Ecological niches and distribution of ground‐dwelling beetles (Coleoptera: Carabidae, Aphodiinae—Scarabaeidae) in a modified wetland landscape

Wetlands are being increasingly affected by anthropogenic activities worldwide. The Lower Delta of the Paraná River, one of the most important wetlands in Argentina, has been profoundly altered because most of the natural environments were drained or diked to make them suitable for different agricultural activities. As a result, the landscape is characterized by a mosaic of Salicaceae afforestations of different ages interspersed with patches of secondary forests and grazing grasslands. The high susceptibility of Carabidae and Aphodiidae to natural and human-induced disturbances and management practices is reflected by changes in their spatiotemporal distribution. We performed a 1-year study to analyze and compare beetle's communities inhabiting different habitat types in this modified wetland landscape. A total of 58 beetle species were recorded, of which 48 were carabids and 10 aphodids. Although species richness and diversity were higher in productive habitats (afforestations and grasslands) than in secondary forests, hydrophilic species were only found in the latter. Community parameters varied seasonally. Our results indicate a close relationship between wetland beetle communities and vegetation cover in each habitat type. Human activity increases heterogeneity across this landscape, which favors the colonization of new species but causes the loss or displacement of autochthonous species. The secondary forests could serve as alternative habitats for beetles typical of humid environments. We propose the maintenance of the current heterogeneous mosaic to favor the diversity of ground beetles and the implementation of changes in water management for the benefit of hydrophilic beetle species.

The existence of beetles depends on the availability of energy and food sources to survive and carry out activities. The diversity of beetles in a habitat can be influenced by other factors, apart from energy and food sources. These factors include land use type, seasonal differences and habitat fragmentation. Regional differences and land use types may not always influence beetle diversity. However, changes in land use can affect the presence and diversity of beetles. So, this research aims to determine the diversity of diurnal beetles around the Muhammadiyah University Palembang campus. Diurnal beetle collection was carried out by purposive sampling using pitfall traps and direct collection at five observation points. The research results showed that 76 individuals from 7 species of diurnal beetles were identified as belonging to the order Coleoptera. The Coccinella transversalis beetle (family Coccinellidae) was the most beetle species found (36 individuals) and the beetle Bradycellus nigrinus (family Carabidae) was the fewest beetle species (2 individuals) found. The impact of changes in land use affects the species richness of diurnal beetles and also impacts the growth of previously different plant vegetation. However, the distribution of diurnal beetle species shows an even distribution and there is no dominant species. Keywords: Number of species, diversity, richness, diurnal beetles

The rapid expansion of planted forests harms native biodiversity. Few studies report the effects of replacing wetlands with planted forests on ground beetles. We analyze how the taxonomic and functional diversity of ground beetles are affected by intensive management of a planted forest landscape in the Lower Delta of the Parana River. We defined six habitat types (n = 3, N = 18): young and mature willow (YW, MW), young and mature poplar without cattle (YP, MP), young and mature silvopastoral poplar (YS, MS). Using pitfall traps (N = 1728), we recorded 35 species (1896 individuals). YW and MS reached the highest taxonomic diversity and richness. YW with more vertical heterogeneity showed higher species richness than MW. Hydrophilic species were more abundant in YW. Zoophagous species were more abundant in MS. YS, MS, and YW reached the highest functional evenness, which implies that a large part of the functional niches was used. Cattle dung and freshwater canals for livestock offer more resources for ground beetles. The planted tree species, stand age, and presence of cattle affects taxonomic and functional diversity of ground beetles. Willow and silvopastoral planted forests are the most suitable habitats for hosting wetland species. So, we recommend using willow species rather than poplar species when planted forests replace fluvial wetlands, increasing irrigation of poplar planted forests through ditches and canals, conserving or restoring different strata of understory to increase vertical heterogeneity, and maintaining the landscape heterogeneity. These management measures are essential to prevent the loss of wetland species and conserve ground beetle’s diversity.

