Evergreen Broad-leaved Forest Research Articles

New quantified climate reconstruction in southern China suggests a potential influence of winter cloud cover across East Asia during the Holocene.

Previous studies have advanced our understanding of paleoclimate features and dynamics in East Asia, particularly within the East Asian monsoon domain (EAMD) since the last glacial period. However, a lack of quantitative reconstructions in the boundary area between tropical and subtropical zones has largely hindered our spatial comprehension of the relationship between precipitation and temperature throughout the EAMD. In this study, we present a continuous pollen record from the Pearl River delta over the past 13.2ka and a quantitative climate reconstruction using an updated modern pollen dataset. The findings indicate that from 13.2ka to 9.9ka, the study area was encompassed by mid-montane moist evergreen broadleaved forest (EBLF), transitioning to semi-humid EBLF or lowland monsoon EBLF during the late Holocene. Anthropochory plants have emerged as dominant taxa by about 1.9ka, indicating a large-scale impact of human activities. The results of quantitative climate reconstruction indicate that the range of annual precipitation varies by ca. 80-120mm, and the changing pattern is consistent with the traditional 'Holocene thermal maximum' mode, with summer solar radiation potentially being the primary controlling factor. The range of annual temperature variability fall between 19.5°C and 22.5°C, exhibiting a warming trend likely influenced by changes in Northern Hemisphere ice volume. There is a phase difference of about 2-4ka between the peak values of precipitation and temperature. The variation patterns of change across eastern Asia exhibit distinct differences when compared to the proxy records in the EAMD. It appears that such asynchrony between precipitation and temperature is more pronounced in southern China. In comparison with model simulations, it is believed that spatiotemporal variation in winter cloud cover may play a crucial role in explaining this phenomenon of regional heterogeneity.

Common Species in the Subtropical Evergreen Broad-Leaved Forest: Dominance in Adaptation Mechanisms and Resource Utilization Capabilities

When species of different abundance coexist, their ecological strategies remain uncertain. Assessing the functional diversity and niche characteristics of species with different levels of abundance contributes to understanding vegetation properties and is essential for species conservation. Based on the species abundance of 380 plots in the Gutianshan subtropical evergreen broad-leaved forest in the Zhejiang Province of China, woody plants were categorized as common species (86 species), occasional species (87 species), and rare species (79 species). Plant functional traits, including maximum height, seed dispersal modes, first flowering stage, flowering duration, and fruit length, were used to assess the functional diversity of the community of common, occasional, and rare species, while 15 environmental factors were used to evaluate their Levins’ niche breadth and Pianka’s niche overlap. The results showed that rare species have the highest functional evenness, while functional dispersion and Rao’s quadratic entropy were higher for common species (2.05 and 5.07, respectively) compared to occasional species (1.57 and 3.10) and rare species (1.35 and 2.48). Furthermore, the 15-dimensional mean value of niche breadth of common species (ranging from 0.277 to 0.955) was also higher than that of occasional (ranging from 0.193 to 0.710) and rare species (ranging from 0.100 to 0.345), and the same trend was also observed in niche overlap. The results suggest that common species have diverse functional traits and a greater ability to adapt to the environment and use resources, whereas occasional species have a limited ability to use the environment. Rare species are evenly distributed within functional space to reduce direct competition with other species, but they thrive only under specific environmental conditions, mainly following a K reproductive strategy. Niche differentiation mechanisms are important determinants of species coexistence in subtropical evergreen broad-leaved forests. In summary, more attention and greater efforts should be paid to the conservation of rare species. Our findings could help forest managers in the restoration and conservation of subtropical forests.

Does a whole plant conservation gradient exist within a subtropical broadleaved evergreen forest?

