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Anthropogenic disturbances are widespread in tropical forests and influence the species composition in the overstory. However, the impacts of historical disturbance on tropical forest overstory recovery are unclear due to a lack of disturbance data, and previous studies have focused on understory species. In this study, the purpose was to determine the influence of historical disturbance on the diversity, composition and regeneration of overstory species in present forests. In the 20-ha Xishuangbanna tropical seasonal rainforest dynamics plot in southwestern China, the historical disturbance boundaries were delineated based on panchromatic photographs from 1965. Factors that drove species clustering in the overstory layer (DBH ≥ 40 cm) were analyzed and the abundance, richness and composition of these species were compared among different tree groups based on multiple regression tree analysis. The coefficient of variation of the brightness value in historical panchromatic photographs from 1965 was the primary driver of species clustering in the overstory layer. The abundance and richness of overstory species throughout the regeneration process were similar, but species composition was always different. Although the proportion of large-seeded and vigorous-sprouting species showed no significant difference between disturbed and undisturbed forests in the treelet layer (DBH < 20 cm), the difference became significant when DBH increased. The findings highlight that historical disturbances have strong legacy effects on functional group composition in the overstory and the recovery of overstory species was multidimensional. Functional group composition can better indicate the dynamics of overstory species replacement during secondary succession. [ABSTRACT FROM AUTHOR]

Subtropical forests are important ecosystems globally due to their extensive role in carbon sequestration. Extreme climate events are known to introduce disturbances in the ecosystem that cause long‐term changes in carbon balance and radiation reflectance. However, how these ecosystem function changes contribute to global warming in terms of radiative forcing (RF), especially in the years following a disturbance, still needs to be investigated. We studied an extreme snow event that occurred in a subtropical evergreen broadleaved forest in south‐western China in 2015 and used 9 years (2011–2019) of net ecosystem CO2 exchange (NEE) and surface albedo (α) data to investigate the effect of the event on the ecosystem RF changes. In the year of the disturbance, leaf area index (LAI) declined by 40% and α by 32%. The annual NEE was −718 ± 128 g C m−2 as a sink in the pre‐disturbance years (2011–2014), but after the event, the sink strength dropped significantly by 76% (2015). Both the vegetation, indicated by LAI, and α recovered to pre‐disturbance levels in the fourth post‐disturbance year (2018). However, the NEE recovery lagged and occurred a year later in 2019, suggesting a more severe and lasting impact on the ecosystem carbon balance. Overall, the extreme event caused a positive (warming effect) net RF which was predominantly caused by changes in α (90%–93%) rather than those in NEE. This result suggests that, compared to the climate effect caused by forest carbon sequestration changes, the climate effect of α alterations can be more sensitive to vegetation damage induced by natural disturbances. Moreover, this study demonstrates the important role of vegetation recovery in driving canopy reflectance and ecosystem carbon balance during the post‐disturbance period, which determines the ecosystem feedbacks to the climate change. [ABSTRACT FROM AUTHOR]

Substantial temperature rise is reported in the Himalayas, and the vulnerability of the region to climate change is well recognized. An apt adaptation strategy to cope with climate change calls for informed people's participation, which was rarely investigated in the western Himalayas. Having been better informed, people in developed areas adopt better actions against climate change that are well guided by their perception. In contrast, Rajouri in Jammu and Kashmir represents a relatively impoverished and climate change--vulnerable region. Therefore, we gauged people's perceptions and actions in this area from a household survey from 717 randomly selected individuals. Further, consistency of perception was compared with meteorological records on temperature, humidity, wind speed, rainfall, and aboveground biomass from 1983 to 2013. The findings revealed that temperature increased significantly while changes in rainfall, wind speed, and relative humidity were insignificant. Although people sensed a rise in temperature and deforestation correctly, most of them differ with respect to rainfall, wind speed, and humidity. They reported rising pollution and traffic but no change in crop productivity or crop varieties.Of the respondents, 91%considered climate change as a risk, 86.8%reported reactive actions to it, and 82.8% reported proactive actions. Locals from varied socioeconomic backgrounds are not much informed about climate change; hence, the reasonability of their responses and positive adaptation actions needs further research. To engage people in climate adaptation actions, we suggest disseminating precise scientific information about local climate through awareness programs and by engaging them in climate change activities through suitable organizations. [ABSTRACT FROM AUTHOR]

