Macrofaunal Diversity Research Articles

The Diversity of Soil Macrofauna on Agroforestry Teak (Tectona grandis) and Polynesian Arrowroot (Tacca leontopetaloides)

Teak and polynesian arrowroot is a new pattern of agroforestry to support food security of communities around forests in coastal areas. The presence of polynesian arrowroot under teak stands is not only expected to be food sources but also to provide ecological benefits for biodiversity, especially soil macrofauna. The study aims is to determine the diversity of soil macrofauna in teak and polynesia arrowroot agroforestry patterns. The study was conducted in Garut Regency in April 2017. The method used in this study was monolithic technique and analyzed by calculating diversity and richness index. The object was an agroforestry demonstration plot with three polynesia arrowroot spacings under 7-years-old teak stand and monoculture teak. The results showed that there were 5 soil macrofaunas in teak and polynesian arrowroot agroforestry which are from five families and five orders. The dominance order was coleoptera with Important Value Index (IVI) = 133.93% -157.78% and opisthophora with IVI = 103.51%. The diversity and richness of soil macrofauna in teak and polynesian arrowroot agroforestry patterns is low (H '= 0.28-0.55; R' = 0.87-1.48). Although agroforestry cultivation is carried out intensively, there is no difference in the diversity of soil macrofauna when compared to teak monoculture.

The Role of Edaphic and Vegetation Factors in Structuring Beta Diversity of the Soil Macrofauna Community of the Dnipro River Arena Terrace

Abstract The article presents the results of evaluation of the role of edaphic and vegetation factors on beta diversity of soil macrofauna by means of the MDM-approach. The multinomial diversity model (MDM) is a method for relating the Shannon diversity to ecological factors. The research was conducted in the ‘Dnipro-Orils’kiy’ Nature Reserve (Ukraine). The research polygon was laid in the forest within the Orlova ravine (48º31’13 “N, 34º48”15 “E). The study site comprises 1.0 ha of deciduous woodland bordered by an area of herbaceous cover within the ravine. In the soil of the studied polygon, 38 species of soil invertebrates were identified, which characterizes the gamma diversity. Alpha diversity, or the number of species on average at each sample point is 4.3. Beta diversity is 8.8. The principal component analysis of the edaphic parameters revealed four statistically significant principal components. For vegetation characteristics, six statistically significant principal components were identified. The sequential analysis of the effects shows that edaphic factors accounted for 20.9% (0.81 bit) of the available entropy (1.71–0.91). The largest decrease in the community entropy takes place under the action of the principal components 2 and 3 (0.06 bit and 0.05, respectively). A permutation test showed that these effects are statistically significant. In turn, 28.4% of the community β-diversity is attributable to vegetation factors. The greatest decrease in community entropy is related to the principal vegetation components 1, 3 and 4 (0.07, 0.05 and 0.04 bits, respectively). A permutation test indicated that this effect is statistically reliable. Geostatistical models substantially describe the varying effects on the beta-diversity of edaphic principal components 1 and 2, and the vegetation principal components 1 and 3. It was found that edaphic and plant factors play an important role in structuring the communities of soil macrofauna on the level of beta diversity. Community sensitivity to environmental factors varies in space and is spatially structured. For different environmental factors, specific spatial patterns of community sensitivity are allocated. Beta diversity may be due to the fact that the species of soil macrofauna communities also vary in the degree of sensitivity to various environmental factors. The species of soil microfauna are also divided according to their extent of sensitivity to different ecological factors.

Soil macrofauna under different land uses in the Colombian Amazon

Abstract: The objective of this work was to evaluate the soil macrofauna and the bioindicator taxonomic groups associated with different land uses in the Colombian Amazon. Twelve agroforestry arrangements were studied and compared with to the native forest and pasture. For each land use, six monoliths were randomly selected and divided into four layers (litter, and 0-10, 10-20, and 20-30 cm soil depths). The variables considered in the analysis of land use effects were: individuals per square meter, order richness, Shannon’s diversity index, and Pielou’s evenness index. The greatest values for soil macrofauna density and diversity occurred in the forest, in contrast with the pasture. The principal component analysis distinguished land use according to macrofauna diversity, separating the native forest from the other land uses. The cluster analysis indicated the potential of some agroforestry systems to conserve the values of soil macrofauna density and diversity similar to those of the forest. According to the analysis of indicator value, five taxonomic groups (Diplura, Pseudoscorpionida, Araneae, Chilopoda, and Gastropoda), identified as bioindicators, are associated with preserved sites because of the sensitivity of their populations.

