects on seed germination, mean time to germination and root growth rates of native grass species. We further demonstrate that these effects are driven by a water-soluble seed leachate. Species with smaller seeds were generally more sensitive than larger seeded species. The results suggest that seed-to-seed allelopathic potential may be an important mechanism driving the dominance of L. virgaurea in degraded alpine grasslands on the Tibetan Plateau. Further studies are required to demonstrate effects of seed-to-seed potential allelopathy in a field setting. [ABSTRACT FROM AUTHOR]

Subtropical China has more than 60% of the total plantation area in China and over 70% of these subtropical plantations are composed of pure coniferous species. In view of low ecosystem services and ecological instability of pure coniferous plantations, indigenous broadleaf plantations are being advocated as a prospective silvicultural management for substituting in place of large coniferous plantations in subtropical China. However, little information is known about the effects of tree species conversion on stock and stability of soil organic carbon (SOC). The four adjacent monospecific plantations were selected to examine the effects of tree species on the stock and chemical composition of SOC using elemental analysis and solid-state C nuclear magnetic resonance (NMR) spectroscopy. One coniferous plantation was composed of Pinus massoniana (PM), and the three broadleaf plantations were Castanopsis hystrix (CH), Michelia macclurei (MM), and Mytilaria laosensis (ML). We found that SOC stock differed significantly among the four plantations in the upper (0-10 cm) layer, but not in the underneath (10-30 cm) layer. SOC stocks in the upper (0-10 cm) layer were 11, 19, and 18% higher in the CH, MM, and ML plantations than in the PM plantation. The differences in SOC stock among the four plantations were largely attributed to fine root rather than aboveground litterfall input. However, the soils in the broadleaf plantations contained more decomposable C proportion, indicated by lower percentage of alkyl C, higher percentage of O-alkyl C and lower alkyl C/ O-alkyl C ratio compared to those in the PM plantation. Our findings highlight that future strategy of tree species selection for substituting in place of large coniferous plantations in subtropical China needs to consider the potential effects of tree species on the chemical composition in addition to the quantity of SOC stock. [ABSTRACT FROM AUTHOR]

We compared species composition and diversity of the soil seed and seedling banks in three secondary vegetation types (shrubland, Populus bonatii forest, Lithocarpus regrowth forest) and a primary old-growth forest in the subtropical Ailao Mountains of southwestern China to clarify the importance of seed and seedling banks for forest dynamics. The average species richness was the highest in soil samples from the shrubland (26.80 ± 1.98), and the lowest from the primary forest (9.93 ± 0.50). The density of germinable tree seeds increased from the secondary vegetation to the primary forest, and the density of shrub, forb, and graminoid seeds decreased significantly. The most abundant seedlings recorded in soil samples were light-demanding species in the shrubland and Populus bonatii forest. For ground flora, the number of shrub seedlings strongly decreased with the increase in stand age, and shade-tolerant tree seedlings tended to increase. The species similarity between the seed bank and the aboveground vegetation in all sites was low (Sørensen's index = 0.11-0.33), however, the shrubland had higher similarity compared with the other three plant communities. In the primary forest, light-demanding woody species dominated in soil seed banks, while shade-tolerant species dominated in the overstory and the forest floor. In the primary forest, seedlings of dominant tree species were rare in the understory, and no seeds of the dominant species were found in the soil. Results indicated that the early stages of vegetation recovery should take into account the possibility of recovering soil seed bank processes. However, colonization and establishment of tree seedlings will be difficult once a primary forest is destroyed. [ABSTRACT FROM AUTHOR]

Canopy organic matter (COM) composed of epiphyte community exists as a complex subsystem in the montane cloud forest (MCF). We estimated the biomass and nutrient pools of COM in a subtropical MCF in the Ailao Mountain National Nature Reserve (NNR). The diameter at breast height (DBH) of host trees was the best parameter in the estimation of epiphytic biomass, compared to the height ( H) of host trees and the combination of both parameters. The effect of host tree species was negligible in the estimation. Therefore, it was concluded that the DBH data of all trees of a forest regardless of species was a suitable index for the non-destructive estimation of epiphytic biomass in field surveys, especially for investigations of larger study areas. According to species-specific equations, the total COM biomass was estimated to be 2,261 ± 537 (SD) kg ha−1, which was dominated by bryophytes (73.6%) and canopy humus (13.9%). The greatest proportion of COM was located on the inner branches (52.2%), followed by outer branches, trunks, the understory, and branch junctions. The nutrient pools (mean ± SD, kg ha−1) of the COM were: N = 37.9 ± 9.0, P = 1.97 ± 0.47, K = 9.6 ± 2.3, Ca = 9.6 ± 2.3, Mg = 2.64 ± 0.63 and Na = 0.25 ± 0.06. Assessments of epiphytic biomass and nutrient capital supported the idea that the canopy subsystem holds a substantial pool of nutrients, especially when compared to the labile components of the forest ecosystem. [ABSTRACT FROM AUTHOR]

