Spatiotemporal variations in ecological quality of Otindag Sandy Land based on a new modified remote sensing ecological index

Otindag Sandy Land in China is an important ecological barrier to Beijing;the changes in its ecological quality are major concerns for sustainable development and planning of this area.Based on principal component analysis and path analysis,we first generated a modified remote sensing ecological index(MRSEI)coupled with satellite and ground observational data during 2001–2020 that integrated four local indicators(greenness,wetness,and heatness that reflect vegetation status,water,and heat conditions,respectively,as well as soil erosion).Then,we assessed the ecological quality in Otindag Sandy Land during 2001–2020 based on the MRSEI at different time scales(i.e.,the whole year,growing season,and non-growing season).MRSEI generally increased with an upward rate of 0.006/a during 2001–2020,with clear seasonal and spatial variations.Ecological quality was significantly improved in most regions of Otindag Sandy Land but degraded in the southern part.Regions with ecological degradation expanded to 18.64%of the total area in the non-growing season.The area with the worst grade of MRSEI shrunk by 15.83%of the total area from 2001 to 2020,while the area with the best grade of MRSEI increased by 9.77%of the total area.The temporal heterogeneity of ecological conditions indicated that the improvement process of ecological quality in the growing season may be interrupted or deteriorated in the following non-growing season.The implementation of ecological restoration measures in Otindag Sandy Land should not ignore the seasonal characteristics and spatial heterogeneity of local ecological quality.The results can explore the effectiveness of ecological restoration and provide scientific guides on sustainable development measures for drylands.

Scale dependence of plant species richness and vegetation-environment relationship along a gradient of dune stabilization in Horqin Sandy Land, Northern China

Ecological patterns and processes in dune ecosystems have been a research focus in recent years, however the information on how dune stabilization influences the spatial scale dependence of plant diversity is still lacking. In this study, we measured the plant species richness, soil properties and altitude across four spatial scales （1, 10, 100 and 1,000 m2） at three different dune stabilization stages （mobile dune, semi-fixed dune and fixed dune） in Horqin Sandy Land, Northern China. We also examined the relationships between plant species richness, community composition and environmental factors along the gradient of dune stabilization. Our results showed that plant species richness increased with the increase of spatial scales in each dune stabilization stage, as well as with the increase of dune stabilization degrees. Canonical correspondence analysis （CCA） showed that plant distribu- tions in the processes of dune stabilization were determined by the combined environmental gradient in relation to soil organic carbon （SOC）, total nitrogen （TN）, carbon/nitrogen （C/N）, pH, electrical conductivity （EC）, soil water content （SWC）, fine sand （FS）, very fine sand （VFS）, silt and clay （SC）, and altitude. Plant species richness was significantly and positively correlated to SOC and TN in mobile dune, and significantly and positively correlated to SOC, TN, C/N, VFS and SC in semi-fixed dune. However, no significant correlation between plant species richness and environmental factors was observed in fixed dune. In addition, plant species richness in different dune stabili- zation stages was also determined by the combined gradient of soil properties and altitude. These results suggest that plant species richness has obvious scale dependence along the gradient of dune stabilization. Soil resources depending on dune habitats and environmental gradients caused by dune stabilization are important factors to de- termine the scale dependence of species diversity in sand dune ecosystems.

Comparison of foliar nutrient concentrations between natural and artificial forests of Pinus sylvestris var. mongolica on sandy land, China

In order to examine the causes of degradation of Pinus sylvestris var. mongolica plantations on sandy land, the foliar concentrations of N, P, K and C were analyzed and compared between the field grown P. sylvestris var. mongolica trees from two provenances （natural forests and plantations）. The results indicated that natural tree needles had lower N, P and C concentrations, and higher K concentrations than those of plantation tree needles. For plantation tree needles, ratios of N： P, P. K and N： K increased with tree age before 45 years old; but they were not clear for the natural tree needles. Compared with the conclusions reported on Pinus spp., we found that the foliar N and P concentrations were in the optimal range for both natural and plantation tree needles. This result suggested that N or P might not be the absolute limit factors in plant nutrient for P sylvestris var. mongolica on sandy land. However, foliar K concentrations in both natural and plantation tree needles were much lower than those reported on Pinus spp. （〉4.80 g kg-1）.The N： P ratio of natural needles was in the adequate ranges, but N： P ratio of plantation needles was out of the adequate ranges. These results indicated that there was a better balanced nutrition status in the natural forest than in the plantations. If only considering the foliar nutrient concentrations of P sylvestris var. mongolica from different provenances, it might be concluded that the degradation phenomenon of P. sylvestris var. mongolica plantations was not induced by nutrition deficiency of absolute nutrients of N and P, but might be induced by other mineral nutrients or by the effectiveness of N and P nutrients. The unbalanced nutrition status and relatively quick decomposition of needles in the plantations might also contribute to the degradation.