Macrobenthic community structure and influence on denitrification capacity in soft sediments (Mobile Bay, Alabama, USA)

Benthic macrofauna play important roles in coastal ecosystems through their impact on nutrient cycling and by serving as an important trophic link. This study investigated the influence of environmental stressors on macrofaunal community abundance, biomass and diversity and evaluated impacts of those benthic organisms on nutrient fluxes and denitrification capacity in Mobile Bay, a shallow subtropical estuary in the northern Gulf of Mexico. Between January and May 2016, 22 stations in the lower bay were sampled, and the distance from the sea and sediment characteristics were identified as the principal constraints for macrofaunal distribution and taxonomic composition. Higher diversity of macrofauna was found near the mouth of the bay, likely due to hydrological characteristics of the bay, in addition to distance from anthropogenic disturbances near coasts. Sediments comprised of 60-80% sand showed higher abundances, biomass and diversity compared to muddier or sandier sediments, potentially because these sediments were more stable. Although macrofaunal abundance, biomass and diversity differed across stations in the bay, we did not find a relationship between macrofaunal abundances or biomass and denitrification capacity. Both abundance and biomass of infauna were low in Mobile Bay (\textless4000 ind. m(-2) and \textless5 g DW m(-2) at most sites) compared to those in previous studies which showed a positive relationship between macrofaunal abundances and denitrification. The lack of the relation between macrofauna and denitrification suggests that a threshold of abundance, biomass and/or burrowing activity is necessary to increase bioturbation or irrigation to sufficient levels to affect denitrification.

Diversity of benthic macrofauna and physical parameters of sediments in natural mangroves and in afforested mangroves three decades after compensatory planting

Mangroves in the Arabian Gulf are under pressure from land use change, leading to compensatory planting at sites without natural mangroves. In this study, we examine the potential long-term success of this form of afforestation of mangroves as a conservation measure supporting biodiversity. We compared the community of benthic macrofauna (in total 13,522 individuals from 75 species) and physical parameters at 15 sampling points in five afforested mangrove communities and 19 stations in four natural mangrove communities in Qatar. Three decades after afforestation, there were no significant differences between the benthic macrofauna in natural and afforested mangroves as regards total abundance, species richness, Shannon’s diversity, effective number of species, or evenness. Only species richness of Crustacea was significantly higher in natural mangroves. Total organic carbon (TOC), sand, and clay content did not differ. This contradicts findings at the same locations 10 years after afforestation, when benthic macrofauna diversity, TOC, and clay content were lower at afforested sites than at natural mangrove sites. Our results suggest that compensatory planting of mangroves in areas without previous natural occurrence can potentially compensate for loss of biodiversity due to coastal development and that physical parameters may become more similar in afforested mangroves and natural mangroves over time. Furthermore, the increase in TOC in sediments in afforested mangroves over time can help mitigation of climate change. Importantly, the results highlight the need for long-term studies and perspectives when evaluating conservation practices.

Diversidad y distribución de la macrofauna edáfica en dos sistemas de manejo de Moringa oleifera (Lam.): relación con las propiedades del suelo