The coordination between leaf and root traits is crucial for plants to synchronize their strategies for acquiring and utilizing above- and belowground resources. Nevertheless, the generality of a whole plant conservation gradient is still controversial. Such testing has been conducted mainly among communities at large spatial scales, and thus evidence is lacking within communities. This is noteworthy because factors that influence leaf and root trait variation differ across scales. Here, we measured pairs of analogous leaf and first-order root traits, including morphological (leaf thickness (LT) and root diameter (RD), leaf mass per unit area (LMA) and specific root length (SRL), and leaf and root tissue density (LTD and RTD)) and chemical traits (carbon (C) and nitrogen (N) concentrations in leaf and root tissues), on the same plants from 60 woody species within a subtropical broad-leaved evergreen forest. The trade-off patterns in and correlations between leaf and root traits were examined using (phylogenetic) principal component analysis and correlation analysis. Our results revealed two dominant dimensions of leaf trait variation, the leaf economics spectrum (LES) and the LT-LTD trade-off axis. Variations in root traits were mainly accounted for by a two-dimensional root economics space (RES) (i.e., root conservation gradient (RTD-RN) and root collaboration gradient (RD-SRL)). The LES and root conservation gradient were correlated and could be integrated into one whole plant conservation gradient, independent of the root collaboration gradient and the leaf LT-LTD trade-off dimension. Leaf and root N concentrations correlated positively, independent of phylogeny, whereas analogous leaf and root morphological traits varied independently of each other. These results support the existence of a whole plant conservation gradient, but also highlight a complex integration of multiple above- and belowground adaptive strategies of plants within a forest community, which offer new insight into ecological trade-offs, species coexistence and community assembly in the forest ecosystem.

Effects of thinning on the structure of soil microbial communities in a subtropical secondary evergreen broad-leaved forest.

Thinning is a common practice to enhance tree growth, but its effect on rhizosphere soil microorganisms in subtropical secondary evergreen broadleaved forests remains unclear. This study used 16S rDNA amplicon sequencing to explore soil microflora of five shrubs and five tree species. The results showed that thinning altered nutrient distribution and pH in rhizosphere soil, impacting microbial richness, which varied by tree species. The dominant bacterial phyla were Acidobacteria, Proteobacteria, Actinobacteria, and Firmicutes. Although the dominant microbial species remained largely unchanged, thinning increased the relative abundance of Firmicutes. Thinning intensity between 10-15% significantly altered the structure of soil microbial communities, demonstrating species-specific responses. These changes in microbial structure may influence tree growth. This study proposed the potential effects of thinning on rhizosphere soil microorganisms and suggests future research to investigate the specific microbial mechanisms affected by thinning.

Impact of Microtopography and Neighborhood Effects on Individual Survival Across Life History Stages.

Understanding drivers of plant community assembly and individual survival in forest ecosystems is crucial for effective conservation and management. While macro-scale factors influencing vegetation patterns are well documented, the combined impact of microtopographic variations and neighborhood effects at neighborhood scales, particularly in subtropical forests, requires further study. To contribute to this area of research, we established a 9.6 ha dynamic plot in a subtropical evergreen broad-leaved forest to examine the interplay between microtopographic factors and neighborhood effects on individual plant survival across different life stages. We conducted a comprehensive analysis of microtopographic variables and neighborhood effects, with individual plant survival censused through repeated surveys at 5-year intervals. Mixed-effects models were employed to assess the combined influence of these factors across life stages. Our results reveal that both microtopographic factors and neighborhood effects significantly influence plant survival, with their impacts varying across life stages. Water availability, represented by flow direction, emerged as a consistently critical factor throughout all life stages. Elevation and the topographic position index showed significant positive effects on survival, particularly in later life stages, possibly reflecting adaptations to light acquisition and water drainage. The influence of topographic factors intensified with succession, while the impact of neighborhood effects, particularly asymmetric competition and conspecific negative density dependence, changed as plants matured. This study enhances our understanding of forest community assembly, emphasizing the importance of considering abiotic and biotic factors across multiple scales for effective forest conservation and management. It provides insights into mechanisms driving spatial variation in community composition, crucial for preserving biodiversity in heterogeneous forest landscapes.

