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In this perspective article we start from the theories of constructivism and conceptual change within the field of education to develop and present hypotheses about how understandings of biodiversity and diversity more generally are formed. We argue that extrinsic and circumstantial elements from everyday experiences are relevant in shaping understandings of biodiversity.We discuss how children’s games and food-related experiences may influence how children form conceptions of biodiversity. We focus on ‘misconceptions,’ areas where conceptions differ from established ideas in ecology. These include: underestimating the importance of diversity for “complementarity” and over-simplifications of how nature works. Firstly, we examine a type of children’s game that often concerns biodiversity and consists of a puzzle where the forming of categories is encouraged. Secondly, we discuss people’s relation to nature through food in their diets. We believe that targeted intervention is needed to move towards an inclusive and multi-faceted representation of biodiversity, one that emphasises fundamental properties that make a whole and interacting parts. We argue that experiences of games and food can be pivotal in developing a deeper understanding of these fundamental properties of biodiversity. These would be important experiences to consider when attempting transformative change of relationships between people and nature.

Yang et al . have raised criticism that the results reported by us would not be relevant for natural forests. We argue that productivity is positively related to species richness also in subtropical natural forests, and that both the species pools and the range of tree species richness used in our experiment are representative of many natural forests of this biome.

Aims Positive plant diversity–ecosystem function relations are ultimately driven by variation in functional traits among individuals that form a community. To date, research has largely focused on the role of species diversity for ecosystem functioning. However, substantial intraspecific trait variation is common and a significant part of this variation caused by genetic differences among individuals. Here, we studied the relative importance of species diversity and seed family (SF) diversity within species for growth and herbivory in experimental subtropical tree assemblages. Methods In 2010, we set up a field experiment in subtropical China, using four species from the local species pool. Trees were raised from seeds, with seeds from the same mother tree forming an SF. We established 23 plots containing one or four species (species diversity treatment) and one or four SFs per species (SF diversity treatment). Tree growth (stem diameter, plant height and crown expansion) and herbivory (percentage leaf loss due to leaf chewers) were monitored annually from 2011 to 2013. Important findings Tree species richness promoted growth but had no effect on herbivory. In contrast, SF diversity reduced growth and increased herbivory but only so in species mixtures. Most of the observed effects were time dependent, with the largest effect found in 2013. Our results suggest that biodiversity can affect plant performance directly via tree species–species interactions, or context dependent, via potential effects on inter-trophic interactions. Two important conclusions should be drawn from our findings. Firstly, in future studies regarding biodiversity and ecosystem functioning (BEF) relationships, intraspecific genetic diversity should be given similar weight as species diversity as it has often been neglected and its effects are not well understood. Secondly, we demonstrate opposite effects of biodiversity among and within species, stressing the importance to consider the effects of multiple levels of biodiversity simultaneously.

Although the protective role of leaf litter cover against soil erosion is known for a long time, little research has been conducted on the processes involved. Moreover, the impact of soil meso- and macrofauna within the litter layer on erosion control is not clear. To investigate how leaf litter cover and diversity as well as meso- and macrofauna influence sediment discharge in subtropical forest ecosystems, a field experiment has been carried out in Southeast China. A full-factorial random design with 96 micro-scale runoff plots and 7 domestic leaf species was established and erosion was triggered by a rainfall simulator. Our results demonstrate that leaf litter cover protects soil from erosion (−82 % sediment discharge on leaf covered plots) by rainfall and this protection is removed as litter decomposes. The protective effect is influenced by the presence or absence of soil meso- and macrofauna. Fauna presence increases soil erosion rates significantly by 58 %, while leaf species diversity shows a non-significant negative trend. We assume that the faunal effect arises from arthropods slackening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Even though the diversity level did not show a significant influence, single leaf species in monocultures show rather different impacts on sediment discharge and thus, erosion control. In our experiment, runoff plots with leaf litter from Machilus thunbergii showed the highest sediment discharge (68.0 g m−2) whereas plots with Cyclobalanopsis glauca showed the smallest rates (7.9 g m−2).

