Soil Macroinvertebrate Communities Research Articles

A global indicator of soil macroinvertebrate community composition, abundance and diversity

Macroinvertebrate communities are highly sensitive indicators of physical and chemical soil qualities. Their evaluation in field conditions is rather simple and could serve as proxy for soil-based ecosystem services that farmers and field technicians could use. We tested the hypothesis that an indicator of soil macroinvertebrate communities, with 14 taxonomic groups characterized at the order level, could be used in any region of the world to assess these communities. A synthetic indicator was calculated using data from 9 reference sites from tropical, subtropical and temperate regions, a set of 3694 data of the open access Macrofauna database and a new site for validation. Invertebrates were extracted with the standard ISO/TSBF methodology and characterized with a set of 14 large taxonomic units, plus an index of taxonomic richness and total density. At each of the 9 reference sites, 27 to 252 sample points, representing different types of plant covers and/or soil management options, were considered and compared with their respective local synthetic GISQ indicator values. These indicators, elaborated from Principal Component Analysis of the sample points data, are set to vary from 0.1 to 1.0 according to the composition, diversity and abundance of the community. Analyses showed great similarities among sites, with Factors 1 (from 21.9 to 36.9 % variance explained) expressing the overall abundance and diversity of the communities and Factors 2 (8.9 to 15.83 %) opposing sites with dominant soil ecosystem engineer populations (Earthworms, Ants, Termites and some Coleoptera) to sites dominated by litter transformer populations (Diplopoda, Isopoda and others). Indicator formulae were designed based on PCA analyses of each data set and a global formula was established with the Macrofauna database. Very high correlations (>0.95) were obtained among values calculated with local data set and the general formula calculated with data of the Macrofauna database, in 8 of 9 sites and in the validation site. We discuss the importance of having a single formula to transform data obtained with a simple standard field method in the building of public policies for soil-based ecosystem services payment.

Management practices and incidence of pests in plantain (Musa paradisiaca AAB) crops. Consequences on the sustainability of the cropping systems

Plantain (Musa paradisiaca AAB) is one of the most important staple crops in the tropics, particularly in the Caribbean. Pests are the main constraint to plantain production and yield increases may be possible by improving pest management. However, there is a lack of data on these cropping systems and a need to identify new elements of improved production systems that can control pests in line with the principles of agroecological transition. In this study, we test the hypothesis that crops grown in good quality soils are less susceptible to pests. To this end, an agroecological diagnosis of the biological, physical, morphological and chemical soil conditions and the occurrence of pests, in particular plant-parasitic nematodes, was carried out on 21 plantain plots with contrasting management in Guadeloupe (French West Indies). After classifying these plots according to their management practices, from conventional to agroecological, we searched for relationships between cropping systems, soil quality and pests using a series of synthetic quality indices. Four different cropping systems were identified and compared: conventional intensive, intermediate, low-input and agroecological, according to the type and amount of agrochemicals used. Our data showed that the Chemical Index was significantly improved in the agroecological systems due to increases in pH, CEC, base saturation and total C and N content. The Morphological Index increased regularly from intensive to agroecological systems and was significantly higher in agroecological systems with higher proportions of biogenic aggregates. Soil macroinvertebrate communities were significantly influenced by production systems, with the highest values of the Macrofauna Index in low input and agroecological production systems. We also showed that plant parasitic nematodes were better regulated in agroecological production systems. Furthermore, the agroecological system achieved similar levels of crop production to conventional systems, without the use of pesticides. In addition, these agroecological cropping systems extend the duration of plantain plots, which is an indicator of the good health of these systems.

Native forest conversion alters soil macroinvertebrate diversity and soil quality in tropical mountain landscapes of northern Ecuador

