Evergreen Broad-leaved Forest Research Articles

Spring phenology rather than climate dominates the trends in peak of growing season in the Northern Hemisphere.

Shifts in plant phenology regulate ecosystem structure and function, which feeds back to the climate system. However, drivers for the peak of growing season (POS) in seasonal dynamics of terrestrial ecosystems remain unclear. Here, spatial-temporal patterns of POS dynamics were analyzed by solar-induced chlorophyll fluorescence (SIF) and vegetation index in the Northern Hemisphere over the past two decades from 2001 to 2020. Overall, a slow advanced POS was observed in the Northern Hemisphere, while a delayed POS distributed mainly in northeastern North America. Trends of POS were driven by the start of growing season (SOS) rather than pre-POS climate both at hemisphere and biome scale. The effect of SOS on the trends in POS was the strongest in shrublands while the weakest in evergreen broad-leaved forest. These findings highlight the crucial role of biological rhythms rather than climatic factors in exploring seasonal carbon dynamics and global carbon balance.

Canopy Phenology and Meteorology Shape the Seasonal Dynamics in Hydrological Fluxes of Dissolved Organic Carbon in an Evergreen Broadleaved Subtropical Forest in Central Japan

Seasonal variabilities in hydrological fluxes of dissolved organic carbon (DOC) and their driving factors in the evergreen broad-leaved forest are inadequately understood. To aid this understanding, we conducted a three-year study to examine seasonal changes in DOC concentration and flux in throughfall, stemflow, and litter leachate in an evergreen broad-leaved subtropical forest in central Japan. We specifically addressed (1) how DOC in different hydrological fluxes vary on a monthly to seasonal basis, and (2) how canopy phenology and meteorology shape the DOC concentration and flux of throughfall, stemflow, and litter leachate trends in this evergreen forest. Clear seasonal changes were found in throughfall and stemflow DOC concentration but not in litter leachate DOC concentration; the highest throughfall DOC concentrations were observed in spring (10.03 mg L−1 in 2017 and 9.59 mg L−1 in 2018, respectively) and the highest stemflow DOC concentrations were observed in summer (13.95 mg L−1 in 2017 and 16.50 mg L−1 in 2018, respectively). Correlation analysis revealed the monthly throughfall DOC concentration to be positively related to the dry weight of fallen leaves (r = 0.72, p < 0.05) and flowers (r = 0.91, p < 0.05). In addition, Random Forest models predicted that the dry weight of flowers was a primary driver of throughfall DOC concentration and that the DOC concentrations of stemflow and litter leachate were constrained by the throughfall DOC concentration. DOC fluxes in different hydrological flux were significantly positive related to bulk precipitation amounts and temperature. Moreover, the throughfall DOC concentration had a considerable effect on throughfall and litter leachate DOC fluxes. Over 75% of annual net tree-DOC (throughfall + stemflow) fluxes and more than 70% of the annual litter leachate DOC fluxes were produced in the flowering season. Thus, we speculated that the seasonal phenological canopy changes (leaf emergence, fallen leaves, flowering, and pollen) and the sufficient rainfall had great impacts on the amount and quality of DOC concentrations in the evergreen forest; and, furthermore, that the DOC from different forest hydrological fluxes was a significant fraction of the carbon that accumulates in soils.

Comparative study of forest biomass and carbon stocks of Margalla Hills National Park, Pakistan