Changes in Ecosystem Service of Soil Conservation Between 2000 and 2010 and Its Driving Factors in Southwestern China

Human activities significantly alter ecosystems and their services; however, quantifying the impact of human activities on ecosystems has been a great challenge in ecosystem management. We used the Universal Soil Loss Equation and county-level socioeconomic data to assess the changes in the ecosystem service of soil conservation between 2000 and 2010, and to analyze its spatial characteristics and driving factors in the southwestern China. The results showed that cropland in the southwestern China decreased by 3.74%, while urban land, forest, and grassland areas increased by 46.78%, 0.86%, and 1.12%, respectively. The soil conservation increased by 1.88 × 10^(11) kg, with deterioration only in some local areas. The improved and the degraded areas accounted for 6.41% and 2.44% of the total land area, respectively. Implementation of the Sloping Land Conversion Program and urbanization explained 57.80% and 23.90% of the variation in the soil conservation change, respectively, and were found to be the main factors enhancing soil conservation. The 2008 Wenchuan earthquake was one of the factors that led to the degradation of soil conservation. Furthermore, industrial adjustment, by increasing shares of Industry and Service and reducing those of Agriculture, has also promoted soil conservation. Our results quantitatively showed and emphasized the contributions to soil conservation improvement made by implementing ecological restoration programs and promoting urbanization. Consequently, these results provide basic information to improve our understanding of the effects of ecological restoration programs, and help guide future sustainable urban development and regional industrial restructuring.

毛乌素沙地黑沙蒿群落多尺度呼吸的季节动态和影响因素

【目的】比较不同观测尺度呼吸对环境因素的响应,特别是对温度和水分的响应,理解多尺度呼吸作用的影响机制,以期提升跨观测尺度呼吸模型模拟精度。【方法】在宁夏盐池选取典型黑沙蒿群落,于2022年5—10月,在固定样地原位连续监测黑沙蒿叶片、土壤与生态系统呼吸速率(即Rl、Rs与Re),拟合呼吸与温度、水分之间的关系,了解多尺度呼吸的季节动态特征及其环境影响因素。【结果】(1)观测期内,Rl主要受温度调控(R^(2)为63.5%),温度敏感性(Q10)为1.48,Rl日均值最大为5.96μmol/(m^(2)·s),出现在7月;Rs和Re季节变化均受水分调控(R2分别为44.4%和50.9%),Q10分别为1.23和1.08,Rs和Re最大日均值均出现在8月,分别为2.94μmol/(m^(2)·s)和4.07μmol/(m^(2)·s)。(2)温度–水分双变量经验模型对Rl、Rs和Re的解释能力相较于单变量模型提升程度有限,平均R2分别增加了0.09、0.05和0.02。(3)水分条件是不同观测尺度呼吸温度敏感性是否趋于一致的关键因素。当土壤水分条件较差时(相对土壤含水量WRE<0.4时),Rl、Rs和Re对温度的响应有显著差异,Q10分别为1.34、0.63和0.84;当土壤水分条件较好时(WRE≥0.4),Rl、Rs和Re对温度的响应趋于一致,Q10约1.8。【结论】不同观测尺度呼吸季节变化的调控因素存在差异,而双变量模型对提升不同观测尺度呼吸模拟的精确性作用有限,充分考虑不同观测尺度以及同尺度水分条件的差异是未来准确模拟干旱或半干旱地区呼吸作用的关键。

山水林田湖草沙一体化保护和修复工程对荆州市生态系统服务价值和稀缺价值的影响

以荆州市为研究区域,利用荆州市2021年相关数据计算和分析了荆州市生态系统服务价值(ESV)和生态系统服务稀缺价值(ESSV)指标,并运用地理信息图谱、景观格局指数、冷热点分析法、供给和需求弹性指数等方法评估和揭示ESV和ESSV的时空异质性变化及其原因和机制。结果表明,土地利用变化主要集中于耕地转变为林地或草地,未利用地转变为水域或其他类型,林地或草地转变为建设用地。各类型土地的多样性和均衡性均提高,山水林田湖草沙一体化保护和修复工程(SLCP)的综合治理和协调发展等措施的效果取得一定成效。ESSV在空间上呈现出由东部向西部递增的分布特征,且在空间上呈现出明显的聚集特征。

