| 1. |
- Fanin, Nicolas, et al.
(författare)
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Relative Importance of Climate, Soil and Plant Functional Traits During the Early Decomposition Stage of Standardized Litter
- 2020
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Ingår i: Ecosystems (New York. Print). - : Springer. - 1432-9840 .- 1435-0629. ; 23:5, s. 1004-1018
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Tidskriftsartikel (refereegranskat)abstract
- Climatic factors have long been considered predominant in controlling decomposition rates at large spatial scales. However, recent research suggests that edaphic factors and plant functional traits may play a more important role than previously expected. In this study, we investigated how biotic and abiotic factors interacted with litter quality by analyzing decomposition rates for two forms of standardized litter substitutes: green tea (high-quality litter) and red tea (low-quality litter). We placed 1188 teabags at two different positions (forest floor and 8 cm deep) across 99 forest sites in France and measured 46 potential drivers at each site. We found that high-quality litter decomposition was strongly related to climatic factors, whereas low-quality litter decomposition was strongly related to edaphic factors and the identity of the dominant tree species in the stand. This indicates that the relative importance of climate, soil and plant functional traits in the litter decomposition process depends on litter quality, which was the predominant factor controlling decomposition rate in this experiment. We also found that burying litter increased decomposition rates, and that this effect was more important for green tea in drier environments. This suggests that changes in position (surface vs. buried) at the plot scale may be as important as the role of macroclimate on decomposition rates because of varying water availability along the soil profile. Acknowledging that the effect of climate on decomposition depends on litter quality and that the macroclimate is not necessarily the predominant factor at large spatial scales is the first step toward identifying the factors regulating decomposition rates from the local scale to the global scale.
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| 2. |
- Fanin, Nicolas
(författare)
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Aboveground litter quality is a better predictor than belowground microbial communities when estimating carbon mineralization along a land-use gradient
- 2016
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 94, s. 48-60
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Tidskriftsartikel (refereegranskat)abstract
- Because of the vegetation cover and anthropogenic disturbances, land-use management strongly influences soil heterotrophic decomposers. Yet, little is known about whether contrasting microbial communities originating from different ecosystems are functionally similar, and only a few studies have disentangled the direct and indirect effects of resource quality on both microbial communities and carbon mineralization rates. To assess the relative importance of aboveground litter quality and belowground microbial communities on litter decomposition, we conducted a reciprocal transplant experiment under controlled conditions using four litters (Triticum aestivum, Fagus sylvatica, Festuca arundinacea and Robinia pseudoacacia) and four soils (culture, plantation, grassland and forest) originating from a land-use gradient. We followed the kinetics of carbon mineralization over 21 dates spanning a 202-day period to assess the variability of responses generated by the plant soil interactions. Furthermore, at four time points (at 0, 27, 97 and 202 days), the mass loss rates for the main sugars within the cell wall, the microbial biomass (fumigation-extraction), the microbial community structure via phospholipid fatty acid (PLFA), and the activities of four carbon-related hydrolytic enzymes were investigated to assess the functional significance of microbial communities. Our results demonstrated that the importance of soil types and heterotrophic decomposers on carbon mineralization rates was minor (1.2% of the variance explained) compared with the predominant role of litter quality. The structure of the microbial communities responded strongly to both long-term land-use changes and short-term litter additions; specifically, (i) higher proportions of fungi were observed in natural ecosystems compared with agro-systems, and (ii) an opportunistic subset of the bacterial community was stimulated after litter additions. Even if the land-use management and litter quality can shape the microbial community structure in a foreseeable way, we found an important degree of plasticity in the responses of contrasting decomposer communities. In particular, the enzymatic efficiency (defined as the amount of enzyme produced by unit of carbon mineralized) differed among, litters but not among soil types, suggesting that the threshold between carbon allocation to growth and acquisition depended more on the 'resource-use strategies' of the soil microorganisms than on the community structure. The recalcitrant litters stimulated 'efficient' communities characterized by low enzymatic activities, microbial biomass and respiration rates at the opposite of labile litters that stimulated 'wasteful' communities characterized by higher activities and metabolic quotient (defined as the amount of carbon respired by unit of biomass). In addition to the direct effects of litter quality, the path analysis reinforced our conclusion that the functional traits of microorganisms via their enzymatic activities are more relevant than their identity for predicting carbon mineralization. Thus, although multiple and coordinated responses of soil microbes can improve our understanding of carbon fluxes, shifts in the plant community composition caused by land-use conversion will have a stronger impact on predictions of carbon mineralization than short-term changes in the microbial community composition. (C) 2015 Elsevier Ltd. All rights reserved.