Forests can play an important role in climate change mitigation. However, limited information is available worldwide regarding forest carbon and biomass stocks. Financial mechanisms such as ‘reducing emissions from deforestation and forest degradation and the role of conservation of forest carbon, sustainable management of forests and enhancement of forest carbon stocks’ (REDD+) also emphasize the quantification of forest biomass and carbon. This study aimed to estimate the forest biomass in two forests of Margalla Hills National Park (MHNP): Sub-tropical Chir Pine Forest (SCPF) and Sub-tropical Broadleaved Evergreen Forest (SBEF). For this, circular sampling plots of a 20 m radius were used for the collection of the variables, “diameter at breast height (DBH) and height”. Statistical analysis was done for exploring regression relationships between the variables. We found a mean Aboveground Carbon (AGC) of 73.36 ± 32.55 Mg C ha−1 in SCPF and a mean AGC of 16.88 ± 25.81 Mg C ha−1 in SBEF. The mean Aboveground Biomass (AGB) for SCPF was recorded as 146.73 ± 65.11 Mg ha−1, while for SBEF it was 33.77 ± 51.63 Mg ha−1. It was therefore concluded that the SCPF had higher mean AGB and mean AGC than the SBEF. Similar differences were also noticed in the structural characteristics of the two forests. These could be valuable information while designing sustainable management plans and afforestation programmes for the future and also for accessing nature-based funding such as REDD+.

Ecological Characteristics of Evergreen Forest in Yesong-ri, Wando-gun (Natural Monument No. 40)

Background and objective: Evergreen broad-leaved forests native to the islands of the southwest coast have been adapted to a range of climatic or geographical environmental factors. Although they are of high importance as cultural and ecological landscape resources, they have been damaged by tourism and climate change, and thus measures to protect and manage them are required. This study was conducted to suggest the characteristics of the vegetation structure and management plan of the evergreen forest in Yesong-ri, Natural Monument No. 40.Methods: Twenty-three quadrats were established in the vegetation communities where broad-leaved evergreens dominate or appear in the canopy, understory, and shrub layers, and the area where the vegetation was restored after the buildings was demolished. Based on survey data on the vegetation, the characteristics were identified after classifying the communities using TWINSPAN and DCA ordination techniques.Results: The plant communities were classified into a total of 5 dominant groups: <i>Castanopsis sieboldii-Camellia japonica, C. sieboldii, Celtis sinensis, Neolitsea sericea, Camellia japonica</i>, and <i>Machilus thunbergii-Quercus glauca</i>. The study site was a windbreak forest that has been protected and managed by the villagers for a long time. As time passes, broad-leaved evergreens including <i>N. sericea, Q. acuta</i>, and <i>C. sieboldii</i> have flowed into and spread to the surrounding area. It seems that a similar but unique ecosystem was formed. Looking into the relationship between environmental factors and vegetation distribution, it was analyzed that the slope, clay, and Na<sup>+</sup> had direct or indirect effects on the vegetation distribution.Conclusion: The width of the windbreak forest was narrow, and the continuity was interrupted by the indiscriminate activities of tourists, installation of facilities, expansion and construction of warehouses and commercial facilities, and the destruction of peripheral and understory vegetation was in progress. To maintain the integrity of the forest, it is necessary to purchase and demolish buildings and facilities belonging to the interior after establishing boundaries and spheres of influence, and to restore it to a good evergreen broad-leaved forest using a reference model for areas with damaged vegetation and manage it.

Genetic structure of an endangered species Ormosia henryi in southern China, and implications for conservation

BackgroundThe evergreen broadleaved forest (EBLF) is an iconic vegetation type of East Asia, and it contributes fundamentally to biodiversity-based ecosystem functioning and services. However, the native habitat of EBLFs keeps on decreasing due to anthropogenic activities. Ormosia henryi is a valuable rare woody species in EBLFs that is particularly sensitive to habitat loss. In this study, ten natural populations of O. henryi in southern China were sampled, and then genotyping by sequencing (GBS) was applied to elucidate the standing genetic variation and population structure of this endangered species.ResultsIn ten O. henryi populations, 64,158 high-quality SNPs were generated by GBS. Based on these markers, a relatively low level of genetic diversity was found with the expected heterozygosity (He) ranging from 0.2371 to 0.2901. Pairwise FST between populations varied from 0.0213 to 0.1652, indicating a moderate level of genetic differentiation. However, contemporary gene flow between populations were rare. Assignment test and principal component analysis (PCA) both supported that O. henryi populations in southern China could be divided into four genetic groups, and prominent genetic admixture was found in those populations located in southern Jiangxi Province. Mantel tests and multiple matrix regression with randomization (MMRR) analyses suggested that isolation by distance (IBD) could be the possible reason for describing the current population genetic structure. In addition, the effective population size (Ne) of O. henryi was extremely small, and showed a continuous declining trend since the Last Glacial Period.ConclusionsOur results indicate that the endangered status of O. henryi is seriously underestimated. Artificial conservation measures should be applied as soon as possible to prevent O. henryi from the fate of extinction. Further studies are needed to elucidate the mechanism that leading to the continuous loss of genetic diversity in O. henryi and help to develop a better conservation strategy.

