A Numerical Experiment Study for Effects of the GrasslandDesertification on Summer Drought in North China

In this paper, the summer climate of 1991 in North China is simulated by using the high-resolution regional climate model (RegCM2) and the effects of the grassland desertification on summer drought in the central and the northern parts of North China as well as Mongolia are studied. It shows that the regional climate model essentially catches the characteristics on distribution and seasonal variation of the precipitation that keep good agreement with the observation. The desertification makes precipitation in the central part of North China during its flood period decrease obviously in July. The border of the precipitation or the soil moisture reduction in the desertification region extends about one latitude southeastward and beyond the southeast edge of the desertification. Thus, vegetation in the border region approaches desertification further. However, there appears evident difference of variation of precipitation over the whole desertification region. The grassland desertification greatly changes the transfers of fluxes between land and atmosphere. The secondary circulation or secondary circulation cells in the desertification region are excited and as a result moisture transport is changed. The variation of flux transfers between land and atmosphere as well as the vertical motion of atmosphere is closely related to that of precipitation.

Classification and Net Primary Productivity of the Southern China's Grasslands Ecosystem Based on Improved Comprehensive and Sequential Classification System(CSCS) Approach

This research classified vegetation types and evaluated net primary productivity （NPP） of southern China＇s grasslands based on the improved comprehensive and sequential classification system （CSCS）, and proposed 5 thermal grades and 6 humidity grades. Four classes of grasslands vegetation were recognized by improved CSCS, namely, tundra grassland class, typical grassland class, mixed grassland class and alpine grassland class. At the type level, 14 types of vegetations （9 grasslands and 5 forests） were classified. The NPP had a trend to decrease from east to west and south to north, and the annual mean NPP was estimated to be 656.3 g C m-2 yr-1. The NPP value of alpine grassland class was relatively high, generally more than 1200 g C m2 yr-1. The NPP value of mixed grassland class was in a range from 1 000 to 1200 g C m-2 yr-1. Tundra grassland class was located in southeastern Tibet with high elevation, and its NPP value was the lowest （〈600 g C m＇2yrl）. The typical grassland class distributed in most of the area, and its NPP value was generally from 600 to 1000 g C m-2 yr-1. The total NPP value in the study area was 68.46 Tg C. The NPP value of typical grassland class was the highest （48.44 Tg C）, and mixed grassland class was the second （16.54 Tg C）, followed by alpine grassland class （3.22 Tg C）, with tundra grassland class being the lowest （0.25 Tg C）. For all the grasslands types, the total NPP of forest meadow was the highest （34.81 Tg C）, followed by sparse forest brush （16.54 Tg C）, and montane meadow was the lowest （0.01 Tg C）.

Ecological pressures on grassland ecosystems and their conservation strategies in Northern China

In this study,we identified ecological pressures on grassland ecosystems and adaptive countermeasures in Northern China.Our research revealed that the main sources of these pressures included population growth,economic development,resources exploitation,and global climate change,with human-related activities being overriding factors.Overgrazing was an important reason for grassland imbalance,causing soil erosion and desertification,especially during the sensitive spring greening phase.In steppe zones,commercial coal mining was destructive to the ecological environment.Regarding long-term strategies,we recommend that policy-makers devote more consideration to a new conceptual approach for transforming grasslands through shifting the focus from die grassland's traditional production functions to meir ecological functions.Applying this concept,adaptive countermeasures should be developed to reduce human impacts based on the environmental capacities of grasslands.Moreover,we recommend the development of environment-friendly industries and reduction of pressures from human activities as effective measures for maintaining the balance between sustainable economic development and grassland conservation.Lastly,we suggest that restoration of degraded grasslands should conform to the principle of natural vegetation to further improve the ecological adaptability of plants and ecosystem stability.This study is expected to provide scientific support for policy-makers engaged in grassland protection.

Developing the Agro-Grassland System to Insure Food Security of China

China’s food security has always been the top priority in China. As the huge increase of animal food consumption, the current agriculture system in China namely “grain farming”, whose major animal feed are grains, seems to meet a great challenge to ensure China’s food security in the future. Not only the current situation, but also the production capacity as developing grassland agriculture is analyzed in this paper. The results show that half of provinces don’t have enough grain to meet their various needs for grain, and the whole country’s potential of grain yield is reaching a limited position. On the other hand, implementing cereal-forage rotation on 20% of the total arable land and developing high productivity sown pastures on 3% of the total rangeland areas could create approximately 1.2 times Arable Land Equivalent Unit (ALEU) than ever. So changing the traditional agriculture system into Grassland Agro-Ecosystems is an effective way to insure China’s food security. It includes utilization of rangeland rationally, establishment of more sown pasture and implementation of cereal-pasture rotation system, increase livestock production, and use of arable land more efficiently.