The land use change from tropical forests to rubber plantations has had a great influence on ecosystem‐level carbon (C) exchange and soil C dynamics. This study aimed to assess the variation of soil respiration and its components in rubber plantations of different stand age. A trenching method was used to partition soil respiration (RS) into autotrophic respiration (RA) and heterotrophic respiration (RH) for 3 years in 12, 24, 32 and 49‐year‐old rubber plantations. Our results showed that RS changed significantly among rubber plantations, with the highest RS in the old‐growth rubber plantation (49‐year plantation, 147.30 ± 6.91 mg CO2‐C m−2 hr−1) followed by the mature (137.16 ± 7.68 and 108.10 ± 4.83 in 24‐year and 32‐year plantations, respectively) and the young (12‐year plantation, 78.43 ± 3.84 mg CO2‐C m−2 hr−1) rubber plantations. RS was significantly and exponentially related to soil temperature (p < .0001) rather than soil water content, which led to higher RS in the rainy season than in the dry season. The contribution of RA to RS was higher in the mature rubber plantation than in the young (27%) and the old‐growth (20%) rubber plantations. The sensitivity of RS to increasing temperature (Q10) was higher in 32‐ and 49‐year plantations than in 12‐ and 24‐year rubber plantations. The largest Q10 value of RH and RA was found in the old‐growth (49‐year plantation, 2.95) and the mature (32‐year plantation, 8.01) rubber plantations, respectively. Our results highlight the importance of environmental factors in determining the variation in RS in rubber plantations with different stand age. However, further studies are still required to elucidate the mechanisms impacting stand age‐related effects on soil respiration, such as the differences in photosynthesis in rubber plantations. Highlights: Soil respiration (RS) in four rubber plantations of different stand age was examined.RS tended to increase with the increasing stand age.The contribution of autotrophic respiration (RA) to RS was higher in the mature stands.Q10 values of heterotrophic respiration (RH) and RA were higher in old‐growth and mature stands, respectively. [ABSTRACT FROM AUTHOR]

Questions: In the changing climate scenario, the decline in precipitation is expected to alter water availability for plants, which in turn affects plant community structure and composition. The responses of community composition and structure to declines in precipitation are well documented in other biomes but remain understudied in water‐limited savannas. Location: A savanna ecosystem in southwest China. Methods: We used a four‐year (2014–2017) precipitation manipulation experiment to examine changes in herbaceous community composition and structure across the species, functional group and community levels under precipitation reduction. Results: Precipitation reduction significantly decreased the average height and percentage cover of the herbaceous community, while increasing species richness and the Pielou evenness index. Precipitation reduction significantly decreased average height, percentage cover and relative abundance of graminoids and perennials, but increased those of forbs and annuals. Precipitation reduction prompted a shift in the dominant species of the herbaceous community towards Fimbristylis monostachya. Conclusions: The results show that precipitation reduction changed the composition and structure of the herbaceous community of this savanna. Furthermore, they provide strong evidence that changes in herbaceous community structure and composition in response to the intensity and duration of precipitation reduction in this savanna exhibited relatively low thresholds, which suggests that the herbaceous community's response to a decline in precipitation was essentially nonlinear. These findings imply that even relatively small declines in precipitation may stimulate shifts in plant community structure and composition and affect the function and stability of savanna ecosystems. [ABSTRACT FROM AUTHOR]