Where and when are plantations established? Land-use replacement patterns of fast-growing plantations on agricultural land

Towards practices favourable to plant diversity in hybrid poplar plantations

AimTo analyse global patterns in soil carbon (C) in tropical successional and plantation forests based on climate, forest age, former land use and soil type to determine factors driving below‐ground C storage.LocationPantropical.MethodsWe conducted a synthesis of 81 studies reporting soil C stocks in more than 400 reforested and tree plantation sites. We used regression models and regression tree analyses to determine the importance of multiple predictor variables on soil C stocks standardized to three common depth ranges: 0–10, 0–30 and 0–100 cm.ResultsMean annual temperature (MAT) was the most important predictor of soil C. Forest age explained little to no variability in soil C, in contrast with above‐ground studies. Data on long‐term trends in soil C are limited, as median time since forest growth was 15 years. Soil C stocks were similar between tropical secondary forests, tree plantations and reference forests. Differences between plantation and successional forests only appeared below 10 cm on sites with MAT < 21.3 °C. Former pastures and cultivated sites differed from each other only to depths of 30 or 100 cm. Climatic variables appeared multiple times across all layers of the regression trees, consistent with strong interactions between MAT and precipitation on soil C stocks.Main conclusionsClimate explained greater variability in soil C in successional and plantation forests than former land use or forest age, despite the tropical location of all sites. Human management factors were more important for predicting soil C stocks in cooler and drier sites, while environmental variables were more important in hotter and wetter sites. The relative importance and interactions between soil type, previous land use and forest cover type differed with soil depth, highlighting the importance of comparing C across consistent depths. Climatic controls suggest sensitivity of soil C stocks in successional and plantation forests to future climate change.

Afforestation is among the most effective means of preventing and controlling desertification. Silver poplar (Populus alba) is commonly planted tree species for afforestation of the Horqin Sandy Land of China. However, this species has exhibited some drawbacks such as top shoot dieback, premature senescence and mortality, and soil and ecosystems degradation. In contrast, Siberian elm (Ulmus pumila) rarely experiences these problems in the same regions. Ecological stoichiometry plays a vital role in exploring ecological processes and nutrient cycle relationships in plant–litter–soil systems. To explore the differences in the carbon (C), nitrogen (N), and phosphorus (P) balance, the stoichiometry characteristics and stoichiometric homeostasis in elm and poplar plantations in the Horqin Sandy Land, we measured C, N, and P concentrations in leaves, branches, roots, litter, and soils and analyzed N and P resorption efficiencies in the two plantations. The results showed that soil C and N concentrations, C:P, and N:P were greater in the elm plantation than in the poplar plantation. The leaf and root C:P and N:P during summer and litter N and P concentrations were greater, whereas N and P resorption efficiencies were lower, in the elm plantation than in the poplar plantation. Generally, elm exhibited greater N:P homeostasis than poplar. N and N:P homeostasis were greater in roots than in leaves and branches in the elm plantation, but they varied with soil N concentration and N:P in the poplar plantation. These findings indicate that poplar exhibited more developed internal nutrient conservation and allocation strategies but poor nutrient accumulation in soil, which may contribute to degradation of poplar plantation. In contrast, elm tended to return more nutrients to the soil, showing an improved nutrient cycle in the plant–litter–soil system and increased soil C and N accumulation in the elm plantation. Therefore, compared with poplar, elm may be a more suitable afforestation tree species for the Horqin Sandy Land, in terms of promoting the accumulation of soil nutrients and enhancing nutrient cycling in the plant–litter–soil system.

Summary 1. Biotic homogenization (BH), a dominant process shaping the response of natural communities to human disturbance, reflects both the expansion of exotic species at large scales and other mechanisms that often operate at smaller scales. 2. Here, we examined the relationship between BH in plant communities and spatio-temporal landscape disturbance (habitat fragmentation and surrounding habitat conversion) at a local scale (1 km²), using data from a standardized monitoring programme in France. We quantified BH using both a spatial partitioning of taxonomic diversity and the average habitat specialization of communities, which informs on functional BH. 3. We observed a positive relationship between local taxonomic diversity and landscape fragmentation or instability. This increase in local taxonomic diversity was, however, paralleled by a decrease in average community specialization in more fragmented landscapes and in more unstable landscapes around forest sites. The decrease in average community specialization suggests that landscape disturbance causes functional BH, but there was limited evidence for concurrent taxonomic BH. 4. Synthesis. Our results show that landscape disturbance is partly responsible for functional BH at small scales via the extirpation of specialist species, with possible consequences for ecosystem functioning. However, this change in community composition is not systematically associated with taxonomic BH. This has direct relevance in designing biodiversity indicators: metrics incorporating species sensitivity to disturbance (such as species specialization to habitat) appear much more reliable than taxonomic diversity for documenting the response of communities to disturbance.