江西省兴国县矿山生态修复对生态系统服务影响研究

本文以兴国县和兴国县矿山生态修复区为研究对象,基于GIS空间分析技术,建立生态系统服务物质量评估模型,评估兴国县和兴国县矿山生态修复区2019年和2021年生态系统服务物质量,探讨矿山修复区修复前后土地利用类型变化对生态系统服务的影响。研究结果显示:兴国县2021年五项生态系统服务较2019年有所下降;从空间分布上看,粮食生产服务分布广泛,高低值分布较为零散,水源涵养服务高值集中于兴国县北部和东北部,土壤保持服务高值较少,分布于兴国县中南部,固碳服务与释氧服务高值则集中于兴国县中部;兴国县矿山生态修复区修复后采矿用地转为耕地与林地,区域内粮食生产量增加了6.17 t,固碳量增加了246992.43 t·C,释氧量增加了187892.85 t·O_(2),土壤保持量增加了5.79 t,水源涵养量减少了3.913×10^(7)m^(3)。研究表明矿山生态修复区的生态修复工程很大程度上导致了土地利用现状发生变化,从而影响区域内的生态环境。耕地、林地对区域生态系统服务贡献显著。

基于LUCC视角山水林田湖草沙一体化保护和修复工程对生态系统服务价值的影响

山水林田湖草沙一体化保护和修复工程对于提升生态环境质量、实现新时代生态文明目标具有重要作用,定量化测算其带来的生态效益逐渐成为该研究的难点和热点。因此,以临沂市山水工程重点项目区为研究区域,基于土地利用变化,建立价值评估方法并探索山水工程实施对于生态系统服务价值影响。2020—2023年,研究区域生态系统服务价值总量分别为121.3517亿元和123.4418亿元,总体上升了2.0901亿元,耕地面积较大,导致其生态系统服务价值在总量中的占比也较高,但是林地和水域以较小的面积,却贡献了约50%的生态系统服务价值,林地和水域面积的变动会较大影响区域总体的生态系统服务价值。本研究对山水工程生态绩效评估,建立生态保护长效机制,持续提升生态系统服务具有借鉴价值。

多源数据视角下生态修复与气候变化对渤海湾北岸典型盐碱化地生态系统韧性影响研究

滨海盐碱地(包括滩涂和盐碱土)作为海陆交错的重要生态过渡区和储备地,在维护中国东部沿海区域的生态环境平衡和保护农业生产方面发挥着关键作用。以渤海湾北岸典型的盐碱化地块为案例,基于多源地面观测数据,总结土壤本底状况和盐碱化情况,并量化人工生态修复和气候变化对该地块生态系统韧性的影响。研究结果表明,该区域的土壤盐碱化程度偏高,其中碱化土壤主要分布在陆地,盐碱化土壤则主要分布在近海区域。通过整合多源遥感数据、数字高程模型、再分析气候数据、国际土壤分层数据和土壤盐碱预测数据等,构建丰富的地球观测数据集,显示出对滨海盐碱地生态系统韧性评估具有潜在应用价值。进一步分析显示,该地区的生态系统稳定性受到土地利用变化历史和气候变化进程的协同调控。过去40年中多次土地覆盖和利用类型的显著变化明显削弱了该地块的植被生态系统韧性,导致近年开展的生态修复工程效果有限。此表现为修复后的植被呈中等丰度的灌草丛为主(NDVI约0.64),而未修复前则为高丰度植被状态(NDVI约0.74)。与此同时,与气候变化相关的极端气候事件(如洪涝和干旱)显著削弱了人工修复植被的生存能力(NDVI降至0.30),进而延缓了该地块的自然恢复进程。研究结果为滨海盐碱地的科学保护与可持续利用提供了重要的技术支撑。

Soil Inorganic Nitrogen and Microbial Biomass Carbon and Nitrogen Under Pine Plantations in Zhanggutai Sandy Soil

