Kinnebrew, EvaNeher, Deborah A.Ricketts, Taylor H.Wallin, Kimberly F....
10页
查看更多>>摘要：New land uses can drive complex changes to local biodiversity. In the Northeastern U.S., cultivated milkweed has arisen as a new crop with potentially promising outcomes for monarch butterflies, but has unknown effects on surface-active and soil-dwelling arthropods. We assessed differences in arthropod communities among nearby sites containing milkweed and three common regional land uses: conventional corn, conventional hay, and forest, representing a spectrum of high to low land use intensity. In each land use, we sampled surface-active and soil-dwelling arthropods, and we classified organisms at the taxonomic order level for all collected arthropods and at the taxonomic genus level for surface-active beetles. To address differences in functional traits between sites, we measured organisms' body sizes and calculated average body mass, total biomass, and abundance of arthropods in small, medium, and large size classes. In almost all analyses, taxonomic diversity values were significantly higher in the milkweed site than in corn and similar between the milkweed and hay sites. Milkweed had significantly higher diversity of surface-active arthropods than forest (for both orders and beetle genera), but did not have higher diversity of soil-dwelling arthropods, indicating possible different mechanisms driving aboveground versus belowground trends. Community composition differed significantly among land uses (demonstrated in NMDS ordination plots), with milkweed most similar to hay. Body size analyses demonstrated high total biomass and generally higher abundance of larger individuals in milkweed than in other land uses, with the exception of corn, which was dominated by large carabid beetles. We discuss the implications of our findings to land use properties and ecological function. Our case study indicates promising benefits of milkweed cultivation for soil biodiversity and soil health, with more research needed to validate and build from our results.
Lapierre, JaredMachado, Pedro Vitor FerrariDebruyn, ZacharyBrown, Shannon E....
12页
查看更多>>摘要：Cover cropping is a practice with potential to reduce post-harvest surplus of soil nitrate (NO3-), a mobile form of nitrogen naturally susceptible to losses. Increased soil NO3- leaching occurs when high soil NO3- coincides with high drainage events - a common occurrence during the non-growing season in cold and humid climates. The potential of cover crops to reduce NO3- leaching can be affected by the performance of the cover crop and by edaphic-climatic conditions (e.g., freeze-thaw cycles, soil type) and is subjected to interannual variation. Here, we evaluate soil type and crop rotation effects on soil parameters (i.e., NO3- concentration, temperature, water content) and on NO3- leaching under freeze-thaw conditions, using a high-frequency weighing lysimeter system. The soil type consisted of silt loam (SIL) and loamy sand (LS) soils and the crop rotation consisted of a rotation with a mixture of leguminous/non-leguminous cover crops (+CC) and no cover crop (-CC). This research was conducted during periods of 2017/2018 and 2018/2019 subjected to significant drainage. Our results indicated that cover crops did not affect drainage but affected soil temperature, with warmer soils observed over the winter when cover crops were used (+CC) than without cover-crops (-CC). Moreover, the cereal-crucifer-legume mixture after spring wheat reduced soil NO3- content by 80% compared to -CC during 2017/2018. For 2018/2019, due to poor establishment of the cereal-legume mixture under-seeded to corn, no reduction in soil NO3--content was observed. The reduction in soil NO3- in +CC plots for 2017/2018 translated to a significant reduction (by 67%) in NO3- leaching averaged across soil types. Soil drainage, NO3- content and NO3- leaching were not affected by soil type, an effect in part influenced by the boundary controls of the lysimeter system which mimicked soil conditions of a non-LS adjacent/reference field. To expand our results, we estimated the potential drainage of a hypothetical excessively drained LS (ED-LS) - a soil naturally subjected to high hydraulic conductivity and low water holding capacity. Overall, our results indicated that cover cropping can reduce NO3- leaching independent of soil type but the effect can be pronounced for ED-LS.
