新疆阿勒泰地区实施草原生态保护补奖政策研究

草原生态保护补助奖励政策在阿勒泰地区的实施,标志着该地区草原生态保护进入兼顾民生的发展时期。该地区的政策实施取得了一定的成效,但是还存在补偿标准低、草畜平衡难度大、基本规章制度尚未完善、配套设施及项目资金滞后、农牧民缺乏现代科学技术等问题。造成这些问题的原因有：草地牧草总产量和实际放牧量难以掌控;法律机制不完善;草原产权不清晰;草原生态建设的投融资机制不完善;生态保护观念尚未建立;农业转型困难等。     

Estimation of Nitrous Oxide Emissions from US Grasslands

2 O) emissions from temperate grasslands are poorly quantified and may be an important part of the atmospheric N₂O budget. In this study N₂O emissions were simulated for 1052 grassland sites in the United States using the NGAS model of Parton and others (1996) coupled with an organic matter decomposition model. N₂O flux was calculated for each site using soil and land use data obtained from the National Resource Inventory (NRI) database and weather data obtained from NASA. The estimates were regionalized based upon temperature and moisture isotherms. Annual N₂O emissions for each region were based on the grassland area of each region and the mean estimated annual N₂O flux from NRI grassland sites in the region. The regional fluxes ranged from 0.18 to 1.02 kg N₂O N/ha/yr with the mean flux for all regions being 0.28 kg N₂O N/ha/yr. Even though fluxes from the western regions were relatively low, these regions made the largest contribution to total emissions due to their large grassland area. Total US grassland N₂O emissions were estimated to be about 67 Gg N₂O N/yr. Emissions from the Great Plains states, which contain the largest expanse of natural grassland in the United States, were estimated to average 0.24 kg N₂O N/ha/yr. Using the annual flux estimate for the temperate Great Plains, we estimate that temperate grasslands worldwide may potentially produce 0.27 Tg N₂O N/yr. Even though our estimate for global temperate grassland N₂O emissions is less than published estimates for other major temperate and tropical biomes, our results indicate that temperate grasslands are a significant part of both United States and global atmospheric N₂O budgets. This study demonstrates the utility of models for regional N₂O flux estimation although additional data from carefully designed field studies is needed to further validate model results.     

近30年青海三江源西部干旱区草地退化特征的遥感分析

使用自20世纪70年代末~2004年的3期遥感图像(70sMSS、90sTM和2004年TM/ETM),研究了近30年青海三江源西部干旱区草地退化的格局与过程,结果表明:整个研究时段内,草地退化发生面积占总草地面积的10%左右,且以草地覆盖度轻度下降为主,其退化面积占总草地退化面积的80%以上,其次是轻度沙化/盐化,相应比重占10%以上。草地退化面积呈东南向西北减少趋势,退化程度呈东南向西北降低格局,而退化类型也由复合型向单一型过渡。整个时段内,草地退化面积呈增加趋势,尤其是沙化面积增加较快。不同海拔、坡度和坡向间草地退化面积差异显著。海拔4 800~5 100m范围内为草地退化发生的主要分布区,4 500~4 800m和5 100m以上草地退化基本相当。退化率较高的坡度级别介于2~8°之间,类似于草地面积随坡度变化的基本趋势。不同坡向呈阴坡、半阴半阳坡高于阳坡的态势。脆弱的基底、极端气候年际间周期波动等限制性因子控制着草地退化的基本格局,人为扰动则决定草地退化的强度和速度。总体看来,研究区地带性自然条件决定的荒漠化草地已占据主导地位,人类活动相对较弱,草地退化程度增加趋势不明显,新的草地退化现象不十分突出。     

关于对包头市达茂旗部分地区土地荒漠化退耕还草问题的浅析

本文介绍了包头市达茂旗部分土地植被生态系统由于逐渐退化为沙漠化已不适宜种植庄稼,加之该地区生蓄超载过数,草牧场沙化、退化严重的问题采取了改造措施,其目的使土地沙漠化问题得以解决。     

Plant biomass allocation strategies of the dominant species in an alpine meadow of northwestern Sichuan,China北大核心CSCD

Plant biomass partitioning is an important driver of whole-plant net carbon gain, as biomass allocation could directly affect plant's future growth and reproduction. Alpine meadow in the northwestern Sichuan was impressed by the abundant community structure and species diversity. This study on biomass allocation pattern of different functional types and lifeforms might help understand plant life-history strategy of alpine meadow plants. We investigated 72 dominant herbaceous species for their compartments, biomass, and morphological traits during 2012-2014. These plants were sampled from natural grassland, disturbed grassland, and wintergreen grassland; they belonged to three functional types (grass, sedge, and forb) and two lifeforms (annual and perennial). The scaling relationships between functional traits of these plants were analyzed using Model type II regression method to estimate the parameters of the allometric equations. (1) Biomass allocation proportion of components significantly differed among grasses, sedges, and forbs owing to phylogeny: grasses had the highest stem biomass percentage, sedges had higher root biomass percentage, and forbs had higher leaf biomass percentage, but the scaling relationships were not significantly different, and isometric scaling was noted between biomass components for the three functional types. (2) Moreover, plant lifeforms affected the biomass allocation proportion of components, owing to the shorter or longer turnover rate and investment strategy between annual and perennial species. Annuals allocated more biomass to the stem and reproduction organs, but perennials invested more biomass to the leaves and roots. (3) In addition, plants from different grassland types differed in both biomass and morphology traits. Moreover, forbs from natural grassland and wintergreen grassland had higher leaf and reproductive biomass, but those from disturbed grasslands had higher stem biomass. Our results suggest that the functional type and lifeform decide the inherent scaling relationships between components of plants, but anthropogenic disturbance significantly impacted the quantity of component biomass. This study has important theoretical and practical significance to understand the response of alpine plants to climate change and anthropogenic disturbance as well as to help in the scientific management of alpine meadow. © 2018 Science Press. All rights reserved.     