Land use changes cause soil degradation and loss of biodiversity, thereby affecting ecological processes and soil-associated ecosystem services. However, land use change impacts on soil health have received little attention in the highland landscapes of the tropics. In this research, using the soil health framework, we assessed the impact of native forest conversion to anthropic systems (planted forests, pastures, and monocultures) on two ecosystem services: biodiversity conservation and soil fertility in the highlands of northern Ecuador. The biological dimension of our assessment focused on the diversity, abundance, and biomass of soil macroinvertebrate communities as proxies to soil functions, whereas soil chemical parameters were used to describe the soil fertility. The soil invertebrate communities and soil chemical parameters were studied in topsoil samples using 25 × 25 × 10 cm monoliths, obtained from 10 sampling sites randomly selected in each land use category. We hypothesized that native forests would present more diverse and even soil macroinvertebrate communities, and together with their soil chemical properties would indicate better soil quality than anthropic environments. Our results showed that the structure and composition of the edaphic macroinvertebrate communities significantly differed among the studied land use categories. As predicted, native forests presented greater values for richness, evenness and diversity of soil biota than did the other categories, demonstrating a significant loss of taxonomic biodiversity at order and genus levels. We also found a significant reduction of trophic diversity in native forests converted to anthropic environments. More trophic groups with greater abundances were found in native forests, where predators and detritivores stood out as dominant groups, indicating the good quality of the soil. The results from the soil chemical parameters also confirmed the distinction in soil health between native forests and anthropic environments. Our results highlight the risk associated with current trends of native forest loss and conversion to anthropic systems in high mountain ecosystems in the tropics, illustrating how these alterations could cause biodiversity loss and degradation of the chemical attributes of soil health. The findings of this research could contribute to the conservation and sustainable management of mountain agricultural landscapes in the study region.

Disturbance of plateau zokor (Eospalax baileyi) mounds increase plant and soil macroinvertebrate richness by offering a diversified microenvironment

Habitat heterogeneity is expected to change community composition and diversity, with large implications for ecosystem processes and function. Understanding the potential mechanisms of habitat heterogeneity affecting community ecological processes is a central issue in biodiversity conservation. In this study, we use a spatial metrics analysis to quantify the spatial pattern of plateau zokor mounds. We integrated soil physicochemical variables and community characteristic data to understand the disturbance effect of plateau zokor mounds on community diversity at a microhabitat scale (400 m2). Results showed that plant species richness increased significantly with increasing disturbance levels. Increases in forb species were largely the reason for the increased plant diversity in the alpine meadow disturbed by plateau zokor mounds. Disturbance caused by the plateau zokor significantly increased the soil macroinvertebrate richness and abundance, with herbivorous taxa playing a key role. Mantel tests and redundancy analysis showed that the composition of plant and soil macroinvertebrate communities are significantly related to soil moisture and soil temperature, and the SEM model revealing soil moisture and soil temperature positive effects on plant and macroinvertebrate richness after plateau zokor disturbance. Furthermore, soil variables (moisture, temperature, and organic carbon) directly affected plant richness, and indirectly affected soil macroinvertebrate communities. Our results suggest that the spatial pattern of plateau zokor mounds facilitate greater biodiversity through increased habitat complexity and heterogeneity. Therefore, it can be regarded as a “key species” in the alpine grassland and researchers should pay more attention to the ecological effects of alpine rodent disturbance on grassland ecosystems.

Soil macroinvertebrate communities: A world‐wide assessment

AbstractAimMacroinvertebrates comprise a highly diverse set of taxa with great potential as indicators of soil quality. Communities were sampled at 3,694 sites distributed world‐wide. We aimed to analyse the patterns of abundance, composition and network characteristics and their relationships to latitude, mean annual temperature and rainfall, land cover, soil texture and agricultural practices.LocationSites are distributed in 41 countries, ranging from 55° S to 57° N latitude, from 0 to 4,000 m in elevation, with annual rainfall ranging from 500 to >3,000 mm and mean temperatures of 5–32°C.Time period1980–2018.Major taxa studiedAll soil macroinvertebrates: Haplotaxida; Coleoptera; Formicidae; Arachnida; Chilopoda; Diplopoda; Diptera; Isoptera; Isopoda; Homoptera; Hemiptera; Gastropoda; Blattaria; Orthoptera; Lepidoptera; Dermaptera; and “others”.MethodsStandard ISO 23611‐5 sampling protocol was applied at all sites. Data treatment used a set of multivariate analyses, principal components analysis (PCA) on macrofauna data transformed by Hellinger’s method, multiple correspondence analysis for environmental data (latitude, elevation, temperature and average annual rainfall, type of vegetation cover) transformed into discrete classes, coinertia analysis to compare these two data sets, and bias‐corrected and accelerated bootstrap tests to evaluate the part of the variance of the macrofauna data attributable to each of the environmental factors. Network analysis was performed. Each pairwise association of taxonomic units was tested against a null model considering local and regional scales, in order to avoid spurious correlations.ResultsCommunities were separated into five clusters reflecting their densities and taxonomic richness. They were significantly influenced by climatic conditions, soil texture and vegetation cover. Abundance and diversity, highest in tropical forests (1,895 ± 234 individuals/m2) and savannahs (1,796 ± 72 individuals/m2), progressively decreased in tropical cropping systems (tree‐associated crops, 1,358 ± 120 individuals/m2; pastures, 1,178 ± 154 individuals/m2; and annual crops, 867 ± 62 individuals/m2), temperate grasslands (529 ± 60 individuals/m2), forests (232 ± 20 individuals/m2) and annual crops (231 ± 24 individuals/m2) and temperate dry forests and shrubs (195 ± 11 individuals/m2). Agricultural management decreased overall abundance by ≤54% in tropical areas and 64% in temperate areas. Connectivity varied with taxa, with dominant positive connections in litter transformers and negative connections with ecosystem engineers and Arachnida. Connectivity and modularity were higher in communities with low abundance and taxonomic richness.Main conclusionsSoil macroinvertebrate communities respond to climatic, soil and land‐cover conditions. All taxa, except termites, are found everywhere, and communities from the five clusters cover a wide range of geographical and environmental conditions. Agricultural practices significantly decrease abundance, although the presence of tree components alleviates this effect.