Since 1985, originally forested mountainous areas of China have been allowed to return to their natural state after years of exploitation including agriculture, development, and logging. The reforms began earlier in less accessible locations, so that today the successional process is more advanced there. The vegetation in Luquan, Qiongzhusi, and Xishan near Kunming, central Yunnan, exhibits, in a limited area, a range of stages of plant succession that are widely encountered throughout the broader region, and thus affords a special opportunity for a comprehensive study. We analyzed the successional sequence of these various plant communities. They ranged from pioneer coniferous and/or pioneer deciduous broad-leaved stands to pre-mature semi-humid evergreen broad-leaved stands, through mixed coniferous and broad-leaved or mixed deciduous and evergreen broad-leaved stands. The succession proceeded from pioneer coniferous Pinus and Keteleeria, and deciduous Platycarya and Alnus, to late-successional evergreen broad-leaved Cyclobalanopsis and Castanopsis. Two regeneration types of woody species in either the early successional (15–50 years), the mid-successional (40–80 years), or the late-successional (80–180 years) stage were classified. Relatively high species diversity was found in the seral phase at the three study sites. The late-successional stage was commonest where human disturbance was least evident. Poor soil chemical properties under pioneer Pinus were seen as a limitation to plant growth, while the abundance of Alnus at the early stage led to an improved level of organic matter and nitrogen. [ABSTRACT FROM AUTHOR]

We used survey data collected from a large plot (20 ha) of sub-tropical forest in the Dinghushan Nature Reserve, Guangdong Province, southern China, in 2005 to test the comparative performance of nine species-richness estimators (number of observed species, three species-individual curve models, five nonparametric estimators). As the true species richness, we used the 210 free-standing shrub and tree species of >1 cm diameter at breast height recorded during the survey. This true species richness was then used to calculate performance measures of bias, accuracy, and precision for each estimator, whereby we distinguished performance for low, medium, and high sampling intensity. Unsurprisingly, all estimators performed better than the number of observed species in terms of bias and accuracy. Surprisingly, however, two curve models ( logistic and logarithm) outperformed all other estimators in terms of bias, accuracy, and precision, which is in contrast to most other previous studies, in which nonparametric methods usually outperform curve models. Intriguingly, relative estimator performance changed between low, medium, and high sampling intensity, sometimes dramatically, reinforcing the assertion that the influence of sampling intensity on estimator performance is an important aspect to investigate and to consider when choosing estimators for ecological surveys. Because these results are based on only one dataset, the results should be treated with caution, both because (1) the generality of these results needs to be confirmed with simulated datasets and (2) more work is needed to establish what “true” species richness is extrapolated by each of the tested estimators in both the statistical and the practical sense. Nevertheless, the two curve estimators, namely Logistic and Logarithm, should be considered in future studies of comparative performance of species-richness estimators because of their outstanding performance in this study. [ABSTRACT FROM AUTHOR]

The relocation of nutrients among dominant plant species, along with hydrological functions and soil chemistry in five plant communities, including Eucalyptus plantation, Pinus plantation, shrubland, semi-natural, and natural secondary forests were investigated in central Yunnan, China. The nutrient P, N, and K accumulation in above-ground biomass of Eucalyptus smithii (stems, barks, branches, and leaves) were the highest, followed by Pinus yunnanensis of both the Pinus plantation and the semi-natural forest. The nutrient retranslocation efficiency (NRE) of E. smithii was the highest for nutrient P, N, and K with values of 56, 66, and 67%, respectively, among the dominant plant species of the five plant communities, while the NRE of P. yunnanensis in Pinus plantation had the second highest value of NRE for nutrient N. The nutrient content (available P, N, and soil organic matter) in the upper two soil layers under Eucalyptus and Pinus plantations was correspondingly found to be lower than that of the other forests. Moreover, under the Eucalyptus and Pinus plantations, surface runoff, soil erosion, and nutrient loss were more serious, and the water storage of litterfall and canopy interception were significantly lower than that in the other plant communities. Accordingly, we suggest that single-species plantations cannot present the same ecological benefits as natural forests, because of their simple, uniform structures, and the characteristics of the dominant plant species. [ABSTRACT FROM AUTHOR]