BACKGROUND: Loss of biodiversity and increased nutrient inputs are two of the most crucial anthropogenic factors driving ecosystem change. Although both received considerable attention in previous studies, information on their interactive effects on ecosystem functioning is scarce. In particular, little is known on how soil biota and their functions are affected by combined changes in plant diversity and fertilization. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the effects of plant diversity, functional community composition, and fertilization on the biomass and respiration of soil microbial communities in a long-term biodiversity experiment in semi-natural grassland (Jena Experiment). Plant species richness enhanced microbial basal respiration and microbial biomass, but did not significantly affect microbial specific respiration. In contrast, the presence of legumes and fertilization significantly decreased microbial specific respiration, without altering microbial biomass. The effect of legumes was superimposed by fertilization as indicated by a significant interaction between the presence of legumes and fertilization. Further, changes in microbial stoichiometry (C-to-N ratio) and specific respiration suggest the presence of legumes to reduce N limitation of soil microorganisms and to modify microbial C use efficiency. CONCLUSIONS/SIGNIFICANCE: Our study highlights the role of plant species and functional group diversity as well as interactions between plant community composition and fertilizer application for soil microbial functions. Our results suggest soil microbial stoichiometry to be a powerful indicator of microbial functioning under N limited conditions. Although our results support the notion that plant diversity and fertilizer application independently affect microbial functioning, legume effects on microbial N limitation were superimposed by fertilization, indicating significant interactions between the functional composition of plant communities and nutrient inputs for soil processes. Open-Access Publikationsfonds 2015 peerReviewed

In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.

Carbon cycling responses of ecosystems to global warming will likely be stronger in cold ecosystems where many processes are temperature‐limited. Predicting these effects is difficult because air and soil temperatures will not change in concert, and will affect above and belowground processes differently. We disentangled above and belowground temperature effects on plant C allocation and deposition of plant C in soils by independently manipulating air and soil temperatures in microcosms planted with either Leucanthemopsis alpina or Pinus mugo seedlings. Daily average temperatures of 4 or 9°C were applied to shoots and independently to roots, and plants pulse‐labelled with 14CO2. We traced soil CO2 and 14CO2 evolution for 4 days, after which microcosms were destructively harvested and 14C quantified in plant and soil fractions. In microcosms with L. alpina, net 14C uptake was higher at 9°C than at 4°C soil temperature, and this difference was independent of air temperature. In warmer soils, more C was allocated to roots at greater soil depth, with no effect of air temperature. In P. mugo microcosms, assimilate partitioning to roots increased with air temperature, but only when soils were at 9°C. Higher soil temperatures also increased the mean soil depth at which 14C was allocated. Our findings highlight the dependence of C uptake, use, and partitioning on both air and soil temperature, with the latter being relatively more important. The strong temperature‐sensitivity of C assimilate use in the roots and rhizosphere supports the hypothesis that cold limitation on C uptake is primarily mediated by reduced sink strength in the roots. We conclude that variations in soil rather than air temperature are going to drive plant responses to warming in cold environments, with potentially large changes in C cycling due to enhanced transfer of plant‐derived C to soils.

Biodiversity enhances ecosystem functions such as biomass production and nutrient cycling. Although the majority of the terrestrial biodiversity is hidden in soils, very little is known about the importance of the diversity of microbial communities for soil functioning. Here, we tested effects of biodiversity on the functioning of methanotrophs, a specialized group of soil bacteria that plays a key role in mediating greenhouse gas emissions from soils. Using pure strains of methanotrophic bacteria, we assembled artificial communities of different diversity levels, with which we inoculated sterile soil microcosms. To assess the functioning of these communities, we measured methane oxidation by gas chromatography throughout the experiment and determined changes in community composition and community size at several time points by quantitative PCR and sequencing. We demonstrate that microbial diversity had a positive overyielding effect on methane oxidation, in particular at the beginning of the experiment. This higher assimilation of CH4 at high diversity translated into increased growth and significantly larger communities towards the end of the study. The overyielding of mixtures with respect to CH4 consumption and community size were positively correlated. The temporal CH4 consumption profiles of strain monocultures differed, raising the possibility that temporal complementarity of component strains drove the observed community-level strain richness effects; however, the community niche metric we derived from the temporal activity profiles did not explain the observed strain richness effect. The strain richness effect also was unrelated to both the phylogenetic and functional trait diversity of mixed communities. Overall, our results suggest that positive biodiversity-ecosystem-function relationships show similar patterns across different scales and may be widespread in nature. Additionally, biodiversity is probably also important in natural methanotrophic communities for the ecosystem function methane oxidation. Therefore, maintaining soil conditions that support a high diversity of methanotrophs may help to reduce the emission of the greenhouse gas methane.

