Han Xu

Chinese Academy of Forestry | CAF · Research Institute of Tropical Forestry

Thismia jinzun, a new fully mycoheterotrophic species has been discovered from Hainan Province, China. Thismia jinzun is similar to T. javanica and T. tentaculata in overall appearance, but it obviously differs from the latter two species in several characters. Thismia jinzun has 10-12 mm long, gold-yellow tepal appendages (vs 20-30 mm long, orange...

Understanding the correlation between topography, species biomass and species life stage would allow forest managers to better foster carbon storage in forests. Using census data from a 60-ha plot in south China, we first quantified aboveground biomass (AGB) and how much it varied among different topographies. Next, the specific contribution of 42...

Herbivorous insects alter biogeochemical cycling within forests, but the magnitude of these impacts, their global variation, and drivers of this variation remain poorly understood. To address this knowledge gap and help improve biogeochemical models, we established a global network of 74 plots within 40 mature, undisturbed broadleaved forests. We a...

Host specialization plays a critical role in the ecology and evolution of plant–microbe symbiosis. Theory predicts that host specialization is associated with microbial genome streamlining and is influenced by the abundance of host species, both of which can vary across latitudes, leading to a latitudinal gradient in host specificity. Here, we quan...

Introduction Tropical forests are characterized by intricate mosaics of species-rich and structurally complex forest communities. Evaluating the functional vulnerability of distinct community patches is of significant importance in establishing conservation priorities within tropical forests. However, previous assessments of functional vulnerabilit...

Soil microbial necromass carbon is an important component of the soil organic carbon (SOC) pool which helps to improve soil fertility and texture. However, the spatial pattern and variation mechanisms of fungal- and bacterial-derived necromass carbon at local scales in tropical rainforests are uncertain. This study showed that microbial necromass c...

The spatial distribution of plant, soil, and microbial carbon pools, along with their intricate interactions, presents a great challenge for the current carbon cycle research. However, it is not clear what are the characteristics of the spatial variability of these carbon pools, particularly their cross-scale relationships. We investigated the cros...

Rising global stoichiometric imbalance between increasing nitrogen (N) availability and depleting phosphorus (P) resources increases the importance of soil microbial P recycling. The contribution of extra- versus intracellular P (re-)cycling depending on ecosystem nutrient status is vastly unclear, making soil microorganisms a blind spot in our und...

Questions The minimum sampling area (minimum area) is the smallest space that reflects species composition and characteristics of a plant community. The quantitative concept of minimum area is often estimated using species–area relationships (SARs) and has become the classical foundation for managing protected areas. However, sampling designs to de...

Ecosystem services refer to the benefits that human obtain from natural ecosystems. Different ecosystem services are generated by the combination of social-ecological driving factors, and exhibit different spatial patterns across scales. The complex relationships and driving mechanisms among ecosystem services under different spatial scales remain...

Predicting and managing the structure and function of plant microbiomes requires quantitative understanding of community assembly and predictive models of spatial distributions at broad geographic scales. Here, we quantified the relative contribution of abiotic and biotic factors to the assembly of phyllosphere bacterial communities, and developed...

Premise: The ever-increasing temperatures of the Anthropocene may facilitate plant invasions. To date, studies of temperature effects on alien plants have mainly focused on plant aboveground traits but ignored belowground roots, which may hinder our predictions of plant invasion risks under climate change. Methods: The temperature effects on the...

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified...

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs, or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified...

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs, or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified...

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs, or even in holes in the ground; however, in the humid rainforests of Jianfengling in Hainan, South China, we show that some flying squirrels cache elliptical or oblate nuts by hanging them securely in vegetation. These small flying squirrels were identified...

Accounting for intraspecific trait variation (ITV) is crucial to plant ecology for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with community d...