Drainage increases species richness and density of soil macro-invertebrates in the Zoige peatland of eastern Tibetan Plateau

Soil macro-invertebrates play an important role in the decomposition process of soil organic matter. As the world’s largest alpine peatland, the Zoige peatland on the eastern Tibetan Plateau is experiencing the decline in water table level primarily because of historic drainage. However, little is known about the responses of soil macro-invertebrate communities to water table decline. To address this issue, we established a field drainage experimental platform in 2013, which consists of low (50 cm deep drainage ditch) and intermediate (20 cm deep drainage ditch) water table level treatments, and the ambient (no drainage ditch) plots. In July (warm season) and November (cold season) of 2019, we examined the species composition, richness, densities and the vertical distribution of soil macro-invertebrates. Results showed that the species composition differed significantly among treatments. Species richness and densities of overall and different trophic groups (i.e., detritivores, herbivores and predators) of soil macro-invertebrates were significantly higher in the drained treatments compared to the ambient plots. Moreover, soil macro-invertebrates moved down to deeper soil layers in the low water table treatments compared to the ambient plots. In addition, sampling season (warm vs. cold) did not affect the responses of soil macro-invertebrates to water table decline. These results indicate that soil macro-invertebrate community is sensitive to water table decline in the Zoige peatland. Given the recognized importance of soil fauna to ecosystem functioning, more attention should be paid to the conservation of peatlands.

Soil Macroinvertebrate Communities as Indicators of Ecosystem Services in American Tropical Environments

Soil Macroinvertebrate Communities as Indicators of Ecosystem Services in American Tropical Environments

Agroforestry systems in the Colombian Amazon improve the provision of soil ecosystem services

In the Colombian Amazon, the provision of soil-based ecosystem services is threatened mainly by loss of plant cover. Methodologies are required that allow for a holistic assessment of soil degradation or restoration and associated changes in the provision of ecosystem services. With this objective, we measured macroinvertebrate communities, soil macroaggregates, soil hydrological properties and chemical soil properties in areas of the deforested Colombian Amazon. The sampled areas are located two landscape units (undulating footslopes and hillsides) and four different land use types (Mature Forest, Forest Implementations, Sylvopastoral Systems and Traditional pastures). Parameters were assembled into soil hydrological, chemical soil properties, macroaggregates and macroinvertebrate communities sub indicators that were subsequently grouped into a General Indicator of Soil Quality (GISQ). Values indicated differences in the provision of soil-based ecosystem services among landscape units and land use types. We confirmed and quantified the negative effects of deforestation and land-use intensification, increasing from Forest Implementation to Sylvopastoral Systems and Traditional Pastures. Soil macroinvertebrate communities and physical properties as proxies for soil biodiversity and soil hydrological functions were the most negatively affected.

Management Intensification of Hay Meadows and Fruit Orchards Alters Soil Macro- Invertebrate Communities Differently

Land-use changes and especially management intensification currently pose a major threat to biodiversity both on and beneath the soil surface. With a comparative approach, we investigated how management intensity in orchards and meadows influences soil macro-invertebrate communities in a North-Italian Alpine region. We compared soil fauna assemblies from traditional low-input sites with respective intensively managed ones. As expected, the taxonomical richness and diversity were lower in both intensive management types. Extensive management of both types revealed similar communities, while intensification led to substantial differences between management types. From these results, we conclude that intensification of agricultural practices severely alters the soil fauna community and biodiversity in general, however, the direction of these changes is governed by the management type. In our view, extensive management, traditional for mountain areas, favors soil fauna communities that have adapted over a long time and can thus be viewed as a sustainable reference condition for new production systems that consider the protection of soil diversity in order to conserve essential ecosystem functions.

