Alpine grassland ecosystem respiration variation under irrigation in Northern Tibet

Grassland ecosystems are important parts of terrestrial ecosystems and play an important role in the global carbon cycle. In recent years, the grasslands in Northern Tibet have experienced warming, and its precipitation has also increased. Alpine grassland irrigation measures could be a reasonable pathway to redistribute and make full use of the increased precipitation. In this study, we measured the soil respiration in alpine grassland in Northern Tibet under sprinkler head irrigation in the growing season to determine the relationships between soil temperature /water and ecosystem/soil respiration, soil moisture and Q₁₀, and soil temperature and Q₁₀. The results showed that after 2 years irrigation, alpine grassland aboveground biomass increased significantly, with 2010 higher than 2009. There was significant annual, seasonal and daily variation of soil respiration. Under irrigation, ecosystem respiration and soil respiration increased 75% and 64% respectively; soil water increase can promote the respiration of ecosystem and its components. In our results, the Q₁₀ value was 2.23–2.81, over the global average. The irrigation can promote ecosystem respiration temperature sensitivity. There was a positive linear correlation between ecosystem respiration and grassland aboveground biomass. The aboveground biomass accounted for 32.8% of ecosystem respiration variation. Soil respiration accounted for more than 70% of ecosystem respiration, indicating that the contribution to carbon emissions of soil respiration is very high. In short, we can project that in grasslands biomass and ecosystem respiration will increase under future precipitation change, which will significantly affect the function of alpine grassland carbon storage.     

藏北地区生态与环境敏感性评价

藏北地区自然条件极为严酷,生态与环境非常脆弱和敏感。采用地理信息系统手段与综合评价方法,对藏北地区主要生态与环境敏感性问题进行评估,分析了土壤侵蚀、沙漠化和草地退化等方面的敏感性空间分异规律,指出了今后生态与环境建设的优先区域。结果表明:藏北地区土壤侵蚀敏感区占土地总面积的42.5%,主要分布于东中部区域;藏北地区沙漠化敏感区面积较大(占土地总面积的78.8%),主要分布在人类活动强度相对较低的西北部;藏北中东部和北部地区草地退化较为严重,尤其是藏北地区冰川与雪山及其周围等气候变化较为敏感区域和交通要道沿线等人类活动较为频繁区域的草地退化相对严重,对草地退化也比较敏感,是今后草地退化治理和恢复的优先区。     

放牧对藏北紫花针茅高寒草原植物群落特征的影响

基于放牧试验,研究了不同放牧强度下藏北地区紫花针茅(Stipa purpurea)高寒草原植物群落特征的变化规律。结果表明,随着放牧强度的增强,植物群落盖度、地上生物量均呈现显著降低的趋势;紫花针茅等禾草类植物的重要值逐渐降低,莎草类中青藏苔草(Carex moorcroftii)、牲畜不喜食的杂类草及有毒有害植物均有增加的趋势;如果持续过度放牧,植物群落表现出由紫花针茅等禾草为建群种的草地型向青藏苔草(Carex moorcroftii)、杂类草(Herbarum variarum)草地型过度的趋势;在中度放牧强度下,紫花针茅高寒草原α物种多样性达到最高水平,而继续增强放牧强度,则造成各项指标的迅速降低。     

基于CASA模型的藏北地区草地植被净第一性生产力及其时空格局

基于1981-2004年遥感监测和气象数据,采用CASA(Carnegie-Ames-Stanford Approach)模型模拟分析藏北地区草地植被净第一性生产力(NPP)及其时空变化特征.结果表明:受水热条件的制约,藏北地区草地植被NPP空间分布规律呈水平地带性分布,由东南向西北逐渐由230g C.m-2.a-1减少到接近0.藏北地区草地植被NPP整体水平较低,年均草地植被总NPP为21.5×1012g C.a-1,多年平均值仅为48.1g C.m-2.a-1,明显低于青藏高原和其它草原区.藏北地区坡度小于1°平地和平滩地,以及南坡的草地植被年平均NPP相对较低.藏北主要高寒草地7-9月NPP占全年NPP的64.0%~70.0%.1981-2004年间,藏北地区草地植被总NPP的年际变化较大,并有进一步下降趋势.     

