Spatially Disaggregated Inventories of Soil NO and N2O Emissions for Great Britain

Estimates of soil N₂O and NOemissions at regional and country scales arehighly uncertain, because the most widely usedmethodologies are based on few data, they do notinclude all sources and do not account forspatial and seasonal variability. To improveunderstanding of the spatial distribution of soilNO and N₂O emissions we have developedsimple multi-linear regression models based onpublished field studies from temperate climates.The models were applied to create spatialinventories at the 5 km² scale of soil NOand N₂O emissions for Great Britain. The N₂O regression model described soilN₂O emissions as a function of soil N input,soil water content, soil temperature and land useand provided an annual N₂O emission of 128 kt N₂O-N yr^-1. Emission rates largerthan 12 kg N₂O-N ha^-1 yr^-1 werecalculated for the high rainfall grassland areasin the west of Great Britain.Soil NO emissions were calculated using tworegression models, which described NO emissionsas a function of soil N input with and without afunction for the water filled pore space. Thetotal annual emissions from both methods, 66 and7 kt NO-N yr^-1, respectively, span the rangeof previous estimates for Great Britain.     

放牧对内蒙古草原温室气体排放的影响

静态箱-气相色谱法用于测定内蒙古典型草原温室气体排放.禁牧草原及放牧草原吸收CH₄、排放N₂O和CO₂各自有其相对固定的季节变化形式,草原和大气交换温室气体通量的季节变化形式主要受年度气候变化所控制,而土壤、植被类型、降雨量等禁牧因素和放牧强度等人为因素仅影响排放强度.与禁牧草原相比,自由放牧降低了羊草草原对CH4的吸收和对N₂O的排放,但大大增加了CO₂的排放量.随着放牧强度的增加,草原温室气体排放强度呈线性迅速增长.     

黄土高原半湿润区苜蓿草地土壤干层形成及氮素消耗研究

为掌握苜蓿连续种植多年土壤干层的形成规律及氮素的消耗规律,促进黄土高原地区苜蓿草地合理施肥及草田轮作,论文系统研究了3年、4年、6年、12年、14年、18年及26年生紫花苜蓿草地土壤干层及氮素的消耗。结果表明:黄土高原地区土壤干层可分为轻度干层（9~11%）、中度干层（7~9%）、重度干层（<7%）三级。荒地在80~100cm土层,出现轻度干层;苜蓿草地土壤干层出现的区域为140~600cm土层,随生长年限的延长,土壤干层厚度向下延伸,干化程度加剧,苜蓿生长至12年,出现中度干层,干层范围达到500cm土层。不同生长年限苜蓿草地土壤碱解氮含量呈现规律性的变化,即随土层深度的增加,碱解氮含量下降,300cm土层以下,变化趋势平缓;苜蓿生长至26年,0~200cm土壤上层的氮素有一定恢复,而200~1000cm深层土壤氮素难以恢复。研究表明,在黄土高原半湿润区紫花苜蓿生长6年以后,应对苜蓿草地进行合理施肥,实施粮草轮作,以维持土壤氮素平衡,持续提高土地生产力水平。     

Optimizing conservation in species-specific agricultural landscapes

Recovery of grassland birds in agricultural landscapes is a global imperative. Agricultural landscapes are complex, and the value of resource patches may vary substantially among species. The spatial extent at which landscape features affect populations (i.e., scale of effect) may also differ among species. There is a need for regional-scale conservation planning that considers landscape-scale and species-specific responses of grassland birds to environmental change. We developed a spatially explicit approach to optimizing grassland conservation in the context of species-specific landscapes and prioritization of species recovery and applied it to a conservation program in Kentucky (USA). We used a hierarchical distance-sampling model with an embedded scale of effect predictor to estimate the relationship between landscape structure and abundance of eastern meadowlarks (Sturnella magna), field sparrows (Spizella pusilla), and northern bobwhites (Colinus virginianus). We used a novel spatially explicit optimization procedure rooted in multi-attribute utility theory to design alternative conservation strategies (e.g., prioritize only northern bobwhite recovery or assign equal weight to each species’ recovery). Eastern meadowlarks and field sparrows were more likely to respond to landscape-scale resource patch adjacencies than landscape-scale patch densities. Northern bobwhite responded to both landscape-scale resource patch adjacencies and densities and responded strongly to increased grassland density. Effects of landscape features on local abundance decreased as distance increased and had negligible influence at 0.8 km for eastern meadowlarks (0.7–1.2 km 95% Bayesian credibility intervals [BCI]), 2.5 km for field sparrows (1.5–5.8 km 95% BCI), and 8.4 km for bobwhite (6.4–26 km 95% BCI). Northern bobwhites were predicted to benefit greatly from future grassland conservation regardless of conservation priorities, but eastern meadowlark and field sparrow were not. Our results suggest similar species can respond differently to broad-scale conservation practices because of species-specific, distance-dependent relationships with landscape structure. Our framework is quantitative, conceptually simple, customizable, and predictive and can be used to optimize conservation in heterogeneous ecosystems while considering landscape-scale processes and explicit prioritization of species recovery.     

