Deforestation has a substantial impact on aboveground biodiversity, but the response of belowground soil fungi remains poorly understood. In a tropical montane rainforest in southwestern China, plots ...were established along a forest degradation gradient ranging from mature and regenerated forests to open land to examine the impacts of forest degradation and deforestation on ecosystem diversity and function. Here, we evaluated the changes in belowground fungal diversity and community composition using a metabarcoding approach. Soil saprotrophic fungal richness declined with increasing forest disturbance. For example,
spp. (phosphorus P-solubilizing fungi) dominated in mature forest but were less abundant in regenerating forests and showed the lowest abundance in open land sites. Conversely, the abundance of facultative pathogenic fungi increased along the disturbance gradient. The decline in soil saprophytic fungi may be a direct result of forest disturbance or it may be associated with increased availability of soil phosphorus indirectly through an increase in soil pH. The increase in abundance of facultative pathogenic fungi may be related to reduced competition with saprotrophic fungi, changes in microclimate, or increased spore rain. These results demonstrate a loss of dominant P-solubilizing saprotrophic fungi along the disturbance gradient, indicating a change from soil P limitation in mature tropical forests to soil C limitation in deforested sites. The increased prevalence of pathogenic fungi may inhibit plant succession following deforestation. Overall, this research demonstrates that soil fungi can be used as a sensitive indicator for soil health to evaluate the consequences of forest disturbance.
The soil fungal functional group changes in response to forest disturbance and indicates a close interaction between the aboveground plant community and the belowground soil biological community. Soil saprotrophic fungi declined in relative abundance with increasing forest disturbance. At the same time, the relative abundance of facultative pathogenic fungi increased. The loss of saprotrophic fungal richness and abundance may have been a direct result of forest disturbance or an indirect result of changes in soil pH and soil P. Furthermore, the dominant P-solubilizing saprotrophic fungi were replaced by diverse facultative pathogenic fungi, which have weaker C decomposition ability. These changes potentially indicate a shift from soil phosphate limitation to carbon limitation following deforestation. This study suggests that changes in fungal functional group composition can be used as an indicator of the effects of forest disturbance on soil carbon and nutrients.
Heavy metal pollution is becoming recurrent and threatens biota biosafety in many agricultural fields. Diverse solutions explore the application of amendments to enable remediation. Sulfur represents ...a nonmetallic chemical element that actively affects heavy metals phytoextraction, and promotes and alternatively mitigates soil functions. In this study, we conduct a meta-analysis to synthesize the current knowledge on the influence of sulfur amendments on plants heavy metals uptake from contaminated soil media. Random-effects model was used to summarize effect sizes from 524 data points extracted from 30 peer reviewed studies. The phytoextraction of cadmium, chromium and nickel were 1.6-, 3.3-, and 12.6-fold, respectively, higher when sulfur amendment was applied; while copper uptake was 0.3-fold lower. Irrespective of the sulfur type, heavy metal extraction increased with the raising sulfur stress. Individual organs showed significant differences of heavy metal uptake between sulfur applied and non-sulfur treatments, and combined organs did not. The heavy metals uptake in leaves and roots were higher in sulfur applied than non-sulfur applied treatments, while those in grain, husk, and stalks were lower. The heavy metals phytoextraction (response ratio) followed the order roots > leaves > stalk > grain > husk. Moreover, heavy metals uptake was 2-fold higher in the sulfur applied than the non-sulfur treatments under ideal (5.5–8) and alkaline conditions (8–14), and 0.2-fold lower under acidic pH (1–5.5). Cadmium, manganese and nickel, and chromium were the most extracted under sulfur application by Vicia sp., Sorghum sp. and Brassica sp., respectively; while chromium, manganese, and iron were the most uptake without sulfur amendments by Oryza sp., Zea sp. and Sorghum sp., respectively. Our study highlights that the influence of sulfur on heavy metal phytoextraction depends on the single or combined effects of sulfur stress intensity, sulfur compounds, plant organ, plant type, and soil pH condition.
