查看更多>>摘要：Interest in economically and ecologically sustainable cocoa has grown in recent years. Cocoa-based agroforestry systems are promoted as a potential win-win option for long-term yields, multiple benefits, and the preservation of biodiversity. Yet, even though recent studies have shown such agroforests can support biodiversity, their value relative to natural areas and open-land systems is not fully known. We estimated the biodiversity intactness (BII) of different land uses associated with cocoa-driven land-use change using mixed-effects models. We distinguished between agroforests established under natural shade and those grown from open land, and compared these to intensively grown cropland (including cocoa monoculture), and primary and secondary forest. We found that species richness in cocoa-based agroforestry systems, under both natural and planted shade, was lower than in primary forests but higher than in open-land systems. However, we found that land-use history influenced the biodiversity intactness of agroforests: whilst open-land-derived cocoa-based agroforestry systems and forestderived cocoa-based agroforestry systems share similar species richness, open-land-derived cocoa-based agroforestry systems have lower community similarity to primary forest than forest-derived cocoa-based agroforestry systems. The results highlight that high levels of BII can be sustained by retaining the natural shade in existing agroforestry systems, but also that incentivising planted shade agroforestry can enhance biodiversity intactness in degraded areas whilst delivering co-benefits. Importantly, the results highlight that cocoa planning seeking to achieve biodiversity benefits should consider the direction of land use and biodiversity transitions.
查看更多>>摘要：The quality of a landscape's matrix is a key condition for the conservation of biodiversity and affects the diversity and composition of bird assemblages in agricultural landscapes with forest remnants. In southern Brazil most agricultural landscapes are a mosaic of cultivated areas, treeless pastures and forest remnants. These landscapes must be planned and managed for food production while synergically enhancing ecological restoration and biodiversity conservation. In this study, we compared the diversity and composition of bird species in High Biodiversity Silvopastoral Systems (SPSnuclei), treeless pasture areas, forest edges and forest interiors. SPSnuclei is a type of silvopastoral system (SPS) whose design was inspired by applied nucleation reforestation techniques using multispecies agroforestry nuclei. In this study, we sought to understand the influence of the SPSnuclei on the diversity and composition of birds by comparing SPSnuclei to treeless pasture areas, forest edges and the forest interior. We hypothesize that multispecies agroforestry nuclei would restore some of the ecosystem biodiversity, and therefore resilience. To quantify bird diversity, sound recorders were installed simultaneously within these habitats during the spring and summer of 2016 and 2017 on three dairy farms. We identified calls from 108 bird species in 2400 min of recordings (600 min/habitat). The High Biodiversity Silvopastoral System increased the diversity of birds in the agroecosystem. Species richness was higher in the parcels with SPSnuclei compared to treeless pastures (P < 0,05). Although, species richness was smaller in the SPSnuclei than forest edge and interior of the forest remnants (P < 0,05). Eight species from the interior and forest edge were observed in the SPSnuclei, but not in the treeless pastures. This research presents evidence that SPSnuclei has positive effects on the diversity and composition of the avifauna in agricultural landscapes and could act as stepping stones that increase connectivity between forest remnants.
Haedo, Joana P.Martinez, Lucia C.Graffigna, SofiaMarrero, Hugo J....
9页
查看更多>>摘要：Biotic pollination is an essential ecosystem service for agricultural production and is reflected in the high number of crops that depend on insect pollination in order to produce profitable yields. Alfalfa (Medicago sativa) is a crop whose flowers need to be visited by a bee to be pollinated for seed production, making it highly pollinatordependent. Two managed bee species are currently used to pollinate this crop: the alfalfa leafcutting bee (ALCB), one of the most efficient alfalfa pollinators, and the honey bee (HB), whose efficiencies could be highly variable among production sites. Besides, there are many other wild bee species (WBs) that are effective pollinators of alfalfa, but little attention has been placed on them, especially in Argentina, where alfalfa seed production is deficient. Here, we evaluate the contribution of both managed species and WBs on alfalfa pollination services in one of the most important alfalfa seed productive regions of Argentina. During the span of two years, we calculated pollen limitation in different pollinator managed scenarios: with and without ALCBs (ALCB+ and ALCB-, respectively), and we also evaluated the relationship between pollen limitation and all bee species visitation rates. Our results show that the ALCB is a very effective pollinator of alfalfa, since ALCB+ lots have less pollen limitation (32%) compared to ALCB- lots. In contrast, HBs seem to have a detrimental effect in pollination service in ALCB+ lots and a positive effect in ALCB- lots. This differential effect could be due to differences in foraging behavior caused by competition between HBs and ALCBs. Finally, in spite of their low abundances, we found that an increase in WB visitation rates substantially reduces pollen limitation. In spite of ALCBs being a good alfalfa pollinators, the difficulty and cost of managing them hinder its widespread use. The use of WBs seems to be a good alternative, and practices that improve their abundance and diversity should be implemented to improve alfalfa pollination service.
