Agriculture, Ecosystems & Environment最新文献

Photosynthesized carbon assimilation and allocation are crucial for plant responses to environmental changes, such as light. Intercropping typically enhances light interception. However, the effects on photosynthesized carbon allocation and microbial immobilization in intercropping systems remain unclear. We investigated light interception, photosynthetic rate, biomass, grain yield, soil organic carbon (SOC), and performed ¹³CO₂ pulse labeling to trace carbon footprints in the plant-soil system under long-term maize-soybean relay strip intercropping and maize monocropping systems. Results showed that, compared to monocropped maize, intercropped maize exhibited a 15.4 % increase in plant ¹³C fixation and significantly greater belowground carbon allocation, with increases of 52.7 % in roots, 64.1 % in rhizosphere soil, and 81.9 % in bulk soil. These outcomes were attributed to enhancements of 30.2 % in light interception and 16.5 % in photosynthetic rate during the post-silking period. At silking, increased light interception in intercropped maize directly contributed to belowground carbon allocation. During the filling period, the source-sink relationship between limited kernel sink capacity and sufficient source strength regulated belowground carbon allocation, resulting in no significant difference in grain yield between intercropping and monocropping. Additionally, the higher ¹³C content in microbial biomass (by 99.8 %) suggested increased microbial utilization of new carbon, potentially enhancing microbial carbon immobilization under intercropping. After 10 years of cultivation, intercropping resulted in a 13.9 % increase in SOC compared to monocropping. Overall, intercropped maize benefited from enhanced light interception, which facilitated plant carbon fixation and increased photosynthesized carbon sequestration in the soil through improved photosynthesized carbon allocation to the soil and microbial carbon immobilization. These findings demonstrate that strip intercropping cultivation can promote photosynthesized carbon sequestration in soil, thereby enhancing the carbon sink capacity of agroecosystems.

Agricultural intensification is debated as one of the major drivers for the decline of insect biodiversity. Agri-environmental schemes (AES) are a common measure to promote biodiversity in agriculture by granting compensational payments to farmers for environmentally friendly practices. In this study we examined the effect of buffer strips of at least 5 m width, adjacent to small watercourses and drainage ditches, on insect biomass and insect species richness in agricultural landscapes. We selected ten arable fields in each of four regions in lower and upper Bavaria, Southern Germany. 25 out of 40 sites had a buffer strip between arable crops and watercourse. Insects were sampled at three time periods (May/June, June/July and August/September) for two weeks each. In each period two samples were collected (one per week). On each site Malaise traps were set up in 5 and 80 m distance to the embankment of the watercourse. Half of the samples was then subjected to metabarcoding and the other half was classified into different insect groups by morphological identification and the number of the individuals for each group was counted. For hoverflies (Syrphidae), individuals were identified at species-level. Data on vegetation structure (cover of grasses and herbs) in the studied riparian buffer strips was collected and correlated with number of species, abundances and biomass of flying insects. The five taxonomic orders with the highest species richness and individual numbers were: Diptera, Hymenoptera, Coleoptera, Lepidoptera and Hemiptera. Diptera dominated hereby with 34% of all species and 81% of all individuals. On average, mixed models indicated 31% higher insect biomass, 15% higher species richness and 29% higher individual numbers of flying insects in buffer strips at 5 m distance to the watercourse compared to sites with no buffer strip. The effect was even stronger for butterflies (32% higher species species richness, 70% more individuals) and hoverflies (24% higher species richness, 51% more individuals). In the presence of a buffer strip significantly higher numbers were found for total individuals, Diptera, Hymenoptera and Coleoptera. In 80 m distance to the watercourse, the samples of flying insects were not significantly influenced by a riparian buffer strip. This study highlights the importance of buffer strips in agricultural regions and their multifunctional potential in fostering biodiversity additionally to their acknowledged use for water protection. Ideally, buffer strips are rich in herbs and inflorescences and are therefore beneficial for the insect fauna by serving as valuable habitat with high potential connectivity at landscape level.

The intensification of agriculture has been identified as one of the main causes of arthropod declines. To halt the decline of arthropods, changes in farming practices and management of surrounding habitats may therefore be needed. A key challenge is to identify which changes in management approaches are most effective in restoring biodiversity. Therefore, this study examines arthropod abundance and diversity in different agricultural and semi-natural habitats, and among different management types. Arthropods were sampled three times in spring and summer of 2022 and 2023 with emergence traps in 128 unique sites in an intensively farmed area in Western Netherlands. These sites included a variety of crops as well as semi-natural habitats. Our study showed that on average the abundance and diversity of arthropods of several taxa was lower in crop habitats compared to semi-natural habitats. However, these effects strongly varied among crop species. For instance, alfalfa, spelt, spring and winter wheat fields (that often had a high plant cover) supported similar arthropod diversity and abundance levels as semi-natural habitats. Interestingly, in crop fields most variables related to field management, such as herbicide applications or amount of nitrogen fertilizers, did not show any significant relationship with arthropod abundances or diversity. The number of days after cultivation was an exception, and was positively related to total arthropod abundance, Hymenoptera and Collembola abundances, and Coleoptera family diversity. Within semi-natural habitats, number of days after mowing was positively related to total arthropod abundance, Diptera, Hemiptera and Hymenoptera abundances, and Hemiptera family diversity. Additionally, plant cover was positively related to total arthropod abundance. Overall, our findings suggest that crop species and management practices that increase plant cover in spring and early summer are increasing arthropod abundance and, to a lesser extent, higher-taxa diversity in intensively farmed agricultural landscapes.