Tropical forests, where the soils are nitrogen (N) rich but phosphorus (P) poor, have a disproportionate influence on global carbon (C) and N cycling. While N deposition substantially alters soil C and N retention in tropical forests, whether P input can alleviate these N-induced effects by regulating soil microbial functions remains unclear. We in...

Squirrels of temperate zones commonly store nuts or seeds under leaf litter, in hollow logs or even in holes in the ground; however, in humid rainforests, it is an evolutionary challenge for squirrels to hang elliptical or oblate nuts securely on trees to minimize germination or fungal infection. Here, we report a unique behaviour used by two speci...

Microorganisms govern soil nutrient cycling. It is therefore critical to understand their responses to human-induced increases in N and P inputs. We investigated microbial community composition, biomass, functional gene abundance, and enzyme activities in response to 10-year N and P addition in a primary tropical montane forest, and we explored the...

Plant-associated microbes influence plant ecology, evolution, and ecosystem function, while explaining the diversity and abundance of these microbes at broad geographic scales remains problematic. Here we quantified the contribution of biotic and abiotic factors to the diversity and biogeography of leaf-associated bacteria on woody plants across a...

[Objective] This study aims to investigate the effects of urban-rural gradient and forest stand type on the fractions of forest soil aggregates and their stability mechanisms and provide a theoretical basis for the elucidation of regional soil quality assessment. [Methods] Three typical forest stand types under the urban-rural gradient of the Pearl...

Aim Diversity may increase the resistance of ecosystem productivity to environmental stress, such as warming, via compensatory processes associated with adjustments of species interactions. However, experimental evidence of compensatory processes that buffer productivity declines in relation to environmental stress is limited, especially in below‐g...

Identifying patterns and drivers of plant community assembly has long been a central issue in ecology. Many studies have explored the above questions using a trait‐based approach; however, there are still unknowns around how patterns of plant functional traits vary with environmental gradients. In this study, the responses of individual and multiva...

Plants respond differently to the identity of their neighbors, such as their sex and kinship, showing plasticity in their traits. However, how the functional traits of dioecious trees are shaped by the recognition of neighbors with different sex and kinship remains unknown. In this study, we set up an experiment with different kin/nonkin and inter/...

Pine forest (PF), mixed pine and broadleaf forest (MF), broad-leaved evergreen forests (BF), along successional stages of forest, were selected to explore the change of soil aggregates stability in typical urban forests in dry season. The distribution of soil aggregates, soil physical and chemical properties, microbial biomass and extracellular enz...

Despite important progress in understanding the impacts of forest clearing and logging on above‐ground communities, how these disturbances affect soil microbial β‐diversity and the ecological processes driving microbial assemblages are poorly understood. Furthermore, whether and how the microbial shifts affect vegetation composition and diversity d...

Recent studies have revealed that interkingdom relationships in below-aboveground metacommunity may contribute to ecosystem functions more than species diversity. While effects of deforestation on aboveground interactions have been well studied, the responses of interactions among plant, soil bacterial and fungal communities to deforestation are po...

Premise: The ever-increasing temperatures of the Anthropocene may facilitate plant invasions. To date, studies of temperature effects on alien plants have mainly focused on plant aboveground traits but ignored belowground roots, which may hinder our predictions of plant invasion risks under climate change. Methods: The temperature effects on the r...

Arbuscular mycorrhizal (AM) and ectomycorrhizal (EcM) associations are critical for host-tree performance. However, how mycorrhizal associations correlate with the latitudinal tree beta-diversity remains untested. Using a global dataset of 45 forest plots representing 2,804,270 trees across 3840 species, we test how AM and EcM trees contribute to t...

Tropical forests are the most diverse and productive ecosystems on Earth. While better understanding of these forests is critical for our collective future, until quite recently efforts to measure and monitor them have been largely disconnected. Networking is essential to discover the answers to questions that transcend borders and the horizons of...