查看更多>>摘要：Biodiversity directly influences the delivery of multiple ecosystem services, most notably within agriculture. Projected future global demands for food, fiber and bioenergy will require enhancement of agricultural pro-ductivity, but favoring biodiversity-based ecosystem services generally remains underutilized in agricultural practice. In addition, agricultural intensification is a key driver of biodiversity loss. A significant obstacle pre -venting the adoption of ecologically sensitive practices is a lack of knowledge of the species delivering the services. Insectivorous bats have long been suggested to regulate insect pest populations and may be a critical component of biodiversity-based ecosystem services. Bats may also serve as agents of insect pest surveillance through environmental DNA (eDNA) monitoring approaches. However, the biological and economic importance of bats to agriculture remains under-quantified. Here we catalogued the dietary niche of two North American bats, little brown bat (Myotis lucifugus) and big brown bat (Eptesicus fuscus), through DNA metabarcoding of guano collected from seven roosting sites over a 26-week period. We measured the frequency of occurrence of known pest species in guano samples, compared interspecific differences in diet, and examined seasonal patterns in prey selection. Overall, we detected 653 unique prey species, 160 of which were known agricultural pests or disease vectors. Species diversity of prey species consumed varied by bat species and across the season, with big brown bats accounting for the majority of arthropod diversity detected. However, little brown bats consumed relatively more aquatic insects than big brown bats, suggesting that increased bat species richness in a landscape can amplify their net pest regulation service. Further, we hypothesized that detection probabilities of target insect pests would be higher in guano samples than in conventional survey methods. Multi-survey occupancy modeling revealed significantly lower detectability in bat guano than in conventional monitoring traps, however, highlighting important tradeoffs in selection of survey methods. Overall, the results presented here contribute to a growing evidence base supporting the role bats play in the provisioning of biodiversity-based ecosystem services.
查看更多>>摘要：Knowledge of species richness patterns in plant communities is biased toward its hidden belowground part and is derived only from the part visible aboveground. Studies on the relationship of the above-to belowground parts of plant communities suffer from the lack of a consistent and uniform approach to assess their taxonomic composition, particularly in species-rich ecosystems. This study described the proportion between above-and belowground parts of vegetation in three grassland types along with the environmental factors that affect them, using eDNA metabarcoding and an observer survey. The internal transcribed spacer 2 (ITS2) region was used to analyze the total plant richness in the soil and the aboveground "green" part of plant communities. Considering all samples, eDNA metabarcoding successfully assigned about 93% of taxa on the species level. Our findings support the notion that metabarcoding analysis of the belowground plant community revealed up to 66% higher species richness than was identified above the ground by a conventional vegetation survey. However, this dif-ference decreases to about 25% when an eDNA-derived taxonomic assignment was applied for the aboveground part of phytocoenosis. We also found that the difference between the below-and aboveground parts of the plant community decreased with increased soil fertility. Finally, the management intensity was found to significantly influence species richness only in the aboveground part of vegetation with the belowground part of grassland remaining unaffected. Overall, since DNA-based metabarcoding and traditional vegetation surveys have limi-tations, their complementary use is recommended to obtain the most reliable vegetation description. However, it should be considered that metabarcoding analysis is destructive and may not be applicable in protected or private areas or on permanent research plots.
Tamagno, SantiagoEagle, Alison J.McLellan, Eileen L.Linquist, Bruce A....