Soil Macroinvertebrate Presence Alters Microbial Community Composition and Activity in the Rhizosphere.

Despite decades of research, our understanding of the importance of invertebrates for soil biogeochemical processes remains incomplete. This is especially true when considering soil invertebrate effects mediated through their interactions with soil microbes. The aim of this study was to elucidate how soil macroinvertebrates affect soil microbial community composition and function within the root zone of a managed grass system. We conducted a 2-year field mesocosm study in which soil macroinvertebrate communities were manipulated through size-based exclusion and tracked changes in microbial community composition, diversity, biomass and activity to quantify macroinvertebrate-driven effects on microbial communities and their functions within the rhizosphere. The presence of soil macroinvertebrates created distinct microbial communities and altered both microbial biomass and function. Soil macroinvertebrates increased bacterial diversity and fungal biomass, as well as increased phenol oxidase and glucosidase activities, which are important in the degradation of organic matter. Macroinvertebrates also caused distinct shifts in the relative abundance of different bacterial phyla. Our findings indicate that within the rhizosphere, macroinvertebrates have a stimulatory effect on microbial communities and processes, possibly due to low-intensity microbial grazing or through the dispersal of microbial cells and spores by mobile invertebrates. Our results suggest that macroinvertebrate activity can be an important control on microbially-mediated processes in the rhizosphere such as nitrogen mineralization and soil organic matter formation.

Structural and functional characteristics of high alpine soil macro-invertebrate communities

Soil macro-invertebrates play an important role in the formation and functioning of soils, which makes them indispensable for all terrestrial ecosystems, including high alpine soils. However, in the latter, knowledge on species identity, diversity, and functionality of macro-invertebrate soil communities is scarce. Here, we address this knowledge gap by investigating the structural and functional composition of soil macro-invertebrate communities in high alpine sites of the European Alps that differ in sheep grazing intensity (low, medium, and high). Abundance data were combined with the analysis of natural variations in stable isotope ratios (13C/12C, 15N/14N) of food sources and soil animals, allowing insight into the trophic structure of the decomposer community. The presence of sheep significantly increased the abundance of Nematocera, but reduced the abundance of most other taxa. Diplopoda were found exclusively at the low elevation site with almost no sheep grazing, while Diptera larvae increased in numbers at higher elevation sites. Lumbricidae species were abundant at all sites except the highest site, which was intensively grazed by sheep and also used as a resting place. In contrast, trophic relations were not affected by sheep grazing intensity, four trophic groups were clearly distinguished, pointing to a relatively simple food web structure: (1) primary decomposers, (2) secondary decomposers and dung feeders, (3) root and fungal feeders, and (4) predators. We suggest that the shallow soils with high organic matter do not allow the formation of more complex food webs.

Soil Moisture Controls the Thermal Habitat of Active Layer Soils in the McMurdo Dry Valleys, Antarctica

AbstractAntarctic soil ecosystems are strongly controlled by abiotic habitat variables. Regional climate change in the McMurdo Dry Valleys is expected to cause warming over the next century, leading to an increase in frequency of freeze‐thaw cycling in the soil habitat. Previous studies show that physiological stress associated with freeze‐thaw cycling adversely affects invertebrate populations by decreasing abundance and positively selecting for larger body sizes. However, it remains unclear whether or not climate warming will indeed enhance the frequency of annual freeze‐thaw cycling and associated physiological stresses. This research quantifies the frequency, rate, and spatial heterogeneity of active layer freezing to better understand how regional climate change may affect active layer soil thermodynamics, and, in turn, affect soil macroinvertebrate communities. Shallow active layer temperature, specific conductance, and soil moisture were observed along natural wetness gradients. Field observations show that the frequency and rate of freeze events are nonlinearly related to freezable soil moisture (θf). Over a 2 year period, soils at θf < 0.080 m3/m3 experienced between 15 and 35 freeze events and froze rapidly compared to soils with θf > 0.080 m3/m3, which experienced between 2 and 6 freeze events and froze more gradually. A numerical soil thermodynamic model is able to simulate observed freezing rates across a range of θf, reinforcing a well‐known causal relationship between soil moisture and active layer freezing dynamics. Findings show that slight increases in soil moisture can potentially offset the effect of climate warming on exacerbating soil freeze‐thaw cycling.

