Forest Biodiversity Research Articles

Tank formation transforms nitrogen metabolism of an epiphytic bromeliad and its phyllosphere bacteria.

Up to half of tropical forest plant species grow on other plants. Lacking access to soils, vascular epiphytes have unique adaptations for mineral nutrition. Among the most distinctive is the tank growth form of certain large bromeliads, which absorb nutrients that are cycled by complex microbial communities in water trapped among their overlapping leaf bases. However, tanks form only after years of growth by juvenile plants, which must acquire nutrients differently. Understanding how nutrient dynamics change during tank bromeliad development can provide key insights into the role of microorganisms in the maintenance of tropical forest biodiversity. We evaluated variations in plant morphology, growth, foliar nitrogen physiology, and phyllosphere bacterial communities along a size gradient spanning the transition to tank formation in the threatened species Tillandsia utriculata. Sequential morphological and growth phases coincided with the transition to tank formation when the longest leaf on plants was between 14 and 19 cm. Before this point, foliar ammonium concentrations were very high, but after, leaf segments absorbed significantly more nitrate. Leaf-surface bacterial communities tracked ontogenetic changes in plant morphology and nitrogen metabolism, with less-diverse communities in tankless plants distinguished by a high proportion of taxa implicated in ureolysis, nitrogen fixation, and methanotrophy, whereas nitrate reduction characterized communities on individuals that could form a tank. Coupled changes in plant morphology, physiology, and microbiome function facilitate the transition between alternative nutritional modes in tank bromeliads. Comparing bromeliads across life stages and habitats may illuminate how nitrogen-use varies across scales.

Ecosystem extent is a necessary but not sufficient indicator of the state of global forest biodiversity

AbstractThe Kunming‐Montreal Global Biodiversity Framework lays out an ambitious set of goals and targets aimed at halting and reversing biodiversity loss. The extent of natural ecosystems has been selected as one of a small set of headline indicators against which countries will report progress under this framework. We evaluate the effectiveness with which this indicator is expected to capture the overall scope of the ecosystem‐focused component of Goal A, and interlinkages with the species‐focused component of this same goal, using extensive global data on the integrity, connectivity, and plant species composition of forests. Results generated for all forest‐supporting countries demonstrate that consideration of these additional factors can profoundly alter understanding of the state of forest biodiversity relative to that based on extent alone. Employment of ecosystem extent as a headline indicator must therefore be augmented by appropriate use of component and complementary indicators addressing other key dimensions of ecosystem change.

Comparing expedient and proactive approaches to the planning of protected area networks on Borneo

Protected areas are an important tool for wildlife conservation; however, research is increasingly revealing both biases and inadequacies in the global protected area network. One common criticism is that protected areas are frequently located in remote, high-elevation regions, which may face fewer threats compared to more accessible locations. To explore the conservation implications of this issue, we consider a thought experiment with seven different counterfactual scenarios for the Sunda clouded leopard’s conservation on Borneo. This allows us to examine two contrasting paradigms for conservation: “proactive conservation” which prioritises areas with high biodiversity and high risk of development, and “expedient conservation” which focusses on areas with the lowest development risk. We select clouded leopards as our focal species not only because of their emerging conservation importance, but also because, as top predators, they represent both keystone species and ambassadors for wider forest biodiversity. Furthermore, a published analysis of the likely impacts of forest loss in their habitat provides a benchmark for evaluating the modelled outcomes of alternative hypothetical conservation scenarios. We find that, across all metrics, expedient reserve design offered few benefits over the business-as-usual scenario, in contrast to the much greater conservation effectiveness of proactive protected area design. This paper sheds light on the challenging trade-offs between conservation goals and the competing land uses essential for the economic development and well-being of local communities.

Assessment of Woody Species Biodiversity and Carbon Stock Potentials in the Arboretum of National School of Water and Forests of Mbalmayo, Center Region of Cameroon