Environmental determinants of species turnover of aquatic Heteroptera in freshwater ecosystems of the Western Ghats, India

The impact of forest management on saproxylic beetles and other arthropods in a semi-deciduous forest in Southern Benin

Distribution, abundance, and diversity of microplastics in the upper St. Lawrence River

Factors such as climate, soil characteristics, habitat type, and land management practices can influence the demography of plant populations harvested by Indigenous Peoples and local communities. Here, we assessed the demographic responses of the palm Syagrus coronata to varying leaf harvest frequencies by the Fulni-ô Indigenous People in sites with different environmental and anthropogenic conditions in Águas Belas, Pernambuco, northeast Brazil. The leaves of this species are primarily harvested for handicraft production. In collaboration with local artisans, we conducted a participatory workshop where they identified harvest locations on a regional map. Plots and subplots were established in six of these sites, and the total height of all S. coronata individuals was recorded. We monitored survival and growth over three consecutive years and counted infructescences on reproductive individuals every three months during the first two years. Newly recruited individuals were also recorded and measured. Environmental variables (light availability, air temperature, and humidity) were measured quarterly in the first year, and soil samples were collected for chemical and physical analysis. We performed a principal component analysis (PCA) to evaluate differences among sites based on environmental and anthropogenic variables. Using demographic data, we constructed integral projection models (IPMs) and conducted a life table response experiment (LTRE) analysis to estimate vital rates and deterministic population growth rates (λ) for each population and sampling interval. Our results showed that S. coronata populations under high harvest frequencies declined during the study period. In contrast, populations with lower harvest frequencies were more influenced by the growth of smaller individuals, though seedling recruitment was reduced, highlighting the need to preserve these younger plants. Higher air temperatures, nutrient availability, and soil pH likely contributed to low adult fecundity and reduced recruitment. Additionally, cattle and livestock presence may have further hindered recruitment by trampling and grazing on smaller plants. In populations subjected to intermediate and high harvest frequencies, larger individuals had the greatest impact on population growth rates. However, these individuals exhibited lower survival, suggesting that harvest pressure may negatively affect this vital rate, as the Fulni-ô harvesters preferentially target larger juveniles and adults for their more substantial leaves. Based on these findings, we recommend management strategies to support S. coronata conservation while ensuring sustainable harvesting and safeguarding Fulni-ô handicraft production.

Responses of soil C stock and soil C loss to land restoration in Ili River Valley, China

Land use conversion affects natural soil processes and can potentially decrease soils productivity. A representative area was selected to study the effects of land use conversion in Unitech Campus, Southeastern lowlands of Papua New Guinea (PNG). Area selected for the study was once covered by tropical rainforest and has been subjected to various land use types over time. Representative soil samples were collected under 4 main land use types (secondary forest, plantation forest, grassland, and agricultural garden) at 2 depths (0-0.15 m and 0.15-0.30 m) with 3 replicates per land use. Soil bulk density, water infiltration rate, and cumulative water infiltration values were significantly greater (p < 0.05) under grasslands than under secondary and plantation forests. Among soil chemical properties, extractable potassium content and pH showed significant differences (p < 0.05) among the land uses, pH values increased upon conversion of forested lands to grassland or agricultural gardens. Conversion of secondary forests into grasslands or agricultural gardens leads to depletion of Bray's phosphorus and extractable potassium. Tree-based land uses were optimum due to better nutrient cycling conditions and lower bulk density compared to grassland and agricultural garden despite the low pH conditions and lower water infiltration.