Effects of cold-dry storage on dormancy break and viability were determined for seeds of the five sub-alpine woody species Philadelphus incanus, Berberis vernae, Berberis dubia, Betula utilis, and Picea purpurea collected along an altitudinal gradient on the eastern part of the Qinghai-Tibet Plateau in China. Germination tests were conducted at 20/5°C for seeds stored dry at ambient room temperature for 4 weeks and then at 3–4°C for 0, 6, 12, and 24 weeks. Dormancy break during dry storage, i.e., afterripening, was indicated by an increase in germination percentages and rates. Duration of cold-dry storage and altitude of seed collection had significant effects on germination. With an increase in duration of storage, germination percentages and rates of P. incanus and B. vernae increased with a decrease in altitude of seed collection, while they increased with an increase in altitude for seeds of B. utilis and P. purpurea. Seeds of B. dubia did not exhibit changes in germination percentages and rates with altitude because a high number of seeds remained dormant during storage. Seed viability after 24 weeks of storage ranged from high (88, 93.3, 92.7%) for B. utilis to low (15% for high altitude) for P. incanus. The potential for dormancy break to occur during cold-dry storage should be considered when studies on basic seed dormancy are conducted or when seeds from various locations are stored prior to propagating plants from them. [ABSTRACT FROM AUTHOR]

The species composition, diversity, and abundance of lianas were studied in four secondary forests (a 100-year-old forest, a middle-aged forest, and two younger secondary forests), and compared with an undisturbed primary forest in the Ailao Mountains of subtropical SW China. The results showed that the species composition of lianas differed greatly from the secondary forests to the primary forest, which exhibit early and late-successional species. The abundance of lianas was relatively higher in the two younger and middle-aged secondary forests than in the old-growth secondary and primary forests. However, liana species richness was very limited in the four secondary forests as compared to the primary forest. Root climbers mainly grew in the primary forest, whereas tendril and hook climbers predominated in the four secondary forests, while stem twiners were common in both. The majority of lianas recorded in this study reproduced by animal dispersal, and there was no variation in dispersal modes across the five forest types. A step-wise regression showed that the abundance of small lianas (dbh <4 cm) was positively correlated with the abundance of small- and medium-sized tree stems and negatively correlated with the abundance of large-sized tree stems, whereas there is a strong positive correlation between the abundance of large lianas (dbh ≥4 cm) and large tree stems. Results from the CCA indicate that canopy openness, soil moisture, and average canopy height were the most important factors that influenced the abundance and distribution of lianas. [ABSTRACT FROM AUTHOR]

Much of the primary vegetation at low altitudes has been greatly altered or destroyed by a long history of human activities. This is particularly true in eastern China, where low-altitude areas are now dominated by secondary forests or plantations. Altitudinal vegetation zonation of this region is often based on these secondary forests, resulting in seral vegetation with an obscure zonal sequence. Here, we deduced the potential climax vegetation according to the regeneration patterns of the dominant species of the secondary forests at low altitudes (below 1,000 m a.s.l.) on Mt. Tianmu (1,506 m a.s.l., 30°18′30″–30°21′37″N, 119°24′11″–119°27′11″E). Based on the potential climax vegetation combined with the floristic composition and community structure, three vegetation zones were identified, viz: (1) evergreen broad-leaved forest zone (400–950 m a.s.l.); (2) evergreen and deciduous broad-leaved mixed forest zone (950–1,100 m a.s.l.); (3) deciduous broad-leaved forest zone (1,100–1,506 m a.s.l.). The altitudinal vegetation zones identified in this study correspond with the thermal conditions on Mt. Tianmu. The distribution of vegetation on Mt. Tianmu was limited by lower temperatures in winter, and the altitudinal thermal vegetation zones on this mountain were more similar to the thermal vegetation of Japan than to that of China. The vertical distributions and roles of conifers were different between the eastern and the western regions along 30°N latitude in humid East Asia. Cryptomeria fortunei formed the emergent layer, towering above the broad-leaved canopy at middle altitudes as C. japonica on Yakushima, but disappeared at high altitudes with hydrothermal limitation on Mt. Tianmu. [ABSTRACT FROM AUTHOR]