Mechanisms Maintaining Biomass Stability in Woody Species Communities in Evergreen Broadleaved Forests of Dong Nai Culture and Nature Reserve, Dong Nai province, Southern Vietnam

Tropical forest ecosystems experience dynamic changes in response to environmental fluctuations and disturbances. Understanding the mechanisms governing their stability is crucial for maintaining ecosystem services. Among these ecosystems, evergreen broadleaved forests play a pivotal global role. This study investigates the impacts of overyielding, stand structure, species asynchrony, and the stability of dominant species on community biomass stability (CBS) within the Dong Nai Culture and Nature Reserve's evergreen broadleaved forests. The study utilized species richness, diameter-at-breast-height (DBH) variation coefficient, species asynchrony, and stability of dominant species as explanatory variables. The response variables included CBS, mean biomass (µ), and biomass standard deviation (σ). Three structural equation models (SEMs) were constructed to assess the relative strengths of direct and indirect effects among these variables. The results indicated that: (1) The SEMs achieved a good fit, explaining 41.8% of the variance in CBS. (2) Species richness negatively correlated significantly with µ (path coefficient = -0.112) and σ (-0.056). (3) DBH variation coefficient showed significant negative correlations with CBS (-0.161) and µ (-0.087). (4) Species asynchrony exhibited significant positive correlations with CBS (0.061), µ (0.076), and σ (0.061). (5) Dominant species stability showed significant positive correlations with CBS (0.588) and µ (0.153) and a negative correlation with σ (-0.588). These findings underscore that while stand structure and species asynchrony significantly influence CBS in evergreen broadleaved forests, the stability of dominant species emerges as the primary predictor of CBS. Therefore, effective forest management strategies should prioritize conserving and enhancing conditions that support dominant species, ensuring the sustainability of forest ecosystems in the study area.

Disentangling the Complex Effects of Seasonal Drought, Floor Mass, and Roots on Soil Microbial Biomass in a Subtropical Moist Forest

Severe seasonal droughts driven by global climate change significantly alter the cycling of carbon and nutrients in forest ecosystems, while the investigation into the impacts of floor mass and plant roots on soil microbial biomass within the context of recurrent seasonal droughts is still rare. To investigate the environmental determinants governing soil microbial biomass with the escalating severity of seasonal droughts, we conducted a study in a montane subtropical moist evergreen broad-leaved forest in southwestern China from June 2019 to May 2023. The study results revealed that soil microbial biomass, as well as soil moisture, floor mass, and plant roots, showed an apparent single-hump modal within one year. In the comparative analysis of the soil microbial biomass fluctuation amplitudes across control and watered plots, a discernible disparity was observed, indicating significant differences in microbial biomass dynamics between the respective experimental conditions. The pooled data revealed a statistically significant influence of seasonal drought, floor mass, plant roots, and their reciprocal interactions on the soil microbial biomass, highlighting these factors as pivotal determinants of microbial community dynamics. This study elucidates the interactive regulatory mechanisms by which seasonal drought, floor mass, and plant roots collectively modulate soil microbial biomass within tropical and subtropical forests, offering insights into the complex ecological processes governing microbial community dynamics. This interactive regulation might influence the trajectory of plant species and soil microbial communities, facilitating their adaptive development and evolutionary responses.

Analyzing the impact of phosphorous and nitrogen on Castanopsis sclerophylla early growth stages

Plant growth elements, particularly nitrogen (N) and phosphorus (P) are vital for their growth and development, particularly for understory vegetation and their excess limits the net productivity of terrestrial ecosystems. This study focuses on the understory vegetation responds and adaptation to key essential nutrients under changing climate scenarios in subtropical evergreen broad-leaved forests, still needs research attention. this, we set up an experiment taking four treatments in a 50-year-old Castanopsis sclerophylla secondary forest under (a) control (CK), (b) N, (c) P, and (d) combined N and P addition, applied to natural forest regeneration seedlings of C. sclerophylla attained similar growth parameters of diameter of 3 cm and 10 cm height. In addition, carbon, N, P, and non-structural carbohydrates (NSC) were determined through the anthrone colorimetric approach in different parts of seedlings. Results show that the combined N + P application enhanced the N and P by 14.48 %−140.55 % in the seedlings in both dry and wet seasons, respectively. However, during wet season, the content of NSC in the plant leaves significantly exceeded under P addition. Remarkably, CK showed increased P in the growing season but lower during the dry season. Furthermore, the root starch content of seedlings showed a significant increase under the application of N and P compared to combined N + P, ranging between 45.60 % and 58.70 %. Overall, the plant growth is attributed to N and P intake. The nutrient addition and seasonal variations have a coupled effect on seedling growth as proved in the in the natural open forest experiment. The study outcomes emphasize that the alterations in NSC allocation in the roots and leaves of C. sclerophylla seedlings under N + P addition could enhance their adaptation to future global climate changes, drought conditions, and high N concentrations.