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| 3. |
- Fanin, Nicolas, et al.
(författare)
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Consistent effects of biodiversity loss on multifunctionality across contrasting ecosystems
- 2018
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Ingår i: Nature ecology & evolution. - : Springer Science and Business Media LLC. - 2397-334X. ; 2, s. 269-278
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Tidskriftsartikel (refereegranskat)abstract
- Understanding how loss of biodiversity affects ecosystem functioning, and thus the delivery of ecosystem goods and services, has become increasingly necessary in a changing world. Considerable recent attention has focused on predicting how biodiversity loss simultaneously impacts multiple ecosystem functions (that is, ecosystem multifunctionality), but the ways in which these effects vary across ecosystems remain unclear. Here, we report the results of two 19-year plant diversity manipulation experiments, each established across a strong environmental gradient. Although the effects of plant and associated fungal diversity loss on individual functions frequently differed among ecosystems, the consequences of biodiversity loss for multifunctionality were relatively invariant. However, the context-dependency of biodiversity effects also worked in opposing directions for different individual functions, meaning that similar multifunctionality values across contrasting ecosystems could potentially mask important differences in the effects of biodiversity on functioning among ecosystems. Our findings highlight that an understanding of the relative contribution of species or functional groups to individual ecosystem functions among contrasting ecosystems and their interactions (that is, complementarity versus competition) is critical for guiding management efforts aimed at maintaining ecosystem multifunctionality and the delivery of multiple ecosystem services.
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| 4. |
- Fanin, Nicolas
(författare)
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Eco-enzymatic stoichiometry and enzymatic vectors reveal differential C, N, P dynamics in decaying litter along a land-use gradient
- 2016
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 129, s. 21-36
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Tidskriftsartikel (refereegranskat)abstract
- To evaluate carbon (C), nitrogen (N), and phosphorus (P) dynamics during the decomposition process, we investigated the temporal variability of extracellular enzymatic activities (EEA) associated with C, N, and P acquisition in microbial communities from different land uses. We hypothesized that EEA ratios would reveal different primary resource requirements with respect to microbial demand, depending on soil properties, litter type and the relative proportion of bacteria:fungi in the microbial community. To test this hypothesis, we implemented an experiment using four litters (Triticum aestivum, Fagus sylvatica, Festuca arundinacea and Robinia pseudoacacia) in four soils (cropland, plantation, prairie and forest) located in close proximity to one another on the same parent material. Analyses of EEA showed that overall N requirement increased relative to P during litter decay, but C requirement increased more rapidly than either N or P in most of these ecosystems. Soil type was the main factor controlling N versus P requirement whereas litter type was the primary driver of C versus nutrient requirement. Shifts in EEA were related to changes in metabolic quotient (C respired per unit biomass) but there was no evidence that the relative proportion of fungi:bacteria drove changes in EEA. We concluded that the use of EEA as a proxy of microbial resource demand improved our understanding of temporal shifts in resource requirements to microbial communities, their associated respiration efficiency and dynamics of C and nutrients among different ecosystems.
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| 5. |
- Fanin, Nicolas, et al.
(författare)
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Effects of plant functional group removal on structure and function of soil communities across contrasting ecosystems
- 2019
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 22, s. 1095-1103
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Tidskriftsartikel (refereegranskat)abstract
- Loss of plant diversity has an impact on ecosystems worldwide, but we lack a mechanistic understanding of how this loss may influence below-ground biota and ecosystem functions across contrasting ecosystems in the long term. We used the longest running biodiversity manipulation experiment across contrasting ecosystems in existence to explore the below-ground consequences of 19 years of plant functional group removals for each of 30 contrasting forested lake islands in northern Sweden. We found that, against expectations, the effects of plant removals on the communities of key groups of soil organisms (bacteria, fungi and nematodes), and organic matter quality and soil ecosystem functioning (decomposition and microbial activity) were relatively similar among islands that varied greatly in productivity and soil fertility. This highlights that, in contrast to what has been shown for plant productivity, plant biodiversity loss effects on below-ground functions can be relatively insensitive to environmental context or variation among widely contrasting ecosystems.