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•Sulfur (S) stress enhances the heavy metal (HMs) uptake by plants, irrespective of S type.•Cd, Cr and Ni are the most uptaken metals by plants under S amendments.•HMs phytoextraction differs between individual and across diverse plants organs.•Oryza sp., Zea sp., and Sorghum sp. inhibit HMs uptake under sulfur amendment.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Climate change and other anthropogenic disturbances are increasing liana abundance and biomass in many tropical and subtropical forests. While the effects of living lianas on species diversity, ...ecosystem carbon, and nutrient dynamics are receiving increasing attention, the role of dead lianas in forest ecosystems has been little studied and is poorly understood. Trees and lianas coexist as the major woody components of forests worldwide, but they have very different ecological strategies, with lianas relying on trees for mechanical support. Consequently, trees and lianas have evolved highly divergent stem, leaf, and root traits. Here we show that this trait divergence is likely to persist after death, into the afterlives of these organs, leading to divergent effects on forest biogeochemistry. We introduce a conceptual framework combining horizontal, vertical, and time dimensions for the effects of liana proliferation and liana tissue decomposition on ecosystem carbon and nutrient cycling. We propose a series of empirical studies comparing traits between lianas and trees to answer questions concerning the influence of trait afterlives on the decomposability of liana and tree organs. Such studies will increase our understanding of the contribution of lianas to terrestrial biogeochemical cycling, and help predict the effects of their increasing abundance.
Climate change and other anthropogenic disturbances are increasing liana abundance and biomass in many tropical and subtropical forests. But the role of dead lianas in forest ecosystems is poorly understood. Trees and lianas coexist as the major woody components of forests worldwide, but they have very different ecological strategies, with lianas relying on trees for mechanical support. Consequently, trees and lianas have evolved highly divergent stem, leaf, and root traits. Here we show that this trait divergence is likely to persist after death, into the afterlives of these organs, leading to divergent effects on forest biogeochemistry.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
More than half of the net primary production in terrestrial ecosystems returns to the soil through leaf litter fall and decomposition. In terrestrial ecosystems, litter constitutes a mixture of ...mainly senescent foliage from multiple species. Yet, the effect of litter mixing on litter decomposition rate remains ambiguous. Quantification of the soil fauna contribution and inclusion of their interaction with litter could remove the prevailing ambiguity, as soil fauna might influence the direction and magnitude of litter mixture effects on decomposition.
We carried out a global meta‐analysis to elucidate how soil fauna influenced litter mixture decomposition rate based on 55 published studies with 873 fauna inclusion/exclusion observations in field litterbag experiments. We hypothesized that soil fauna inclusion in litter mixture experiments would cause a positive change in the magnitude of mixed litter decomposition. That is, the presence of soil fauna would lead to synergistic litter mixture effects while the absence of soil fauna would lead to antagonistic litter mixture effects. Furthermore, we hypothesized that soil fauna would have a greater positive impact on the litter mixture effect in environments with low precipitation.
While litter mixture had a neutral effect on decomposition on average across studies, non‐additive mixture effects were common, with a key role for soil fauna, which generally enhanced decomposition rate compared to the component single‐species litters. In contrast, fauna exclusion resulted in diminished decomposition rate overall. The overall synergistic soil fauna effect on litter mixture decomposition increased under low precipitation. Under high precipitation, the litter mixture effect was positive in the absence of soil fauna but non‐significant in the presence of fauna. Climate imposes a great effect on litter mixture, with synergistic effects increasing towards the equator.
Synthesis. These results highlight the importance of soil fauna in mixed litter decomposition, most strongly in dry environments. In this era of global climate change, where some regions are projected to become drier, soil fauna might compensate the expected slower decomposition of litter by increasingly enhancing litter mixture decomposition.