开展高寒退化生态系统恢复与重建技术研究,助力西藏生态安全屏障保护与建设

西藏是青藏高原的核心,是我国重要的生态安全屏障。由于高、寒、旱的特点,西藏高寒生态系统极为脆弱,在自然和人为因素影响下极易发生退化,治理难度大。草地退化和土地沙化治理一直是西藏生态安全屏障保护与建设的重中之重。为此,国家在"典型脆弱生态修复与保护研究"重点专项里启动了"西藏退化高寒生态系统恢复与重建技术及示范(2016YFC0502000)"项目,旨在研究生态系统演变规律和影响机理的基础上,针对西藏高原不同的退化区域,重点研发高寒退化草地恢复、沙化土地治理、生态产业及生态畜牧业发展等技术与模式,开展县域水平的集成示范,实现高寒生态系统功能的提升与适应性优化管理的目标,为西藏生态安全屏障保护与建设提供技术支撑。     

喷灌对藏北高寒草地生产力和物种多样性的影响

通过3a(2008—2010年)的藏北高寒草地喷灌试验,研究了不同喷灌量对草地群落生产力和物种多样性的影响。结果表明,丰水年灌溉对藏北高寒草地的影响较小;而在相对干旱年份灌溉对高寒草地生产力和物种多样性影响显著。喷灌条件下高寒草地生物量显著提高,最高增幅出现在高水(GS)样地中,达到116%。喷灌明显促进物种重要值提高,其中灌木和阔叶杂草比例增加趋势更为明显。不同喷灌条件下优势物种相对重要值均有不同程度的降低,高水处理降低幅度最大。物种多样性方面,喷灌措施能够明显促进高寒草地Simpson指数和Shannon-weiner指数增加(P0.05),E.Pielou均匀度指数无显著变化(P0.05)。Shannon-weiner指数与生物量之间存在显著正相关关系(P0.05)。未来降水增多的气候条件可以减少干旱对高寒草地带来的负面影响,有利于提高草地生产力和维持草地物种多样性,促进高寒草地畜牧业健康发展。     

西藏河谷地区人工种草的投入产出比较分析

分析了西藏河谷地区六种草地的经济投入、产出和生态系统服务价值,模拟了投入增加下村落草地利用结构的改变与经济、生态产出的响应。结果表明:草地恢复管理中,围栏草地成本最低,为67元/hm~2,是一年生人工刈割草地的0.9%。围栏等草地恢复管理的经济产出为772元/hm~2,其中补贴收入占14.6%,另85.4%来自打工收入;而多年生人工放牧和一年生人工刈割草地的经济产出为4250元/hm~2与13135元/hm~2。相比经济产出,不同草地管理方式下生态系统服务价值差距有限,最大仅为27%。草地投入增加下,天然放牧草地转变为围栏草地及一年生人工刈割草地,并最终保持约1∶1的面积比。合理配置围栏草地与一年生人工刈割草地,可以实现区域较大的经济收入增长和生态系统服务的保障。     

On the Relationship between Economic Development,Environmental Integrity and Well-Being: The Point of View of Herdsmen in Northern China Grassland

Inner Mongolia is among the most important regions in terms of contribution to the socio-economic development of China. Furthermore, its grassland is a major ecological barrier for Northern China. The present study evaluates the changes in ecosystem services availability and human wellbeing based on a survey on864 herdsmen of the grassland and 20 governmental officials. The survey provided the following results: (1) The supporting and provisioning services of the grassland have recently declined, thus affecting the herdsmen’s wellbeing. The intensity of grazing, coal exploitation and tourism development heavily limits the availability of ecosystem services, among which provisioning ones are perceived as the most important. Below a certain threshold, grazing and mining are likely to promote the improvement of herdsmen’s wellbeing, while trespassing that point, the enhancement of the herdsmen’s living standards is curbed. (2) The herdsmen’s cultural exchange, health conditions and social relations are better now than before; however, the threats on herdsmen’s health and safety have increased. (3) A better income is among the most urgent herdsmen’s needs. Livestock revenues did not increase at the same rate as the damage to the grassland and human risk exposure did. (4) The governmental ecological compensation policy did not entirely solve the problem of grassland desertification and environmental degradation, although it is also true that the degree of implementation and effectiveness of government policies is related to the still insufficient herdsmen’s understanding and acceptance of these policies.     