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| 6. |
- Fanin, Nicolas, et al.
(författare)
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Ericoid shrubs shape fungal communities and suppress organic matter decomposition in boreal forests
- 2022
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 236, s. 684-697
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Tidskriftsartikel (refereegranskat)abstract
- Mycorrhizal fungi associated with boreal trees and ericaceous shrubs are central actors in organic matter (OM) accumulation through their belowground carbon allocation, their potential capacity to mine organic matter for nitrogen (N) and their ability to suppress saprotrophs. Yet, interactions between co-occurring ectomycorrhizal fungi (EMF), ericoid mycorrhizal fungi (ERI), and saprotrophs are poorly understood. We used a long-term (19 yr) plant functional group manipulation experiment with removals of tree roots, ericaceous shrubs and mosses and analysed the responses of different fungal guilds (assessed by metabarcoding) and their interactions in relation to OM quality (assessed by mid-infrared spectroscopy and nuclear magnetic resonance) and decomposition (litter mesh-bags) across a 5000-yr post-fire boreal forest chronosequence. We found that the removal of ericaceous shrubs and associated ERI changed the composition of EMF communities, with larger effects occurring at earlier stages of the chronosequence. Removal of shrubs was associated with enhanced N availability, litter decomposition and enrichment of the recalcitrant OM fraction. We conclude that increasing abundance of slow-growing ericaceous shrubs and the associated fungi contributes to increasing nutrient limitation, impaired decomposition and progressive OM accumulation in boreal forests, particularly towards later successional stages. These results are indicative of the contrasting roles of EMF and ERI in regulating belowground OM storage.
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| 7. |
- Fanin, Nicolas
(författare)
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Functional breadth and home-field advantage generate functional differences among soil microbial decomposers
- 2016
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Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 97, s. 1023-1037
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Tidskriftsartikel (refereegranskat)abstract
- In addition to the effect of litter quality (LQ) on decomposition, increasing evidence is demonstrating that carbon mineralization can be influenced by the past resource history, mainly through following two processes: (1) decomposer communities from recalcitrant litter environments may have a wider functional ability to decompose a wide range of litter species than those originating from richer environments, i.e., the functional breadth (FB) hypothesis; and/or (2) decomposer communities may be specialized towards the litter they most frequently encounter, i.e., the home-field advantage (HFA) hypothesis. Nevertheless, the functional dissimilarities among contrasting microbial communities, which are generated by the FB and the HFA, have rarely been simultaneously quantified in the same experiment, and their relative contributions over time have never been assessed. To test these hypotheses, we conducted a reciprocal transplant decomposition experiment under controlled conditions using litter and soil originating from four ecosystems along a land-use gradient (forest, plantation, grassland, and cropland) and one additional treatment using C-13-labelled flax litter allowing us to assess the priming effect (PE) in each ecosystem. We found substantial effects of LQ on carbon mineralization (more than two-thirds of the explained variance), whereas the contribution of the soil type was fairly low (less than one-tenth), suggesting that the contrasting soil microbial communities play only a minor role in regulating decomposition rates. Although the results on PE showed that we overestimated litter-derived CO2 fluxes, litter-microbe interactions contributed significantly to the unexplained variance observed in carbon mineralization models. The magnitudes of FB and HFA were relatively similar, but the directions of these mechanisms were sometimes opposite depending on the litter and soil types. FB and HFA estimates calculated on parietal sugar mass loss were positively correlated with those calculated on enzymatic activity, confirming the idea that the interaction between litter quality and microbial community structure may modify the trajectory of carbon mineralization via enzymatic synthesis. We conclude that although litter quality was the predominant factor controlling litter mineralization, the local microbial communities and interactions with their substrates can explain a small (<5%) but noticeable portion of carbon fluxes.