Con el objetivo de determinar la relación entre diversidad y distribución vertical de la macrofauna edáfica, y propiedades físico-químicas del suelo, se llevó a cabo un estudio en predios de la Universidad Nacional Agraria. Los ensayos tuvieron una duración de 9 meses, en los que se implementaron prácticas de manejo agroecológico, y manejo convencional en ocho unidades experimentales con dimensiones de 15 m x 30 m, seleccionadas de manera aleatoria. La metodología de muestreo fue la desarrollada por el Programa Internacional Biología y Fertilidad del Suelo Tropical. Fueron levantados 12 monolitos de 25 cm x 25 cm por práctica de manejo, a una profundidad de 30 centímetros. Se realizó identificación taxonómica a nivel de Phylum, clase, orden y familia; así como de grupos funcionales detritívoros, ingenieros del suelo, herbívoros y depredadores. Fue registrada mayor densidad de macrofauna en el sistema de conversión agroecológica (7424 ind/m2) en comparación al sistema de manejo convencional (1984 ind/m2), con alta concentración de individuos (7488 ind/m2) en los primeros 20 centímetros del perfil; y densidad proporcional del 56.2% en la profundidad 0 a 10 centímetros. Taxonómicamente se determinó dominancia de la clase Insecta en ambos sistemas de manejo. La distribución de familias de la macrofauna edáfi ca fue diferente entre sistemas, con evidente influencia del rol por profundidad de muestreo. El grupo funcional ingenieros del suelo predominó en conversión agroecológica; mientras los detritívoros lo hicieron en manejo convencional. Fue determinada la infl uencia de la calidad de micro hábitat en las propiedades físico-químicas del suelo con el componente biológico; demostrándose efecto de las prácticas de manejo sobre la densidad, diversidad y distribución de la macrofauna edáfica.

Soil macrofauna diversity as a key element for building sustainable agriculture in Argentine Pampas

The agricultural activity in the Argentine Pampas, characterized by an important trend towards no-till soybean monocropping, has completely transformed the original Pampas landscape into a monotonous scenario with a continuous succession of farms of very low crop diversity. This process has led to soil physical, chemical and biological degradation in those systems. The increase of crop rotation rates in no-till and reduced tillage systems has been proposed as an alternative with reduced negative impact on soils in the context of conventional agriculture. On the other hand, extensive organic farming is also suggested as an alternative to high-input agriculture systems. In this article, we aim to explore how different variations of farming practices and systems impact soil macrofauna, along an edaphoclimatic gradient in the Pampas region. We studied the following systems: natural grassland (Gr) as indicator of the original community, extensive organic farming (Org), conventional agriculture with no-tillage and three crop rotation levels (Nt-R1, Nt-R2 and Nt-R3), and reduced tillage with two levels of crop rotation (Til and Til-R). We assessed soil macrofauna, with emphasis on earthworm, beetle and ant communities; and soil physical and chemical properties. Macrofaunal taxa composition was significantly affected by both management systems and edaphoclimatic conditions. The Gr community had pronounced differences from all the agricultural systems. The earthworm community from Gr had distinctive features from those of most agricultural systems, with Org and Nt-R3 being the most similar to Gr in native and exotic earthworm species, respectively. The beetle community in Org was the most different one, and the communities from the other systems did not show a pattern related to management. Ant community composition was not determined by management systems, but it was affected by edaphoclimatic conditions. All the studied macrofauna groups had a significant co-variation with soil physical and chemical properties, showing that both the characteristics of each soil relative to the geographic location and the effect of management on abiotic soil attributes have an important effect on soil macrofauna. This study confirms that biodiversity is being lost in Pampas soils, which implies a possible threat to the soil capacity to perform the processes that sustain soil functioning and hence plant productivity. Further considerations about the sustainability of the current agricultural model applied in the Argentine Pampas are needed.

The influence of different deep-sea coral habitats on sediment macrofaunal community structure and function.

