Evergreen Broad-leaved Forest In China Research Articles

Effects of seasonal precipitation regimes on microbial biomass and extracellular enzyme activity during shrub foliar litter decomposition in a subtropical forest

Elucidating the mechanisms underlying microbial biomass and extracellular enzyme activity responses to the seasonal precipitation regime during foliar litter decomposition is highly important for understanding the material cycle of forest ecosystems in the context of global climate change; however, the specific underlying mechanisms remain unclear. Hence, a precipitation manipulation experiment involving a control (CK) and treatments with decreased precipitation in the dry season and extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season and proportionally increased precipitation in the wet season (IP) was conducted in a subtropical evergreen broad-leaved forest in China from October 2020 to October 2021. The moisture, microbial biomass, and extracellular enzyme activities of foliar litter from two dominant shrub species, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that (1) both IE and IP significantly decreased the microbial biomass carbon and microbial biomass nitrogen content and the activities of β-1,4-glucosidase, β-1,4-N-acetylglucosaminidase, acid phosphatase and cellulase in the dry season, while the opposite effects were observed in the wet season. (2) Compared with those of IE, the effects of IP on foliar litter microbial biomass and extracellular enzyme activity were more significant. (3) The results from the partial least squares model indicated that extracellular enzyme activity during foliar litter decomposition was strongly controlled by the foliar litter water content, microbial biomass nitrogen, the ratio of total carbon to total phosphorus, foliar litter total carbon, and foliar litter total nitrogen. These results provide an important theoretical basis for elucidating the microbial mechanisms driving litter decomposition in a subtropical forest under global climate change scenarios.

Effect of the seasonal precipitation regime on shrub litter decomposition in a subtropical forest

Changes in the seasonal precipitation regime induced by global climate change may alter moisture and the dynamics of related microbes and enzymes, thereby significantly affecting forest litter decomposition; however, the specific mechanisms remain unclear. Hence, a precipitation manipulation experiment including the treatments of control (CK), decreased precipitation in the dry season with extremely increased precipitation in the wet season (IE) and decreased precipitation in the dry season with proportionally increased precipitation in the wet season (IP) was performed from October 2020 to October 2021 in a subtropical evergreen broad-leaved forest in China. The moisture, chemical properties, microbial biomass, enzyme activity, and decomposition rates of two dominant shrub species foliar litter, Phyllostachys violascens and Alangium chinense, were measured at six stages during the dry and wet seasons. The results showed that both IE and IP significantly increased the litter decomposition rates (more than 2.0% for P. violascens and more than 4.7% for A. chinense, respectively), while the effects of IE were the most significant, which was mainly related to the precipitation availability and the frequency of dry-wet cycle. Furthermore, the IE and IP increased the wet season’s contribution to the annual total decomposition regardless of litter species, and more significant effects were also observed in IE. Additionally, the results of structural equation model indicated that the seasonal precipitation regime could regulate the decomposition process directly by changing moisture and the contents of elements and refractory substances, as well as indirectly by influencing the related microbial biomass and enzyme activity. These results deepen the understanding of the biogeochemical cycle in forest ecosystems under the global climate change scenarios.

Nitrogen addition changes the canopy biological characteristics of dominant tree species in an evergreen broad-leaved forest

Many studies have focused on the impact of nitrogen deposition on plants, but due to technical limitations, research on the responses of forest canopy to manipulated nitrogen deposition is relatively scarce. Based on a canopy nitrogen addition (CN) platform, this study used laboratory analysis and unmanned aerial vehicle (UAV) observations to assess the impact of CN on the canopy traits of dominant tree species (Engelhardia roxburghiana, Schima superba, and Castanea henryi) in an evergreen broad-leaved forest in China. The results showed that nitrogen application at 25 kg N ha−1 y−1 (CN25) and 50 kg N ha−1 y−1 (CN50) significantly increased the actual net photosynthetic rate (An) of all the three tree species. CN25 significantly increased superoxide dismutase (SOD), catalase (CAT), and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activities in C. henryi. CN50 significantly increased the leaf area of all the three tree species and significantly reduced the leaf thickness of C. henryi, and significantly increased the POD and Rubisco activities in S. superba and C. henryi. CN significantly changed the number of forest gaps, but did not significantly change the area of forest gaps within the sample plots. CN25 significantly decreased the vertical projection area but increased the canopy flowering coverage of S. superba in dominant directions. CN25 and CN50 significantly increased the flowering coverage of C. henryi in favorable directions. It is found that under long-term (10-year) nitrogen addition, the balance between carbon fixation and antioxidant defense functions of E. roxburghiana may be broken down, but the carbon assimilation, antioxidant capacity and reproduction potential of S. superba and C. henryi may be well coordinated, which will have a potential impact on the species composition and ecological functions of the evergreen broad-leaved forest. This study may also provide scientific basis for forest management in the context of enhanced atmospheric nitrogen deposition.