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| 8. |
- Fanin, Nicolas, et al.
(författare)
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The ratio of Gram-positive to Gram-negative bacterial PLFA markers as an indicator of carbon availability in organic soils
- 2019
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Ingår i: Soil Biology and Biochemistry. - : Elsevier BV. - 0038-0717 .- 1879-3428. ; 128, s. 111-114
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Tidskriftsartikel (refereegranskat)abstract
- Despite recent progress in understanding soil microbial responses to carbon (C) limitation, the functional shifts in microbial community structure associated with decreasing soil C availability and changes in organic matter chemistry remain poorly known. It has been proposed that Gram-negative (GN) bacteria use more plant-derived C sources that are relatively labile, while Gram-positive (GP) bacteria use C sources derived from soil organic matter that are more recalcitrant. Because these two groups may differ in how they influence the fate of different C forms in soils, it is important to understand how they vary across ecosystems that differ in their vegetation cover and ecosystem productivity or across environmental gradients. In this study, we used a 19-year plant functional group removal experiment across a long term post-fire chronosequence to assess how microbial community structure (assessed using phospholipids fatty acids; PLFAs) and the association of bacterial functional groups (specifically, the GP:GN ratio) responded to changes in organic matter chemistry (measured via nuclear magnetic resonance; NMR). We found that the GP:GN ratio increased upon removal of shrubs and tree roots and with decreasing ecosystem productivity along the chronosequence, thus showing the greater dependence of GN than GP bacteria on more labile plant-derived C. Overall, GN bacteria were associated with simple C compounds (alkyls) whereas GP bacteria were more strongly associated with more complex C forms (carbonyls). Therefore, we conclude that the GP:GN ratio has potential as a useful indicator of the relative C availability for soil bacterial communities in organic soils, and can be used as a coarse indicator of energy limitation in natural ecosystems.
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| 9. |
- Kardol, Paul, et al.
(författare)
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Long-term effects of species loss on community properties across contrasting ecosystems
- 2018
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 557, s. 710-713
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Tidskriftsartikel (refereegranskat)abstract
- Biodiversity loss can heavily affect the functioning of ecosystems, and improving our understanding of how ecosystems respond to biodiversity decline is one of the main challenges in ecology(1-4). Several important aspects of the longer-term effects of biodiversity loss on ecosystems remain unresolved, including how these effects depend on environmental context(5-7). Here we analyse data from an across-ecosystem biodiversity manipulation experiment that, to our knowledge, represents the world's longest-running experiment of this type. This experiment has been set up on 30 lake islands in Sweden that vary considerably in productivity and soil fertility owing to differences in fire history(8,9). We tested the effects of environmental context on how plant species loss affected two fundamental community attributes-plant community biomass and temporal variability-over 20 years. In contrast to findings from artificially assembled communities(10-12), we found that the effects of species loss on community biomass decreased over time; this decrease was strongest on the least productive and least fertile islands. Species loss generally also increased temporal variability, and these effects were greatest on the most productive and most fertile islands. Our findings highlight that the ecosystem-level consequences of biodiversity loss are not constant across ecosystems and that understanding and forecasting these consequences necessitates taking into account the overarching role of environmental context.
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| 10. |
- Sarneel, Judith M., et al.
(författare)
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Reading tea leaves worldwide : decoupled drivers of initial litter decomposition mass-loss rate and stabilization
- 2024
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Ingår i: Ecology Letters. - : John Wiley & Sons. - 1461-023X .- 1461-0248. ; 27:5
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Tidskriftsartikel (refereegranskat)abstract
- The breakdown of plant material fuels soil functioning and biodiversity. Currently, process understanding of global decomposition patterns and the drivers of such patterns are hampered by the lack of coherent large-scale datasets. We buried 36,000 individual litterbags (tea bags) worldwide and found an overall negative correlation between initial mass-loss rates and stabilization factors of plant-derived carbon, using the Tea Bag Index (TBI). The stabilization factor quantifies the degree to which easy-to-degrade components accumulate during early-stage decomposition (e.g. by environmental limitations). However, agriculture and an interaction between moisture and temperature led to a decoupling between initial mass-loss rates and stabilization, notably in colder locations. Using TBI improved mass-loss estimates of natural litter compared to models that ignored stabilization. Ignoring the transformation of dead plant material to more recalcitrant substances during early-stage decomposition, and the environmental control of this transformation, could overestimate carbon losses during early decomposition in carbon cycle models.