Deep-sea corals can create a highly complex, three-dimensional structure that facilitates sediment accumulation and influences adjacent sediment environments through altered hydrodynamic regimes. Infaunal communities adjacent to different coral types, including reef-building scleractinian corals and individual colonies of octocorals, are known to exhibit higher macrofaunal densities and distinct community structure when compared to non-coral soft-sediment communities. However, the coral types have different morphologies, which may modify the adjacent sediment communities in discrete ways. Here we address: (1) how infaunal communities and their associated sediment geochemistry compare among deep-sea coral types (Lophelia pertusa, Madrepora oculata, and octocorals) and (2) do infaunal communities adjacent to coral habitats exhibit typical regional and depth-related patterns observed in the Gulf of Mexico (GOM). Sediment push cores were collected to assess diversity, composition, numerical abundance, and functional traits of macrofauna (>300 µm) across 450 kilometers in the GOM at depths ranging from 263–1,095 m. Macrofaunal density was highest in L. pertusa habitats, but similar between M. oculata and octocorals habitats. Density overall exhibited a unimodal relationship with depth, with maximum densities between 600 and 800 m. Diversity and evenness were highest in octocoral habitats; however, there was no relationship between diversity and depth. Infaunal assemblages and functional traits differed among coral habitats, with L. pertusa habitats the most distinct from both M. oculata and octocorals. These patterns could relate to differences in sediment geochemistry as L. pertusa habitats contained high organic carbon content but low proportions of mud compared to both M. oculata and octocoral habitats. Distance-based linear modeling revealed depth, mud content, and organic carbon as the primary factors in driving coral infaunal community structure, while geographic location (longitude) was the primary factor in functional trait composition, highlighting both the location and ecological differences of L. pertusa habitats from other coral habitats. Enhanced habitat structural complexity associated with L. pertusa and differences in localized hydrodynamic flow may contribute to the dissimilarities in the communities found among the coral types. Our results suggest a decoupling for infaunal coral communities from the typical depth-related density and diversity patterns present throughout soft-sediment habitats in the GOM, highlighting the importance of deep-sea corals in structuring unique communities in the nearby benthos.

Environmental change and predator diversity drive alpha and beta diversity in freshwater macro and microorganisms.

Global biodiversity is eroding due to anthropogenic causes, such as climate change, habitat loss, and trophic simplification of biological communities. Most studies address only isolated causes within a single group of organisms; however, biological groups of different trophic levels may respond in particular ways to different environmental impacts. Our study used natural microcosms to investigate the predicted individual and interactive effects of warming, changes in top predator diversity, and habitat size on the alpha and beta diversity of macrofauna, microfauna, and bacteria. Alpha diversity (i.e., richness within each bromeliad) generally explained a larger proportion of the gamma diversity (partitioned in alpha and beta diversity). Overall, dissimilarity between communities occurred due to species turnover and not species loss (nestedness). Nevertheless, the three biological groups responded differently to each environmental stressor. Microfauna were the most sensitive group, with alpha and beta diversity being affected by environmental changes (warming and habitat size) and trophic structure (diversity of top predators). Macrofauna alpha and beta diversity was sensitive to changes in predator diversity and habitat size, but not warming. In contrast, the bacterial community was not influenced by the treatments. The community of each biological group was not mutually concordant with the environmental and trophic changes. Our results demonstrate that distinct anthropogenic impacts differentially affect the components of macro and microorganism diversity through direct and indirect effects (i.e., bottom-up and top-down effects). Therefore, a multitrophic and multispecies approach is necessary to assess the effects of different anthropogenic impacts on biodiversity.

An ecological survey of the abundance and diversity of benthic macrofauna in Indonesian multispecific seagrass beds

Seagrasses are one of the most productive ecosystems in coastal areas and support a wide variety of associated fauna. The tropical Indo-Pacific region is considered to have the highest diversity of seagrass plant species and the largest distribution areas of seagrass, yet the seagrass macrofauna in this region are poorly understood. To help fill this gap in our knowledge, an ecological survey was conducted to describe the abundance and diversity of benthic macrofauna from tropical seagrass beds and to determine between-station variations within a transect and between-site variations in macrofaunal abundance, taxa richness and community structure. Benthic macrofaunal samples associated with seagrass beds were collected with a core sampler on the east coast of North Sulawesi in May 2014 and on the west coast in October 2015. A total of 149 species from 14 higher taxa was collected. The most species-rich groups were polychaetes (56 species, 26% of total individual numbers), decapods (20 species, 9% of total numbers) and amphipods (18 species, 35% of total numbers). Between-station variations within a transect displayed different patterns between the east coast and the west coast. On the east coast, there were marked variations in abundance between stations within a transect for the macrofauna and amphipod assemblages. Both taxa richness and abundance varied with station for the macrofauna and polychaete assemblages on the west coast, resulting from the heterogeneity of the substrate along a transect. One-way ANOSIM together with MDS ordination indicated that macrofaunal community structure in seagrasses differed significantly between the east coast and the west coast, corresponding with the division of seagrasses into two broad categories of habitats, i.e., mangrove-seagrass-reef continuum and seagrass-reef continuum. Compared with other studies in tropical areas, the abundance and diversity of benthic macrofauna in the present study were moderate. The reason for the two markedly distinct macrofaunal communities might be attributed to multiple factors, including sediment pattern, seagrass structure and temporal changes.

