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opencc-zeroMay 2020View details →

Data from: The functional trait space of tree species is influenced by the species richness of the canopy and the type of forest

Analysing how species modify their trait expression along a diversity gradient brings insight about the role that intraspecific variability plays over species interactions, e.g. competition versus complementarity. Here, we evaluated the functional trait space of nine tree species dominant in three types of European forests (a continental-Mediterranean, a mountainous mixed temperate and a boreal) growing in communities with different species richness in the canopy, including pure stands. We compiled whole-plant and leaf traits in 1719 individuals, and used them to quantify species trait hypervolumes in communities with different tree species richness. We investigated changes along the species richness gradient to disentangle species responses to the neighbouring environment, in terms of hypervolume size (trait variance), shape (trait relative importance) and centroid translation (shifts of mean trait values) using null models. Our main results showed differences in trait variance and shifts of mean values along the tree diversity gradient, with shorter trees but with larger crowns in mixed stands. We found constrained functional spaces (trait convergence) in pure stands, suggesting an important intraspecific competition, and expanded functional spaces (trait divergence) in two-species admixtures, suggesting competition release due to interspecific complementarity. Nevertheless, further responses to increasing species richness were different for each forest type, waning species complementarity in sites with limiting conditions for growth. Our results demonstrate that tree species phenotypes respond to the species richness in the canopy in European forests, boosting species complementarity at low level of canopy diversity and with a site-specific pattern at greater level of species richness. These outcomes evidence the limitation of functional diversity measures based only on traits from pure stands or general trait database values.

opencc-zeroSep 2020View details →

Data from: Isolated trees support lower bird taxonomic richness than trees within habitat patches but similar functional diversity

Large isolated trees are keystone structures that can help maintain biodiversity in fragmented landscapes, with evidence that open areas with isolated trees may support similar levels of taxonomic diversity to nearby patches of habitat. However, it is not clear if isolated trees can support the same diversity of ecological functions as trees in habitat patches. We compared species richness, community composition and functional diversity of birds in trees at forest edges and isolated trees. Twenty isolated trees and ten edge trees of American muskwood (Guarea guidonia) were selected, and sampled on 11 occasions, each of 20 minutes, over four months. All individual birds that landed at trees were recorded using a standardized protocol. Species richness was, on average, almost twice as high at edge trees than at isolated trees. Taxonomic composition differed between edge and isolated trees, with many forest-dependent birds restricted to edge trees, and some open-area birds restricted to isolated trees. Overall functional diversity was similar at edge and isolated trees, but some ecological functions (e.g. frugivory) were less frequent, while others (e.g. granivory) were more frequent at isolated compared to edge trees. Isolated trees are important for supporting many ecological functions in modified areas. However, the maintenance of forest patches is essential to complement the provision of such functions in modified landscapes.

opencc-zeroOct 2019View details →

Data from: Neighbour species richness and local structural variability modulate aboveground allocation patterns and crown morphology of individual trees

Local neighbourhood interactions are considered a main driver for biodiversity–productivity relationships in forests. Yet, the structural responses of individual trees in species mixtures and their relation to crown complementarity remain poorly understood. Using a large‐scale forest experiment, we studied the impact of local tree species richness and structural variability on above‐ground wood volume allocation patterns and crown morphology. We applied terrestrial laser scanning to capture the three‐dimensional structure of trees and their temporal dynamics. We found that crown complementarity and crown plasticity increased with species richness. Trees growing in species‐rich neighbourhoods showed enhanced aboveground wood volume both in trunks and branches. Over time, neighbourhood diversity induced shifts in wood volume allocation in favour of branches, in particular for morphologically flexible species. Our results demonstrate that diversity‐mediated shifts in allocation pattern and crown morphology are a fundamental mechanism for crown complementarity and may be an important driver of overyielding.

opencc-zeroDec 2014View details →

Data from: Arthropod but not bird predation in Ethiopian homegardens is higher in tree-poor than in tree-rich landscapes

Bird and arthropod predation is often associated with natural pest control in agricultural landscapes, but the rates of predation may vary with the amount of tree cover or other environmental factors. We examined bird and arthropod predation in three tree-rich and three tree-poor landscapes across southwestern Ethiopia. Within each landscape we selected three tree-rich and three tree-poor homegardens in which we recorded the number of tree species and tree stems within 100 × 100 m surrounding the central house. To estimate predation rates, we attached plasticine caterpillars on leaves of two coffee and two avocado shrubs in each homegarden, and recorded the number of attacked caterpillars for 7–9 consecutive weeks. The overall mean daily predation rate was 1.45% for birds and 1.60% for arthropods. The rates of arthropod predation varied among landscapes and were higher in tree-poor landscapes. There was no such difference for birds. Within landscapes, predation rates from birds and arthropods did not vary between tree-rich and tree-poor homegardens in either tree-rich or tree-poor landscapes. The most surprising result was the lack of response by birds to tree cover at either spatial scale. Our results suggest that in tree-poor landscapes there are still enough non-crop habitats to support predatory arthropods and birds to deliver strong top-down effect on crop pests.