查看更多>>摘要：Biodiversity is rapidly declining worldwide, with agricultural intensification being among the main drivers of this process. Effective conservation measures in agricultural landscapes are therefore urgently needed. Here we introduce a novel low-cost conservation measure called artificial field defects, i.e., areas where crop is not sown and spontaneous vegetation grows. To evaluate their biodiversity potential, we compared abundance and species richness of various arthropod taxa between artificially created field defects and control plots within oilseed rape (OSR) fields. The effectiveness of field defects to support biodiversity was examined using an experiment with a factorial design comparing OSR flowering and ripening phases, location of field defects (field edge vs interior) and field defect type (sown with a nectar-rich plant vs no sowing). Arthropod sampling was conducted by employing several complementary methods: pitfall trapping, pan trapping, sweep netting and individual counting. Butterflies, true bugs, bees and wasps were more abundant and species-rich in both types of defects than in OSR controls. In contrast, ground-dwelling taxa had more individuals and species in controls. Overall, arthropod abundance and species richness increased, and field defects became relatively more attractive, during OSR ripening compared to OSR flowering. Location of defects had little effect, with only butterfly and spider assemblages being more abundant and species-rich at field edges compared to interiors. Our data indicate that artificial field defects can provide a simple agri-environmental measure to support various arthropod groups. However, further studies are needed to assess their biodiversity value at the landscape scale, and evaluate the balance between costs and benefits for farmers.
查看更多>>摘要：In order to act as effective agricultural pollinators wild bees must not only pollinate the target crop, but also have nesting behaviours that allow them to nest nearby or in situ. To establish their potential as crop pollinators we studied stem-nesting bees in the genus Exoneura, in and around Rubus berry farms in the Yarra Valley, Australia, where they had been observed nesting in nearby forested areas. Honey bees (Apis mellifera L.) are used as managed pollinators of Rubus crops, but we found that a single Exoneura visit to blackberry (Rubus fruticosus L. sp. agg.) was equivalent to a single honey bee visit, causing a three-fold increase in drupelet count. We found Exoneura nesting on farm in the stems of raspberry (Rubus idaeus L.) plants, at an estimated density of 3320 bees per hectare. Nests were more likely to be found in stems that were narrow and upright, suggesting that crop pruning strategies could focus on preserving select suitable stems for nesting. Exoneura were more abundant on flowers when local nest density was high (at 50 m) and when there was more native vegetation cover nearby (1 km), indicating that Exoneura are flexible in their selection of nesting habitat and able to nest on farm, but with their broader-scaled abundance still influenced by presence of native vegetation.
Heldbjerg, HenningClausen, Kevin K.Balsby, Thorsten J. S.Clausen, Preben...
10页
查看更多>>摘要：The population of barnacle geese wintering in Denmark has shown a steep increase during the last decades, prompting a parallel escalation of agricultural conflicts. In Denmark, economic compensation to farmers suffering goose damage to crops is not practiced, but despite that the barnacle goose is fully protected, landowners can obtain a permit to undertake so-called derogation shooting (lethal scaring) to reduce local damage to agricultural crops where other means of scaring have been insufficient. Here, we describe the development in numbers and derogation efforts of barnacle geese in Denmark in the period 2010/11 - 2018/19. We demonstrate that differences in the number of issued derogation permits across the country is primarily explained by differences in barnacle goose abundance, and secondarily, by prevalence of vulnerable crops and differences in crop productivity. Hence, derogation efforts are highest in areas with many geese, high proportions of crops vulnerable to goose grazing and high crop yields. Our analysis indicates that the level of conflict, and probably the economic impact of affected farmers, is proportional to the abundance of geese present locally. While the increasing derogation shooting may be a temporary solution to individual farmers, current unorganised practice might only redistribute geese locally and increase energy demands of the affected birds. Currently, there is a lack of alternative and undisturbed accommodation areas in the Danish agricultural landscape for the displacement of geese to achieve a satisfactory effect of derogation shooting.