10页
查看更多>>摘要：Growing public concern over agricultural nitrogen (N) pollution is now reflected in consumers' food choices and shareholders' resolutions, causing rapid changes in global food supply chains. Nitrate (NO3) leaching represents the primary N source for groundwater contamination and freshwater ecosystem degradation. However, simplified science-based indicators are still lacking to facilitate improved N management practices at the farm-level. We conducted a global analysis of published field studies to evaluate N balance (N inputs minus N outputs) as a robust predictor for NO3 losses. Using 82 studies (1110 observations) for rainfed cereal crops in temperate regions, we 1) quantified the response of NO3 losses to changes in N balance for major rainfed cereal crops while accounting for environmental and management variables; and 2) assessed the feasibility of improving water quality through lower N balance under different scenarios using the case study of maize (Zea mays L.) data from the US Corn Belt. Observations were grouped in studies from the US and non-US regions. Results show that NO3 losses increased exponentially as N balance increases for both the US and non-US regions, though they were 60% higher in the US at a given N balance. Scenario analysis revealed that reducing the N rate from the agronomic optimum to the lower point within the economic optimum N rate range decreased NO3 losses by 13% without impacting economic returns. The case study for maize showed that improvements in N use efficiency that increase grain yield at a given fertilizer rate can substantially reduce N balance and mitigate NO3 losses. This study provides an evidence-based foundation for food supply chain companies to mitigate global NO3 pollution, specifically by using the generalized relationships presented here to track progress in NO3 leaching mitigation. To further resolve uncertainties and improve region-specific estimates for NO3 losses, we propose a tiered monitoring and assessment framework similar to the IPCC (Intergovernmental Panel on Climate Change) methodology for N2O emissions, widely implemented in science and used for policy.
Isla, JorgeRey, Pedro J.Garcia-Navas, VicenteMartinez-Nunez, Carlos...
9页
查看更多>>摘要：Agroforests are of well-known importance for biodiversity conservation, especially in the tropics, because they are structurally stable and may resemble natural forests. Previous studies have characterized jointly taxonomic, functional and phylogenetic diversity in these agro-ecosystems to comprehensively examine the mechanisms by which agriculture impacts on biodiversity. However, this approach has been barely applied to other woody crops of economic importance, such as olive grove, which is a remarkable overwintering habitat for frugivorous/ insectivorous birds from central and northern Europe, and whose original distribution overlaps with the Mediterranean biodiversity hotspot. We examined the effects of landscape complexity and intensive management practices at a local scale (recurrent plowing and pesticides use) on the functional and phylogenetic diversity of animal communities inhabiting olive groves. Since the response of functional traits or clades may vary across different taxonomic groups, we conducted our study at two levels: ants, which are considered semi-sessile organisms, and birds, which exhibit a high dispersal capacity. In birds, neither management type nor landscape complexity had an effect on phylogenetic diversity (PD) indices. Extensively managed farms harbored bird communities with higher values of functional diversity (FD), but this effect only was evident when considering cultivated (productive) zones within the farm (i.e., infield diversity). Ant assemblages on intensively managed farms exhibited a lower level of phylogenetic clustering than those located in extensive farms, but this effect vanished when excluding non-cultivated zones. Ant functional diversity increased with landscape complexity. Our results indicate that PD and FD exhibit different responses to farming intensification in olive groves. Although intensive management does not erode PD due to the existence of phylogenetic redundancy, the loss of species associated to modern farming leads to a reduction in FD being this indicative of functional complementarity. This study provides evidence that land-use extensification (extensive farming and landscape diversification) promotes more functionally rich assemblages than modern intensive practices in olive groves. Our findings also show the need to set apart the effect of non-cultivated zones (e.g., hedgerows, margins) when evaluating the effectiveness of agri-environment schemes as the joint consideration of non-cultivated and cultivated areas may obscure the benefits of local extensification on infield biodiversity.
查看更多>>摘要：Mineral nutrient fluxes derived from litterfall are key components of nutrient biogeochemical cycles in both natural and agroforesty systems. Cocoa production systems are generally nutrient depleted and may benefit from on external nutrient application to maintain primary productivity. However, in developing countries the main source of nutrients is often nutrient recycling through decomposing leaf litter, and in this regard shade-tree species play an important role in cocoa agroforestry. This study aimed to investigate the nutrient inputs of litter from two shade-tree species (Canarium indium and Gliricidia sepium) and cocoa trees (Theobroma cacao) after 15 months of decomposition in a cocoa plantation. Litter from G. sepium lost more mass (59%) than T. cacao (37%) and C. indium (10%), and showed a higher average concentration of total nitrogen (TN), boron (B), iron (Fe) and phosphorus (P) after 15 months of field incubation than that of C. indium. It also showed a low C:N ratio and N release, which suggest N mineralisation. All litter species showed high C:P ratio and negative P release, which suggests P immobilisation. Litter from G. sepium and T. cacao showed a rapid K release after 1 month of decomposition. The differing mass loss rates and litter nutrient concentrations of the three species could benefit T. cacao by providing asynchronous nutrient inputs and improve long-term sustainability of mixed-species plantations.