A remote sensing based method for assessing the impact of O3 on the net primary productivity of terrestrial ecosystems in China

O3 pollution in China has been increasing in recent years, but the process of O3 impact on net primary productivity of terrestrial ecosystems remains unclear. We attempts to explore a remote sensing-based method to assess the impact of O3 on NPP of China’s terrestrial ecosystems by combining MODIS NPP and the latest ground observation data of O3 concentration. By comparing the NPP data of MODIS image pixels with the 6-year average AOT40 data of corresponding pixels, we extracted the signal data that highlighted the effects of O3 on NPP and established the response relationships between AOT40 and NPP. It was found that NPP was significantly negatively correlated with AOT40 in farmland and grassland ecosystems in China (farmland: r = 0.8674, p < 0.003, grassland: r = 0.7181, p < 0.03). Then the response relationships were adopted to evaluate the effect in China in 2014. The results showed that the estimated percentage of O3-induced NPP decline was in the range of 5%–35%. Among them, the most significant declines were found in farmland ecosystems, with the vast majority of declines in 10%–35%. The decrease rate of evergreen coniferous forests ranked second, mostly in the range of 15%–20%. The grassland ecosystems declined at a lower rate, almost between 5% and 15%. And the evergreen broad-leaved forests has the lowest decline rate, most distributed in 0%–5%. The highest percentage decreases were mainly found in the Beijing-Tianjin-Hebei region and Shandong Province. And the decline rate of farmland ecosystems was significantly higher than other ecosystem types.

Soil water movement changes following conversion from evergreen and deciduous broad-leaved mixed forests to Chinese fir plantations

Soil water movement changes following conversion from evergreen and deciduous broad-leaved mixed forests to Chinese fir plantations

A chromosome-scale genome assembly of Castanopsis hystrix provides new insights into the evolution and adaptation of Fagaceae species.

Fagaceae species dominate forests and shrublands throughout the Northern Hemisphere, and have been used as models to investigate the processes and mechanisms of adaptation and speciation. Compared with the well-studied genus Quercus, genomic data is limited for the tropical-subtropical genus Castanopsis. Castanopsis hystrix is an ecologically and economically valuable species with a wide distribution in the evergreen broad-leaved forests of tropical-subtropical Asia. Here, we present a high-quality chromosome-scale reference genome of C. hystrix, obtained using a combination of Illumina and PacBio HiFi reads with Hi-C technology. The assembled genome size is 882.6 Mb with a contig N50 of 40.9 Mb and a BUSCO estimate of 99.5%, which are higher than those of recently published Fagaceae species. Genome annotation identified 37,750 protein-coding genes, of which 97.91% were functionally annotated. Repeat sequences constituted 50.95% of the genome and LTRs were the most abundant repetitive elements. Comparative genomic analysis revealed high genome synteny between C. hystrix and other Fagaceae species, despite the long divergence time between them. Considerable gene family expansion and contraction were detected in Castanopsis species. These expanded genes were involved in multiple important biological processes and molecular functions, which may have contributed to the adaptation of the genus to a tropical-subtropical climate. In summary, the genome assembly of C. hystrix provides important genomic resources for Fagaceae genomic research communities, and improves understanding of the adaptation and evolution of forest trees.