Aims The evolutionary history and functional traits of species can illuminate ecological processes supporting coexistence in diverse forest communities. However, little has been done in decoupling the relative importance of these mechanisms on the turnover of phylogenetic and functional characteristics across life stages and spatial scales. Therefore, this study aims to estimate the contribution of environment and dispersal on the turnover of phylogenetic and functional diversity across life stages and spatial scales, in order to build a coherent picture of the processes responsible for species coexistence. Methods We conducted the study in Xishuangbanna Forest Dynamics Plot in Yunnan Province, southwest China. We used four different spatial point process models to estimate the relative importance of dispersal limitation and environmental filtering. The functional traits and phylogenetic relationships of all individual trees were incorporated in the analyses to generate measures of dissimilarity in terms of pairwise and nearest-neighbor phylogenetic and functional characteristics across life stages and spatial scales. Important Findings We found non-random patterns of phylogenetic and functional turnover across life stages and spatial scales. Environmental filtering structured pairwise phylogenetic and functional beta diversity across spatial scales, while dispersal limitation alone, and in combination with environment filtering, shaped nearest neighbor phylogenetic and functional beta diversity. The relative importance of dispersal limitation and environmental filtering appeared to change with life stage but not with spatial scale. Our findings suggest that phylogenetic and functional beta diversity help to reveal the ecological processes responsible for evolutionary and functional assembly and highlight the importance of using a range of different metrics to gain full insights into these processes. [ABSTRACT FROM AUTHOR]

The potential impact of drought on the carbon balance in plants has gained great attention. Non-structural carbohydrate (NSC) dynamics have been suggested as an important trait reflecting carbon balance under drought conditions. However, NSC dynamics under drought and the response mechanisms of NSC to drought remain unclear, especially in water-limited savanna ecosystems. A precipitation exclusion experiment was performed to simulate different drought intensities in a savanna ecosystem in Yuanjiang valley in southwestern China. Growth, total NSC concentration and diurnal change of NSC were determined for the leaves and non-photosynthetic organs of three dominant species (Lannea coromandelica, Polyalthia cerasoides and Heteropogon contortus) throughout the growing season. Drought significantly reduced the growth of all the three species. Total NSC concentration averaged ~8.1%, varying with species, organ and sampling period, and did not significantly decrease under drought stress. By contrast, the diurnal change of NSC in these three species increased under drought stress. These results indicate that these three dominant species did not undergo carbon limitation. Thus, relative change in NSC is a more sensitive and effective indicator than carbon reserves in evaluation of plant carbon balance. These findings provide new insights for the understanding of carbon balance and the mechanisms of carbon starvation. [ABSTRACT FROM AUTHOR]

Litter inputs are expected to have a strong impact on soil N2O efflux. This study aimed to assess the effects of the litter decomposition process and nutrient efflux from litter to soil on soil N2O efflux in a tropical rainforest. A paired study with a control (L) treatment and a litter-removed (NL) treatment was followed for 2 years, continuously monitoring the effects of these treatments on soil N2O efflux, fresh litter input, decomposed litter carbon (LCI) and nitrogen (LNI), soil nitrate (NO3−-N), ammonium (NH4+-N), dissolved organic carbon (DOC), and dissolved nitrogen (DN). Soil N2O flux was 0.48 and 0.32 kg N2O-N ha−1 year−1 for the L and NL treatments, respectively. Removing the litter caused a decrease in the annual soil N2O emission by 33%. The flux values from the litter layer were higher in the rainy season as compared to the dry season (2.10 ± 0.28 vs. 1.44 ± 0.35 μg N m−2 h−1). The N2O fluxes were significantly correlated with the soil NO3−-N contents (P < 0.05), indicating that the N2O emission was derived mainly from denitrification as well as other NO3− reduction processes. Suitable soil temperature and moisture sustained by rainfall were jointly attributed to the higher soil N2O fluxes of both treatments in the rainy season. The N2O fluxes from the L were mainly regulated by LCI, whereas those from the NL were dominated jointly by soil NO3− content and temperature. The effects of LCI and LNI on the soil N2O fluxes were the greatest in the 2 months after litter decomposition. Our results show that litter may affect not only the variability in the quantity of N2O emitted, but also the mechanisms that govern N2O production. However, further studies are still required to elucidate the impacting mechanisms of litter decomposition on N2O emission from tropical forests. [ABSTRACT FROM AUTHOR]