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| 11. |
- Spitzer, Clydecia, et al.
(författare)
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Root traits and soil micro-organisms as drivers of plant-soil feedbacks within the sub-arctic tundra meadow
- 2022
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 110, s. 466-478
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Tidskriftsartikel (refereegranskat)abstract
- Plant-soil feedback (PSF) results from the influence of plants on the composition and abundance of various taxa and functional groups of soil micro-organisms, and their reciprocal effects on the plants. However, little is understood about the importance of fine root traits and root economic strategies in moderating microbial-driven PSF. We examined the relationships between PSF and 11 chemical and morphological root traits from 18 sub-arctic meadow plant species, as well as the soil microbial community composition which we characterized using phospholipid fatty acids (PLFAs) and high-throughput sequencing. We also investigated the importance of the root economics spectrum in influencing PSF, because it indicates plant below-ground economic strategies via trade-offs between resource acquisition and conservation. When we considered the entire root economics spectrum, we found that PSFs were more negative when root trait values were more acquisitive across the 18 species. In addition, PSF was more negative when values of root nitrogen content and root forks per root length were higher, and more positive when root dry matter content was higher. We additionally identified two fungal orders that were negatively related to PSF. However, we found no evidence that root traits influenced PSF through its relationship with these fungal orders. Synthesis. Our results provide evidence that for some fine root traits, the root economics spectrum and some fungal orders have an important role in influencing PSF. By investigating the roles of soil micro-organisms and fine root traits in driving PSF, this study enables us to better understand root trait-microbial linkages across species and therefore offers new insights about the mechanisms that underpin PSFs and ultimately plant community assembly.
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| 12. |
- Wardle, David, et al.
(författare)
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Impact of plant functional group and species removals on soil and plant nitrogen and phosphorus across a retrogressive chronosequence
- 2020
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 108, s. 561-573
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Tidskriftsartikel (refereegranskat)abstract
- In the prolonged absence of catastrophic disturbance, ecosystem retrogression occurs, which is characterized by declining soil nitrogen (N) and phosphorus (P) availability, increasing plant and soil N to P ratios, and reduced plant biomass and productivity. It is, however, largely unknown as to how the effects of plant communities on soil nutrients change during retrogression or might contribute to declining nutrient availability as retrogression proceeds. We studied a well-characterized system of 30 lake islands in northern Sweden that collectively represent a 5,000-year post-fire retrogressive chronosequence. For each island, we established an experiment that involved full factorial removal of three plant functional groups (tree roots, dwarf shrubs and mosses), and of three species of dwarf shrub (Vaccinium myrtillus, V. vitis-idaea and Empetrum hermaphroditum). After 19 years, we took various measures of soil N and P availability, and measured foliar N and P for each dwarf shrub species, for each plot in the experiment. Although plant removal effects (and particularly removal of tree roots, shrubs and Vaccinium species) on below-ground N and P measures sometimes changed during retrogression, this seldom happened in a way that explains the decline in nutrient availability and increase in N to P ratios that characterize ecosystem retrogression. The only exceptions were that the positive effects of tree roots on soil mineral N and P, and of V. myrtillus on soil mineral P, declined during retrogression. Plant removal effects on community-level measures of shrub N and P varied greatly across the chronosequence, but these effects again did not align with the changes in soil nutrient availability or N to P ratios that characterize ecosystem retrogression. Synthesis. Our results suggest that retrogression, and associated changes in nutrient availability and soil N to P ratios, is driven mainly by longer-term pedogenic processes as opposed to shorter-term effects of plant communities on soil N and P availability. More generally, they illustrate the value of long-term and large-scale experimental manipulations of plant communities for showing how effects of biodiversity loss on ecosystem properties vary across contrasting ecosystems.
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