Soil macroinvertebrates community and its temporal variation in a well-drained savannah of the Venezuelan Llanos

In the well-drained savannahs of Venezuelan Llanos, intensive agricultural activities could be causing damage to the soil, with negative consequences for the ecosystem. In order to avoid this problem, some agroecological alternatives are needed. Consequently, it is necessary to know the biologic dimension in this ecosystem, and within this, the soil macroinvertebrate community. The purpose of this work was to characterize this community in the natural savannah: its structure and diversity, its time variation and its relationship with the physical-chemical properties of the soil. A total of 72 samples were taken in different season along a period of time of 1405 days. The results revealed that the soil macrofauna had an average density of 243.5 ± 183.6 ind·m−2, distributed in 32 families of 11 orders, with a diversity of N1 = 4.5 ± 2.8 families. Coleoptera, Hymenoptera and Isoptera was the most dominants orders. The density, richness and diversity of families showed a temporal variation (r ≥ −0.5; p < 0,05). Additionally, the structure of the soil macroinvertebrate community showed a vertical variation. The relationship with soil properties differed according families: Lampyridae, Aphodiidae and Formicidae had a positive correlation with soil macro-porosity (radius of the pores > 15 μm); Tenthredinidae and Tenebrionidae had a positive correlation with the micro-porosity (pores ≤ 15 μm). The community in general, correlated positively with soil porosity and negatively with bulk density. This suggests that these soil properties need to be considered when designing agroecological technics in this area.

Comparison of soil macro-invertebrate communities in Malaysian oil palm plantations with secondary forest from the viewpoint of litter decomposition

Biodiversity decline in rapidly expanding oil palm plantations is of global concern. Many studies have demonstrated that fauna species diversity is lower in oil palm plantations than forests. However, information about the flow-on effects of these declines in species diversity on ecosystem functioning is scarce for oil palm plantations. Litter decomposition performed by soil organisms is a vital ecosystem function that regulates nutrient cycling and carbon sequestration. Some studies have found a high level of redundancy among litter decomposing species. In order to evaluate the effects of the conversion of forests to oil palm plantations on decomposition, we investigated the abundance and biomass of soil macro-invertebrates at sites in two oil palm plantations and a secondary forest in Malaysia. Biodiversity of soil macro-invertebrates were lower in the oil palm plantations than in the secondary forest. The abundance and biomass of surface–living litter transformers was lower in oil palm plantations than forest, probably due to the isolated piles of frond litter that occur in plantations, instead of the more continuous litter layer observed in forests. However, we found dense populations of wood (litter)–feeding termites in the thick rachises of fronds heaped on the ground surface. A pantropical earthworm species, Pontoscolex corethrurus, which buries the litter through cast deposition, abounded more in the oil palm plantations than in the secondary forest. These characteristics of soil macro-invertebrates have also been reported in other oil palm plantations. Thus, we conclude that the conversion of forests to oil palm plantations may reduce diversity of soil macro-invertebrates, increase the heterogeneity of macro-invertebrates distribution and decrease populations of some functional groups of soil macro-invertebrates. However, overall, forest conversion does not appear to have a negative impact on the decomposition process to a great extent, owing to the colonization of plantation sites by other groups of decomposer animals that are favored by disturbance and/or the great amount of localized input of fresh fronds pruned at the time of fruit harvesting.

Soil Macroinvertebrate Communities Across a Productivity Gradient in Deciduous Forests of Eastern North America

Abstract Within the temperate, deciduous forests of the eastern US, diverse soil-fauna communities are structured by a combination of environmental gradients and interactions with other biota. The introduction of non-native soil taxa has altered communities and soil processes, and adds another degree of variability to these systems. We sampled soil macroinvertebrate abundance from forested sites in Missouri (MO), Michigan (MI), Massachusetts (MA), and New Hampshire (NH), with the objective of comparing community assemblages and evaluating the role of invasive earthworms along the temperature—productivity gradient represented by the sites. The primary detritivores encountered were earthworms and millipedes. Earthworms were collected only in MO and MI, and at much greater density in MO. Millipedes were found at every site except in MO, and at their highest mean density in NH. Warmer temperatures, higher litter productivity, and low Oa horizon depth (as found in MO) were correlated with high earthworm activi...