Background and aims: Drought is expected to be more frequent and more intense with global warming. Our aim was to investigate how soil respiration would respond to different levels of precipitation exclusion (‘drought strength’).Methods: We conducted a two-year drought experiment in a woody savanna ecosystem in south west of China, which consisted of four treatments: a control treatment (CK); 30% precipitation exclusion (PE3), 50% precipitation exclusion (PE5) and 70% precipitation exclusion (PE7).Results: The cumulative soil respiration rates were significantly decreased in both rainy and dry seasons as drought became more intense. The sensitivity of soil respiration to soil moisture decreased as drought severity increased. There were bursts of CO2 emission when dry soils were rewetted by rainfall after the dry season. Unlike most other exponential relationships between soil respiration and soil temperature, a parabolic function was observed in all treatments (P < 0.05), which was due to higher soil temperature (>28 °C) coinciding with insufficient soil water content (<11% Vol). Respiration rate is best represented by a model which combines soil moisture and temperature.Conclusion: Soil respiration rates were significantly decreased as drought enhanced. The response of soil respiration to drought in the dry season should not be ignored especially when evaluating the effect of drought on soil respiration in a whole year in savanna ecosystems. The quadratic relationship between soil respiration and soil temperature may be important for modeling the response of soil respiration to climate change (drought) in savanna ecosystems. [ABSTRACT FROM AUTHOR]

Sulfur spraying is a conventional prevention and control measure for rubber leaf diseases in the northern margin of tropical Southeast Asia. The aim of this study was to determine the long-term (48 years) accumulated effects of sulfur spraying on some major soil microbial and nutrient properties in the area of rubber plantation. The results indicate a significant decrease in pH along the rubber chronosequence with yearly sulfur application. A negative effect of sulfur spraying on soil total sulfur content was also observed. Apart from that, soil microbial characteristics increased significantly, except for microbial biomass carbon. Soil nutrient bioavailability-related characteristics showed a complex pattern of response to sulfur spraying, among which bio-available ammonium nitrogen increased linearly, bio-available nitrate nitrogen showed a trend resembling a large resting capital letter 'S', bio-available phosphorus showed a contrary trend to nitrogen, a capital letter 'S' resting the other direction, whereas bio-available potassium had no response to sulfur spraying. Based on the comprehensive response indexes, soil microbial characteristics had a pulsing response to sulfur spraying accumulation and two critical turning points were sometime between the 23rd and 32nd year and between the 40th and 48th year. Soil nutrient bioavailability showed a volatile comprehensive pattern, but there was no significant difference during the chronosequence. There is need for control sulfur deposition frequency and dosage under the soil and environmental safety threshold in the diseases prevention and control in monoculture rubber plantation. [ABSTRACT FROM AUTHOR]

Conspecific negative density dependence ( CNDD) has been recognized as a key mechanism underlying species coexistence, especially in tropical forests. Recently, some studies have reported that seedling survival is also negatively correlated with the phylogenetic relatedness between neighbors and focal individuals, termed phylogenetic negative density dependence ( PNDD). In contrast to CNDD or PNDD, shared habitat requirements between closely related individuals are thought to be a cause of observed positive effects of closely related neighbors, which may affect the strength and detectability of CNDD or PNDD. In order to investigate the relative importance of these mechanisms for tropical tree seedling survival, we used generalized linear mixed models to analyze how the survival of more than 10 000 seedlings of woody plant species related to neighborhood and habitat variables in a tropical rainforest in southwest China. By comparing models with and without habitat variables, we tested how habitat filtering affected the detection of CNDD and PNDD. The best-fitting model suggested that CNDD and habitat filtering played key roles in seedling survival, but that, contrary to our expectations, phylogenetic positive density dependence ( PPDD) had a distinct and important effect. While habitat filtering affected the detection of CNDD by decreasing its apparent strength, it did not explain the positive effects of closely related neighbors. Our results demonstrate that a failure to control for habitat variables and phylogenetic relationships may obscure the importance of conspecific and heterospecific neighbor densities for seedling survival. [ABSTRACT FROM AUTHOR]