Strategic differentiation of subcommunities composed of evergreen and deciduous woody species associated with leaf functional traits in the subtropical mixed forest

The joint assembly of evergreen and deciduous tree species, typical karst vegetation of evergreen and deciduous broad-leaved mixed forests through respective subcommunities, play an important role in maintaining biodiversity in subtropical karst regions, and leaf functional traits can strategically specify plant resource utilization. However, it is unclear how these assembled subcommunities of evergreen and deciduous species maintain differentiation strategies. This study surveyed 53 forest plots of 20 m × 20 m dividing 212 adjacent lattices in a typical karst forest. Leaf traits of woody plants were measured regarding the specific leaf area (SLA), leaf dry matter content (LDMC), leaf tissue density (ltd), and leaf C, N, and P contents. The differences between deciduous and evergreen subcommunities were compared using the community-weighted means (CWM). The SLA and LDMC of the deciduous subcommunity were greater than the evergreen subcommunity; meanwhile, the leaf C, C/N and C/P ratios of the evergreen subcommunity were significantly higher than those of the deciduous subcommunity. However, the leaf N, P and N/P ratios of the deciduous subcommunity were significantly enhanced than the evergreen subcommunity. Moreover, both subcommunities showed significant negative correlations between SLA, leaf N and ltd, LDMC, signifying a trade-off of leaf-economic trait in deciduous and evergreen subcommunities. Furthermore, principal component analysis (PCA) on leaf functional traits specified the strategic differentiation mainly located at the side of the resource acquisition with high SLA and leaf N content for the deciduous subcommunity and situated at the side of the resource conservation with high LDMC and ltd for the evergreen subcommunity. In conclusion, the trade-off correlated with leaf functional trait differentiation suggested a resource acquisition strategy for the deciduous subcommunity and a resource conservation strategy for the evergreen subcommunity in the subtropical climate-dominating mixed forest of karst ecosystem.

Rare species contribute greater to ecosystem multifunctionality in a subtropical forest than common species due to their functional diversity

Global environmental change and increased human activities have led to rare species being given vulnerable status, as well as species losses and extinctions in recent years. However, most of the species in the community are rare species and they usually harbor unique functional traits that disproportionately contribute to community functional diversity. Numerous studies have also shown that functional diversity is a better predictor of ecosystem functioning than species diversity. Consequently, the evaluation of functional diversity of rare species and their contribution to ecosystem function is essential for the conservation of rare species. In this study, differences in functional diversity between rare and common plant species were analyzed based on functional diversity indices and species richness metrics in 30 1-ha plots comprising monsoonal evergreen broad-leaved forest in Pu’er City in the Yunnan Province of China. The roles of functional diversity of rare and common species in affecting ecosystem functions were also evaluated, in addition to the extent that either species group contributes to ecosystem functions or multifunctionality. The results indicated that functional diversity metrics including functional evenness and functional richness of rare species were higher than for common species in this subtropical forest. In addition, the functional diversity indices of rare species contributed greater to most ecosystem functions compared to those of common species. Moreover, the functional divergence of both rare and common species exerted obvious effects on ecosystem multifunctionality, although rare species exerted greater overall contributions. Rare species in the forest community of this study exhibited higher functional diversity and played a more important role in ecosystem multifunctionality via their diverse functional traits. Based on these results, it is necessary to focus greater conservation efforts on rare plants in a community.

Consistent effects of nitrogen addition on soil microbial communities across three successional stages in tropical forest ecosystems