Few studies have examined leaf-trait relationships in the distribution of individual species along an environmental gradient. Here we address the issue by testing for the leaf-trait relationships of Quercus liaotungensis, a dominant deciduous woody species in northern China, along an altitudinal gradient in Dongling Mountain, Beijing. These leaf traits included specific leaf area (SLA), leaf dry matter content (LDMC), and leaf nitrogen, phosphorus, and potassium concentration on mass basis (Nmass, Pmass and Kmass, respectively). Along the altitudinal gradient, negative relationships between SLA and LDMC and Nmass were found, and Nmass, Pmass and Kmass correlated with each other positively. Relationship between Nmass and Pmass was stronger than the ones between Nmass and Kmass, and between Pmass and Kmass. The weak and negative relationship between SLA and Nmass might result from trade-offs that limit photosynthesis and water use efficiency along the altitudinal gradient, suggesting many environmental factors of local site being the collective forcing of drivers. Out of our expectations, Nmass and Pmass related very weakly to soil N and P, and no significant relationship between Kmass and soil K was found along elevation. These relationships could be used to predict the productivity of the population with changing environment in this region. [ABSTRACT FROM AUTHOR]

Seasonal drought may have a high impact on the karst ecosystem. The transpiration from Cyclobalanopsis glauca (syn. Quercus glauca) stand on a rocky hilly slope in South China was measured during the dry period of 2006 by using the Granier’s sap-flow method. During the experimental period, maximum sap flux density ( Js) ranged from 20 to 40 g H2O m−2 s−1 according to diameter of breast height (DBH) of individual trees. On sunny days, daily transpiration varied between 3.4 and 1.8 mm day−1. Transpiration of C. glauca was closely correlated to the radiation, air temperature, and vapor pressure deficit (VPD). Soil moisture was a very important factor influencing transpiration. The very low soil water content might result in low stand transpiration even when VPD is high, but high soil water content might also result in low transpiration if it was low VPD. However, VPD rather than soil moisture, affected largely the stand transpiration under high soil water content. The amount of transpiration was much more than that of the total soil moisture loss during the continuous sunny days, indicating that the dry shallow soils were probably not the only source for root-uptake water. C. glauca grows deep roots through the rock fissures of epikarst, indicating that epikarst might be another main source for sustaining transpiration in response to dry demand in autumn. Therefore, a large amount of deep roots of karst species would be a very important hydraulic connecting from the epikarst to above ground by transpiration, which would promote the biogeochemical process in a karst system. [ABSTRACT FROM AUTHOR]

Bryophytes are widely distributed in alpine meadow and wetlands on the Tibetan Plateau, where light intensity and air moisture are highly variable in time. To address how bryophytes respond to their light and moisture environments, we examined dynamic photosynthesis in two moss species, Distichium inclinatum common in meadow, and Encalypta alpine frequently found in wetland. Photosynthetic induction response was faster in the two moss species than in most vascular species. In both species the 90% induction time after a sudden light increase from 50 to 600 μmol m−2 s−1 was within 3 min. The induction was faster in mosses experiencing a period of weak light than in those in total darkness. E. alpina, the wetland species, showed more rapid induction response and shorter post-illumination CO2 fixation to sunflecks than D. inclinatum, the meadow species. Photosynthetic rate ( Amax) under saturated light in the two species increased linearly with increasing air relative humidity (RH). The meadow species D. inclinatum showed higher Amax under low RHs, but exhibited lower Amax under high RHs in comparison with the wetland moss E. alpina. Moreover, the quantum efficiency increased linearly with increasing RH, indicating that air humidity plays a critical role in photochemical activities in the alpine mosses. The study suggests that there are acclimations in dynamic photosynthesis in response to light and humidity, and the acclimations would benefit a high leaf carbon gain in the two alpine moss species in their common habitats. [ABSTRACT FROM AUTHOR]

Four independent experiments were designed to investigate the effects of the pericarp on seed imbibition, dehydration, germination, seedling establishment, and seed longevity in the field in seeds of Hedysarum scoparium Fisch. et Mey. The results showed that the presence of the pericarp decreased seed imbibition rates in the first 6 h, but the seeds attained significantly higher final water content after 24 h of soaking. The pericarp caused seed dormancy, and removal of the pericarp improved the germination percentage to 90 from 44%. In the pot experiment, where the level of moisture was maintained at field capacity (control), seeds with the pericarp removed had significantly improved seedling establishment. However, no statistical differences were observed in seedling establishment when the experiment was repeated under dry conditions at 40% of the field water capacity. The seedling biomass derived from seeds without the pericarp was much higher in the control but the trend was reversed under dry conditions. For seed longevity, 2 months burial in the field killed almost all seeds without the pericarp, while more than 70% of the seeds with the pericarp intact remained viable. These results indicated that the pericarp was beneficial for seedling establishment and seed longevity in arid environments. The results of this study may have practical application in grassland restoration in dry areas, especially for aerial seeding, which has been extensively used in the northern part of China. [ABSTRACT FROM AUTHOR]