opencc-zeroMay 2020View details →

Data from: Structural complexity and large-sized trees explain shifting species richness and carbon relationship across vegetation types

1. It is prominently claimed that enhancing forest diversity would play a dual role of nature conservation and climate regulation. While the idea is intuitively appealing, studies show that species richness effects on aboveground carbon (AGC) are not always positive, but instead unpredictable especially across scales and complex terrestrial systems having large-diameter and tall-stature trees. Previous studies have further considered structural complexity and larger trees as determinants of AGC. Yet it remains unclear what drives differential diversity-AGC relationships across vegetation types. 2. Here, we test whether structural complexity and large-sized trees play an influential role in explaining shifting diversity-AGC relationships across vegetation types, using a 22.3 ha sampled dataset of 124 inventory plots in woodlands, gallery forests, tree/shrub savannahs and mixed plantations in West Africa. 3. Natural vegetation had greater species richness and structural complexity than mixed plantations, as expected. In addition, AGC was highest in gallery forests and mixed plantations, which is consistent with favorable environmental conditions in the former and high stocking densities and presence of fast-growing species in the latter. Significant interaction effects of species richness and vegetation on AGC revealed a vegetation-dependent species richness-AGC relationship: consistently, we found positive species richness-AGC relationship in both mixed plantations and woodlands, and nonsignificant patterns in gallery forests and tree/shrub savannah. Further, there was a vegetation-dependent mediation of structural complexity in linking species richness to AGC, with stronger positive structural complexity effects where species richness-AGC relationships were positive, and stronger positive large-sized trees' effect where species richness-AGC relationships were neutral. 4. Our study provides strong evidence of vegetation-dependent species richness-AGC relationships, which operated through differential mediation by structural complexity of the species richness and large trees' effects. We conclude that even higher species richness in diversified ecosystems may not always relate positively with AGC, and that neutral pattern may arise possibly as a result of larger dominant individual trees imposing a slow stand dynamic flux and overruling species richness effects.

opencc-zeroDec 2015View details →

Data from: Trees as islands: canopy ant species richness increases with the size of liana-free trees in a Neotropical forest

The physical characteristics of habitats shape local community structure; a classic example is the positive relationship between the size of insular habitats and species richness. Despite the high density and proximity of tree crowns in forests, trees are insular habitats for some taxa. Specifically, crown isolation (i.e. crown shyness) prevents the movement of small cursorial animals among trees. Here, we tested the hypothesis that the species richness of ants (Sa) in individual, isolated trees embedded within tropical forest canopies increases with tree size. We predicted that this pattern disappears when trees are connected by lianas (woody vines) or when strong interactions among ant species determine tree occupancy. We surveyed the resident ants of 213 tree crowns in lowland tropical forest of Panama. On average, 9.2 (range = 2–20) ant species occupied a single tree crown. Average (± SE) Sa was ca 25% higher in trees with lianas (10.2 ± 0.26) than trees lacking lianas (8.0 ± 0.51). Sa increased with tree size in liana-free trees (Sa = 10.99A0.256), but not in trees with lianas. Ant species composition also differed between trees with and without lianas. Specifically, ant species with solitary foragers occurred more frequently in trees with lianas. The mosaic-like pattern of species co-occurrence observed in other arboreal ant communities was not found in this forest. Collectively, the results of this study indicate that lianas play an important role in shaping the local community structure of arboreal ants by overcoming the insular nature of tree crowns.

opencc-zeroDec 2017View details →

Data from: Tree species richness increases ecosystem carbon storage in subtropical forests