Global nitrogen (N) deposition has been having broad impacts on soil microorganisms. It remains unclear how soil microbial biomass and community structure respond to elevated N deposition during forest succession, especially in tropical forest ecosystems. In this study, we conducted a field manipulative experiment of long-term N addition (14 years) at three levels (CK, LN, MN, which stand for 0, 50 kg N ha−1 yr−1 and 100 kg N ha−1 yr−1) along a 3-step succession sequence of tropical forests (early stage: a pine conifer forest, CF; middle stage: a mixed pine conifer and broad-leaved forest, MF; and late stage: a monsoon evergreen broad-leaved forest, BF), and investigated the responses of microbial composition, biomass and community structure using fumigation-extraction and phospholipid fatty acid (PLFA) methods. We found that: 1) Microbial biomass (microbial biomass carbon and nitrogen and PLFA contents) remained stable under long-term N addition, even though N addition significantly increased soil N nutrients (P < 0.05); it increased significantly with forest succession (P < 0.05), and was dominated by soil water content, which was not affected by N treatment; 2) microbial community structure was significantly changed by N addition, but not by forest succession. N addition, especially MN, significantly increased the ratio of cyclopropyl to its precursor (cyc/pre) in the MF and BF (P < 0.05), and cyc/pre of the BF showed the highest correlations with ammonium-N, nitrate-N and electrical conductivity (>0.85, P < 0.05). Consistently, the pure N treatment effect could explain 71.13% of the variance of cyc/pre; and 3) N treatment contributed more variance to the fungal community than to the bacterial community. Our results indicated that soil microbial community structure was more sensitive to N addition than community biomass under long-term N addition, and the structure would be more severely altered under N addition during forest succession or with the increase in N input.

Effects of Landscape Context on Bird Community in the Subtropical Evergreen Broad-Leaved Forest of Wuyishan National Park.

Landscape context can reflect the habitat structure and play an important role in bird species occurrences and abundance. For local biodiversity conservation and restoration, we examined the effects of landscape context on bird communities at different altitude gradients. Our study was conducted in four altitude gradients (<300 m, 300-599 m, 600-899 m, 900-1200 m) of subtropical evergreen broad-leaved forest in Wuyishan National Park, China. The bird survey was carried out in 115 transects in spring, summer, autumn and winter. We examined the effects of altitude, season and landscape context. The result showed that (1) species richness and abundance at <300 m altitude were highest among the four altitude gradients, and they showed more significant differences than those at other altitude gradients; (2) the species richness of birds was associated with altitude, season and landscape context, as the season is more significant than other explanatory variables; (3) at the landscape level, habitat configuration is more important. The average canopy height and contagion index positively correlated with the species richness and abundance of birds at all four altitude gradients. In particular, the average canopy height is significant at 300-599 m and 600-899 m altitude gradients. The study results can provide a theoretical basis and guidance for future national park conservation and management and ecological restoration in the subtropical evergreen broad-leaved forest regions.

An Overview of Oak Species in Pakistan: Past, Present, and Future Research Perspectives

Quercus spp. have formed broad-leaved evergreen forests in the Hindu Kush and Himalayan regions of Pakistan. Seven species of the genus Quercus (Q. baloot Griff., Q. dilatata Royle., Q. glauca Thunb., Q. incana Roxb., Q. robur Linn., Q. semecarpifolia Smith., and Q. leucotrichophora A. Camus.) have been identified. These species have received little attention compared with other economically valuable plant species in Pakistan, which has been mainly linked to traditional medicine and the identification of phytonutrients to evaluate their bioactivities and toxicological effects. Quercus spp. are promising for commercial applications, so government policy should encourage their management and conservation. However, they are currently threatened by severe human activities and climate change. The goal of this review is to highlight the relevance of these forgotten species, describing overall aspects related to their distribution, morphology, traditional uses, phytochemical constituents, and threats. To date, no proper and comprehensive molecular studies on the populations of these species found in Pakistan have been conducted, which is a critical gap as molecular studies are essential for conservation and management strategies. Finally, we discuss future directions in molecular approaches for Quercus that follow the strategies that are being used for other species of the genus Quercus that are not found in Pakistan.

Regeneration characteristics and influencing factors of woody plant on natural evergreen secondary broad-leaved forests in the subtropical, China