Reduced macrofauna diversity and abundance in response to red macroalgal detritus

Macrophyte detritus from exogenous sources can play an important role in structuring benthic communities. Macrofaunal responses to seagrass wrack, mangrove leaf litter, and detritus from brown and green macroalgae have previously been examined through enrichment experiments. Yet effects from red macroalgal detritus, which is a major component of algal drift in many regions, are not well understood. In this study, enrichment experiments were performed on a shallow subtidal sandflat in Puget Sound, Washington, USA with detritus from three species of red macroalgae to assess: (1) whether macrofaunal assemblages were affected by two different “dosages” of red macroalgal enrichment (100 ml vs 500 ml per 0.079 m3 of sediment); (2) whether macrofaunal response differed between one-time and repeated (weekly) additions of red macroalgae; and (3) whether responses to red macroalgal enrichment changed over time. There appeared to be little or no effect on macrofauna from one-time enrichment regardless of the amount/dosage of algae added. However, weekly additions of red macroalgae led to negative responses across macrofaunal taxa. These responses occurred rapidly, within the first 3 weeks, and were largely unchanged after 7 weeks, intensifying for only 2 of the 10 most common taxa. No opportunistic responses to weekly additions were observed. Frequent influx of some types of red macroalgae may degrade the quality of sedimentary habitats by leaching chemically defensive compounds or through other mechanisms, which should be investigated in future studies. Although weekly enrichment treatments were informed by previous estimates of detrital delivery rates near hard-bottom habitats in the same locality, further research is needed to assess detrital influx frequency and community response in other regions where red macroalgal detritus is common, and to understand the broader implications of exogenous detritus from red macroalgae on benthic ecosystems.

Combined effects of cropping types and simulated extreme precipitation on the community composition and diversity of soil macrofauna in the eastern Qinghai-Tibet Plateau

Extreme precipitation as global change greatly affects above- and below-ground biodiversity. Soil macrofauna play a key role in the agroforestry ecosystem processes. Extreme precipitation might negatively impact soil macrofauna by changing soil water content. Particularly, whether cropping types are beneficial to alleviate response of soil macrofauna to extreme precipitation remains unexplored. Effects of simulated extreme precipitation of 1 month on soil macrofauna were studied under Chinese prickly ash (Zanthoxylum bungeanum) intercropped with soybean (Glycine max), Chinese prickly ash intercropped with sweet pepper (Capsicum annuum), and Chinese prickly ash monoculture. Soil macrofauna and soil samples were collected in three soil depths (0–10, 10–20, and 20–30 cm) per plot. The abundance, diversity, and vertical distribution of soil macrofauna were analyzed for each sample at genus and trophic level. Each sieved soil sample was analyzed for soil water content, soil nitrate nitrogen (NO3−–N), ammonium nitrogen (NH4+–N) and organic matter. Descriptive statistics and significance tests on raw data were carried out using the SPSS 16.0 software at P < 0.05. A total of 502 soil macrofauna individuals were observed, and belonged to 14 genera, and consisted mainly of earthworms, arthropods. The richness, density, and biomass, as well as vertical distribution of total soil macrofauna were unaffected by extreme precipitation. Only Eisenia density and biomass were significantly decreased by extreme precipitation. The plots intercropped with soybean had higher density, biomass, and richness than the plots intercropped with sweet pepper and prickly ash monoculture. Cropping types significantly influenced density of total soil macrofauna under control condition but not extreme precipitation treatment. The abundance of total soil macrofauna was significantly and positively related to soil NH4+–N, total soil inorganic N, and soil organic matter. Our results suggest that the impacts of cropping types rather than extreme precipitation on soil macrofauna abundance, diversity, and vertical distribution are significant. However, extreme precipitation changes the response of soil macrofauna to cropping types.