The decline in species richness at higher latitudes is among the most fundamental patterns in ecology. Whether changes in species composition across space (beta-diversity) contribute to this gradient of overall species richness (gamma-diversity) remains hotly debated. Previous studies that failed to resolve the issue suffered from a well-known tend...

Accounting for intraspecific trait variation (ITV) is central to plant ecology and crucial for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with...

Accounting for intraspecific trait variation (ITV) is crucial to plant ecology for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with community d...

Accounting for intraspecific trait variation (ITV) is central to plant ecology and crucial for vegetation modeling efforts. ITV can be substantial; however, it remains unclear how ITV influences community-weighted mean (CWM) trait estimates. We use leaf and root trait data from 423 trees of 72 species from 15 Angiosperm families in combination with...

Aim Biological invasions threaten biodiversity globally. Large‐scale studies of non‐native plant species invasiveness typically focus on identifying ecological differences between naturalized and invasive species that account for their spread from sites of initial establishment (i.e., invasion success). However, invasive species differ widely in th...

Aims: For plants, elemental nutrients are important belowground resources that sustain growth and survival. To understand how tropical plant nutrient status responds to environmental variation, we asked whether concentrations of nutrients in root and leaf tissues track gradients in soil nutrient concentrations and if tissue nutrient concentrations...

A new species of Gastrodia (Orchidaceae: Epidendroideae, Gastrodieae), G. qingyunshanensis, is described and illustrated from Guangdong, China. It is closely related to G. appendiculata C. S. Leou & N. J. Chung but can be distinguished by an urceolate (vs bell-like) and dark brown (vs pale greenish brown) perianth tube, the smaller petals (2.5 × 1....

en Conspecific negative density dependence (CNDD) is an important mechanism facilitating species coexistence in plant communities. Yet, which factors influence CNDD is still not clear. Here, we examined the factors influencing CNDD in tree species within a 60‐ha tropical rainforest dynamics plot. Point pattern analysis was used to test the existenc...

ForestGEO is a network of scientists and long-term forest dynamics plots (FDPs) spanning the Earth's major forest types. ForestGEO's mission is to advance understanding of the diversity and dynamics of forests and to strengthen global capacity for forest science research. ForestGEO is unique among forest plot networks in its large-scale plot dimens...

Aim Beta diversity can be partitioned into the contributions of individual sampling units to overall beta diversity, which are comparative indicators of the ecological uniqueness of species assemblages in the sampling units. Yet, what determines ecological uniqueness has rarely been examined. Here, we investigated the determinants of ecological uni...

We studied the biogeography and community structure of root-associated and ectomycorrhizal fungal communities in two related species of tropical Juglandaceae that have disjunct distributions in Asia and Mesoamerica. We tested the effects of environmental and dispersal factors in structuring root-associated fungi at a regional scale. We used Illumin...

This correction stands to correct the listed errors in the original article: 1. In the Abstract, under the Results subheading, a sentence reads: "From secondary to primary forests, mean root system diameter increased 0.4 mm, mean specific root length decreased 3.5 m kg −1 , and mean root system branching intensity decreased by 0.3 tips cm −1 ." The...

The rapid urbanization and industrialization have increased global atmosphere nitrogen (N) deposition year by year, and the N deposition amount in tropical and subtropical areas is higher than the global average value. However, majority of the soil from tropical and subtropical forests is almost N saturation. The elevated N deposition will continuo...

--Key message-- In older, unlogged rainforest of Hainan Island, China, leaves of saplings were larger, and fine root systems of saplings were thicker with fewer root tips than in historically logged areas. These results were consistent among 15 Angiosperm lineages, even though families differed widely in their leaf and root traits. --Context-- How...

The latitudinal gradient of declining species richness at higher latitudes is among the most fundamental patterns in ecology. However, whether changes in species composition across space (beta-diversity) contribute to this global gradient of species richness remains debated. Previous studies that failed to resolve the issue suffered from a well-kno...