Community structure and species diversity dynamics of a subtropical evergreen broad-leaved forest in China: 2005 to 2020

Here, we characterize the temporal and spatial dynamics of forest community structure and species diversity in a subtropical evergreen broad-leaved forest in China. We found that community structure in this forest changed over a 15-year period. Specifically, renewal and death of common species was large, with the renewal of individuals mainly concentrated within a few populations, especially those of Aidia canthioides and Cryptocarya concinna. The numbers of individual deaths for common species were concentrated in the small and mid-diameter level. The spatial distribution of community species diversity fluctuated in each monitoring period, showing a more dispersed diversity after the 15-year study period, and the coefficient of variation on quadrats increased. In 2010, the death and renewal of the community and the spatial variation of species diversity were different compared to other survey years. Extreme weather may have affected species regeneration and community stability in our subtropical monsoon evergreen broad-leaved forests. Our findings suggest that strengthening the monitoring and management of the forest community will help better understand the long- and short-term causes of dynamic fluctuations of community structure and species diversity, and reveal the factors that drive changes in community structure.

The carbon and nitrogen metabolisms of Ardisia quinquegona were altered in different degrees by canopy and understory nitrogen addition in a subtropical forest

Although effects of atmospheric nitrogen (N) deposition on forest plants have been widely investigated, N interception and absorption effects by forest canopy should not be neglected. Moreover, how N deposition change the molecular biological process of understory dominant plants, which was easily influenced by canopy interception so as to further change physiological performance, remains poorly understood. To assess the effects of N deposition on forest plants, we investigated the effects of understory (UAN) and canopy N addition (CAN) on the transcriptome and physiological properties of Ardisia quinquegona, a dominant subtropical understory plant species in an evergreen broad-leaved forest in China. We identified a total of 7394 differentially expressed genes (DEGs). Three of these genes were found to be co-upregulated in CAN as compared to control (CK) after 3 and 6h of N addition treatment, while 133 and 3 genes were respectively found to be co-upregulated and co-downregulated in UAN as compared to CK. In addition, highly expressed genes including GP1 (a gene involved in cell wall biosynthesis) and STP9 (sugar transport protein 9) were detected in CAN, which led to elevated photosynthetic capacity and accumulation of protein and amino acid as well as decrease in glucose, sucrose, and starch contents. On the other hand, genes associated with transport, carbon and N metabolism, redox response, protein phosphorylation, cell integrity, and epigenetic regulation mechanism were affected by UAN, resulting in enhanced photosynthetic capacity and carbohydrates and accumulation of protein and amino acid. In conclusion, our results showed that the CAN compared to UAN treatment had less effects on gene regulation and carbon and N metabolism. Canopy interception of N should be considered through CAN treatment to simulate N deposition in nature.

Influences of the bark economics spectrum and positive termite feedback on bark and xylem decomposition.

The plant economics spectrum integrates trade-offs and covariation in resource economic traits of different plant organs and their consequences for pivotal ecosystem processes, such as decomposition. However, in this concept stems are often considered as one unit ignoring the important functional differences between wood (xylem) and bark. These differences may not only affect the performance of woody plants during their lifetime, but may also have important "afterlife effects." Specifically, bark quality may strongly affect deadwood decomposition of different woody species. We hypothesized that (1) bark quality strongly influences bark decomposability to microbial decomposers, and possibly amplifies the interspecific variation in decomposition by invertebrate consumption, especially termites; and (2) bark decomposition has secondary effects on xylem mass loss by providing access to decomposers including invertebrates such as termites. We tested these hypotheses across 34 subtropical woody species representing five common plant functional types, by conducting an insitu deadwood decomposition experiment over 12-month in two sites in subtropical evergreen broad-leaved forest in China. We employed visual examination and surface density measurement to quantify termite consumption to both bark and the underlying xylem, respectively. Using principal component analysis, we synthesized seven bark traits to provide the first empirical evidence for a bark economics spectrum (BES), with high BES values (i.e., bark thickness, nitrogen, phosphorus, and cellulose contents) indicating a resource acquisitive strategy and low BES values (i.e., carbon, lignin, and dry matter contents) indicating a resource conservative strategy. The BES affected interspecific variation in bark mass loss and this relationship was strongly amplified by termites. The BES also explained nearly half of the interspecific variation in termite consumption to xylem, making it an important contributor to deadwood decomposition overall. Moreover, the above across-species relationships manifested also within plant functional types, highlighting the value of using continuous variation in bark traits rather than categorical plant functional types in carbon cycle modeling. Our findings demonstrate the potent role of the BES in influencing deadwood decomposition including positive invertebrate feedback thereon in warm-climate forests, with implications for the role of bark quality in carbon cycling in other woody biomes.