Habitat Change and Plant Demography: Assessing the Extinction Risk of a Formerly Common Grassland Perennial

Abstract:  An important aim of conservation biology is to understand how habitat change affects the dynamics and extinction risk of populations. We used matrix models to analyze the effect of habitat degradation on the demography of the declining perennial plant Trifolium montanum in 9 calcareous grasslands in Germany over 4 years and experimentally tested the effect of grassland management. Finite population growth rates (λ) decreased with light competition, measured as leaf-area index above T. montanum plants. At unmanaged sites λ was <1 due to lower recruitment and lower survival and flowering probability of large plants. Nevertheless, in stochastic simulations, extinction of unmanaged populations of 100 flowering plants was delayed for several decades. Clipping as a management technique rapidly increased population growth because of higher survival and flowering probability of large plants in managed than in unmanaged plots. Transition-matrix simulations from these plots indicated grazing or mowing every second year would be sufficient to ensure a growth rate ≥1 if conditions stayed the same. At frequently grazed sites, the finite growth rate was approximately 1 in most populations of T. montanum . In stochastic simulations, the extinction risk of even relatively small grazed populations was low, but about half the extant populations of T. montanum in central Germany are smaller than would be sufficient for a probability of survival of >95% over 100 years. We conclude that habitat change after cessation of management strongly reduces recruitment and survival of established individuals of this perennial plant. Nevertheless, our results suggest extinction processes may take a long time in perennial plants, resulting in an extinction debt. Even if management is frequent, many remnant populations of T. montanum may be at risk because of their small size, but even a slight increase in size could considerably reduce their extinction risk.     

公共资源可持续利用的微观影响因素分析

草地被称为世界性的公共资源。以往对于草地退化的关注多侧重在技术研究和推广上。为揭示微观行为对公共资源利用的影响,以寻求有效途径保护具有重要生态战略意义的草地资源,论文利用2005年西部6省区17县231个农户数据以及2006和2007年环青海湖地区的实地调查经验,采用农户模型和计量分析方法,研究现有产权制度下牧民的草地管理行为对草地资源退化的影响。结果表明,牧民参与非农就业、扩大牧户的草场规模以及进行围栏和舍棚建设有利于减轻草场的退化。据此,提出以下政策建议:目前政府提供围栏和舍棚建设方面的相关政策扶持,同时,制定有利于牧民参与非农就业机会的政策,降低牧区的人口压力,可有效促进草地公共资源的可持续利用。     

Spatial and Temporal Evaluation of Hydrological Response to Climate and Land Use Change in Three South Dakota Watersheds

This study analyzed changes in hydrology between two recent decades (1980s and 2010s) with the Soil and Water Assessment Tool (SWAT) in three representative watersheds in South Dakota: Bad River, Skunk Creek, and Upper Big Sioux River watersheds. Two SWAT models were created over two discrete time periods (1981‐1990 and 2005‐2014) for each watershed. National Land Cover Datasets 1992 and 2011 were, respectively, ingested into 1981‐1990 and 2005‐2014 models, along with corresponding weather data, to enable comparison of annual and seasonal runoff, soil water content, evapotranspiration (ET), water yield, and percolation between these two decades. Simulation results based on the calibrated models showed that surface runoff, soil water content, water yield, and percolation increased in all three watersheds. Elevated ET was also apparent, except in Skunk Creek watershed. Differences in annual water balance components appeared to follow changes in land use more closely than variation in precipitation amounts, although seasonal variation in precipitation was reflected in seasonal surface runoff. Subbasin‐scale spatial analyses revealed noticeable increases in water balance components mostly in downstream parts of Bad River and Skunk Creek watersheds, and the western part of Upper Big Sioux River watershed. Results presented in this study provide some insight into recent changes in hydrological processes in South Dakota watersheds. Editor's note: This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Responses of CH(4), CO(2) and N(2)O fluxes to increasing nitrogen deposition in alpine grassland of the Tianshan Mountains

To assess the effects of nitrogen (N) deposition on greenhouse gas (GHG) fluxes in alpine grassland of the Tianshan Mountains in central Asia, CH₄, CO₂ and N₂O fluxes were measured from June 2010 to May 2011. Nitrogen deposition tended to significantly increase CH₄ uptake, CO₂ and N₂O emissions at sites receiving N addition compared with those at site without N addition during the growing season, but no significant differences were found for all sites outside the growing season. Air temperature, soil temperature and water content were the important factors that influence CO₂ and N₂O emissions at year-round scale, indicating that increased temperature and precipitation in the future will exert greater impacts on CO₂ and N₂O emissions in the alpine grassland. In addition, plant coverage in July was also positively correlated with CO₂ and N₂O emissions under elevated N deposition rates. The present study will deepen our understanding of N deposition impacts on GHG balance in the alpine grassland ecosystem, and help us assess the global N effects, parameterize Earth System models and inform decision makers.     

环青海湖地区草地蝗虫发生的生态环境条件分析

为了有效地进行草地蝗虫的防治,必须摸清其生长和繁殖与生态环境条件的关系。研究表明,在环青海湖地区气温对草地蝗虫影响较为明显是在蝗卵越冬期和孵化期。降水量太多不利于草地蝗虫的发育,但降水适量因有利于蝗蝻出土可能会增加蝗虫基数。青海湖级湖成阶地和构造台地有利于蝗虫的繁育。土壤的温度、质地及水分和盐分含量对草地蝗虫的发生和繁育也有一定影响。