Assessing forest biodiversity is crucial for supporting sustainable forest planning. We investigated the potential for biodiversity and carbon sequestration in both artificial and natural forests of the arboretum of the National School of Water and Forests (ENEF) of Mbalmayo. A floristic inventory was carried out in 72 plots measuring 25m x 25m in the artificial forest covering an area of 4.5ha, and in a quadrat measuring 250m x 180m in the natural forest of the arboretum. Carbon stocks were determined by the non-destructive method using allometric equations. The results of the woody biodiversity inventories identified 77 species belonging to 69 genera and 33 families. This species richness varied from 69 species in the natural forest to 58 species in the artificial forest. Tree density was slightly higher in the artificial forest (616 ±339 ind/ha) than in the natural forest (312 ±176 ind/ha), without being significantly different. Basal area was constant in both types of forest studied, with an average of 55.97 ±36.28 m2/ha in the artificial forest and 58.33 ±19.42 m2/ha in the natural forest. The greatest quantity of sequestered carbon was found in the natural forest with 432±146.49 tC/ha compared with 400.69±328.37 tC/ha in the artificial forest. Nevertheless, these rates were not significantly different according to the ANOVA test. Given the importance of this massif in carbon sequestration and the needs of local populations, ENEF should support these populations in agroforestry practices and in the domestication of priority tree species.

Veteranising Scots pine trees by initiating tree hollowing: Inoculation with the fungal keystone species Porodaedalia pini

Hollow trees are crucial for forest biodiversity but are becoming increasingly rare in many ecosystems, including the Scots pine forests of northern Europe. Here, we inoculated heartwood of live Scots pine trees with the fungal keystone species Porodaedalia pini to initiate tree hollowing. The fungus was inoculated in 50-, 110- and 170-year old stands, using wood dowels containing mycelia. Three different strains were used to test for intraspecific variation. Molecular analysis of samples from inoculated trees seven years after treatment showed that 67% were successfully colonised, with no differences between stands. Fungal strain had no effect on colonisation success. Our findings suggest that inoculation with P. pini has the potential to be an efficient method to restore a key ecological process, tree hollowing, in degraded Scots pine forests. The possibility of initiating the process even in young trees may be a way to accelerate the formation of hollow pines in younger forests.

Is there variation in ten woody species reproductive phenology within the Atlantic Forest biodiversity hotspot?

ABSTRACT Understanding reproductive phenology in tropical and subtropical forests is challenging. Thus, there are scarce large-scale phenological studies for those forests. Digitized herbarium collections can provide valuable information for understanding biological rhythms, e.g. timing of reproduction. Our aim was to verify the geographical variability of flowering and fruiting patterns and the effects of local climate on the reproductive phenology of woody species in the Atlantic Forest biodiversity hotspot. We used herbarium records compiled from the Global Biodiversity Information Facility – GBIF, speciesLink, JABOT, and the “Portal de Datos de Biodiversidad Argentina” as a main source of data to assess differences in reproductive phenology for 10 species with wide geographical distribution in the Atlantic Forest. Contrary to our expectations, we observed a non-seasonal reproductive phenology of all species and relations with temperature in the northern forests and to precipitation in the southern forests. When considered individually, there was no obvious relationship between phenophases and climatic factors. We expected that species occurring in a broad geographic distribution would change their biological rhythms related to local environmental factors, but it is likely that widely distributed species are abundant exactly because they are less dependent on biophysical characteristics of the environment. This is the first study comparing species located in the northern and southern regions of the Atlantic Forest using herbarium data, highlighting its importance to understand large scale ecological rhythms in tropical biomes.

21 МАРТ СВЕТОВЕН ДЕН НА ГОРАТА

This article presents an innovative interdisciplinary open lesson conducted on March 21, 2024, in celebration of World Forest Day. The lesson aimed to provide students with comprehensive knowledge about forests and their ecosystems, including the processes of erosion, the diversity of plant and animal species, and the importance of environmental preservation. The methodology combines theoretical learning with practical activities, such as planting seeds and observing forest biodiversity, both in the classroom and in a real forest environment. The lesson was divided into two parts: the first part included a presentation on the significance of forests, interactive discussions, and creative tasks using artificial intelligence tools. The second part involved a field trip to a local forest park, where students engaged in hands-on activities like tree planting and cleaning up the forest. The expected outcomes were to enhance students’ understanding of the natural environment, instill a sense of responsibility towards nature, and develop practical skills in environmental conservation. The interdisciplinary approach, integrating subjects such as science, physical education, language arts, and technology, provided a holistic learning experience that emphasized the interconnectedness of different areas of knowledge and the importance of protecting our planet.