The impact of heavy metals on the soil fauna of selected habitats in Niepołomice forest

Pollution of soils with heavy metals is particularly dangerous to living organisms. Invertebrates are sensitive to changes in soil conditions, and, therefore, may be considered invaluable indicators of soil disruptions. This study has been undertaken to determine heavy metal content in the in soil and extracted soil fauna in two types of forest habitats of Niepolomice Forest and to establish their impact on pedofauna– their density, diversity and trophic structure. The investigated sites varied in the soil or humus type, and the composition of forest stand and ground cover. The analysis of the pH value showed that the studied soils had acidic (pH 4.45-4.85). Small differences were observed in the content of heavy metals (lead, cadmium, nickiel, zinc and copper) in soil humid forest and fresh mixed forest. It results from the studies that the heavy metal content did not exceed the standards set out for the soils of Poland . The bioconcentration factor shows that both saprophytes and predatory invertebrates collected the largest amounts of zinc and smaller amounts of cadmium, and the remaining metals were collected in the following order: Cu> Ni> Pb. The results obtained show that the tested heavy metals could have an impact on the density and diversity of meso-and macrofauna. Probably soil fauna affected by other factors (soil moisture, organic matter content, type of humus) .

Biomass-dependent seagrass resilience to sediment eutrophication

Seagrass beds provide a wealth of ecosystem services that benefit society (e.g., habitat and feeding ground for juvenile fisheries species), but the Anthropocene has seen to a global decline of these productive habitats. Many temperate estuaries are becoming eutrophic due to horticultural, agricultural, and urban nutrient run off, but the role of this enrichment in seagrass decline is not fully understood. In a multi-site manipulative field experiment (Tauranga Harbour, New Zealand; 37°S, 176°E), we elevated pore water nitrogen (N) concentrations (mimicking the consequences of long-term eutrophication) to examine effects on seagrass meadows. At six intertidal seagrass sites with differing sediment properties and macrofaunal communities, slow release urea fertiliser (200 g N m−2) was buried in 1 m2 plots at the start of the peak growing season (early summer). After 60 d, we measured several seagrass morphological variables (cover, leaf length and width, and above and below ground biomass), sediment properties, and macrofauna community structure. Results demonstrate that the resilience of seagrass meadows to N enrichment is highly site-dependent. Two of the six sites showed significant declines in a multivariate indicator of seagrass morphology, driven by marked reductions in seagrass cover and leaf length (of up to 78%). Whereas, other sites appeared resilient to N enrichment. It was expected that these site-specific responses would be correlated with changes in sediment properties that alter nutrient processing capacity (permeability and biogeochemistry). However, site-specific responses were instead correlated with the ambient seagrass biomass and macrofaunal diversity. Sites with low ambient seagrass biomass and macrofaunal diversity were less resilient to enrichment. These results highlight that seagrass biomass could be a good indicator of resilience to nutrient enrichment, and the biomass where resilience is lost may lie between 140 and 285 g DW m−2. This study contributes knowledge that is required for predicting and mitigating future impacts of estuarine eutrophication on seagrass ecosystems.

Rubber plantation ageing controls soil biodiversity after land conversion from cassava

The rapid expansion of perennial crops is a major threat to biodiversity in Southeast Asia. The biodiversity losses related to the conversion of forest lands to oil palm or rubber plantations (RP) are well documented by recent studies. However, the impact of the conversion from intensively managed annual crops to perennial crops on soil biodiversity has not yet been addressed. This study aims at assessing the impact on soil biodiversity of a) the short-term effect of land use conversion from cassava crop to RP, and b) the long-term effect of RP ageing. Soil biodiversity (bacterial, fungal and macrofaunal), microbial activities and pedoclimatic characteristics were measured over a chronosequence of 1–25 years old of RP compared to cassava fields, the former crop, in Thailand. The conversion from cassava to young RP (1–3 yr) had a significant effect on microbial biomass and activities and fungal composition, but did not impact the bacterial and macrofaunal diversity. This effect of land use conversion could be explained by the change in land management due to the cultivation of pineapple in the inter-row of the young RP. Canopy closure appeared to be the main driver of soil biota shifts, as most of the biotic parameters, composition, abundance and activities were significantly modified after 7 years of RP. The changes of composition in older rubber plantations originated from the dominance of Trichoderma (fungi), Firmicutes (bacteria), and earthworms. Old rubber plantations (23–25 yr) harboured the highest microbial and macrofaunal biomass; however, they were also characterised by a significant decrease in bacterial richness. The change in pedoclimatic conditions across the rubber chronosequence, i.e. increase in soil moisture, litter and organic carbon content, was a stronger driver of soil biota evolution than land use conversion. The macrofaunal composition was more resistant to land use conversion than the bacterial composition, whereas the microbial biomass was sensitive to land use conversion, but showed resilience after 20 years. However, bacterial, fungal and macrofaunal diversity, macrofaunal and microbial biomass and microbial activities were all sensitive to RP ageing.