青藏高寒区退化草地生态恢复:退化现状、恢复措施、效应与展望

青藏高寒区属于独特而典型的高原生态系统,草地生态系统作为其重要组成部分,在对高寒区生态安全以及农牧民生计的维系中,占有举足轻重的地位。目前,青藏高寒区的草地生态系统退化严重,因此该区退化草地的生态恢复工作是国家生态工作的重中之重。近年来,已有大量研究提出了各种有效的恢复手段,但缺乏因地制宜的系统性总结和论述。基于此,在已有研究的基础上,阐述了青藏高寒区退化草地现状,总结了高寒区各生态类型分区的主要生态问题,明确了不同集成技术与模式的适用区域和范围,同时对这些技术、措施和模式的恢复效果和恢复机制进行分析和讨论。并对未来高寒草地生态系统的研究进行了展望,以期为青藏高寒区退化草地的恢复治理、高寒草地生态系统结构和功能稳定性维系提供系统的理论基础与技术支撑。     

The study of chalk grassland in Northern France An historical review

The study of chalk grassland in Northern France has evolved through three main phases. During the period from the early 19th century to the First World War, the general flora of Northern France was studied in some detail, but there was little ecological understanding of plant communities. Some workers, however, did attempt to group chalk grassland species ecologically, and the primitive concepts of plant sociology unconsciously developed. Between the wars, with the growth of plant sociology, chalk grassland studies became more elaborate. Specific associations were now described and the wider aspects of chalk grassland phytogeography considered. The post-war period has seen a great increase in botanical activity in Northern France. There have been many regional chalk grassland studies, all of which, in varying degrees, have employed the techniques of plant sociology. It may at last be possible to synthesise these studies, and to describe the chalk grassland associations of Northern France.     

The study of chalk grassland in Northern France An historical review

The study of chalk grassland in Northern France has evolved through three main phases. During the period from the early 19th century to the First World War, the general flora of Northern France was studied in some detail, but there was little ecological understanding of plant communities. Some workers, however, did attempt to group chalk grassland species ecologically, and the primitive concepts of plant sociology unconsciously developed. Between the wars, with the growth of plant sociology, chalk grassland studies became more elaborate. Specific associations were now described and the wider aspects of chalk grassland phytogeography considered. The post-war period has seen a great increase in botanical activity in Northern France. There have been many regional chalk grassland studies, all of which, in varying degrees, have employed the techniques of plant sociology. It may at last be possible to synthesise these studies, and to describe the chalk grassland associations of Northern France.     

The study of chalk grassland in Northern France: An historical review

The study of chalk grassland in Northern France has evolved through three main phases. During the period from the early 19th century to the First World War, the general flora of Northern France was studied in some detail, but there was little ecological understanding of plant communities. Some workers, however, did attempt to group chalk grassland species ecologically, and the primitive concepts of plant sociology unconsciously developed. Between the wars, with the growth of plant sociology, chalk grassland studies became more elaborate. Specific associations were now described and the wider aspects of chalk grassland phytogeography considered. The post-war period has seen a great increase in botanical activity in Northern France. There have been many regional chalk grassland studies, all of which, in varying degrees, have employed the techniques of plant sociology. It may at last be possible to synthesise these studies, and to describe the chalk grassland associations of Northern France.     

基于草地生态系统服务认知的牧民生计选择——以新疆喀拉峻天山世界自然遗产地为例

牧民对草地生态系统服务的重要性认知成为推动牧区生态环境保护以及牧民生计可持续发展的重要前提。以喀拉峻180份牧户实地调研数据为基础，在分析牧民对草地生态系统服务的认知程度和生计选择的基础上，运用灰色关联分析探究生态认知与生计选择的总体关联性，并采用多元Logistic模型探究生态系统服务认知对生计选择的具体影响。结果显示：（1）生态系统服务认知水平依次为调节服务（79.83%） > 支持服务（78.21%） > 文化服务（77.06%），且对气体调节的认知度最高（82.67%），对科研教育的认知度最低（72.11%）；（2）生态系统服务认知与生计选择的总体关联度均在0.47以上，处于中等关联水平；3）生态系统服务认知对选择旅游畜牧兼业生计影响相对显著，其中气体调节和土壤保持正向影响旅游畜牧兼业生计选择，而废物处理对其产生负向影响。     