查看更多>>摘要：Although grazing is the primary land use in the savanna lowland of southern Kenya, the effects of grazing on soil carbon dioxide flux (RS) remain unclear. A 12-month study was conducted from January to December 2020 on the effects of six grazing intensities sites (overgrazed (OG), heavily grazed (HG), moderately grazed (MG), moderately to lightly grazed (M-LG), lightly grazed (LG) and no grazing (NG)) on RS on. A camera trap was used to monitor the total number of animals at each site, indicating the grazing intensity. Weekly measurements of RS were taken using static greenhouse gas chambers along with simultaneous measurements of soil temperature (TS) and volumetric soil water content (WS) (depth of 5 cm). Mean RS at HG, MG, M-LG and LG sites was approximately 15-25% higher than at NG and OG sites (p < 0.001). Mean WS increased with decrease in grazing especially in the dry season, while TS increased with increase in grazing. We observed bimodal temporal variation in RS and WS due to two wet seasons in the year. Thus, variation in RS across the study period followed the changes in WS rather than those in TS. Mean values of RS in the wet seasons were significantly higher (> 45%) than those in the dry seasons, and WS accounted for 71% of the temporal variability in RS (p < 0.05). In addition, the enhanced vegetation index (EVI, interpreted as a proxy for vegetation cover) explained 60% of the variance of RS, and WS and EVI together explained 75%. EVI showed a negative relationship (p < 0.05) with animal intensity, indicating that more grazing reduced vegetation cover and, consequently, soil organic carbon and biomass. Soil bulk density was lower at less grazed sites. While RS variability was unaffected by total nitrogen content, pH, and texture, correspondence analysis demonstrated that the main factors influencing RS dynamics across the year under different grazing intensities were WS and vegetation cover. Our results contribute to closing the existing knowledge gap regarding the effects of grazing intensity on RS in East Africa savannas. Therefore, this information is of great importance in understanding carbon cycling in savanna grassland, as well as the identification of the potential consequences of increasing land pressure caused by rising livestock numbers, and will assist in the development of climate-smart livestock management in East Africa.
查看更多>>摘要：Understanding the mechanisms of interannual variations (IAVs) in cropland respiration (ER) can aid in optimizing field management strategies and accurately assessin bon budget. The long-term carbon exchange over a (winter) wheat-(summer) maize double-cropping system was measured with the eddy covariance technique to identify the IAVs in ER and the influencing factors, and investigate whether field management strategy (crop residue retuning) affects ER. Results showed that the growing season-related ER values for wheat (w-ER) and maize (s-ER) ranged from 471.77 to 681.96 g C m(-2) y(-1) and from 433.91 to 826.89 g C m(-2) y(-1), respectively, during 2007-2012. Pearson's correlation analysis indicated that the IAVs in w-ER were controlled by the crop residual carbon levels for maize from the prior season (s-C-r) and the gross ecosystem productivity. The seasonal mean air temperature (T-a) and maximum leaf area index for maize were found to be factors affecting the IAVs in s-ER. Because of the high correlation between the controlling factors, path analysis was used to deconvolute their respective contributions to the IAVs in ER. Integration analysis of path coefficients showed that s-C-r and T-a were the primary influencing factors, because they explained approximately 81% and 68% of the IAVs in ER for wheat and maize, respectively. Overall, our findings highlighted the importance of crop residue management for agroecosystem carbon cycling, but its effects may depend on ecosystem types.
查看更多>>摘要：Soil erosion can dramatically alter soil nitrogen (N) cycling, but it has rarely been examined under in-situ conditions due to the complicated interaction between erosion and vegetation. Comparing the effects of vegetation presence at eroding and depositional sites would provide a direct understanding of such effects. Herein, we investigated how soil N dynamics (mineral N pools and net N mineralization rates) responded to vegetation presence (plot with vs. without vegetation), landscape position (eroding vs. depositional sites) and vegetation type (grassland vs. woodland) during a two-year manipulation experiment using an in-situ incubation method in the hilly-gully region of China's Loess Plateau. The results showed that soils on eroding site had higher concentrations of nitrate (3.820 +/- 0.302 vs. 2.642 +/- 0.280 mg kg-1) and mineral N (5.853 +/- 0.320 vs. 4.308 +/- 0.287 mg kg-1) but similar rates of net nitrification (0.057 +/- 0.013 vs. 0.051 +/- 0.011 mg kg-1 d-1) and mineralization (0.056 +/- 0.014 vs. 0.056 +/- 0.013 mg kg-1 d-1) in comparison to depositional site in all grassland plots. The concentrations of soil nitrate and mineral N and rates of net nitrification and mineralization in legume woodland were 26%, 19%, 88% and 64% higher than that in grassland in all slope plots, respectively. Although vegetation presence significantly decreased soil nitrate (-57%) and total mineral N (-27%) concentrations, it did not affect the rates of net nitrification and mineralization. The effects of vegetation presence on soil net N mineralization occurred irrespective of landscape position and vegetation type(P > 0.05), but varied with season or year, with greater effects in 2017 growing season than in the non-growing season and 2018 growing season. Redundancy analysis and hierarchical partitioning indicated that the above- and blow-ground biomass accounted for most of the variation in soil N mineralization. These results suggested that the variations in soil mineral N and net N mineralization in relation to vegetation presence in this eroding watershed were consistent across different landscape positions and vegetation types, but showed intra- and inter-annual variability.