Ecological and socio-economic factors influence stand biodiversity

Biodiversity is associated with functional protection, adaptation to external conditions, and ecosystem resilience. Therefore, maintaining forest ecosystems with high biodiversity is essential for improving resistance and resilience to disturbances. In addition to the ecological factors influencing forest ecosystems, various socio-economic factors associated with forests can influence the ecosystem. However, socio-economic impacts on forest biodiversity have rarely been addressed. In this study, we investigated whether tree species diversity (TSD) of forest stands varies with ownership status (national vs. private forests). In addition, selected ecological (stand characteristics, site conditions, and climate) and socio-economic (regional forest management sectors, population, forestry population, forest coverage, and forestry income) factors influencing TSD were determined using data from the National Forest Inventory in South Korea. National forests had higher TSD than private forests, reflecting differences in management objectives. Among ecological factors, stand structural diversity (SDivI) was the most influential in both national and private forests. Socio-economic factors, such as population, forest coverage, forest income, and forest management bodies, significantly influenced the TSD, although the impact was smaller compared to ecological factors. Our results suggest that securing stand growth and development is essential for increasing stand structural diversity, which leads to an increase in TSD. Furthermore, our study shows that socio-economic factors can influence forest conditions over time. To better understand the factors influencing the state of forests and manage forests sustainably in the future, collaborative research bridging ecological and sociological fields is necessary.

Bioindicator aquatic insects at risk from climate change in a biodiversity hotspot

Climate change can affect biological assemblages by shifting their species' geographic range and changing species richness. Aquatic insects represent more than half of the freshwater animal species but have been neglected mainly in climate change assessments, particularly in tropical ecosystems. Among the aquatic insect taxa, Ephemeroptera, Plecoptera, and Trichoptera (EPT) are well-known bioindicators of environmental changes and encompass an essential metric for rivers and streams' biomonitoring. Here, we use ecological niche models to project the impact of climate change on the distribution range and richness of EPT in the Atlantic Forest biodiversity hotspot. We found EPT to be at high risk from future climate change, with Plecoptera as the order of greatest concern. We projected range contraction of ca. 90 % of the analyzed EPT genera, resulting in a reduction in the richness of EPT genera under future climatic conditions. We projected >50 % contraction in the distribution of 50 % of Plecoptera, ≈14 % of Trichoptera, and ≈7 % of Ephemeroptera genera. The remaining climatically suitable regions in the Atlantic Forest are concentrated in the high-altitude areas, which may act as climate refuges for EPT biodiversity in the future. The projected changes in EPT's distribution range and richness may impact biomonitoring programs conducted in tropical ecosystems. Restricting EPT's geographic distribution may undermine its potential as a bioindicator and influence the composition of EPT assemblages at reference sites, which may lead to shifting baseline conditions. We reinforce the importance of considering future climatic conditions when planning long-term biomonitoring and priority areas for conservation.

Estimating the dynamics of ecosystem functions under climate change in a temperate forest region

Understanding the dynamics and spatial patterns of forest biodiversity and functioning is vital for effective conservation and management. This study introduces a new framework for estimating the spatio-temporal dynamics of biodiversity and ecosystem functions in northeastern China. Our novel approach evaluates 96 future scenarios, including four points in time, four socio-economic pathways, and six global climate models based on an extensive network of permanent field plots with specific bioclimatic, topographic, and soil data. Our findings indicate a future trend of diminishing biodiversity and forest biomass productivity and increasing biomass density and carbon storage. The relationship between biodiversity and ecosystem functionality indicates a non-linear response to changes in temperature and precipitation, and a stable correlation between biodiversity and ecosystem stability across most of the socio-economic pathways. Unravelling the complex relationship between biodiversity, ecosystem functions, and stability of production, in the face of global change, requires new methods of analysis that were used in this study, including machine learning and other advanced methods.

Diel rhythms of fish frequentation in a temperate mesophotic antipatharian forest and sleeping behaviour of the red swallowtail perch Anthias anthias (Linnaeus, 1758)

A 21-day continuous monitoring of a highly tridimensional forest of the black coral Antipathella subpinnata (Ellis and Solander 1786) was carried out in the NW Mediterranean Sea at 63 m depth using an autonomous lander to investigate the diel short-term dynamics of the vagile fauna associated to the forest. The survey allowed to assess several aspects of the forest attractiveness and its use, especially by the ichthyofauna, including (i) the diversity and shifts of the fish community inhabiting three layers of the environment (seafloor, canopy, water column) between four light phases (dawn, day, dusk, night), (ii) the diel rhythm in forest use of the red swallowtail perch Anthias anthias (Linnaeus 1758) and its sleeping behaviour in terms of fidelity towards resting sites, duration of rests, and awakenings triggers, and, finally, (iii) the influence of biotic and abiotic variables on the fish behaviour. Considering that, so far, only spot censuses have been carried out in these habitats, this study provides a dynamic approach to the study of biodiversity in temperate mesophotic coral forests and offers an insight into the functioning of these complex and vulnerable ecosystems.