查看更多>>摘要：Vegetation Fractional Cover (VFC) is an important indicator of the condition of the terrestrial surface of the Earth. The dynamics of bare soil (BS), non-photosynthetic vegetation (NPV) and photosynthetic vegetation (PV) fractions reveal patterns of growth, senescence, dormancy and regeneration. The dynamics also reveal trends in land cover and land use management across the globe. Analysis of satellite data has indicated increasing greenness of the land surface however the dynamics of the NPV and BS fractions are equally important indicators of many elements of ecosystem function and sustainability. In this study, we provide a comprehensive assessment of trends in VFC for the global terrestrial land surface based on a trend analysis over the period 2001-2018 using the Global Vegetation Fractional Cover Product. Trends were analysed by Mann-Kendell regressions over 18 years for each month of the year. Monthly maps of significant trend areas were aggregated to provide seasonal assessments. Areas and percentage areas of positive and negative trends were compiled for United Nations Subregions, Countries and Ecoregions. Significant negative trends in BS occurred across 20 M km2 of the terrestrial land surface. Although the areas of negative trends in BS were largest in China and India, the top 24 countries by area were widely distributed across the world. However, BS increased significantly across more than 11 M km2. Eleven of the top 24 ranked countries for area of increasing BS were in Africa. Substantial areas exhibited negative trends in NPV split between China and India where PV was increasing, and drylands in Asia and Africa where BS was increasing. Analysis of covariate factors at country scale inferred an association between significant increase in BS and long-term drought and increases in livestock populations. The positive trends in BS and negative trends in NPV are indicators of current and future risk for soil erosion, habitat change, and reduction in ecosystem health across heavily populated regions of the developing world.
Applegate, Roger D.Smith, RayLituma, Christopher M.Buckley, Byron R....
12页
查看更多>>摘要：Declines in native warm season grasslands have been linked to grassland bird population decline due to habitat loss including conversion to non-native grasses. Rotational grazing (ROT) and patch-burn grazing (PBG) are two possible tools to restore native warm-season grasses (NWSG) on working-lands in the Mid-South USA and thus aid in the recovery of grassland bird populations. This project compares ROT, PBG, and before treatment implementation to assess their effects on grassland-associated bird species. At three research sites between KY and TN, 14-10 ha NWSG pastures were established and randomly assigned 7 pastures each to ROT and PBG treatment and monitored avian relative abundance during the breeding season from 2014 to 2017. Avian call count data and vegetation characteristics were collected in 2014 and treated as a before treatment year. Following 2014, ROT and PBG treatments were implemented across each respective research site. We used the open N-mixture model framework to estimate avian relative abundance related to year, treatments, research site, and landscape and within-field variables. Avian species richness and diversity were calculated for each treatment, research site, and year. Landscape variables, within-field variables, and research sites exerted more influence on relative abundance than ROT or PBG. Grassland-associated bird species relative abundance and species richness/diversity were affected by habitat disturbances (both ROT and PBG) but varied by species and site. Field sparrows [Spizella pusina] had the highest increase in relative abundance (9.68 +/- 1.24 birds/point count location or 1.77 ha) while northern cardinals [Cardinalis cardinalis] exhibited a significant decrease in relative abundance (3.44 +/- 1.54 birds/point count location) following treatment implementation on specific research sites. Species diversity and richness did not differ between ROT and PBG treatments. However, a site and year difference were observed for both estimates. Using ROT and/or PBG to create habitat disturbances can alter within-field variables (i.e., vegetation height) which, taken into context with landscape variables, could impact grassland bird populations and diversity depending on grassland bird species habitat requirements. Our research provided the baseline information for ROT and PBG impacts on grassland birds in the east/southeastern USA. However, we believe future research should focus on breeding and annual fecundity to better understand how populations will change over time and how working lands conservation might aid this conservation effort without a reduction in livestock productivity.
NSTL
Elsevier