Soil ecosystems actively regulate climate by controlling methane and nitrous oxide fluxes into the atmosphere. Soils have been, however, drastically altered by agricultural practices, such as nitrogen amendment which increases nitrous oxide emission while it reduces methane uptakes in well-aerated soils by affecting methane-oxidizing bacteria. New nitrification inhibitors, such as 3,4-dimethylpyrazole phosphate (DMPP), are often applied in combination with nitrogen-based fertilizer to increase plant productivity by increasing available ammonium and inhibiting denitrification processes reducing in turn nitrous oxide emissions. However, the increase in ammonium due to nitrification inhibition might also affect methane oxidizing bacteria. We therefore investigated the effects of nitrogen-based fertilizer and DMPP on methane and nitrous oxide fluxes in an extensively managed grassland. We also determined the spatial distribution of active methane oxidizing bacteria by radiolabeling. Short-term reduction in methane uptake and methanotrophic activity occurred after application of 600 kg N ha−1 while DMPP did not alter methane uptake but reduced nitrous oxide emission. The combination of both radio-labeling and field measurement revealed that methane uptake collapsed in the field when methanotrophic activity was inhibited not only in the surface but also in deeper soil. Finally, both methane uptake and methanotrophic activity recovered with time.

Methanotrophic bacteria drive upland soil methane (CH4) uptake. Land-use change often affects their activity, but the mechanisms involved are not well understood. We studied soil-atmosphere CH4 fluxes along a 120-year Norway spruce afforestation chronosequence on subalpine pasture, testing whether effects were related to shifts in the spatial niche of methanotrophs. Previous field data had shown that soil 14CH4 uptake increased with forest age, and that this effect was driven by decreased water filled pore space due to higher rainfall interception in the more developed canopies of older forest stands. The spatial distribution of methanotrophic activity was determined by 14CH4-labelling followed by soil section preparation, aggregate size fractionation, aggregate erosion, and micro-autoradiographic imaging. Uptake rates of CH4 measured in laboratory incubations of soil cores as well as their water contents largely followed the in situ measurements previously made in the field. 14CH4 assimilation was heterogeneously distributed, and occurred further down the soil profile in older forest that had a more developed organic layer that did not contribute to CH4 uptake. Assimilation was largest in 2—8 mm aggregates, and higher at the exterior than in the interior of aggregates. Our data indicates that differences in soil aggregation and related methanotrophic activities did not contribute substantially to higher CH4 uptake in older forest, mostly because aggregation did not change much with age. On a per mass basis, however, large aggregates contributed less to CH4 uptake due to their unfavorable surface to volume ratio. More generally, we argue that the (sub-)aggregate heterogeneity of soil microbial activity and diversity is underexplored, although it critically determines ecological interactions that drive ecosystem-level processes.

Aims: Most biodiversity–ecosystem functioning research has been carried out in grassland ecosystems, and little is known about whether forest ecosystems, in particular outside the temperate zone, respond similarly. Here, we tested whether productivity, assessed as leaf area index (LAI), increases with species richness in young experimental stands of subtropical trees, whether this response is similar for early-season leaf area (which is dominated by evergreens) and seasonal leaf area increase (which is dominated by deciduous species), and whether responses saturate at high species richness. Methods: We used a planted tree biodiversity experiment in south-east China to test our hypotheses. LAI was determined three times by digital hemispheric photography in 144 plots that had been planted with 400 trees each, forming communities with 1, 2, 4, 8 or 16 tree species. Important Findings: LAI increased significantly with tree species richness in the fifth year of stand establishment. Similar, but weaker, statistically non-significant trends were observed 1 year before. We did not observe leaf area overyielding and the presence of particularly productive and unproductive species explained large amounts of variation in leaf area, suggesting that selection-type effects contributed substantially to the biodiversity effects we found in this early phase of stand establishment. Effects sizes were moderate to large and comparable in magnitude to the ones reported for grassland ecosystems. Subtropical (and tropical) forests harbor substantial parts of global net primary production and are critical for the Earth’s carbon and hydrological cycle, and our results suggest that tree diversity critically supports these ecosystem services.