The forest biodiversity index (FOBI): monitoring forest biodiversity potential over space and time

Public forest agencies are obligated to take steps to conserve and where possible enhance biodiversity, but they often lack information and tools that support and evidence their decision making. To help inform and monitor impact of management actions and policies aimed at improving forest biodiversity, we have co-developed a quantitative, transparent and repeatable approach for assessing the biodiversity potential of the United Kingdom’s (UK) publicly owned forests over space and time. The FOrest Biodiversity Index (FOBI) integrates several forest biodiversity indicators or ‘metrics’, which characterise management-sensitive woodland and landscape features associated with biodiversity. These are measured or modelled annually using spatially comprehensive forest survey data and other well-maintained spatial environmental datasets. Following metric normalisation and a correlation analysis, a statistically robust selection of these metrics is aggregated using a hierarchical procedure to provide composite index scores. The FOBI metric and index results are provided for every individual public forest, and can be summarised across any reporting region of interest. Compared to existing indicators that rely on sample-based forest data, the results thus better support decisions and obligations at a range of scales, from locally targeted action to national, long-term biodiversity monitoring and reporting. We set out how the FOBI approach and associated bespoke online interfaces were co-developed to meet public forest agency needs in two constituent countries of the UK (England and Scotland), whilst providing a conceptual framework that can be adapted and transferred to other geographic areas and private forests. Example results are reported for England’s public forests for four annual timestamps between 2014 and 2021, which indicate improvements to the biodiversity potential of public forests and surrounding landscapes over this time via increases in their diversity, extent, condition and connectivity.

Old-growth mapping in Patagonia’s evergreen forests must integrate GEDI data to overcome NFI data limitations and to effectively support biodiversity conservation

Structural metrics from the NASA Global Ecosystem Dynamics Investigation (GEDI) are vital to support monitoring, restoration and protection of high biodiversity spots. The Chilean Patagonia is home of pristine and unique ecosystems where GEDI data can provide knowledge on structure and biomass and expand the current limitation in Patagonia on field measurements and open lidar data. Conservation efforts are ramping up across our study area in the Aysén Region. Ongoing and future conservation efforts precise from unbiased estimates of forest carbon stocks to value and to protect forest biodiversity. We evaluate GEDI structural metrics and biomass estimates in the evergreen forests of the Chilean Patagonia using National Forest Inventory (NFI) data and unmanned aerial vehicle (UAV) lidar mapping to assess aboveground biomass density (AGBD) across six conservation projects. Estimates from GEDI ranged between 186 and 255 Mg ha-1. Both AGBD distributions for NFI plots and the gridded map were similarly centered as both converged in the median value (100 Mg ha-1). However, the NFI gridded map turned asymptotic after 200 Mg ha-1, showing the lack of representation in the NFI sampling of dense high-C forests, whereas GEDI estimates were able to sense these areas of old-growth forests. The distribution of GEDI tracks, the scale extension of the projects and the available NFI information explained the differences between using GEDI samples and the NFIcalibrated solution using UAV-lidar. Our results showed the limitations of the Chilean NFI over steep locations and uplands where old-growth forests dominate, and where only GEDI can depict structural metrics and reliable estimates of ADGB and forest carbon. This study is highly relevant to support conservation projects in Patagonia using publicly available GEDI data science, and to enforce ambitious legislation in Chile designed to protect biodiversity and for which quantification, reporting and verification of forest carbon stocks is crucial.

The impact of grazing on biodiversity and forest succession in the Brazilian dry forest region is constrained by non-equilibrium dynamics