Effects of Wind Energy Development on Nesting Ecology of Greater Prairie‐Chickens in Fragmented Grasslands

Wind energy is targeted to meet 20% of U.S. energy needs by 2030, but new sites for development of renewable energy may overlap with important habitats of declining populations of grassland birds. Greater Prairie‐Chickens (Tympanuchus cupido) are an obligate grassland bird species predicted to respond negatively to energy development. We used a modified before–after control–impact design to test for impacts of a wind energy development on the reproductive ecology of prairie‐chickens in a 5‐year study. We located 59 and 185 nests before and after development, respectively, of a 201 MW wind energy facility in Greater Prairie‐Chicken nesting habitat and assessed nest site selection and nest survival relative to proximity to wind energy infrastructure and habitat conditions. Proximity to turbines did not negatively affect nest site selection (β = 0.03, 95% CI = ?1.2–1.3) or nest survival (β = ?0.3, 95% CI = ?0.6–0.1). Instead, nest site selection and survival were strongly related to vegetative cover and other local conditions determined by management for cattle production. Integration of our project results with previous reports of behavioral avoidance of oil and gas facilities by other species of prairie grouse suggests new avenues for research to mitigate impacts of energy development. Efectos del Desarrollo de la Energía Eólica sobre la Ecología de Anidación de Gallinas de la Gran Pradera en Pastizales Fragmentados     

Natural food resources bank in the form of forestry and grassland: Scenarios to ensure sustainable food security

An evaluation was conducted to establish the feasibility of a Natural Food Resources Bank (NFRB), in the form of forestry or grassland, to achieve both continuous food production and an accumulation of primary nutrients in living perennial plants. The development of an NFRB protects our living environment from deterioration (especially soil erosion) by increasing the surface coverage of the world's land, even in mountainous areas. Additionally a functioning NFRB enhances food sustainably and security, representing a tangible and renewable food resource production system. Research has identified the prospects of cultivating the NFRB in the form of forestry and also grassland. The review investigated the distinct differences of an NFRB from a range of approaches and discusses the environmental advantage and feasibility of cultivating NFRB. The ability of the NFRB to realize sustainable food resources production for ensuring food security is evaluated in terms of environmental and economical feasibility. A NFRB can attenuate climatic change by increasing CO₂ absorption and fixation. It is worth considering the replacement of the annual food production system by the NFRB (especially in steeplands) in environmental law, and replacing the policy of maintaining annual food reserves by the NFRB in food security policy.     

单次降水对高寒草地温室气体通量昼夜变化的影响研究

在全球变化背景下,青藏高原降水格局发生改变,并影响高寒草地温室气体排放.为了更好地认识降水变化与高寒草地温室气体排放的关系,在2015年7月24日,通过人工降水6.7 mm,研究了单次降水对高寒草地温室气体昼夜变化的影响.表明:(1)单次降水没有改变土壤温度,但显著增加了土壤湿度;(2)单次降水后24小时内,高寒草地CH4吸收量降低了2.46倍,CO2和N2 O排放量分别提高15.3%和98.9%;(3)单次降水弱化了高寒草地CH4和N2 O排放量与土壤温度的关系.     

喀斯特山地草地植物群落物种数量特征及多样性分析

选择贵州典型喀斯特山地草地植物群落为研究对象,采用标准样地调查法,对不同海拔、坡向的植物群落数量特征、物种特性、以及物种丰富度、多样性、均匀性等特征展开研究,结果表明,（1）喀斯特山地草地植物群落密度随海拔升高呈显著增加趋势（F=20.600;P≤0.01）。植物群落中矛叶荩草（Arthraxon lanceolatus）和扭黄茅（Heteropogon contortus）种群在数量上占优势,同时矛叶荩草和扭黄茅种群密度随海拔升高呈现出增加趋势;但矛叶荩草种群密度在群落中的比例呈现出下降趋势,而扭黄茅种群密度在群落中的比例呈现出升高趋势。（2）喀斯特山地草地植物群落以禾本科（Gramineae）、菊科（Compositae）、蔷薇科（Rosaceae）、唇形科（Labiatae）为主;其中禾本科植物种类比例随海拔升高呈现出下降趋势,而菊科、蔷薇科、唇形科植物种类比例呈现出升高趋势。（3）喀斯特山地草地植物群落丰富度指数随海拔升高呈现出增加趋势,Simpson多样性指数、Shannon-Wiener多样性指数随海拔升高呈现先降后升趋势,Peilow均匀性指数随海拔升高呈现下降趋势。     

我国草地资源生产潜力分析及其可持续利用对策

本文分析了我国草地资源生产力的现状及区域分布特征 ,初步建立了草地资源生产潜力预测分析的方法 ,估算了各农业生态区草地资源的生产潜力 ,在此基础上提出了我国草地综合生产能力可持续发展的基本对策     

Rodent Communities in an Exurbanizing Southwestern Landscape (U.S.A.)

Abstract:  Ranches are being converted to exurban housing developments in the southwestern United States, with potentially significant but little-studied impacts on biological diversity. We captured rodents on 48 traplines in grasslands, mesquite savannas, and oak savannas in southeastern Arizona that were grazed by livestock, embedded in exurban housing developments, grazed and embedded in development, or neither grazed nor embedded in development. Independent of habitat or development, rodent species richness, mean rank abundance, and capture rates of all rodents combined were negatively related to presence of livestock grazing or to its effects on vegetative ground cover. Exurban development had no obvious effects on rodent variety or abundance. Results suggest southwestern exurban developments can sustain a rich assemblage of grassland and savanna rodents if housing densities are low and houses are embedded in a matrix of natural vegetation with little grazing.