Background and aims: Drought is predicted to have a profound impact on soil respiration. This study aimed to assess the effects of long-term precipitation decrease on soil respiration in a tropical rainforest. Methods: A precipitation reduction experiment was conducted in a tropical forest in southwest China at the beginning of 2011. Soil respiration and environmental parameters were measured monthly for three years. Results: The continuous precipitation reduction treatment did not affect the seasonal patterns of soil respiration, but it significantly increased soil respiration in the study plot during the rainy season, and the relationship between soil respiration and soil moisture differed in the control and reduction treatment in the rainy season. Compared with the net ecosystem exchange of carbon in this system, the increment of annual soil carbon emissions in the reduction treatment was considerable and should not be ignored. Conclusions: Our results indicate that the responses of soil respiration to precipitation decrease may vary seasonally and the variation of volumetric water content in different seasons may be an important factor leading to the seasonal variation. The variation of soil moisture among different ecosystems as well as in different seasons should be taken into consideration when predicting the future response of soil respiration to drought globally. [ABSTRACT FROM AUTHOR]

Aims: The aims were to identify the effects of interactions between litter decomposition and rhizosphere activity on soil respiration and on the temperature sensitivity of soil respiration in a subtropical forest in SW China. Methods: Four treatments were established: control (CK), litter removal (NL), trenching (NR) and trenching together with litter removal (NRNL). Soil CO efflux, soil temperature, and soil water content were measured once a month over two years. Soil respiration was divided into four components: the decomposition of basic soil organic matter (SOM), litter respiration, root respiration, and the interaction effect between litter decomposition and rhizosphere activity. A two-factor regression equation was used to correct the value of soil CO efflux. Results: We found a significant effect of the interaction between litter decomposition and rhizosphere activity ( R) on total soil respiration, and R exhibited significant seasonal variation, accounting for 26 and 31 % of total soil respiration in the dry and rainy seasons, respectively. However, we found no significant interaction effect on the temperature sensitivity of soil respiration. The temperature sensitivity was significantly increased by trenching compared with the control, but was unchanged by litter removal. Conclusions: Though the interaction between litter decomposition and rhizosphere activity had no effects on temperature sensitivity, it had a significant positive effect on soil respiration. Our results not only showed strong influence of rhizosphere activity on temperature sensitivity, but provided a viable way to identify the contribution of SOM to soil respiration, which could help researchers gain insights on the carbon cycle. [ABSTRACT FROM AUTHOR]

Increasingly, ecologists are using functional and phylogenetic approaches to quantify the relative importance of stochastic, abiotic filtering and biotic filtering processes shaping the pattern of species co-occurrence. A remaining challenge in functional and phylogenetic analyses of tropical tree communities is to successfully integrate the functional and phylogenetic structure of tree communities across spatial and size scales and habitats in a single analysis., We analysed the functional and phylogenetic structure of tree assemblages in a 20-ha tropical forest dynamics plot in south-west China. Because the influence of biotic interactions may become more apparent as cohorts age, on local scales, and in resource-rich environments, we perform our analyses across three size classes, six spatial scales and six distinct habitat types, using 10 plant functional traits and a molecular phylogeny for the >400 tree taxa found in the plot., All traits, except leaf area and stem-specific resistance, had significant, albeit weak phylogenetic signal. For canopy species, phylogenetic clustering in small and medium size classes turned to phylogenetic overdispersion in the largest size class and this change in dispersion with size was found in each habitat type and across all spatial scales. On fine spatial scales, functional dispersion changed from clustering to overdispersion with increasing size classes. However, on larger spatial scales assemblages were functionally clustered for all size classes and habitats., Phylogenetic and functional structure across spatial and size scales and habitats gave strong support for a deterministic model of species co-occurrence rather than for a neutral model. The results also support the hypothesis that abiotic determinism is more important at larger scales, while biotic determinism is more important on smaller scales within habitats. [ABSTRACT FROM AUTHOR]