The impacts of grazing on rangelands have historically been studied within the framework of the equilibrium model, which predicts significant impacts of grazing on ecosystems. However, in recent decades, studies have observed a non-equilibrium pattern, suggesting that abiotic factors play a primary role compared to grazing. These studies are primarily focused on rangelands, despite animal husbandry occurring in other biomes, such as seasonally dry tropical forests. Our study examines the influence of goat grazing on biodiversity and forest succession in the Brazilian dry forest (Caatinga). Considering its high interannual precipitation variability, we hypothesize a response that aligns with the non-equilibrium paradigm. We established a gradient of grazing intensity and history in areas at different stages of vegetation succession. A survey of tree - shrub and herbaceous species was conducted at each site and the biomass of both strata was quantified. Linear mixed models and Permanova were employed to assess differences in richness, composition, structure, and biomass among the areas. Our results suggest that grazing (history and intensity) and forest fallow age did not affect species richness, but only species composition. Low and high grazing intensity drive ecosystems toward similar compositions, which align with the non-equilibrium model predictions. Biomass in the herbaceous layer remained unaffected by grazing history, intensity, or forest fallow age, whereas woody biomass was influenced by grazing intensity in older forest fallows. Although trees in low-intensity grazing sites were significantly taller compared to those in other levels, overall, grazing did not disrupt the natural succession process. Older forest fallows exhibited greater diversity and higher basal area compared to new forest fallows, irrespective of grazing intensity. Our findings suggest that: a) grazing has minimal effects on biodiversity and biomass due to non-equilibrium dynamics, and b) with appropriate management, grazing can coexist with the conservation of the Caatinga.

40 years of forest dynamics and tree demography in an intact tropical forest at M’Baïki in central Africa

A vast silvicultural experiment was set up in 1982 nearby the town of M’Baïki in the Central African Republic to monitor the recovery of tropical forests after disturbance. The M’Baïki experiment consists of ten 4-ha Permanent Sample Plots (PSPs) that were assigned to three silvicultural treatments in 1986 according to a random block design. In each plot, all trees with a girth at breast height greater than 30 cm were spatially located, numbered, measured, and determined botanically. Girth, mortality and newly recruited trees, were monitored almost annually over the 1982–2022 period with inventory campaigns for 35 years. The data were earlier used to fit growth and population models, to study the species composition dynamics, and the effect of silvicultural treatments on tree diversity and aboveground biomass. Here, we present new information on the forest stand structure dynamics and tree demography. The data released from this paper cover the three control plots and constitute a major contribution for further studies about the biodiversity of intact tropical forests.

Ecologically sustainable retention forestry supports spider biodiversity in the Lower Morava UNESCO Biosphere Reserve

Abstract Floodplain forests are among the most endangered ecosystems worldwide, even though they are hotspots for numerous taxa. The abandonment of traditional management and large‐scale timber extraction, such as clear‐cutting, has led to a decline in floodplain forest biodiversity. Retention forestry has the potential to facilitate the implementation of an ecologically sustainable forest management approach. Despite the increasing popularity of this method, its potential for spider diversity conservation, especially its comparison with the widespread practice of clear‐cutting, is still poorly studied. We studied the short‐term effect of forestry treatments (dispersed retention with 60% retained trees and clear‐cutting) on the diversity of ground‐dwelling spiders in the floodplain forests along the Lower Morava (March) and Dyje (Thaya) rivers in the Czech Republic. Spiders were sampled using pitfall traps during 2021 (pre‐harvest year) and 2022 (post‐harvest year). A total of 10,005 specimens from 167 species were recorded. Both forestry treatments simplified habitat structure compared with pre‐harvest conditions, resulting in lower beta‐diversity within sites. However, dispersed retention had higher alpha‐ and beta‐diversity than clear‐cuts, indicating that retention provided a more complex‐structured habitat. Dispersed retention and clear‐cuts hosted distinct spider assemblages with characteristic indicator species. Species typical of open and significantly disturbed habitats preferred clear‐cuts, while species typical of forests and (semi‐) open habitats, including threatened species, showed a preference for dispersed retention. Our results demonstrated, for the first time, that dispersed retention forestry could serve as an effective management tool for conserving the ground‐dwelling assemblages of spiders in floodplain forests.

Global changes in the odonate family ratios in response to the tropical forest degradation