A new species of Polygonatum (Asparagaceae), P. daminense is described and illustrated from Pan’an, Zhejiang, China. The new species is similar to P. filipes, but differs from it for some features of the rhizome, the inflorescence, the peduncle, the pedicel, the bract, the bractlet and the perianth. The new species is only known from Zhejiang Provi...

Legumes provide an essential service to ecosystems by capturing nitrogen from the atmosphere and delivering it to the soil, where it may then be available to other plants. However, this facilitation by legumes has not been widely studied in global tropical forests. Demographic data from 11 large forest plots (16–60 ha) ranging from 5.25° S to 29.25...

Biotic diversity of ecological communities can be driven by a mixture of climatic, soil and biotic factors from local to regional scales. Patterns of diversity change were often examined along latitudinal or elevational gradients, which were mainly driven by climatic factors. However, few studies have assessed biodiversity patterns along both abiot...

Climate change could alter plant aboveground and belowground resource allocation. Compared with shoots, we know much less about how roots, especially root system architecture (RSA) and their interactions, may respond to temperature changes. Such responses could have great influence on species'acquisition of resources and their competition with neig...

A new species of Thismia (Thismiaceae), T. jianfenglingensis, is described and illustrated from Hainan Island, China. The new species is similar to T. hongkongensis, displaying a urecolate perianth tube, a loose dome with six perianth lobes, six stamens, and three stigmas. T. jianfenglingensis differs from T. hongkongensis in the color and morpholo...

Understanding the ecological processes that regulate microbial community assembly in different habitats is critical to predict microbial responses to anthropogenic disturbances and environmental changes. Rubber (Hevea brasiliensis) and Eucalypt (Eucalyptus urophylla) plantations (thereafter RP and EP) are rapidly established at the expense of fores...

Acacia mangium (AM) and Pinus massoniana (PM) are widely planted in tropical regions, whereas their effects on soil microbial communities remain unclear. We did a comprehensive investigation of soil denitrifying bacterial communities in AM and PM monoculture plantations in Southern China based on the high throughput sequencing data of their functio...

Research Highlights: We try to evaluate the relative contribution of environmental factors and functional traits on aboveground biomass in a species rich tropical forest ecosystem after a 40-years natural recovery. Background and Objectives: Functional traits have a potential to incorporate community dynamics into the impacts of disturbance histori...

Isotrema sanyaense R.T.Li, X.X.Zhu & Z.W.Wang, sp. nov. , a new species from Hainan island, China, is described and illustrated here. It is morphologically most similar to I. ledongense (Han Xu, Y.D.Li & H.J.Yang) X.X.Zhu, S.Liao & J.S.Ma and I. jianfenglingense (Han Xu, Y.D.Li & H.Q.Chen) X.X.Zhu, S.Liao & J.S.Ma in the shape of leaf, flower, and...

Symbiotic nitrogen (N)‐fixing trees can provide large quantities of new N to ecosystems, but only if they are sufficiently abundant. The overall abundance and latitudinal abundance distributions of N‐fixing trees are well characterised in the Americas, but less well outside the Americas. Here, we characterised the abundance of N‐fixing trees in a n...

Understanding the relative contribution of abiotic and biotic factors to the formation of ecosystem functioning across scales is vital to evaluate ecosystem services. Here, we elucidate the effects of abiotic site conditions (i.e., soil and topographic properties) and plant functional traits on variations of stand aboveground carbon (AGC) stock in...

1. Quantifying the dimensions and magnitude of intraspecific root trait variation is key to understanding the functional trade-offs in the belowground plant strategies of tropical forest trees. Additionally, accurately measuring how belowground functional trait variation relates to soil environment and forest age is crucial to tropical forest model...

Understanding the underlying mechanisms of diversity maintenance in tropics remains a challenge for ecologists. To reveal the underlying mechanism from a plant‐eye‐view perspective, we examined the patterns of local species richness which was defined as the number of species around individuals of a target species within circles of different radii a...