The complete mitochondrial genome of Castanopsis carlesii and Castanea henryi reveals the rearrangement and size differences of mitochondrial DNA molecules

BackgroundCastanopsis carlesii is a dominant tree species in subtropical evergreen broad-leaved forests and holds significant ecological value. It serves as an excellent timber tree species and raw material for cultivating edible fungi. Henry Chinquapin (Castanea henryi) wood is known for its hardness and resistance to water and moisture, making it an exceptional timber species. Additionally, its fruit has a sweet and fruity taste, making it a valuable food source. However, the mitogenomes of these species have not been previously reported. To gain a better understanding of them, this study successfully assembled high-quality mitogenomes of C. carlesii and Ca. henryi for the first time.ResultsOur research reveals that the mitochondrial DNA (mtDNA) of C. carlesii exhibits a unique multi-branched conformation, while Ca. henryi primarily exists in the form of two independent molecules that can be further divided into three independent molecules through one pair of long repetitive sequences. The size of the mitogenomes of C. carlesii and Ca. henryi are 592,702 bp and 379,929 bp respectively, which are currently the largest and smallest Fagaceae mitogenomes recorded thus far. The primary factor influencing mitogenome size is dispersed repeats. Comparison with published mitogenomes from closely related species highlights differences in size, gene loss patterns, codon usage preferences, repetitive sequences, as well as mitochondrial plastid DNA segments (MTPTs).ConclusionsOur study enhances the understanding of mitogenome structure and evolution in Fagaceae, laying a crucial foundation for future research on cell respiration, disease resistance, and other traits in this family.

Progress in Research on Terpenoid Biosynthesis and Terpene Synthases of Lauraceae Species

Lauraceae, an important family of Angiospermae, comprises over 2500 species widely distributed in tropical and subtropical evergreen broad-leaved forests. This family is renowned for its rich resource of terpenoids, particularly monoterpenes, sesquiterpenes, and diterpenes. These compounds not only impart specific scents to Lauraceae species but also play crucial roles in plant growth, development, and environmental adaptation. These compounds also possess extensive bioactivities, such as antioxidant, antibacterial, anti-inflammatory, and neuroprotective effects, making them valuable in the fields of perfumery, cosmetics, food, and medicine, and thus holding significant economic value. Recent advancements in high-throughput technologies, especially genomics, transcriptomics, and metabolomics, have significantly advanced our knowledge of the chemical constituents and biosynthetic pathways of terpenoids in Lauraceae species. Such progress has also shed light on the diversity and functionality of the terpene synthases (TPSs) gene family, a key enzyme involved in terpenoid biosynthesis. This paper reviews the latest research findings on the biosynthetic pathways of terpenoids and their key enzyme-encoding gene families in Lauraceae plants. We also analyze the evolutionary patterns of TPS gene family members of four Lauraceae species at the whole-genome level and summarize their mechanisms of action in secondary metabolite synthesis. Furthermore, this paper highlights the current research challenges and proposes prospects, such as the complexity of gene families, the uncertainties in functional predictions, and unclear regulatory mechanisms. Our objective is to provide scientific foundations for the in-depth analysis of terpenoid biosynthesis mechanisms and the development and utilization of natural products in Lauraceae plants.