Natural regeneration occupies an important position in forest ecosystems and is affected by various factors. Exploring natural regeneration and its influencing factors is helpful to understand the forest community dynamic. Evergreen broad-leaved forest is an essential zonal vegetation type in China. However, the natural regeneration of evergreen broad-leaved forests in the northernmost margin of subtropical zone has not been reported. Here we investigated 22 observed variables, and selected four categories of latent variables stand factor, topographical factor, soil factor and tree diversity as influential factors based on the survey data of 50 (20 m × 20 m) permanent sample plots. The structural equation model was introduced to distinguish the direct, indirect and total effect of influencing factors on understory woody plant regeneration diversity and regeneration density, respectively. We found 51 regeneration species under 31 families and five dominant species Loropetalum chinense, Symplocos sumuntia, Quercus glauca, Ilex chinensis, and Eurya japonica in the study area. Soil factor was the primary control of regeneration, which had the greatest and negative total effect on regeneration diversity (-0.436) and regeneration density (-0.298). The main soil factors that affected regeneration diversity and regeneration density were total phosphorus and soil organic matter, respectively. Soil factor mainly affected indirectly regeneration by mediating through its impacts on tree diversity. Tree diversity and topographical factor all were significantly positively correlated with the regeneration diversity and regeneration density. Stand factor had a significantly negative correlation with regeneration density but a significantly positive with regeneration diversity. Our study provides the basis to introduce appropriate artificial auxiliary measures for improving the natural regeneration of forest stands, so as to promote sustainable forest management.

Effects of warming on quantity and structure of litter-derived dissolved organic matter in subtropical natural Castanopsis kawakamii forests.

Litter-derived dissolved organic matter (DOM) is an important source of soil DOM, and the response of which to climate warming may change forest soil carbon and nitrogen dynamics, such as soil carbon and nitrogen mineralization. In this study, we conducted a field manipulative warming experiment in natural Castanopsis kawakamii forests. Combined with litter leaching solution collected in the field and ultraviolet-visible and three-dimensional fluorescence spectroscopy analyses, we explored the effects of warming on the content and structure of litter-derived DOM in subtropical evergreen broad-leaved forests. The results showed that litter-derived dissolved organic carbon and nitrogen content exhibited monthly dynamics, with the peak (in April) and the mean monthly content being 1.02 and 0.15 g·m-2, respectively. Litter-derived DOM had higher fluorescence index and lower biological index, indicating the microbial-origin of DOM from litter. The litter DOM mainly included humic-like fractions and tryptophan-like substances. Warming did not affect the content, aromaticity, hydrophobicity, molecular weight, fluorescence index, biological index and humification index of DOM, suggesting neutral effect of warming on the quantity and structure of litter DOM. Warming also did not affect the relative contribution of main components in DOM, indicating that the temperature variation exerted no effects on microbial degradation. In summary, warming did not change the quantity and quality of litter-derived DOM in subtropical evergreen broadleaved forests, indicating warming had little effect on litter-derived DOM input to soil.

A dataset of groundwater level in the small watershed of Dinghushan Forest (2002 – 2020)

Groundwater is one of the important components in the hydrological cycle of the basin. Its dynamic change is of great value for understanding the hydrological regulation mechanism, the cycle of material elements and ecosystem service function of terrestrial ecosystem. Covered with subtropical monsoon evergreen broad-leaved forest and its transitional vegetation types, Dinghushan National Nature Reserve has been well protected since the 1950s. Dinghushan Forest Ecosystem Research Station set up four groundwater level observation wells downstream of the complete catchment area of Dinghushan Nature Reserve according to the observation specifications and quality control requirements of terrestrial ecosystem water environment, so as to carry out long-term standardized positioning observation of the depth of groundwater level. This dataset collates the long-term monitoring data of four groundwater level observation wells from 2002 to 2020. It is aimed to provide basic data support for the study of groundwater response process, the evaluation of hydrological service function of forest ecosystem and the sustainable management of forest resources under the background of global climate change.

Roots, Litter, and Seasonal Drought Together Inhibit Plant Growth in the Herbaceous Layer in a Subtropical Moist Forest of Southwestern China