Forest ecosystems are an integral component of the global carbon cycle as they take up and release large amounts of C in short time (C flux) or accumulate it over longer time (C stock). However, there remains uncertainty about whether and in which direction C fluxes and in particular C stocks may differ between forests of high vs. low species richness. Based on a comprehensive dataset derived from field-based measurements, we tested the effect of species richness (3–20 tree species) and stand age (22–116 years) on six compartments of above- and belowground C stocks and four components of C fluxes in subtropical forests in south-east China. Across forest stands, total C stock was 149 ± 12 Mg ha-1 with richness explaining 28.5% and age explaining 29.4% of variation in this measure. Species-rich stands had higher C stocks and fluxes than stands with low richness; and, in addition, old stands had higher C stocks than young ones. Overall, for each additional tree species the total C stock increased by 6.4%. Our results provide comprehensive evidence for diversity-mediated above- and belowground C sequestration in species-rich subtropical forests in south-east China. Therefore, afforestation policies in this region and elsewhere should consider a change from the current focus on monocultures to multi-species plantations to increase C fixation and thus slow increasing atmospheric CO2 concentrations and global warming.

opencc-zeroDec 2017View details →

Data from: Contrasting patterns of local richness of seedlings, saplings and trees may have implications for regeneration in rainforest remnants

Remnants of lowland rainforest remain following deforestation, but the longer-term effects of fragmentation remain poorly understood, partly due to the long generation times of trees. We study rainforest trees in three size classes: seedlings (<1 cm dbh), saplings (1-5 cm dbh) and trees (>5 cm), that broadly reflect pre- and post-fragmentation communities, and we examine the impacts of fragmentation on forest regeneration in Sabah, Malaysian Borneo. We found that seedling richness (measured as the number of genera per plot) in fragments was about 30 percent lower than in plots in undisturbed forest, and about 20 percent lower than in an extensive tract of selectively logged forest, providing evidence of recruitment declines in fragments. Seedling richness was lowest in small, isolated, and disturbed fragments, potentially signalling an extinction debt given that these fragmentation impacts were not observed in trees. Unlike seedlings, saplings showed no declines in richness in fragments, suggesting that density dependent mortality (where rare individuals have a higher survival rate) and/or year-to-year variation in which species are recruiting could potentially compensate for the reductions in seedling richness we observed. Longer-term studies are required to determine whether sporadic or failed recruitment in small fragments will eventually translate into reduced richness of mature trees, or whether the processes that currently retain high sapling richness will continue in fragments.

opencc-by-4.0Nov 2024View details →

R code and data for "Intraspecific and intraindividual trait variability decrease with tree species richness in a subtropical tree diversity experiment"

R codes and dataset for tha statistical analyses and production of figures in "Intraspecific and intraindividual trait variability decrease with tree species richness in a subtropical tree diversity experiment" by Castro Sánchez-Bermejo et al.

opencc-zeroDec 2023View details →

Data for: Sun, Ogushi, Tseng -Lepidoptera species richness and community composition in urban street trees

The triple threats of climate change, habitat loss, and environmental pollution have stimulated discussion on how urban areas can be modified to both mitigate heat increases and provide habitat for wildlife such as insects. The strategy of using trees to reduce temperatures has been adopted by numerous cities. However, the majority of street trees planted around the world are non-native. Studies conducted in non-urban areas have demonstrated in comparison to native plants, non-native plants are less likely to support native insect diversity. Here we use a database approach to quantify the number of native Lepidoptera species associated with 76 of the most common street tree species planted in Vancouver, Canada. We tested the prediction that compared to non-native trees, native street trees will support a higher diversity and unique community of native Lepidoptera. As predicted, native street trees were associated with five times as many native Lepidoptera species, and the Lepidoptera communities supported by native vs. non-native street trees were distinct. There was no difference in native Lepidoptera associations between broadleaf vs. coniferous street trees. These results are consistent with studies that have used active sampling techniques to investigate insect richness on a smaller subset of native and non-native tree species. Collectively, these data provide good evidence that the planting native instead of non-native trees will help stem the loss of insect diversity in urban areas.

opencc-zeroDec 2022View details →

Data from: Plastic responses of belowground foraging traits to soil phosphorus-rich patches across 17 coexisting AM tree species in a subtropical forest

1. Belowground plastic responses to soil nutrient "hot-spots" form a key nutrient foraging strategy of plants coexisting in natural ecosystems. However, it is unclear how plant species differ in these belowground plastic responses and how they co-vary. 2. Plastic responses to soil phosphorus (P)-rich patches of absorptive root, mycorrhizal, and exudation traits of 17 co-existing arbuscular mycorrhizal (AM) tree species in a subtropical evergreen broad-leaved forest were investigated using a root bag method. 3. There was considerable variation and heterogeneity in species-specific responses to P-rich patches. Negative log response ratios usually occurred for high-cost traits and positive log response ratios for low-cost traits. There were tradeoffs in the plastic responses between root acid phosphatase activity and extraradical hyphal length, which were unaffected by phylogeny, and between root acid phosphatase activity and specific root length. Thicker-rooted species responded to P-rich patches more through root exudation plasticity than mycorrhizal plasticity. Thinner-rooted species relied more on mycorrhizal plasticity. 4. Synthesis. Our results revealed diverse P foraging strategies comprising different combinations of plastic adjustments in absorptive root, mycorrhizal, and exudation traits among coexisting AM tree species, which suggest the potential for complementary exploitation of different soil P sources.