A New Fossil Genus of Altingiaceae Based on Unlobed Leaves from Eocene Subtropical Evergreen Broad-leaved Forest in Europe

A New Fossil Genus of Altingiaceae Based on Unlobed Leaves from Eocene Subtropical Evergreen Broad-leaved Forest in Europe

Arsenic and cadmium in the hydrological cycle and soil in a maquis broadleaved evergreen forest stand in Greece. Sources of some uncertainties

ABSTRACT The concentrations and fluxes of arsenic (As) and cadmium (Cd) were examined in the hydrological cycle, litterfall and soils in a maquis broadleaved evergreen forest stand in western Greece. The concentrations of the metals in the hydrological cycle ranged from 0.076 to 0.306 μg L−1 and 0.040–0.050 μg L−1 for As and Cd, respectively. It was found that the enrichment of As in the atmosphere was both due to suspended geogenic material and long range transfer, whereas for Cd the long range transfer was the predominant way for deposition. Two models were assessed to find the volumes of percolation water to compare the fluxes with the estimated ones derived from soil solution measurements. The daily deterministic forest-hydrological model (WBS3) was found to perform better than the physically based 1D semi-distributed soil-plant-atmosphere model (BROOK90). When calculating the total amounts of the heavy metals in soils, the statistical uncertainty derived from every soil layer has to be taken into account. The residence time of Cd in the forest floor (L + FH) of the soils was found 6.4 years, whereas that of As 36.3 years. This difference shows the mobility of Cd in comparison to As in the soils of the area.

Leaf functional traits and ecological strategies of common plant species in evergreen broad-leaved forests on Huangshan Mountain

Leaf functional traits and ecological strategies of common plant species in evergreen broad-leaved forests on Huangshan Mountain

Dendrobium namdongense (D. sect. Dendrobium), a new miniature orchid from limestone mountains of northern Vietnam

Dendrobium namdongense is described here as a new species from limestone areas of the Nam Dong Conservation Area, Thanh Hoa Province, Quan Hoa District (northern Vietnam). This species inhabits primary evergreen broad-leaved and mixed forests on karstic limestone at elevations of 900–1100 m a.s.l. in a zone of humid, cool tropical climate. A detailed illustrated description and comparison of the discovered plant with the morphologically closest species, D. fuscifaucium and D. hekouense is provided, along with data on its distribution, ecology, and phenology. The new species has a potential in ornamental horticulture. According to the criteria of the IUCN Red List, the conservation status of the species is determined as Critically Endangered (CR).

Phylogenetic relatedness and habitat affect seedling abundance of a mid-montane humid evergreen broad-leaved forest in the Gaoligong Mountains, Southwestern China

The neighborhood effect has become an important framework with which to study the mechanisms that maintain the coexistence of tree species. Phylogenetic relatedness among neighboring plants directly affects species coexistence and the maintenance of tree diversity. And some studies have reported that seedling performance is negatively correlated with phylogenetic relatedness, which termed phylogenetic negative density dependence. Soil-borne fungal pathogens affected seedling performance of phylogenetically related host species, i.e., phylogenetic Janzen–Connell effect. Seedlings may be particularly vulnerable to habitat and neighbor characteristics. Although previous studies have demonstrated the influence of neighborhood effects, phylogenetic relatedness, and habitat filtering on seedling survival, growth, and mortality, the effect of variation in these factors on seedling abundance remains unclear. To address this question, we used a 4-ha (200 m × 200 m) and monitored four-year (2020–2023) seedling dataset from a mid-montane humid evergreen broad-leaved subtropical forest in the Gaoligong Mountains, Yunnan, Southwestern China, and which consisted of 916 seedlings belonging to 56 species. The results of generalized linear mixed models showed no significant effect of conspecific adult neighbors on seedling abundance at any of the intervals evaluated. In contrast, we found evidence of phylogenetic distance density dependence in the forests of the Gaoligong Mountains. Specifically, there was a significant positive effect of the relative average phylogenetic distance between heterospecific adult neighbors and focal seedlings on focal seedling abundance in 2020; however, the relative average phylogenetic distance between heterospecific seedling neighbors and focal seedlings had a significant negative effect on seedling abundance over the four-year period (2020–2023). Among the habitat factors, only light (canopy opening) had a negative effect on seedling abundance in all four years. Light resources may be a limiting factor for seedlings, and determine seedling dynamics in subtropical forests. Overall, our results demonstrated that phylogenetic density dependence and habitat filtering affected subtropical seedling abundance. Our findings provide new evidence of the impact of phylogenetic density dependence on seedling abundance in a subtropical mid-montane humid evergreen broad-leaved forest and highlight the need to incorporate the neighborhood effect, phylogenetic relatedness, and habitat factors in models assessing seedling abundance.