A modificação antropogênica da paisagem nos trópicos tem causado perdas da biodiversidade de diferentes grupos taxonômicos, ameaçando importantes processos ecológicos. Agroflorestas de café manejadas de forma tradicional são os únicos remanescentes de vegetação com considerável sombra em algumas regiões tropicais, e têm sido enfatizadas como importantes áreas de refúgio para a biodiversidade e pela sua contribuição na supressão de pragas devido a sua complexa estrutura vegetacional. O manejo de agroflorestas varia grandemente entre cafeicultores e pode influenciar padrões populacionais através de mudanças nas condições ambientais. Experimentos sobre interações ecológicas entre organismos são geralmente usados para predizer e explicar padrões e processos encontrados no campo. Não obstante, muitos fatores que influenciam populações, como variáveis ambientais são determinados pelo uso da terra, tornando padrões reais no campo difíceis de prever a partir de experimentos conduzidos em escalas menores. \nO estudo foi conduzido em pequenas propriedades rurais localizadas na região cafeicultora de Jipijapa, na província de Manabi, Equador. Essa região é considerada importante para a conservação da biodiversidade (hotspot) e sua vegetação original foi convertida em agricultura. Foram selecionadas três agroflorestas de café, de acordo com o manejo local praticado pelos cafeicultores: agroflorestas com baixa diversidade arbórea, agroflorestas com diversidade arbórea intermediária, e agroflorestas abandonadas com uma alta diversidade arbórea. No capítulo 2, estudou-se o papel do manejo de agroflorestas e da sazonalidade na comunidade de ácaros na cultura do café. A intensificação do manejo de agroflorestas afetou negativamente a riqueza de espécies de ácaros na cultura do café. Ademais, foram encontradas mais espécies e maiores densidades de ácaros na época seca comparada com a época chuvosa. \nNo capítulo 3, investigou-se a dinâmica populacional de pragas de café (ácaro-vermelho-do-cafeeiro, bicho-mineiro-do-cafeeiro, e broca-do-cafeeiro) em relação ao manejo de agroflorestas. Adicionalmente, foi acessado o efeito do manejo de agroflorestas sobre as diversas fases de desenvolvimento de cada praga. O manejo de agroflorestas influenciou padrões populacionais de pragas do café, sendo que maiores picos populacionais ocorreram em agroflorestas manejadas de forma mais intensiva. Além disso, houve uma interação entre a diversidade vegetacional e a estrutura populacional, na qual diferentes fases de desenvolvimento das pragas atingiram maiores densidades em agroflorestas manejadas de forma mais intensiva. No capítulo 4, foi determinada a importância relativa de variáveis ambientais sobre densidades de pragas do café usando análises de partição hierárquica. As variáveis ambientais temperatura, umidade relativa, e diversidade arbórea explicaram a maior parte da variância da densidade das pragas de café. A temperatura influenciou positivamente densidades do ácaro-vermelho-do-cafeeiro, enquanto a umidade relativa e a diversidade arbórea influenciaram negativamente densidades do bicho-mineiro-do-cafeeiro e da broca-do-cafeeiro, respectivamente. \nNo capítulo 5, experimentos de laboratório e de campo foram combinados, para se estudar a importância relativa de interações bióticas e do manejo de agroflorestas sobre a densidade de pragas de café no campo. Preferência e sucesso reprodutivo equipararam-se em condições de laboratório, levando-se a predição de que as pragas iriam evitar competidores coespecíficos e heteroespecíficos no campo. No entanto, densidades das pragas de café foram positivamente correlacionadas no campo, portanto, contrastando com predições baseadas em experimentos de laboratório. Ademais, a intensidade de manejo, definida por variáveis bióticas e abióticas, foi mais importante do que a preferência e o sucesso reprodutivo sobre densidades de pragas de café no campo. \nConcluindo, agroecossistemas com intermediária e alta diversidade arbórea têm o potencial de conservar a diversidade de ácaros, e portanto, deveriam ser incorporados em programas de conservação de paisagens. Sazonalidade e estrutura populacional devem ser consideradas em estudos de dinâmica populacional de artrópodes em diferentes hábitats, pois as respostas mudam com a época do ano e com as diferentes fases de desenvolvimento. Variáveis abióticas e bióticas determinando um dado hábitat podem ter um importante papel no entendimento dos efeitos do uso da terra sobre densidades populacionais de pragas. O entendimento da relação entre a densidade populacional de espécies e variáveis ambientais ajuda na predição e manejo de pragas no campo. Estudos de laboratório e de campo devem ser combinados para se determinar a importância relativa de experimentos conduzidos em pequenas e grandes escalas espaciais sobre densidades populacionais de artrópodes no campo.