This study seeks a further understanding on climate trends in a subtropical mountain forest, SW China. Air ( Ta) and soil temperature ( Ts), both in open land (1983-2010) and under a forest canopy (1986-2010), were investigated. Short-term radiation components were also measured simultaneously both in open land and understory to explore the relationships of microclimatic variables. Correlations of Ta and Ts with sunshine hours ( St) and wind speed ( Ws) were also analysed as driving factors of the temperature trends. The results showed that (1) Understory radiation components were greatly reduced by the forest canopy, showing a strong effect of forest canopy on microclimatic variables. Ts_0 in open land was significantly correlated with solar radiation. Wind speed had significant influences on differences between Ta and Ts_0, between open land Ts_0 and understory Ts_0. The long-term data showed that Ts_0 under forest canopy were closely coupled with Ta in open land. (2) Ta had a larger increase than Ts_0 in open land, and temperature increases in winter were greater than in other seasons. Soil temperature at depths under forest canopy had nearly twice the increases of those on open land; we attributed this to the higher relative increase of Ws over St. (3) A slope change in 1998 was detected in the Ts_0 and Ta difference ( Ts_0 − Ta) series, suggesting different response of Ts_0 and Ta since that year. Deceleration of St and stability of Ws may have been factors. This study improves our understanding of warming in a nature reserve where anthropogenic influences are absent. Further studies are needed for the biological and biochemical implications on subtropical mountain forest. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

CO concentrations and related environmental factors were measured in an Asian tropical rainforest located in a small valley in Xishuangbanna, SW China, with the aim of investigating the CO pooling effect and its mechanism of formation. Pooling of CO was observed during the evening (1600-2200 hours local time); the accumulated CO subsequently flowed away after dusk. We consider that along-slope drainage flow, soil CO efflux, and temperature inversion contribute to the development of CO pooling. A new model is proposed to track the mechanism of the formation and dissipation of CO pooling (e.g., drainage flow, compensatory mechanisms). Given its influence on the storage term, we suggest that CO pooling and subsequent disappearance should be taken into account when calculating eddy covariance and other micrometeorological measurements of carbon flux for valley sites. [ABSTRACT FROM AUTHOR]

Epiphytic plants play an important role in the nutrient cycle of forest ecosystems. There had been fewer studies in subtropical regions than in other climate zones. Prior research showed that the canopy epiphyte could fix nitrogen combined with microorganism in tropical forest. The epiphytic plants enwrapping trees in canopy layer are very abundant in the subtropical mountainous cloud forest of Ailao Mountain (central and southern Yunnan Province, SW China). This forest lacks widespread nitrogen-fixing plants, and the nitrogen origin is elusive. Maybe there also exist such nitrogen-fixing systems in epiphyte community. Nitrogen-fixing potentials of canopy epiphytes increased greatly from dry season to wet season. There occurred an obvious difference on the epiphytic nitrogen fixation abilities between upper canopy layer and sub-canopy layer in alternant period between wet season and dry season. Epiphytic nitrogen-fixing potentials for the subtropical moist forest in Ailao Mountains ranged between 0.027 and 2.24 kg ha year. Our results indicate that the canopy epiphytes in the subtropical moist forest of Ailao Mountains can fix a significant amount of atmospheric nitrogen. This finding suggests a new nitrogen source for the subtropical forest ecosystem, thus can have profound impact on the studies of nitrogen cycling. [ABSTRACT FROM AUTHOR]