The mechanisms of the maintenance of plant diversity in forests have been extensively studied because of their ecological importance. The study of the regeneration and growth dynamics of herbaceous understory communities in forests is relatively more common than that of woody plant overstory and understory communities. To investigate which environmental factors (plant roots, forest litter, or both) control seedling survival, growth, and production in the herbaceous layer in the context of increasingly severe seasonal drought caused by global climate change, we performed a seedling growth experiment of the herbaceous layer influenced by the interaction of plant roots and forest litter through a manipulative complete block experiment, crossed with an irrigation experiment, in a montane subtropical moist evergreen broad-leaved forest of southwestern China. Within both the control and watered plots, we established four experimental subplots with plant roots and forest litter included (R+L+); plant roots included, but forest litter excluded (R+L−); plant roots excluded, but forest litter included (R−L+); and both plant roots and forest litter excluded (R−L−). After one year, the R+L+ treatment in the control plot had statistically less species richness and plant individuals, shorter mean and maximum seedling heights, and less dry biomass of plant seedlings than those in the other seven experimental treatments. Across all the experimental replicates, the pooled data showed that plant roots, forest litter, and seasonal drought, together, inhibited all the dependent herbaceous growth variables. Our study demonstrates how plant roots, forest litter, and seasonal drought synergistically regulate seedling establishment and the growth of the herbaceous layer in tropical and subtropical forest understory. This synergistic regulation changes plant physiological responses and forest evolution through controlling plant diversity and the individual richness of the herbaceous layer in the context of sustained global climate change.

Changes in and driving forces of ecosystem services in tropical southwestern China

Tropical forests provide important ecosystem services and biodiversity for the world. With human activities and economic growth, tropical forests are becoming the primary sources of new plantations, making tropical regions hotspots of ecosystem service degenerations and biodiversity losses. Understanding the driving forces of ecological consequences is the key to local sustainable development and human well-being improvements. Therefore, we spatially quantified the changes in ecosystem services in tropical China in the past twenty years by remote sensing and InVEST model. The driving forces were further investigated by using Geodetector. We found that: 1) in the past twenty years, the area of evergreen broad-leaved forests, coniferous forests, and rubber forests have increased by 13.01%, 43.39%, and 101.23%, respectively. The shrublands and agricultural lands are the major contributors to these increased areas; 2) with the area increasing of forests, carbon storage and soil retention have increased by 9.40% and 0.30%, while nitrogen export and water yield have decreased by 43.30%, and 12.27%. This pattern of increase in carbon storage and soil retention was found in the highlands, while not in the lowlands, where large areas of evergreen broad-leaved forests have been converted to rubber forests; 3) NDVI was highly correlated to the carbon storage (q value = 0.201) and nitrogen export (q value = 0.109), while slope and precipitation mainly affected the soil retention (q value = 0.253) and water yield (q value = 0.073), respectively. This study provides a reference for ecological protection and management in tropical China.

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.

Coupling Relationship between Rural Settlement Patterns and Landscape Fragmentation in Woodlands and Biological Reserves—A Case of Nanshan National Park

Exploring the influence of settlement patterns on the landscape fragmentation in woodlands and biological reserves is key to achieving ecologically sustainable development. In this research, we chose the Nanshan National Park in Hunan Province, China, as a case study, to explore the influence mechanisms. First, we identified the biological reserves through the landscape security patterns of biological conservation. Second, we constructed a coupling coordination model to analyze the coupling relationship between the settlement patterns and landscape fragmentation in the woodlands and biological reserves. The analysis showed that, overall, the effect of the settlement area on the landscape fragmentation in the biological reserves was more pronounced, while the effect of the settlement spread and shape on the landscape fragmentation in the woodlands was more obvious. From a type-specific perspective, we analyzed the coupling relationship between the settlement patterns and (1) the landscape fragmentation in different woodlands and (2) the landscape fragmentation in the biological reserves, namely concerning Leiothrix lutea and Emberiza aureola. We found that the effect of the settlement patterns on the landscape fragmentation of the Leiothrix lutea biological reserve was more significant than that of the landscape fragmentation of its main habitat, the evergreen broad-leaved forest. The effect of settlement patterns on the landscape fragmentation of the Emberiza aureola biological reserve was more significant than that of the landscape fragmentation of its other habitats. In addition, the results demonstrated that the habitat protection of the woodlands was not a substitute for the systematic protection of biosecurity patterns. This research could assist in developing more efficient conservation measures for ecologically protected sites with rural settlements.