Soil Macrofaunal Communities are Heterogeneous in Heathlands with Different Grazing Intensity

Moderate grazing by cattle increases the heterogeneity of soil and vegetation. This has been suggested as an ecologically sustainable mean of managing natural environments endangered by tree encroachment, such as heathlands. Our study was performed to test the impact of grazing intensity on soil macroinvertebrate communities in heterogeneous landscapes in a private property eligible to the Natura 2000 European Network of Special Protection Areas within the Brenne Natural Regional Park (Indre, France). We sampled macroinvertebrates along a broken line crossing 5 different land-use types, from pasture to pine forest, passing through a besom heath (Erica scoparia) heathland at 3 levels of cattle pressure. We hypothesized that: i) litter-dwelling (mostly arthropods and mollusks) and soil-dwelling macroinvertebrates (mostly earthworms) would respond in an opposite manner to various grazing intensities, and ii) intermediate cattle pressure (pastured heath) would increase soil and community heterogeneity. The results supported the first hypothesis, which was explained by land-use impacts mediated by soil properties. However, our results supported only partly the second hypothesis since maximum dissimilarity (whether in the composition of soil macroinvertebrate communities or in soil features) was observed in only one out of the two pastured heaths where cattle pressure was intermediate.

If we build it, will they colonize? A test of the field of dreams paradigm with soil macroinvertebrate communities

Soil invertebrates transfer energy and material between belowground and aboveground systems, but a clear understanding of their recovery following long-term disturbance to soil is lacking. We quantified trophic, taxonomic, and compositional change of soil macroinvertebrates in cultivated fields, prairies restored for 1–21 years, and prairies that had never been cultivated. Taxonomic diversity (H′; based on morphospecies), richness, and evenness did not change across the chronosequence. Average taxonomic richness across all restorations was intermediate to cultivated fields and remnant prairie. Detritivores increased linearly across the chronosequence, while omnivores peaked at 5–8 years following restoration, coinciding with high plant richness. Spiders were the only predators that increased across the chronosequence. Proportional similarity of the macroinvertebrate communities to the average structure of remnant prairies increased across the chronosequence, but this relationship was not upheld when individual remnant prairies with different community structures were used. This study demonstrates that remnants can vary widely in macroinvertebrate trophic structure, diversity, and taxonomic composition and include exotic macroinvertebrate species, indicating a real dilemma for assessing recovery of restorations to a “target” community.

The response of soil macroinvertebrates to alpine meadow degradation in the Qinghai–Tibetan Plateau, China

The alpine meadow in the Qinghai–Tibetan Plateau has degraded in recent years; however, the response of soil macroinvertebrates to the alpine meadow degradation is unknown. We hypothesized that (i) soil macroinvertebrate diversity and abundance decrease gradually during alpine meadow degradation and (ii) the composition of soil macroinvertebrate communities is specific to particular degradation phases. We investigated the soil macroinvertebrates, plant communities and soil properties in a swampy meadow, grassland meadow, moderately degraded meadow and severely degraded meadow to test the hypotheses from April 2009 to October 2011. These areas represent four degradation phases of alpine meadows. The structure of the soil macroinvertebrate community in the moderately degraded meadow was notably different from that of the swampy meadow and the grassland meadow. Most of the macroinvertebrate groups disappeared from the severely degraded meadow. Taxonomic richness and abundance were significantly greater in the moderately degraded meadow and were significantly lower in the severely degraded meadow. Significant seasonal dynamics were only found for taxonomic richness in the moderately degraded meadow. Furthermore, the abundances of Polydesmida and Coleoptera differed significantly between the four habitats, but no significant seasonal changes were observed in the four habitats. The soil macroinvertebrate structures were influenced by the plant and soil variations, particularly the available soil P and K, the pH and vegetation heights, which changed significantly among the habitats. The soil macroinvertebrate taxonomic richness was also significantly correlated with the species richness, species coverage, vegetation height, aboveground biomass of the plant community, bulk density, organic matter, available soil N, P and K and pH. However, the abundances of the soil macroinvertebrate community and Polydesmida were only correlated with the available soil P and K, while Coleoptera was significantly correlated with all measured soil parameters, plant species richness and species coverage. Our results demonstrated that moderate and severe degradation in the alpine meadow have significant effects on the structure, diversity and abundance of soil macroinvertebrate communities, and the available soil P and K, pH and vegetation height are the determining factors. Our results also indicated that the soil macroinvertebrates in moderately degraded meadows will be more easily affected by climate changes in the future.