Two years of eddy covariance measurements of above-and below-canopy carbon fluxes and static opaque chamber and gas chromatography technique measurements of soil respiration for three treatments (bare soil, soil+litterfall, soil+litterfall+seedling) were carried out in a tropical seasonal rain forest. In addition, data of photosynthesis of dominant tree species and seedlings, leaf area index, litter production and decomposing speed, soil moisture, soil temperature and photosynthetic photon flux density within the forest were all measured concurrently. Data from January 2003 to December 2004 are used to present annual variability of carbon flux and relationships between carbon flux and impact factors. The results show that carbon flux of this forest presented unusual tendency of annual variation; above-canopy carbon fluxes were negative in the dry season (November–April) and mainly positive in the rainy season, but overall the forest is a carbon sink. Carbon flux has obviously diurnal variation in this tropical seasonal rain forest. Above-canopy carbon fluxes were negative in the day-time and absolute values were larger in the dry season than that in the rainy season, causing the forest to act as a carbon sink; at night, carbon fluxes were mainly positive, causing the forest to act as a carbon source. Dominant tree species have greater photosynthesis capability than that of seedlings, which have a great effect on above-canopy carbon flux. There was a significant correlation between above-canopy carbon flux and rate of photosynthesis of tree species. There was also a significant correlation between above-canopy carbon flux and rate of photosynthesis of seedlings; however, the below-canopy carbon flux was only significantly correlated with rate of photosynthesis of seedlings during the hot-dry season. Soil respiration of the three treatments displayed a markedly seasonal dynamic; in addition, above-canopy carbon fluxes correlated well with soil respiration, litterfall pro-duction, litterfall decomposition rate, precipitation, and soil moisture and temperature. A primary sta-tistical result of this study showed that above-canopy carbon flux in this forest presented carbon source or sink effects in different seasons, and it is a carbon sink at the scale of a year. [ABSTRACT FROM AUTHOR]

As one of the important factors affecting plant productivity and plant distribution, temperature also affects the physiological and ecological characteristics of plants to a large extent. We report canopy leaf temperature distribution over a 36 m tall primary tropical rain forest and samplings of 28 tree species in SW China by means of two high resolution thermal cameras (P25, Flir systems, Wilsonville, OR, USA). The leaf temperature of dominant tree Species Pometia tomentosa was the highest (31.8 °C), 10.2 °C higher than that of tree species Mezzettipsis creaghii (21.6 °C). The mean leaf to air temperature difference (Tc–Ta) of Pometia tomentosa was the highest (6.4 K), the second highest was Barringtonia pendula (6.1 K), and Mezzettipsis creaghii had the lowest (Tc–Ta) (1.9K). (Tc–Ta) of tree species with smaller leaves and larger stomatal conductance was lowly sensitive to climate factors. Leaf size and stomatal conductance together decided the effect of climate change to (Tc–Ta) of the different tree species. We have shown that the composition of tree species in tropical rain forest areas is important to the climate through our research. [ABSTRACT FROM AUTHOR]

The distribution of forest vegetation and forest carbon sequestration potential are significantly influenced by climate change. In this study, a map of the current distribution of vegetation in Yunnan Province was compiled based on data from remote sensing imagery from the Advanced Land Observing Satellite (ALOS) from 2008 to 2011. A classification and regression tree (CART) model was used to predict the potential distribution of the main forest vegetation types in Yunnan Province and estimate the changes in carbon storage and carbon sequestration potential (CSP) in response to increasing temperature. The results show that the current total forest area in Yunnan Province is 1.86 × 107 ha and that forest covers 48.63% of the area. As the temperature increases, the area of forest distribution first increases and then decreases, and it decreases by 11% when the temperature increases from 1.5 to 2 °C. The mean carbon density of the seven types of forest vegetation in Yunnan Province is 84.69 Mg/ha. The total carbon storage of the current forest vegetation in Yunnan Province is 871.14 TgC, and the CSP is 1100.61 TgC. The largest CSP (1114.82 TgC) occurs when the temperature increases by 0.5 °C. Incremental warming of 2 °C will sharply decrease the forest CSP, especially in those regions with mature coniferous forest vegetation. Semi-humid evergreen broad-leaved forests were highly sensitive to temperature changes, and the CSP of these forests will decrease with increasing temperature. Warm-hot coniferous forests have the greatest CSP in all simulation scenarios except the scenario of a 2 °C temperature increase. These results indicate that temperature increases can influence the CSP in Yunnan Province, and the largest impact emerged in the 2 °C increase scenario. [ABSTRACT FROM AUTHOR]