Changes of soil organic and inorganic carbon in relation to grassland degradation in Northern Tibet

The effect of livestock grazing on grassland degradation and the resulting impact on soil carbon concentration is an important factor in carbon estimation. We addressed this issue using field observations and laboratory analysis of samples from Tibetan grassland. Based on the field measurements, we investigated the soil organic carbon (SOC) and soil inorganic carbon (SIC) under two contrasting degradation states: lightly or non-degraded grasslands (LDG) and heavily degraded grasslands (HDG). We assessed their relationships with environmental factors using data collected from 99 sites across Northern Tibet during 2011–2012. Data were analyzed using a linear mixed-effects model and one-way ANOVA. The results showed that: (1) SOC concentration decreased and SIC concentration increased following grassland degradation, especially at soil depths in the range of 0–10 cm (P < 0.05); (2) the major environmental factors affecting SOC and SIC were soil pH and plant biomass; (3) spatially, the SOC density increased with the mean annual temperature and mean annual precipitation, whereas SIC exhibited the opposite trend; (4) the SOC density increased at first and then decreased with increasing grazing intensity, with an opposite trend in SIC; and (5) soil carbon storage in this region was 0.14 Pg smaller in the HDG than in the LDG. This study suggests that grassland degradation can significantly affect the vertical distribution and storage of SOC and SIC. The carbon sequestration capacity of the top 100 cm of soil in Northern Tibet was estimated as 0.14 Pg.     

内蒙古典型草原生态系统定位研究最新进展

中国科学院内蒙古草原生态系统定位研究站最近几年在草原生态系统多功能、草原生态系统碳循环与温室气体、气候变化对植物群落结构影响长期观测、草原生态系统退化与恢复过程、草原生态系统硫生物地球化学循环、放牧生态系统管理等领域取得较大进展。研究结果指出,农垦活动使有机碳损失34%,草原植被——土壤系统是甲烷的弱汇;20多年来,这一地区气候变化有变暖趋势,冬季增温明显,春季干旱进一步加剧,影响初级生产力生产;系统提出草原退化是草原生态系统退化,并对退化阶段进行了划分;在内蒙古冷蒿小禾草退化草原施用硫肥对提高初级生产力与羊毛性能方面有明显效果。     

内蒙古典型草原生态系统定位研究最新进展

中国科学院内蒙古草原生态系统定位研究站最近几年在草原生态系统多功能、草原生态系统碳循环与温室气体、气候变化对植物群落结构影响长期观测、草原生态系统退化与恢复过程、草原生态系统硫生物地球化学循环、放牧生态系统管理等领域取得较大进展。研究结果指出,农垦活动使有机碳损失34％,草原植被——土壤系统是甲烷的弱汇;20多年来,这一地区气候变化有变暖趋势,冬季增温明显,春季干旱进一步加剧,影响初级生产力生产;系统提出草原退化是草原生态系统退化,并对退化阶段进行了划分;在内蒙古冷蒿小禾草退化草原施用硫肥对提高初级生产力与羊毛性能方面有明显效果。     

青藏高原地区生态资产核算研究——以西藏自治区山南市为例

生态资产是重要的自然资源资产,也是优质生态产品提供的基础,生态资产的变化趋势可作为衡量生态保护和恢复成效的重要指标。山南市拥有青藏高原地区各种生态资产类型,以山南市为例开展生态资产核算可为青藏高原地区生态资产评估与保护提供参考。以生态资产数量、质量和生态资产指数为主要指标,揭示山南市2000-2015年生态资产的变化趋势及影响因素。结果表明：（1）2015年山南市生态资产以草地和森林为主,分别占生态资产总面积的40.6%和35.8%;但质量不高,优、良等级比例仅占11.8%和12.0%;生态资产综合指数为38.26,草地、森林、灌丛和湿地生态资产指数分别为16.23、14.88、5.37和1.78;（2）2000-2015年,山南市生态资产面积总体变化不大,森林和荒漠生态资产分别增加50.2 km²和43.9 km²,但湿地、农田、草地、灌丛、冰川生态资产面积分别减少97.4、29.8、2.9、2.7、0.3 km²;生态资产质量明显提升,优级和良级生态资产增幅分别为40.5%和108.5%;生态资产指数增加了16.1%;（3）退耕还林还草等生态保护和修复政策、城镇扩张以及气候变化等是山南市生态资产变化的主要因素。     