摘要
陆地生态系统中大部分净生产量通过凋落物分解过程返回土壤。生态系统中叶片凋落物来自不同物种并混合存在，但凋落物分解的混合效应仍不明确。土壤动物对凋落物分解具有调控作用，量化分解过程中土壤动物的作用及其与凋落物的交互作用对全面认识混合凋落物分解过程具有重要意义。
我们基于全球55篇已发表的研究开展整合分析（Meta‐analysis），探讨土壤动物如何影响混合凋落物的分解速率。我们假设有土壤动物参与分解会正向改变混合凋落物的分解速率，即土壤动物的参与会导致混合凋落物的协同效应，没有土壤动物参与则会导致混合凋落物的拮抗效应。我们提出进一步假设，土壤动物的作用会随环境改变，在降雨量较少的环境中土壤动物对凋落物混合效应的作用会增大。
凋落物混合效应总体上呈现加和效应，但在有土壤动物参与的情况下混合凋落物质量损失高于各组分凋落物质量损失。而在排除土壤动物影响的情况下，凋落物的质量损失总体上出现降低。土壤动物对混合凋落物分解的影响随着降雨量的减少而增强。在降雨量较大的情况下，排除土壤动物参与分解的凋落物具有正向的混合效应，有土壤动物参与的情况下凋落物混合效应不显著。气候可对混合凋落物分解产生影响，混合凋落物之间的协同效应在热带地区更高。
研究表明，土壤动物对混合凋落物分解具有重要作用，此作用在干旱环境中尤为明显。在全球气候变化下，土壤动物可能可以调节因干旱导致的混合凋落物分解的改变。
Our study results highlight the importance of soil fauna in mixed litter decomposition, most strongly in dry environments. In this era of global climate change, where some regions are projected to become drier, soil fauna might compensate the expected slower decomposition of litter by increasingly enhancing litter mixture decomposition.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Tropical volcanoes are an important but understudied ecosystem, and the relationships between plant species diversity and compositional change and elevation may differ from mountains created by ...uplift, because of their younger and more homogeneous soils. We sampled vegetation over an altitudinal gradient on Mt. Rinjani, Lombok, Indonesia. We modeled alpha- (plot) and beta- (among plot) diversity (Fisher's alpha), compositional change, and biomass against elevation and selected covariates. We also examined community phylogenetic structure across the elevational gradient. We recorded 902 trees and shrubs among 92 species, and 67 species of ground-cover plants. For understorey, subcanopy and canopy plants, an increase in elevation was associated with a decline in alpha-diversity, whereas data for ground-cover plants suggested a hump-shaped pattern. Elevation was consistently the most important factor in determining alpha-diversity for all components. The alpha-diversity of ground-cover vegetation was also negatively correlated with leaf area index, which suggests low light conditions in the understorey may limit diversity at lower elevations. Beta-diversity increased with elevation for ground-cover plants and declined at higher elevations for other components of the vegetation. However, statistical power was low and we could not resolve the relative importance to beta-diversity of different factors. Multivariate GLMs of variation in community composition among plots explained 67.05%, 27.63%, 18.24%, and 19.80% of the variation (deviance) for ground-cover, understorey, subcanopy and canopy plants, respectively, and demonstrated that elevation was a consistently important factor in determining community composition. Above-ground biomass showed no significant pattern with elevation and was also not significantly associated with alpha-diversity. At lower elevations communities had a random phylogenetic structure, but from 1600 m communities were phylogenetically clustered. This suggests a greater role of environmental filtering at higher elevations, and thus provides a possible explanation for the observed decline in diversity with elevation.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lianas account for a small fraction of forest biomass, but their contribution to leaf or litter biomass and thus to food webs can be substantial. Globally liana exhibit fast life‐history traits. ...Thus, liana litter may decompose faster than tree litter, and could enhance the decomposition of tree litter (complementarity effect). The differences in decomposition may also vary with mesofauna access or across forest communities. The contribution of these factors to nutrient biogeochemical cycling is poorly understood.