The dynamics of soil inorganic nitrogen （NH4^＋ -N and NO3^- -N） and microbial biomass carbon （Cmic） and nitrogen （Nmic） under 30-year-old fenced Pinus sylvestris L. var. mongolica Litvin （SF）, unfenced P. sylvestris L. var. mongolica Litvin （SUF）, and unfenced Pinus densiflora Siebold et Zucc. （DUF） plantations in the Zhanggutai sandy soil of China were studied during Apr. to Oct. 2004 by the in situ closed-top core incubation method. All mentioned C and N indices in each stand type fluctuated over time. The ranges of inorganic N, Cmic, and Nmic contents in the three stand types were 0.7-2.6, 40.0-128.9, and 5.4-15.2 μg g^-1, respectively. The average contents of soil NH4^＋ -N and Cmic under the three 30-year-old pine plantations were not different. However, soil NO3^ -N and total inorganic N contents decreased in the order of SUF ≥ SF ≥ DUF, the Nmic content was in the order of SF = SUF 〉 DUF, and the Cmic：Nmic ratio was in the order of SUF = DUF 〉 SF. Seasonal variations were observed in soil inorganic N, microbial biomass, and plant growth. These seasonal variations had certain correlations with microbe and plant N use in the soil, and their competition for NH4^＋ -N was mostly regulated by soil N availability. The influence of tree species on inorganic N and Nmic were mainly because of differences in litter quality. Lack of gazing decreased the Cmic：Nmic ratio owing to decreased carbon output and increased the ability of soil to supply N. The soil N supply under the P. sylvestris var. mongolica plantation was lower than under the P. densiflora plantation.

基于水-陆耦合生态系统服务的生态安全格局构建研究——以长三角生态绿色一体化发展示范区为例

快速城市化和国土空间规划大背景下,评估区域生态系统服务、构建生态安全格局是实现城市精细化发展的有效手段。本研究立足生态系统服务供给效能,以长三角生态绿色一体化发展示范区为例,从陆域、水域两个层面进行量化计算,构建水-陆耦合生态系统服务综合评价体系,将高供给区域识别为生态源地,并基于MCR模型和电路理论分别提取廊道和节点,构建区域生态安全格局。研究结果表明:1)分别识别陆域和水域生境斑块面积34.31km^(2)、272.50km^(2),为江南水乡空间存续和城市绿地空间选址提供了理论依据;2)水-陆耦合度评价得到源地41个,总面积206.79km^(2),占研究区总面积8.57%,呈现“西北多东南少”的格局;3)提取89条生态廊道和91个生态节点,生态廊道总长度586.35km,呈均匀网状分布,节点包括44个夹点及47个障碍点,主要位于吴江区。通过区域生态安全格局的构建与优先级评价,分级提出国土空间生态保护与修复建议,为我国其他快速城市化地区及都市圈周边区域的国土空间合理布局、土地利用的转化与管理提供参考。

近30年东北沙地生态系统服务动态

东北沙地位于北方农牧交错带,揭示该区长时间序列生态系统服务功能时空演化特征,可为沙地生态恢复与水土保持提供科学依据。基于InVEST模型,对1990—2020年该区土壤保持、水源涵养、碳储存量和生境质量功能进行评估。结果表明:1)东北沙地土壤保持总量呈现波动增加的变化趋势,增幅0.198亿t/a,高值区集中于科尔沁沙地的西南地区、松嫩沙地的东部和西部以及呼伦贝尔沙地的东部;2)水源涵养量总体呈现增加趋势,高值区集中于科尔沁沙地东南部、松嫩沙地东北部和呼伦贝尔沙地的东部;3)碳储存量呈增加趋势,增幅0.016亿t/a,高值区主要分布于科尔沁沙地东北部、松嫩沙地的东部、西部和呼伦贝尔沙地的东部;4)平均生境质量指数总体变化不大,呈现先上升后下降趋势,高值区域集中于松嫩沙地东部和西部、呼伦贝尔沙地的东部。东北沙地土壤保持、水源涵养、碳储存量和生境质量4大生态系统服务功能总体呈现增加趋势,增加的区域在空间上表现一定聚集性。

成都环城生态公园土地综合整治与生态修复对生态系统生产总值(GEP)的影响

成都是中国“公园城市”首提地和国家先行示范区,研究其大型城市公园建设与管理成效意义重大。论文以成都市环城生态公园为对象,开展2020和2021年生态系统生产总值(GEP)核算,探析全域土地整治与生态修复工程建设对GEP的影响。结果表明,城市公园土地整治与生态修复会改变生态系统组成与景观格局,短期内造成物质产品价值略有增加、调节服务价值略有降低,而文化服务价值快速增加。基于环城生态公园GEP构成特征和城市特色,提出生态产品价值实现与转化策略。