Phylogeographic patterns match the floristic subdivisions: The diversification history of a widespread herb in subtropical China.

Subtropical China is dominated by evergreen broad-leaved forests (EBLFs) and is acknowledged as a critical region for its high floristic richness and endemism. Understanding of evolutionary mechanisms of such global biodiversity hotspots comes almost exclusively from long-lived tree species. Herbaceous plants represent critical biodiversity components in forests, however, the diversification history of understory herbs in subtropical EBLFs remain poorly understood. Here, we investigated the phylogeographic patterns and demographic history of Oreocharis auricula, a widespread perennial herb endemic to the EBLFs of subtropical China. Both cpDNA sequences and single-copy nuclear genes were used to investigate the genetic variation among 657 individuals from 68 populations. Evidences from molecular dating, demographic history construction, and species distribution modeling were also combined to infer the phylogeography and evolutionary history of O. auricula. Strong phylogeographic signals have been congruently observed using nuclear and plastid DNA markers, with the diversification patterns generally consistent with the recognized floristic subdivisions of subtropical China. Notably, we revealed an important phylogeographic barrier along the Nanling mountain range, which is also around a climatic transition at 24-26°N latitude in subtropical China, separating the south monsoon subtropical EBLFs from the mid-subtropical EBLFs. Demographic expansion and significant niche divergence were detected among the extant lineages, which may have diverged during the early Pleistocene. The inherent characteristics of understory herbs with limited dispersal and short generation time intensify the genetic divergence response of O. auricula to abiotic forces, contributing to the profound phylogeographic imprints of mountains and climate in such herbaceous flora. To further substantiate the generality of the identified patterns, it is paramount to extend phylogeographic investigations to other understory herbaceous taxa in subtropical China. These results have expanded our understanding of the diversification processes of subtropical forests in China.

Leaf Functional Traits and Their Influencing Factors in Six Typical Vegetation Communities.

Leaf functional traits (LFTs) have become a popular topic in ecological research in recent years. Here, we measured eight LFTs, namely leaf area (LA), specific leaf area (SLA), leaf thickness (LT), leaf dry matter content (LDMC), leaf carbon content (LCC), leaf nitrogen content (LNC), leaf phosphorus content (LPC), and leaf potassium content (LKC), in six typical vegetation communities (sclerophyllous evergreen broad-leaved forests, temperate evergreen coniferous forests, cold-temperate evergreen coniferous forests, alpine deciduous broad-leaved shrubs, alpine meadows, and alpine scree sparse vegetation) in the Chayu River Basin, southeastern Qinghai-Tibet Plateau. Our aim was to explore their relationships with evolutionary history and environmental factors by combining the RLQ and the fourth-corner method, and the method of testing phylogenetic signal. The results showed that (i) there were significant differences in the eight LFTs among the six vegetation communities; (ii) the K values of the eight LFTs were less than 1; and (iii) except for LCC, all other LFTs were more sensitive to environmental changes. Among these traits, LA was the most affected by the environmental factors, followed by LNC. It showed that the LFTs in the study were minimally influenced by phylogenetic development but significantly by environmental changes. This study further verified the ecological adaptability of plants to changes in environmental factors and provides a scientific basis for predicting the distribution and diffusion direction of plants under global change conditions.