We examined the decomposition of litter of 20 liana and 20 tree species of three different tropical forest communities in southern China, over 1 year. (i) We incubated the litter in bags with coarse and fine mesh to distinguish mesofaunal and microfaunal effects. (ii) We used single‐species litter bags to compare decomposition rates of lianas and trees, to test which functional traits best explained decomposition, and whether those traits differed between lianas and trees, and among forest types. (iv) We used mixed‐species litter bags to test whether liana litter enhances decomposition in litter mixtures. (v) We evaluated how leaf litter nutrients decayed in relation to litter mass.
Litter decayed faster in coarse‐mesh than fine‐mesh bags, but there was no interaction effect with forest type or growth form. Liana litter decayed faster than tree litter in single‐species bags with mesofauna access and in mixed bags (liana‐only mix, tree‐only mix) without mesofauna. Lianas had higher nitrogen content and specific leaf area and lower leaf dry matter content (LDMC) and toughness than trees. Decomposition rate was significantly negatively related to LDMC. Litter of evergreen broadleaved forest decomposed slower than that of other forest types. Liana litter did not enhance the decomposition of tree litter in mixtures. Liana litter released calcium slightly faster than trees.
Synthesis: Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry.
Leaf litter decomposes faster for lianas than trees, despite high variability of traits and decomposition rates within each growth form and overlap between growth forms, and we found no evidence for the complementarity hypothesis. Our study sheds light on the potential role of lianas within brown food webs and their importance on terrestrial biogeochemistry.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Soil organic matter contributes to productivity in terrestrial ecosystems and contains more carbon than is found in the atmosphere. Yet, there is little understanding of soil organic carbon (SOC) ...sequestration processes during tropical forest succession, particularly after land abandonment from agriculture practices.
Here, we used vegetation and environmental data from two large‐scale surveys covering a total landscape area of 20,000 ha in Southeast Asia to investigate the effects of plant species diversity, functional trait diversity, phylogenetic diversity, above‐ground biomass and environmental factors on SOC sequestration during forest succession.
We found that functional trait diversity plays an important role in determining SOC sequestration across successional trajectories. Increases in SOC carbon storage were associated with indirect positive effects of species diversity and succession age via functional trait diversity, but phylogenetic diversity and above‐ground biomass showed no significant relationship with SOC stock. Furthermore, the effects of soil properties and functional trait diversity on SOC carbon storage shift across elevation.
Synthesis. Our results suggest that reforestation and restoration management practices that implement a trait‐based approach by combining long‐lived and short‐lived species (conservative and acquisitive traits) to increase plant functional diversity could enhance SOC sequestration for climate change mitigation and adaptation efforts, as well as accelerate recovery of healthy soils.
Results suggest that reforestation and restoration management practices that implement a trait‐based approach by combining long‐lived and short‐lived species (conservative and acquisitive traits) to increase plant functional diversity could enhance SOC sequestration for climate change mitigation and adaptation efforts, as well as accelerate recovery of healthy soils.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Enhancing knowledge on the role of evolutionary history during forest succession and its relationship with ecosystem function is particularly relevant in the context of forest landscape restoration ...for climate change mitigation and adaptation.
We used fine resolution vegetation and environmental data (soil, elevation and slope) from two large‐scale surveys (320 × 1000 m2 plots in two 10 km × 10 km blocks) in the Upper Mekong to quantify (1) the role of abiotic and biotic (species interactions) factors in community assembly processes and (2) the effect of biodiversity, environmental factors and forest succession on above‐ground biomass (AGB).
We found strong correlation between soil fertility and community structure in the early successional seres, while species interactions played an increasingly important role in older seres, presumably due to species complementary.
We detected a significant relationship between AGB and phylogenetic diversity, elevation and soil fertility across successional gradients. Within successional stages, soil fertility was not significantly associated with AGB, while elevation was significantly associated with AGB only in forest <100 years old. Phylogenetic diversity was positively correlated with AGB in the young secondary forest (< 15 years old) but not significantly associated with AGB in older seres.