The complete plastid genome sequence of Quercus ciliaris (Fagaceae)

Quercus ciliaris C.C.Huang & Y.T.Chang is one of the dominant tree species in the subtropical evergreen broad-leaved forests of China. In this study, we sequenced and analyzed the complete chloroplast (cp) genome of the species. The circular genome is 160,842 bp in size, consisting of two copies of inverted repeat (IR) regions of 25,823 bp, one large single-copy (LSC) region of 90,294 bp, and one small single-copy (SSC) region of 18,902 bp. It encodes a total of 114 unique genes, including 80 protein-coding genes, 30 tRNA genes, and four rRNA genes. Phylogenetic analysis based on cp genome sequences of 35 Fagaceae species indicated that Q. ciliaris was among the members of section Cyclobalanopsis, and was most closely related to Q. myrsinifolia.

The Use of DNA Barcoding to Assess Phylogenetic β-Diversity in Mid-Subtropical Evergreen Broad-Leaved Forests of China

The application of quantifying phylogenetic information into measures of forest β-diversity is increasing for investigating the underlying drivers of community assembly along environmental gradients. In terms of assessing evolutionary inferences of community processes, a variety of plant DNA barcodes has been widely used in phylogenetic diversity measurements. However, relatively few studies have evaluated the effectiveness of DNA barcodes with using nuclear region in estimating phylogenetic β-diversity, particularly for communities in tropical or subtropical forests. In this study, we employed DNA barcodes combing with the nuclear region to construct the community phylogeny and examined the patterns of phylogenetic β-diversity of three mid-subtropical evergreen broad-leaved forests (EBLFs) in South China. Three phylogenetic construction methods were performed, including a Phylomatic-generated tree and two ML trees based on the combination of rbcL +matK +ITS with or without a constrained tree. Our results showed that the DNA barcodes including nuclear ITS constructed a highly resolved phylogenetic tree, but the application of a constrained tree had little influence on estimation of phylogenetic diversity metrics (mean pairwise distances and mean nearest taxon distances) based on branch lengths. Using both metrics and their standardized effect size metrics, we found that the patterns of phylogenetic β-diversity in mid-subtropical forests were non-random. There was a slight decline of phylogenetic β-diversity with increasing latitudes, but no trend was found along the altitude gradient. According to the analysis of variation partition, both environmental filtering and dispersion limitation could explain the variation of phylogenetic dissimilarity between communities in mid-subtropical EBLFs of China. Our results highlight the importance of neutrality and the niche conservatism in structuring the patterns of species diversity in subtropical woody communities.

Development of defoliating insects and their preferences for host plants under varying temperatures in a subtropical evergreen forest in eastern China

The aim of this work was to understand the development of defoliating insects and their preferences for host plants under varying temperatures in a subtropical evergreen broad-leaved forest in China. We measured the main developmental parameters of three typical defoliating insects (i.e., Ourapteryx ebuleata szechuana, Biston marginata, and Euproctis angulata) and their preferences for five host plants at temperatures from 16°C to 31°C at 3°C intervals in the Tiantong National Forest Research station in eastern China. The results showed the following. 1) An appropriate rise in temperature increases the survival rate with an increase in the number of offspring. The developmental durations for these three insects were shortened, and pupal weight increased with an increase in temperature. 2) A shift in the preference for host plants for these three insects was observedat elevated temperatures. They all preferred to feed on Schima superba and Castanopsis sclerophylla at elevated temperatures, showing an opposite response to the other three plants. The daily leaf consumption of the three insects was positively correlated with their feeding preference, with more leaves being consumed from the plants they preferred. 3) For O. ebuleata szechuana larvae, daily leaf consumption initially increased and then decreased with increasing temperatures. In contrast, Biston marginata and Euproctis angulata larvae consumed more leaves at elevated temperatures. The feeding preferences of O. ebuleata szechuana and Biston marginata were more sensitive to changing temperatures than that of Euproctis angulata laevae. We concluded that increased numbers of offspring and generations, pupal weights, and a shift in preference to two plants for these three defoliating insects might lead to severe damage to these two plants which would enhance the fragmentation and decrease the stability of the forest communities under changing temperatures. Meanwhile, the variations in the responses of defoliating insects to the changing temperatures should be taken into consideration for the pest management of forests to adapt to the changing climate.