Decreased P Cycling Rate and Increased P-Use Efficiency after Phyllostachys edulis (Carrière) J. Houz. Expansion into Adjacent Secondary Evergreen Broadleaved Forest

(1) Background: Moso bamboo (Phyllostachys edulis (Carrière) J. Houz.) expansion has seriously altered the species composition and structure of adjacent forest ecosystems in subtropical regions. However, the shift in phosphorus (P) biogeochemical cycling has yet to be assessed, which is a critical gap considering the great variation in ecophysiological properties between invasive bamboo and the displaced native tree species. (2) Methods: We investigated and compared expansion-induced changes in P pools (plant, litter, and soil) and P fluxes (plant uptake and litterfall return) using paired sampling of the bamboo-dominated forest (BDF) and secondary evergreen broadleaved forest (EBF) at Jiangxi province’s Dagang Mountain National Forest Ecological Station. (3) Results: Both the P storage of the plants and litter were significantly greater by 31.8% and 68.2% in the BDF than in the EBF, respectively. The soil total P and available P storage were 28.9% and 40.4% lower, respectively, in the BDF than in the EBF. Plant P uptake was 15.6% higher in the BDF than in the EBF, and the annual litter P return was 26.1% lower in the BDF than in the EBF due to higher P resorption efficiency for moso bamboo compared with evergreen broadleaved tree species. The ecosystem P cycling rate was reduced by 36.1% in the BDF compared with the EBF. (4) Conclusions: Moso bamboo expansion slowed the broadleaved forest ecosystem’s P cycle rate, likely because moso bamboo has higher P-use efficiency, reserving more P in its tissues rather than returning it to the soil. The results from this study elucidate an understudied element cycle in the context of forest succession, demonstrating the ecosystem consequences related to bamboo invasion.

High-precision estimation of plant alpha diversity in different ecosystems based on Sentinel-2 data

At present, the accuracy of remote sensing estimation models of plant alpha diversity is generally low, and high-precision estimation models in deciduous broadleaved forest (DBF), deciduous coniferous forest (DCF) and evergreen coniferous forest (ECF) are still lacking. The main purpose of this study is to construct high-precision remote sensing models for plant alpha diversity in multiple ecosystems at global scale. Normalized Difference Vegetation Index (NDVI) were derived from Sentinel-2 data. NDVI and NDVI based spectral diversity/heterogeneity indices were selected as predictive variables, and alpha diversity indices were selected as response variables. Simple linear regression (SLR), partial linear regression (PLSR), and random forest (RF) models were used to evaluate the predictive ability of the predictive variables against the response variables under six ecosystems (evergreen broadleaved forest (EBF), DBF, ECF, DCF, shrub, and grassland), and to compare the estimated robustness of various spectral diversity indices. In terms of prediction accuracy, the SLR models were the worst, and the PLSR model were average. RF performed best, outperforming most current models. Especially in DBF, ECF, shrub and grassland, the determination coefficient R2 of RF models can be as high as 0.9. In terms of the prediction of α-diversity, the prediction effect of species richness was better than that of Shannon index, Simpson index and Pielou index. The higher the vegetation complexity, the more accurate the assessment of vegetation α-diversity tends to be, especially in DBF, shrub and grassland. According to the importance of predictive variables and model stability evaluation results, NDVI, standard deviation of NDVI (SD), and NDVI derived Shannon’s diversity index (Sha), Cumulative Residual Entropy (CRE), Pielou’s evenness index (Pie), Hill’s numbers (Hill), Berger-Parker’s diversity index (Ber), Parametric Rao’s index of quadratic entropy(paRao) are all powerful indicators for predicting plant alpha diversity. Among them, the prediction performance of NDVI and SD is better. This study is not only an exploration of the practicability of R package “rasterdiv”, but also an attempt to construct high-precision remote sensing estimation models of plant alpha diversity at global scale.

Increased Soil Moisture in the Wet Season Alleviates the Negative Effects of Nitrogen Deposition on Soil Microbial Communities in Subtropical Evergreen Broad-Leaved Forest

Increased Soil Moisture in the Wet Season Alleviates the Negative Effects of Nitrogen Deposition on Soil Microbial Communities in Subtropical Evergreen Broad-Leaved Forest