Odonates (dragonflies and damselflies) can indicate the ecological health of aquatic biota within the rich but vulnerable biodiversity of tropical forests. The reaction of odonates to deforestation can be measured by changes in coarse taxonomic ratios. Suborder Zygoptera are thermal conformers susceptible to overheating, having the affinity with shaded, intact sites. Anisoptera have exothermic regulation and better dispersal capacities, suggesting their association with more altered, open environments. Similarly, with an increasing degradation, the proportion of Anisoptera species in assemblages should increase. However, based on the data from different continents, the Zygoptera/Anisoptera ratio may be too simple, strongly biased, and not applicable at the global scale. The main reason is that the most diverse, abundant, and cosmopolitan families, Coenagrionidae (Zygoptera) and Libellulidae (Anisoptera), comprise a great proportion of habitat generalists with high migratory capacity and affinity with open habitats. In this study, we sampled odonates from three bioregions (Indomalaya, Afrotropics, and Neotropics) over the gradient of tropical forest degradation with a comparable sampling effort to assess the suitability of species richness and suborder-based (Zygoptera/Anisoptera) and family-based (Libellulidae/other Anisoptera and Coenagrionidae/other Zygoptera) ratios and their abundance-weighted versions for monitoring tropical forest degradation. Our results show that simple Odonata as well as Zygoptera and Anisoptera richness are poor indicators of the forest biota alteration. Family-level indices weighted by relative abundance, especially those involving Coenagrionidae, were more sensitive to changes in forest conditions compared to suborder-level indices. Collectively, our results suggest that for biomonitoring, where financial resources and time are commonly critical, family-level ratio metrics may be effective tools to indicate even slight alterations of aquatic biota resulting from forest degradation. Although these indices have the potential for broader application, their effectiveness across tropical bioregions warrants further validation.

Litterfall Carbon and Nitrogen Content of Beech Forests in Serbia

This study aimed to analyze the N storage capacity of litterfall and its impact on C mineralization in beech forests. The research was conducted at 15 sample plots under European beech stands located in different ecological conditions on the territory of Serbia. More than half (53%) of the sample plots are characterized by low and very low litterfall N content (<8 g·kg−1; 9–12 g·kg−1), and a wide C/N ratio, which indicates a slow decomposition of the organic soil layer. These results could be useful indicators of the capacity and dynamics of litterfall N storage and its impact on C mineralization in the context of preserving biodiversity, stability, and longevity of beech forests in Serbia.

Canopy cover and soil moisture influence forest understory plant responses to experimental summer drought.

Extreme droughts are globally increasing in frequency and severity. Most research on drought in forests focuses on the response of trees, while less is known about the impacts of drought on forest understory species and how these effects are moderated by the local environment. We assessed the impacts of a 45-day experimental summer drought on the performance of six boreal forest understory plants, using a transplant experiment with rainout shelters replicated across 25 sites. We recorded growth, vitality and reproduction immediately, 2 months, and 1 year after the simulated drought, and examined how differences in ambient soil moisture and canopy cover among sites influenced the effects of drought on the performance of each species. Drought negatively affected the growth and/or vitality of all species, but the effects were stronger and more persistent in the bryophytes than in the vascular plants. The two species associated with older forests, the moss Hylocomiastrum umbratum and the orchid Goodyera repens, suffered larger effects than the more generalist species included in the experiment. The drought reduced reproductive output in the moss Hylocomium splendens in the next growing season, but increased reproduction in the graminoid Luzula pilosa. Higher ambient soil moisture reduced some negative effects of drought on vascular plants. Both denser canopy cover and higher soil moisture alleviated drought effects on bryophytes, likely through alleviating cellular damage. Our experiment shows that boreal understory species can be adversely affected by drought and that effects might be stronger for bryophytes and species associated with older forests. Our results indicate that the effects of drought can vary over small spatial scales and that forest landscapes can be actively managed to alleviate drought effects on boreal forest biodiversity. For example, by managing the tree canopy and protecting hydrological networks.

Functional diversity of neighbours mediates sap flow density and radial growth of focal trees, but in different ways between evergreen and deciduous broadleaved species

Abstract The functioning of a tree is shaped by the neighbouring species through the interspecific interaction and local environments. The functional trait composition of the neighbourhood could provide mechanistic insights into the effects of neighbours on the resource strategies of focal trees. In this study, we deployed an automated high‐frequency measurement of the sap flow density (SFD) and the radial growth of 48 trees of 12 species at BEF‐China, a large‐scale forest biodiversity manipulation experiment, to investigate the consequences and underlying mechanisms of the functional trait composition of the neighbourhood on the sap flow and radial growth of focal trees. We found a positive relationship between SFD and growth, reflecting the important supportive role of sap flow in tree growth. High functional diversity (FD) of the neighbourhood depressed SFD but promoted growth when considering all species, and thus promoted water‐use efficiency. Acquisitiveness of neighbouring trees positively affected growth, suggesting interspecific facilitation. Furthermore, neighbourhood FD benefits evergreen focal trees by promoting growth. However, in deciduous focal trees, neighbourhood FD reduced SFD but had no significant effects on growth. Our findings suggest that considering the functional trait composition of neighbourhood communities will support effective afforestation and forest management. Read the free Plain Language Summary for this article on the Journal blog.