Traits of dominant tree species predict local scale variation in forest aboveground and topsoil carbon stocks

Background and Aims Forests play a vital role in regulation of the global carbon cycle. Mechanistically understanding how their ecosystem functioning relates to biodiversity is necessary for predicting the consequences of biodiversity loss and for setting conservation priorities. Here, we test whether carbon stocks in a subtropical evergreen broad-leaved forest in China are more strongly influenced by plant functional diversity (FD), as would be predicted by the ‘niche complementarity hypothesis’, or by community-weighted mean (CWM) functional trait values, as would be predicted by the ‘mass ratio hypothesis’.

Effects of Varying Temperature on Leaf Phenology and Herbivory of Dominant Tree Species in Subtropical Evergreen Broad-Leaves Forest in Eastern China

ABSTRACT The aim of this work was to analyse the response of dominant tree species to the changing climate in a subtropical evergreen broad-leaved forest in China. We investigated the main leaf phenology and herbivory parameters of four typical trees (i.e., Schima superba, Castanopsis fargesii, Castanopsis sclerophylla and Cyclobalanopsis sessilifolia) in spring from 2010 to 2014 in the Tiantong National Forest Research Station in eastern China. The results showed that the accumulated temperature was the principle factor which affected the leaf phenology and herbivory. All four trees got an earlier, shorter and more synchronised leaf expansion in years with higher accumulated temperature, and also they suffered more sever leaf damage in these years. However the trees responded differently to climate warming in leaf phenology and herbivory. The S. superba and Ca. sclerophylla were more sensitive to the varying accumulated temperature than the Ca. fargesii and Cy. sessilifolia both in leaf phenology and her...

Completing the life history of Castanopsis fargesii: changes in the seed dispersal, seedling and sapling recruitment patterns

The spatial distribution of species in forest ecosystems involves the underlying ecological processes or mechanisms of population and community structure, as well as forest dynamics. Because the relative importance of these factors can shift across life history stages, assessment of local population and community structures in the context of life history stages is essential for understanding forest dynamics. In this study, we investigated the changes in the spatial patterns of seed dispersal as well as seedling and sapling recruitment for Castanopsis fargesii, a dominant tree species in a subtropical evergreen broad-leaved forest in China. We found notably aggregated spatial patterns for C. fargesii seeds during the seed dispersal. A majority of seeds and newly germinated seedlings aggregated under adult tree canopies, suggesting a decreased efficiency in secondary dispersal for C. fargesii within this evergreen broad-leaved forest. During the later stages of life history (i.e., seedling and sapling stages), the spatial distribution of C. fargesii getting segregated. This is caused by a negative density dependence mechanism in seedling recruitment, rather than by spatial dispersion due to secondary dispersal. By incorporating the patterns and processes across the life history stages of dominant species of evergreen broad-leaved forests, we can add specific details in developing methods of stage-based in situ forest management and conservation frameworks.

亚热带中山常绿阔叶林木本幼苗数量动态及其与生境的相关性

亚热带中山常绿阔叶林木本幼苗数量动态及其与生境的相关性

Correction: Topographic Variation in Aboveground Biomass in a Subtropical Evergreen Broad-Leaved Forest in China

Correction: Topographic Variation in Aboveground Biomass in a Subtropical Evergreen Broad-Leaved Forest in China

Topographic Variation in Aboveground Biomass in a Subtropical Evergreen Broad-Leaved Forest in China

The subtropical forest biome occupies about 25% of China, with species diversity only next to tropical forests. Despite the recognized importance of subtropical forest in regional carbon storage and cycling, uncertainties remain regarding the carbon storage of subtropical forests, and few studies have quantified within-site variation of biomass, making it difficult to evaluate the role of these forests in the global and regional carbon cycles. Using data for a 24-ha census plot in east China, we quantify aboveground biomass, characterize its spatial variation among different habitats, and analyse species relative contribution to the total aboveground biomass of different habitats. The average aboveground biomass was 223.0 Mg ha−1 (bootstrapped 95% confidence intervals [217.6, 228.5]) and varied substantially among four topographically defined habitats, from 180.6 Mg ha−1 (bootstrapped 95% CI [167.1, 195.0]) in the upper ridge to 245.9 Mg ha−1 (bootstrapped 95% CI [238.3, 253.8]) in the lower ridge, with upper and lower valley intermediate. In consistent with our expectation, individual species contributed differently to the total aboveground biomass of different habitats, reflecting significant species habitat associations. Different species show differently in habitat preference in terms of biomass contribution. These patterns may be the consequences of ecological strategies difference among different species. Results from this study enhance our ability to evaluate the role of subtropical forests in the regional carbon cycle and provide valuable information to guide the protection and management of subtropical broad-leaved forest for carbon sequestration and carbon storage.