Synthesis. Our results support the hypothesis that abiotic filtering influences species assembly in the initial stages of forest succession, while biotic interactions dominate community assembly processes in older seres. We found that phylogenetic diversity, soil fertility and elevation gradients were strongly predictive of AGB in a secondary tropical montane forest in Southeast Asia. However, elevation may reflect other underlying abiotic gradients, such as water availability. Phylogenetic diversity was significantly associated with AGB only in youngest seres (<15 years old). Considering phylogenetic diversity in restoration plantings and the management of forests younger than 15 years old could enhance forest biomass and the climate mitigation function forest landscape restoration.
We found that phylogenetic diversity, soil fertility and elevation gradients were strongly predictive of above‐ground biomass (AGB) in a secondary tropical montane forest in Southeast Asia. However, elevation may reflect other underlying abiotic gradients, such as water availability. While phylogenetic diversity was significantly associated with AGB in youngest seres (<15 years old). Considering phylogenetic diversity in restoration plantings and the management of forests younger than 15 years old could enhance forest biomass and the climate mitigation function forest landscape restoration.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
•In forest habitats there was a peak of litterfall toward the end of dry season.•Total litterfall was significantly lower in open habitats compared to forests.•Litter nutrient concentrations did not ...vary significantly across seasons.•Litter nutrient concentrations also did not vary across the disturbance gradient.•Patterns of nutrient input were determined solely by the litterfall pattern.
Litterfall plays an important role in nutrient cycling and maintenance of soil fertility in terrestrial ecosystems. Annual and seasonal variation in litterfall have been investigated in various habitats, however, seasonality in nutrient supply is less well documented. We studied litterfall over two years and seasonal litter nutrient input over one year across a tropical disturbance gradient from mature forest to monoculture tea plantation. Total litter production in the mature forests and regenerating forests was not significantly different. However, tea plantations had significantly lower litter production. Total litterfall in forest habitats showed a clear seasonal pattern with a peak during the dry season (Mar.–May), as has been reported for other tropical seasonal forests. Contrary to expectations, there was no significant difference in litter nutrient concentrations across the disturbance gradient, although there was a substantial change in plant species composition. Litter nutrient concentrations also did not vary significantly across seasons, again contrary to our expectations. Thus, nutrient input was driven solely by the seasonal litterfall pattern. Our results suggest that at a landscape scale turnover in species composition linked to anthropogenic disturbance may not always lead to changes in litter quality, presumably because a similar spectra of leaf types may exist across communities. Seasonal litterfall patterns, which have been more commonly studied, may prove a reasonable proxy for nutrient input in forests.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Premise
Determining how xylem vessel diameters vary among plants and across environments gives insights into different water‐use strategies among species and ultimately their distributions. Here, we ...tested the vessel dimorphism hypothesis that the simultaneous occurrence of many narrow and a few wide vessels gives lianas an advantage over trees in seasonally dry environments.
Methods
We measured the diameters of 13,958 vessels from 15 liana species and 10,430 vessels from 16 tree species in a tropical seasonal rainforest, savanna, and subtropical evergreen broadleaved forest. We compared differences in mean and hydraulically weighted vessel diameter (MVD and Dh), vessel density (VD), theoretical hydraulic conductivity (Kt), vessel area fraction (VAF), and wood density (WD) between lianas and trees and among three sites.
Results
Nine liana species and four tree species had dimorphic vessels. From the tropical seasonal rainforest to the savanna, liana MVD, Dh and Kt decreased, and VD and WD increased, while only tree WD increased. From the tropical seasonal rainforest to the subtropical forest, six wood traits remained unchanged for lianas, while tree MVD, Dh and Kt decreased and VD increased. Trait space for lianas and trees were more similar in the savanna and more divergent in the subtropical forest compared to the tropical seasonal rainforest.
Conclusions
These results suggest that lianas tend to possess greater vessel dimorphism, which may explain how lianas grow well during seasonal drought, influencing their unique distribution across tropical rainfall gradients.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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