Intercropping Maize With Legumes for Sustainable Highland Maize Production

Residue burning to prepare soil for maize growing deprives the soil of both protective cover and organic matter, and it exacerbates environmental issues such as Southeast Asia's haze problem. This paper reports on a study that evaluated the effectiveness of maize/legume intercropping as an alternative to maize cultivation with residue burning. Cowpea (Vigna unguiculata), mung bean (V. radiata), rice bean (V. umbellata), and lablab (Lablab purpureus) were sown into a standing maize crop 30 days before harvest, and the results were compared with a maize crop grown using residue burning as the method for land preparation at Pang Da Agricultural Station in Chiang Mai, Thailand, in a replicated trial conducted over 3 growing seasons from 2012 to 2014. Intercropping increased maize grain yield by 31–53% and left 70–170% more residue containing 113–230% more nitrogen than the maize sown after residue burning, depending on the legume, and decreased weed dry weight by two-thirds after 2 seasons. Soil biodiversity was enriched by the intercrops, with a doubling in the spore density of arbuscular mycorrhizal fungi in the root-zone soil and increased abundance, diversity (Shannon index), and richness of the soil macrofauna. The abundance of soil animals increased with crop residue dry weight (r = 0.90, P < 0.05) and nitrogen content (r = 0.98, P < 0.01). The effect of intercropping on maize grain yield and accumulation of residue and nitrogen were then confirmed in a participatory experiment involving farmers in 2 highland villages in the Phrao and Chiang Dao districts of Chiang Mai Province with maize and rice bean in 2015. The effects of maize/legume intercropping—increased nitrogen accumulation and crop residue, enhanced soil biodiversity, suppression of weeds, and protection of the soil surface, which enabled the maize to be sown without land clearing with fire—should all contribute to sustainable highland maize production.

Caracterización ecológica de la macrofauna edáfica en dos sitios de bosque siempreverde en El Salón, Sierra del Rosario, Cuba

The richness, abundance, diversity and functional composition of soil macrofauna were studied in two sites of the evergreen medium forest (Helechal and Vallecito), located at the Ecological Reserve El Salon from Sierra del Rosario; they were analyzed with respect to other land use systems evaluated in Cuba. The macrofauna was collected in situ from 25 × 25 × 20 cm monoliths extracted from the soil. In this type of ecosystem, 34 families of the edaphic macrofauna belonging to 18 orders were found. The Vallecito site showed higher families richness, density and diversity of the macrofauna (34 families, 1,298.5 individuals m-2 and H’ = 2.72) compared to Helechal (19 families, 749.2 individuals m-2 and H’ = 2.57). Although, only richness showed significant differences between the two locations. The seasonality in the sampling marked the variations between the sites, which was carried out during a rainy month in Helechal (October 2009) and during a dry month in Vallecito (March 2011). The functional composition of the edaphic community was similar in both sites, where the most outstanding guilds were litter detritivores, soil engineers and predators. However, the dominant families within each functional group changed between sites. The structure found of the macrofauna was very similar to those of other tropical forests, and hardly changed in relation to secondary forests studied in Cuba, although it did change in relation to more disturbed systems such as pastures and crops.