林型和林龄对嫩江沙地人工林生态系统碳储量影响规律研究

【目的】揭示林型和林龄对温带半干旱地区嫩江流域固沙人工林生态系统碳储量的影响规律及机制,为沙地人工林碳汇管理实践提供科学依据。【方法】采用相对生长方程、碳氮分析仪测定法,同步估算具有幼龄林、中龄林、成熟林年龄序列的11、30、45年生樟子松和6、15、26年生小黑杨2种人工林,以及28年生天然榆树疏林的生态系统碳储量(植被和土壤)、植被年净固碳量及其相关环境因子(土壤含水率、有机质、全氮等),确定林型和林龄对沙地人工林生态系统碳储量影响效果。【结果】(1)在植被固碳方面,樟子松和杨树人工林均强于天然榆树疏林,尤以樟子松人工林为最佳;且樟子松、杨树人工林的植被碳储量均随林龄而递增,但两者植被年净固碳量随林龄变化规律却不同,前者为幼龄林>中龄林=成熟林,后者随林龄而递增。(2)在土壤固碳方面,杨树人工林优于天然榆树疏林,而樟子松人工林却不及天然榆树疏林;且樟子松、杨树人工林土壤碳储量随林龄的变化规律也不同,分别为先增后稳型和递增型。两者的土壤碳储量的空间分布格局也被改变,在水平空间上,前者降低了上、下部土壤层的碳储量,且在上部土壤层碳储量随林龄增强;后者增加了中上部土壤层碳储量,且在底部土壤层碳储量随林龄增强;在垂直空间上,两者幼龄林土壤碳储量垂直分层明显,至成熟林趋于弱化;(3)在生态系统固碳方面,樟子松和杨树人工林相近且均强于天然榆树疏林;樟子松和杨树人工林生态系统碳储量均随林龄而递增,但其分配格局多以植被碳储量占优势,明显不同于以土壤占优势的天然榆树疏林;(4)樟子松人工林生态系统碳储量与植被年净固碳量主要受土壤全氮所控制,而杨树人工林生态系统碳储量与植被年净固碳量主要受土壤有机质所控制。【结论】在我国温带半干旱地区流动沙丘上营造樟子松和杨树人工林不仅能够固沙而且能够增加森林碳汇,且以植被固碳占优势,故在沙地人工林碳汇管理实践中既要加强对植被碳库的维持,也要注重其土壤碳库长期固碳潜力的发挥。

基于生态系统服务供需的国土生态修复分区探讨

以抚松县为研究区,在计算生态系统服务供需量基础上,运用双变量局部空间自相关模型和供需协调度分析了生态系统服务供需空间聚集程度及协调关联性,并划分了生态修复区.结果表明:(1)抚松县各乡镇生态系统服务供给和需求空间分异明显,北部生态系统服务供给量较高、中部较低;需求量则呈环状由中心向四周递减.(2)生态系统服务供需匹配呈现低供高需、低供低需和高供低需3种类型且生态系统服务供需协调度平均值为0.2647,处于基本平衡.(3)结合生态系统服务供需匹配类型和协调度,将抚松县划分为3个一级国土生态修复区和7个二级国土生态修复区.分区结果符合实际社会经济生态现状,可为抚松县生态修复总体布局和分区修复策略提供参考.

基于自然的陆海统筹生态修复途径——以北海滨海国家湿地公园为例

北海滨海国家湿地公园是我国南部沿海“库塘—河流—近海”复合湿地生态系统的典型代表,而不合理的人类活动导致其所在流域及北部湾海域生态系统受损。通过水产养殖塘的海绵化改造及淡水、咸淡水、咸水三类生境的生态修复,降低流域生态风险;并通过提供游憩服务,推动生态产品价值实现。采用基于自然的陆海统筹生态修复途径恢复本地生态系统,为滨海地区流域生态治理提供参考。