Ocampo-Ariza, CarolinaMaas, BeaCastro-Namuche, Jean P.Thomas, Evert...
12页
查看更多>>摘要：Agricultural expansion and intensification increasingly threaten birds and bats, especially insectivorous species from the tropics. Cacao agroforests in tropical rainforest areas have been shown to support higher bird and bat biodiversity than other land-use systems, but their suitability for tropical dry forest biodiversity remains unclear. We present the first assessment of bird and bat diversity patterns in cacao agroforests inside tropical dry forest landscapes. We investigated the response of bird and bat species richness and abundance to forest distance and season across 12 smallholder, organic cacao agroforests and adjacent tropical dry forests in the Peruvian lowlands of Piura. We found that insectivorous bird abundance and species richness increased with forest distance in the dry but not in the rainy season, indicating the value of cacao agroforests for these birds when resources are scarce in forests. In the case of bats, we observed more species in agroforests with increasing forest distance independent of season, and the abundance of insectivorous species increased along the gradient. Other dietary groups and forest specialists of both taxa did not vary notably across the forest distance gradient. Our findings point to the relevance of cacao agroforests as alternative habitats for insectivorous birds and bats in tropical dry forest landscapes, especially during the dry season. We suggest that the maintenance of wildlife friendly cacao agroforests, parallel to dry forest conservation and restoration, creates win-win situations for both the conservation of tropical dry forest fauna and the maintenance of related ecosystem services from which cacao smallholders may benefit.
查看更多>>摘要：Organic amendment often affects both crop yield and greenhouse gas (GHG) emission. Yet the impact of organic amendment on yield gains and GHG emissions is still unclear, particularly in long-term soybean-wheat cropping system. Based on a 30-year soybean-wheat cropping system experiment, the impact of organic amendments (i.e. straw and manure) on soil properties, crop yield, N2O and CH4 emissions, and net ecosystem economic budget (NEEB) were investigated. The treatments were: chemical NPK fertilizer (NPK), chemical NPK plus low amount of wheat straw (NPKLS), chemical NPK plus high amount of wheat straw (NPKHS), chemical NPK plus pig manure (NPKPM), chemical NPK plus cattle manure (NPKCM), and a control with no fertilizer applied (CK). The long-term straw and manure amendments enhanced soybean yield by 13.1% and 44.0%, and improved wheat yield by 6.4% and 9.9%, respectively. Meanwhile, they stimulated N2O emissions by 25.1% and 49.0% respectively, without significant effect on CH4 emissions, compared to the chemical NPK fertilizer treatment (NPK). The results of structural equation model showed that soil properties tested explained 76% of the variations observed in N2O emissions, which were directly affected by soil nitrification capacity, pH and denitrification capacity. Although straw and manure amendments increased the total GHG emissions investigated by 25.7% and 48.6% respectively, they showed insignificant effects on the greenhouse gas intensity (GHGI), and increased NEEB by 8.6% and 21.1%, respectively, compared to the NPK treatment. This indicates that the benefits arising from crop yield improvement through the use of organic amendments can cover the carbon fees caused by increased GHG emissions. Our findings suggest that organic amendment can be an effective strategy to simultaneously increase crop yield while mitigating greenhouse gas emissions from the perspective of carbon fees.
NSTL
Elsevier