草地退化影响高原鼠兔血清总IgG水平、肠道寄生物感染及肝脏和肾脏指数

高原鼠兔 (Ochotona curzoniae) 作为青藏高原高寒草地生态系统中的关键物种,其种群数量随着过度放牧导致的草地退化而暴发式增长。阐明此过程中高原鼠兔天然免疫能力及肝脏和肾脏器官指数的变化,对深入揭示青藏高原草地退化引起的高原鼠兔种群暴发机理具有重要意义。本研究在青海海北高寒草地生态系统国家野外科学观测研究站地区,调查了轻度、中度、重度退化草地中高原鼠兔洞口数量,并测定了成体高原鼠兔血清总IgG含量、肠道寄生物感染状况及肝脏和肾脏指数。结果发现：随着草地退化,高原鼠兔洞口数量和血清总IgG水平显著增加;绦虫和线虫的感染率和感染强度以及肝脏和肾脏指数均显著降低。雄性对绦虫的感染率和肝脏指数显著低于雌性;雌性在重度退化草地中对绦虫和线虫的感染率及感染强度显著低于轻度退化草地。以上结果表明,过度放牧介导的草地退化增强了高原鼠兔的天然免疫功能,缓解了毒素对肝脏和肾脏的损伤,进而可能促进其种群暴发式增长。     

阴山北麓农牧交错区退耕地草地生态系统碳交换及水分利用效率

内蒙古阴山北麓农牧交错区由于长期不合理的开垦造成了荒漠草地生态系统碳交换等生态功能的显著丧失。我国20世纪末开始实施的退耕还林还草工程产生了大量退耕地,随着自然恢复演替,这些退耕地的生态功能得到了有效的修复,其巨大的碳汇潜力成为了荒漠草地生态系统碳循环研究的热点。研究通过空间代替时间的方法,对内蒙古阴山北麓典型区域——武川县周边无干扰的荒漠草原以及3个退耕恢复阶段草地的生态系统CO₂交换(NEE、GEP和ER)、水分利用效率(WUE)以及生物量等指标进行了实地测量。结果表明：(1)随着退耕恢复演替时间的推移,生态系统CO₂交换呈显著上升趋势,演替晚期植被NEE与未受干扰的荒漠草地无明显差异;(2)生态系统水分利用效率的变化趋势与生态系统CO₂交换基本一致,但已退耕17年后的退耕地WUE仍没有恢复至未受干扰荒漠草地的水平;(3)导致以上结果的原因主要与退耕地地上植被生物量的恢复以及一、二年生植物和多年生植物比例的演替变化有关。结果表明荒漠草地退耕地恢复过程中生态系统功能的恢复可能并非是同时的,而是分阶段有选择进行的。     

西藏草地多项供给及调节服务相互作用的时空演变规律

基于统计数据及MODIS产品,计算西藏草地2000与2010年载畜支持服务、肉类供给服务、水源涵养服务和碳吸收服务的功能量。构建Pearson相关系数、总生态系统服务(TES)、供给-调节服务互竞指数(TO),分析了4项生态系统服务相互作用关系随纬度、海拔及时间变化的规律。结果表明:西藏草地两项供给服务和两项调节服务之间分别为相互协同作用,且随时空变化不大。供给服务和调节服务之间的相互作用随海拔和纬度升高时,基本由相互竞争转变为相互协同,在高纬度时则无相互作用。4项服务在低纬度及低海拔呈相互竞争关系时,其生态系统服务总体水平也较低,中纬度及中高海拔呈协同关系时,其总体水平较高。从2000年到2010年,西藏草地4项生态系统服务皆发生较大变化。在变化中,12%的草地供给服务与调节服务发生相互竞争作用,33%的草地则为相互协同关系。发生相互竞争作用的草地主要集中在中低纬度的一江两河地区,而相互协同的区域主要为藏北羌塘高原中南部。