opencc-zeroFeb 2023View details →

Tree species richness and soil organic carbon stock

Recently, the perspectives for the stronger persistence of soil organic carbon (SOC) caused by the higher molecular diversity of organic compounds were proposed. Therefore, the effects of tree species richness and composition on the diversity of molecular components of SOC need to be explored. In this study, we collected data on tree species diversity and composition, SOC concentration, chemical composition, litter and fine root properties, and examined the relationships between the richness, composition and functional diversity of tree species, and the evenness of SOC chemical compositions at a molecular level by 13C nuclear magnetic resonance, across six natural forest types encompassing a diversity gradient, ranging from cold temperate to tropical forests. Across the range, tree species richness correlated to the evenness of SOC chemical components through tree species composition. The negative correlation of evenness of SOC chemical components with tree species composition and the positive correlation of evenness of SOC chemical components with tree functional diversity were found. The positive correlation of the evenness of SOC chemical components with indicator tree species. These findings suggest that the indicator tree species conservation might be preferable to simply increasing tree species richness, for enhancing the potential resistance of SOC to decomposition.

Fig. 7 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 7. The expression patterns of two gene pairs (i.e. Vf01G2125 and Vf03G1740, and Vf06G2687 and Vf10G1659) were generated by tandem duplication events. Numbers on the x-axis indicate the following: seeds at 10, 15, 20, 25, and 30 weeks after flowering (WAF; 10_WAF, 15_WAF, 20_WAF, 25_WAF, and 30_WAF), male flowers at 30, 20, 10, and 1 days before flowering (X1-X4), female flowers at 30, 20, 10, and 1 days before flowering (C1–C4), young leaves, roots, stems, and hermaphrodite (CX).

Fig. 5 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 5. Expression of VfLRR-RLK gene family members. The heat map depicts expression profiles of VfLRR-RLKs in V. fordii (left) and V. montana (right) in response to Fusarium wilt at four infection stages: 0, uninfected stage; 1, 2 days after Fusarium wilt infection (dpi); 2, 8 dpi; 3, 13 dpi. F0–F3 indicated the expression of VfLRRRLKs in V. fordii during the infection stage (0, 1, 2, 3) by the pathogen Fusarium wilt; M0-M3 indicated the expression of VfLRR-RLKs in V. montana during the infection stage (0, 1, 2, 3) by the pathogen Fusarium wilt. The innermost circle represents 0, followed by 1, 2, and the outermost circle represents 3.

Fig. 4 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 4. The similar expression patterns between duplicated VfLRR-RLK gene pairs during vegetative and reproductive development. Numbers on the x-axis indicate the following: seeds at 10, 15, 20, 25, and 30 weeks after flowering (WAF; 10_WAF, 15_WAF, 20_WAF, 25_WAF, and 30_WAF), male flowers at 30, 20, 10, and 1 days before flowering (X1-X4), female flowers at 30, 20, 10, and 1 days before flowering (C1–C4), young leaves, roots, stems, and hermaphrodite (CX).

Fig. 6 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 6. The qRT-PCR experiments of four VfLRR-RLKs in response to Fusarium wilt. Black represents these VfLRR-RLKs in response to Fusarium wilt in V. fordii. Grey represents these VfLRR-RLKs in response to Fusarium wilt in V. montana. The numbers in the x-axis indicate the two stages of infection, as follows: 1, uninfected stage; 2, late stage of infection.

Fig. 3 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 3. Collinearity relationships of LRR-RLKs in V. fordii and the other four Euphorbiaceae genomes. The chromosomes of different Euphorbiaceae species were depicted as blocks of different colors. Gene pairs with a syntenic relationship between different Euphorbiaceae species were connected by different colored lines. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)

Fig. 1 in Deciphering the roles of leucine-rich repeat receptor-like protein kinases (LRR-RLKs) in response to Fusarium wilt in the Vernicia fordii (Tung tree)

Fig. 1. The maximum likelihood tree and synteny analysis among these five Euphorbiaceae genomes. All LRR-RLKs were divided into 22 groups and were distinguished by different colors. These different groups were determined and defined based on the A. thaliana homologs nomenclature within the same group (Shiu and Bleecker, 2001b). The synteny relationships between different Euphorbiaceae genomes were represented by different links. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)