Soil macroinvertebrate communities and ecosystem services in deforested landscapes of Amazonia

Land use changes in the Amazon region strongly impact soil macroinvertebrate communities, which are recognized as major drivers of soil functions (Lavelle et al., 2006). To explore these relations, we tested the hypotheses that (i) soil macrofauna communities respond to landscape changes and (ii) soil macrofauna and ecosystem services are linked. We conducted a survey of macrofauna communities and indicators of ecosystem services at 270 sites in southern Colombia (department of Caqueta) and northern Brazil (state of Pará), two areas of the Amazon where family agriculture dominates. Sites represented a variety of land use types: forests, fallows, annual or perennial crops, and pastures. At each site we assessed soil macroinvertebrate density (18 taxonomic units) and the following ecosystem service indicators: soil and aboveground biomass carbon stock; water infiltration rate; aeration, drainage and water storage capacities based on pore-size distribution; soil chemical fertility; and soil aggregation. Significant covariation was observed between macrofauna communities and landscape metric data (co-inertia analysis: RV=0.30, p<0.01, Monte Carlo test) and between macrofauna communities and ecosystem service indicators (co-inertia analysis: RV=0.35, p<0.01, Monte Carlo test). Points located in pastures within 100m of forest had greater macrofauna density and diversity than those located in pastures with no forest within 100m (Wilcoxon rank sum test, p<0.01). Total macroinvertebrate density was significantly correlated with macroporosity (r2=0.42, p<0.01), as was the density of specific taxonomic groups: Chilopoda (r2=0.43, p<0.01), Isoptera (r2=0.30, p<0.01), Diplopoda (r2=0.31, p<0.01), and Formicidae (r2=0.13, p<0.01). Total macroinvertebrate density was also significantly correlated with available soil water (r2=0.38, p<0.01) as well as other soil-service indicators (but with r2<0.10). Results demonstrate that landscape dynamics and composition affect soil macrofauna communities, and that soil macrofauna density is significantly correlated with soil services in deforested Amazonia, indicating that soil macrofauna have an engineering and/or indicator function.

Soil ecosystem services and land use in the rapidly changing Orinoco River Basin of Colombia

In the Orinoco River Basin of eastern Colombia large scale and rapid conversion of natural savannas into commercial agriculture exists as a critical threat for the ecological integrity of this fragile region. The highly acidic and compacted soils inherent to this region require thorough physical and chemical conditioning in order for intensive cropping systems to be established. Assessing the impact of this dramatic soil perturbation on biodiversity, ecosystem services and other elements of the natural capital is an urgent task for designing sustainable management options in the region. To address this need, we evaluated soil macro invertebrate communities and soil-based ecosystem services (climate regulation, hydrologic functions, soil stability provided by macro aggregation and nutrient provision potential) in four major production systems: improved pastures, annual crops (rice, corn and soy bean), oil palm and rubber plantations, and compared them to the original savanna. Fifteen plots of each system were sampled along a 200km natural gradient of soil and climatic conditions. In each plot, we assessed climate regulation by measuring green house gas emissions (N2O, CH4 and CO2) and C storage in aboveground plant biomass and soil (0–20cm). Soil biodiversity (macro invertebrate communities) and three other soil-based ecosystem services, were assessed using sets of 12–20 relevant variables associated with each service and synthesized via multivariate analyses into a single indicator for each ecosystem function, adjusted in a range of 0.1–1.0. Savannas yielded intermediate values for most indicators, while each production system appeared to improve at least one ecosystem service. For example, nutrient provision (chemical fertility) was highest in annual cropping systems (0.78±0.03) due to relatively high concentrations of Ca, Mg, N, K, and available P and low Al saturation. Hydrological functions and climate regulation (C storage and GHG emissions) were generally improved by perennial crops (oil palm and rubber), while indicators for macro invertebrate biodiversity and activity (0.73±0.05) and soil macro aggregation (0.76±0.02) were highest within improved pastures. High variability within each system indicates the potential to make improvements in fields with lowest indicator values, while differences among systems suggest the potential to mitigate negative impacts by combining plots with contrasted functions in a strategically designed landscape mosaic.