Most experimental biodiversity-ecosystem functioning research to date has addressed herbaceous plant communities. Comparably little is known about how forest communities will respond to species losses, despite their importance for global biogeochemical cycling. We studied tree species interactions in experimental subtropical tree communities with 33 distinct tree species mixtures and one, two, or four species. Plots were either exposed to natural light levels or shaded. Trees grew rapidly and were intensely competing above ground after 1.5 growing seasons when plots were thinned and the vertical distribution of leaves and wood determined by separating the biomass of harvested trees into 50 cm height increments. Our aim was to analyze effects of species richness in relation to the vertical allocation of leaf biomass and wood, with an emphasis on bipartite competitive interactions among species. Aboveground productivity increased with species richness. The community-level vertical leaf and wood distribution depended on the species composition of communities. Mean height and breadth of species-level vertical leaf and wood distributions did not change with species richness. However, the extra biomass produced by mixtures compared to monocultures of the component species increased when vertical leaf distributions of monocultures were more different. Decomposition of biodiversity effects with the additive partitioning scheme indicated positive complementarity effects that were higher in light than in shade. Selection effects did not deviate from zero, irrespective of light levels. Vertical leaf distributions shifted apart in mixed stands as consequence of competition-driven phenotypic plasticity, promoting realized complementarity. Structural equation models showed that this effect was larger for species that differed more in growth strategies that were characterized by functional traits. In 13 of the 18 investigated two-species mixtures, both species benefitted relative to intraspecific competition in monoculture. In the remaining five pairwise mixtures, the relative yield gain of one species exceeded the relative yield loss of the other species, resulting in a relative yield total (RYT) exceeding 1. Overall, our analysis indicates that richness-productivity relationships are promoted by interspecific niche complementarity at early stages of stand development, and that this effect is enhanced by architectural plasticity.

International audience; Plant diversity effects on ecosystem functioning can potentially interact with global climate by altering fluxes of the radiatively active trace gases nitrous oxide (N2O) and methane (CH4). We studied the effects of grassland species richness (116) in combination with application of fertilizer (nitrogen:phosphorus:potassium = 100:43.6:83 kg ha-1 a-1) on N2O and CH4 fluxes in a long-term field experiment. Soil N2O emissions, measured over 2 years using static chambers, decreased with species richness unless fertilizer was added. N2O emissions increased with fertilization and the fraction of legumes in plant communities. Soil CH4 uptake, a process driven by methanotrophic bacteria, decreased with plant species numbers, irrespective of fertilization. Using structural equation models, we related trace gas fluxes to soil moisture, soil inorganic N concentrations, nitrifying and denitrifying enzyme activity, and the abundance of ammonia oxidizers, nitrite oxidizers, and denitrifiers (quantified by real-time PCR of gene fragments amplified from microbial DNA in soil). These analyses indicated that plant species richness increased soil moisture, which in turn increased N cycling-related activities. Enhanced N cycling increased N2O emission and soil CH4 uptake, with the latter possibly caused by removal of inhibitory ammonium by nitrification. The moisture-related indirect effects were surpassed by direct, moisture-independent effects opposite in direction. Microbial gene abundances responded positively to fertilizer but not to plant species richness. The response patterns we found were statistically robust and highlight the potential of plant biodiversity to interact with climatic change through mechanisms unrelated to carbon storage and associated carbon dioxide removal.

Plant and Soil, 282 (1-2), ISSN:0032-079X, ISSN:1573-5036