The net ecosystem services value in China's Mainland

Protection of the ecological environment is an effective strategy for maintaining ecosystem health,improving provision of ecosystem services,and increasing human well-being.However,traditional calculations of the value of ecosystem services(VES)provide weak guidance because they ignore the costs of these services,leading to economically inefficient strategies.To understand the difference between VES and the net ecosystem services value(NES,after subtracting costs from VES)and to improve evaluations of ecosystem services,we estimated NES for China's Mainland(including farmland,grassland,forest,and wetland).NES totaled 10.0×10~3RMB ha^(-1)yr^(-1)in 2014,which is only 35.1%of the corresponding VES.Grassland NES was–0.7×10~3RMB ha^(-1)yr^(-1),in contrast with a positive grassland VES.NES of farmland,grassland,forest,and wetland in2014 totaled 7.2×10^(12)RMB,accounting for 27.0%of China’s GNP.Recent Chinese planning based on VES emphasizes forest conservation and ignores the conservation of other important ecosystems,such as grassland,leading to a continuing loss of China’s natural capital.Due to regional differences in economic conditions,resource endowments,and geographical characteristics,VES and NES differ among regions.To maximize the ecological benefits from conservation,it is necessary to account for these differences by comparing strategies based on NES,thereby choosing projects that maximize both economic and ecological benefits.To maintain the ecological balance,ecological restoration and socioeconomic activities should account for the costs of providing ecosystem services.This is essential to minimize the costs and maximize the benefits of projects.

国土整治与生态修复中面临的问题及解决对策

人类社会生产生活对国土空间与生态环境产生了极大的影响,并且人类经济活动的扩张,致使生态系统消耗过大,自然恢复能力受损,生态环境破坏严重影响了物种的多样性,再加上生态保护与修复跟进滞后,增加了国土整治与生态修复的紧迫性和严峻性。国土整治与生态修复是保护生态环境、改善提升生态功能的重要措施。基于此,对国土整治与生态修复存在的问题进行分析,并就问题提出相应的解决对策。

浑善达克退化沙地草地生态恢复试验研究

选择草地退化十分严重的浑善达克沙地腹地开展恢复生态学研究 ,试图寻求沙地草地生态恢复的新途径。采取“以地养地”模式 ,在小范围的土地上 ,建立高产饲草基地 ,使牲畜的压力逐步向高效地集中 ,同时改变畜群结构 ,解决当地牧民生活出路 ;而大面积的退化草地 ,主要借助自然力恢复。结果表明 ,自然力在浑善达克沙地退化生态系统恢复中起到巨大的作用 ,群落生物量、平均高度和总盖度 2年后均随恢复时间增加而增加 ( P<0 .0 5 )。流动沙丘的裸沙 ,经 2 a自然恢复后 ,生物量达 1 0 1 2 g/m,总盖度高达 60 %。与对照相比 ,封育 2 a后固定沙地群落盖度增加近 3倍 ;滩地群落生物量提高了 9倍 ,平均高度增加 4倍。植被组成方面 ,恢复前固定沙地以冷蒿 ( Artemisia frigida)、糙隐子草 ( Cleistogens squarrosa)和寸草苔 ( Carexduriuscula)等为主 ,恢复 2 a后冰草 ( Agropyron cristatum)、褐沙蒿 ( Artemisia intramongolica)等占优势 ;滩地植被中 ,羊草 ( L eymus chinensis)、披碱草 ( Elymus dahuricus)等逐步取代了灰绿藜 ( Chenopodiumglaucum)和尖头叶藜 ( Chenopodium acuminatum)等。生态恢复不仅使自然生态系统得以保护 ,而且带动了社会经济的发展 ,项目中的正蓝旗巴音胡舒嘎查牧民 。

浑善达克地区生态环境劣化原因分析及治理对策

本文阐述了浑善达克沙化草原区的自然环境特征、社会经济情况和生态环境退化现状。从系统物流平衡、环境气候变化 ,以及人类活动对草地生态系统的影响等方面探讨了该地区生态环境劣变的原因。分析结果表明 ,放牧畜牧业是该地区的牧业主要生产方式 ,家畜是生态系统中植被的主要控制者 ,系统内物流 (以 N为例 )的出入失调和季节性的草 -畜供求失衡是引起草地生态系统迅速退化的主要因素。而其它因素 (如气候变化、垦荒、挖药材等 )对系统的劣变起了推波助澜的作用。著者指出 ,增加向系统内的物质投入 ,调整四季放牧的自然畜牧业生产方式 ,积极引种入牧 ,缓解草地春季敏感期放牧压力等 。