Environmental DNA metabarcoding of benthic bacterial communities indicates the benthic footprint of salmon aquaculture

We evaluated benthic bacterial communities as bioindicators in environmental impact assessments of salmon aquaculture, a rapidly growing sector of seafood industry. Sediment samples (n=72) were collected from below salmon cages towards distant reference sites. Bacterial community profiles inferred from DNA metabarcodes were compared to reference data from standard macrofauna biomonitoring surveys of the same samples. Deltaproteobacteria were predominant in immediate vicinity of the salmon cages. Along the transect, significant shifts in bacterial community structures were observed with Gammaproteobacteria dominating the less-impacted sites. Alpha- and beta-diversity measures of bacterial communities correlated significantly with macrofauna diversity metrics and with five ecological status indices. Benthic bacterial communities mirror the reaction of macrofauna bioindicators to environmental disturbances caused by salmon farming. The implementation of bacterial eDNA metabarcoding in future Strategic Framework Directives is an alternative cost-effective high-throughput biomonitoring solution, providing a basis for management strategies in a matter of days rather than months.

Diversity and feeding strategies of soil microfauna along elevation gradients in Himalayan cold deserts.

High-elevation cold deserts in Tibet and Himalaya are one of the most extreme environments. One consequence is that the diversity of macrofauna in this environment is often limited, and soil microorganisms have a more influential role in governing key surface and subsurface bioprocesses. High-elevation soil microfauna represent important components of cold ecosystems and dominant consumers of microbial communities. Still little is known about their diversity and distribution on the edge of their reproductive and metabolic abilities. In this study, we disentangle the impact of elevation and soil chemistry on diversity and distribution of rotifers, nematodes and tardigrades and their most frequent feeding strategies (microbial filter-feeders, bacterivores, fungivores, root-fungal feeders, omnivores) along two contrasting altitudinal gradients in Indian NW Himalaya (Zanskar transect from 3805 to 4714 m a.s.l.) and southwestern Tibet (Tso Moriri transect from 4477 to 6176 m a.s.l.), using a combination of multivariate analysis, variation partitioning and generalized additive models. Zanskar transect had higher precipitation, soil moisture, organic matter and available nutrients than dry Tso Moriri transect. In total, 40 species of nematodes, 19 rotifers and 1 tardigrade were discovered. Species richness and total abundance of rotifers and nematodes showed mid-elevation peaks in both investigated transects. The optimum for rotifers was found at higher elevation than for nematodes. Diversity and distribution of soil microfauna was best explained by soil nitrogen, phosphorus and organic matter. More fertile soils hosted more diverse and abundant faunal communities. In Tso Moriri, bacterivores represented 60% of all nematodes, fungivores 35%, root-fungal feeders 1% and omnivores 3%. For Zanskar the respective proportions were 21%, 13%, 56% and 9%. Elevational optima of different feeding strategies occurred in Zanskar in one elevation zone (4400–4500 m), while in Tso Moriri each feeding strategy had their unique optima with fungivores at 5300 m (steppes), bacterivores at 5500 m (alpine grassland), filter-feeders at 5600 m and predators and omnivores above 5700 m (subnival zone). Our results shed light on the diversity of microfauna in the high-elevation cold deserts and disentangle the role of different ecological filters in structuring microfaunal communities in the rapidly-warming Himalayas.

Short-term effects of non-grazing on plants, soil biota and aboveground-belowground links in Atlantic mountain grasslands

Mountain grasslands in the Iberian Peninsula are the result of extensive grazing. However, a progressive abandonment of grazing activity is currently observed in the study region. The objective of this work was to evaluate the short-term (2 years) effects of non-grazing on the diversity and composition of plants, soil microorganisms (prokaryotes, fungi, arbuscular mycorrhiza), mesofauna, macrofauna and aboveground-belowground links, through the study of 16 grazed vs. non-grazed areas in Atlantic grasslands located in the Basque Country (Spain). Sites were divided between 4 habitat types with different elevation, pasture productivity, vegetation type and parent material. Herbivores appeared to influence plant community composition, contributing to increase aboveground diversity, while having unequal effects on belowground communities depending on the organisms analysed. This may be explained by the different habitat and trophic level of each soil organism, which may be more or less affected by the predominating negative effects of grazing, such as soil compaction, and only partially compensated by other positive effects. Finally, habitat type appeared to be the strongest influence on both above- and belowground communities, also influencing the effect of the absence of grazing.