The lasting imprint of phylogenetic history on current day ecological patterns has long intrigued biologists. Over the past decade ecologists have increasingly sought to quantify phylogenetic signals in environmental niche preferences and, especially, traits to help uncover the mechanisms driving plant community assembly. However, relatively little is known about how phylogenetic patterns in environmental niches and traits compare, leaving significant uncertainty about the ecological implications of trait-based analyses. We examined phylogenetic signals within known environmental niches of 64 species, at seedling and adult life stages, in a Chinese tropical forest, to test whether local environmental niches had consistent relationships with phylogenies. Our analyses show that local environmental niches are highly phylogenetically labile for both seedlings and adult trees, with closely related species occupying niches that are no more similar than expected by random chance. These findings contrast with previous trait-based studies in the same forest, suggesting that phylogenetic signals in traits might not a reliable guide to niche preferences or, therefore, to community assembly processes in some ecosystems, like the tropical seasonal rainforest in this study. [ABSTRACT FROM AUTHOR]

Savanna ecosystems play a crucial role in the global carbon cycle. However, there is a gap in our understanding of carbon fluxes in the savanna ecosystems of Southeast Asia. In this study, the eddy covariance technique (EC) and the biometric-based method (BM) were used to determine carbon exchange in a savanna ecosystem in Southwest China. The BM-based net ecosystem production (NEP) was 0.96 tC ha−1 yr−1. The EC-based estimates of the average annual gross primary productivity (GPP), ecosystem respiration (Reco), and net ecosystem carbon exchange (NEE) were 6.84, 5.54, and −1.30 tC ha−1 yr−1, respectively, from May 2013 to December 2015, indicating that this savanna ecosystem acted as an appreciable carbon sink. The ecosystem was more efficient during the wet season than the dry season, so that it represented a small carbon sink of 0.16 tC ha−1 yr−1 in the dry season and a considerable carbon sink of 1.14 tC ha−1 yr−1 in the wet season. However, it is noteworthy that the carbon sink capacity may decline in the future under rising temperatures and decreasing rainfall. Consequently, further studies should assess how environmental factors and climate change will influence carbon-water fluxes. [ABSTRACT FROM AUTHOR]

The relative degree to which stochastic and deterministic processes underpin community assembly is a central problem in ecology. Quantifying local-scale phylogenetic and functional beta diversity may shed new light on this problem. We used species distribution, soil, trait and phylogenetic data to quantify whether environmental distance, geographic distance or their combination are the strongest predictors of phylogenetic and functional beta diversity on local scales in a 20-ha tropical seasonal rainforest dynamics plot in southwest China. The patterns of phylogenetic and functional beta diversity were generally consistent. The phylogenetic and functional dissimilarity between subplots (10 × 10 m, 20 × 20 m, 50 × 50 m and 100 × 100 m) was often higher than that expected by chance. The turnover of lineages and species function within habitats was generally slower than that across habitats. Partitioning the variation in phylogenetic and functional beta diversity showed that environmental distance was generally a better predictor of beta diversity than geographic distance thereby lending relatively more support for deterministic environmental filtering over stochastic processes. Overall, our results highlight that deterministic processes play a stronger role than stochastic processes in structuring community composition in this diverse assemblage of tropical trees. [ABSTRACT FROM AUTHOR]