N_2O emissions from forest and grassland soils in northern China

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THE GRASSLAND RESOURCES OF CHINA AND ITS MANAGEMENT STRATEGY

The total area of grassland in the world is about 50 million km^2, accounting for 33.5% of the total land area (Lieth, 1975). The permanent grassland used by mankind is 33.04 million km^2, accounting for 25.3% of the total land area (FAO,1990). Grassland can provide feed for herbivore and produce high-quality food,clothing,medicines and industrial materials for man.On the other hand,it also plays an important role in the fertility of the soil,the conservation of water, the improvement of the environment and maintaining the ecological balance of the Earth’s surface.

Study on Evaluation of Grassland Eco-system Coordination Based on Environment-Economy Coordination Degree Model

Based on the current studies,a reasonable evaluation index system was established by the development coordination of analysis systems.Furthermore,taking grassland resources in Nagchu Tibet as an example and according to the coordination degree evaluation model of the environmental economy system,a coordination degree evaluation index system of environmental economy was set up,and the coordination conditions of 11 counties in Nagchu district were analyzed by coordination function.

中国西北地区3种10m全球土地覆被产品林草灌专题要素的一致性评价

中国西北地区的土地利用/土地覆被信息对全球气候变化和生态环境保护有重要影响,因此,及时掌握目前公开发布的几种较高分辨率土地覆被产品的空间一致性极其重要。采用FROM-GLC、ESA和ESRI 3种10 m全球土地覆被产品,通过面积比较、逐像元空间叠加和基于样本点的绝对精度评价等方法,分析了这3种产品在林草灌专题要素准确性和空间格局上的差异特征。结果表明:(1)FROM-GLC的总体精度最高,为83.74%;其次是ESA,为68.30%;ESRI的总体精度最低,为52.80%。(2)3种产品林草灌空间一致性较低,完全一致区域面积占比为41.67%,主要分布在研究区的东部;完全不一致区域分布较零散,这些区域地表覆被类型较复杂,地表空间异质性较高。(3)3种产品林地类型的空间一致性较高,草地和灌木类型的判别差异较大。总的来说,草地、灌木等植被类型的精度需要进一步提高。

Frontier Grassland Degradation and Its Countermeasures

Firstly, the status quo of Hulunbuir Grassland degradation was introduced, and then the main reasons for the degradation were discussed, such as overgrazing, excessively mining mineral resources and so forth. Finally some targeted countermeasures, like improving grassland legislation and policy as well as grassland ecological compensation system, actively implementing ecological animal husbandry and reasonably exploiting mineral resources, were put forward to restore the ecological environment of Hulunbuir Grassland.

Shrubs proliferated within a six-year exclosure in a temperate grassland—Spatiotemporal relationships between vegetation and soil variables

Overgrazing has been considered one of the maj or causes that trigger shrub encroachment of grassland. Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification. In China, various conservation measures, including enclosures to reduce livestock grazing, have been taken to reverse the trend of grassland desertification, yet shrubs have been reported to increase in the grasslands over the past decades. In late 2007, we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia, with the ob- jective to quantify the spatiotemporal relationship between vegetation dynamics, soil variables, and grazing exclusion. Soil moisture was continuously monitored within the exclosure, and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007, 2009, 2010, 2012, and 2013, and outside the exclosure in 2012 and 2013. We found the average shrub cover and biomass significantly increased in the six years by 103 % and 120%, respectively. The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland. Our results, limited to a single gradient, suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub en- croachment in grassland. The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocor- relation. The result indicates that the grass cover and biomass significantly increased with the top, but decreased with the bottom layer soil moisture. The shrub cover and biomass, on the other hand, decreased with the top, but increased with bottom soil moisture, although the regression coefficients for the shrubs were not statistically significant. Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in dif- ferent depths.

Simulation Experimental Study on Hydrodynamics Process of Erosion and Sediment by Runoff in Grassland

[Objective]The aim was to study the simulation test of hydrodynamics process of erosion.[Method]Through the runoff scouring experiment,the property of soil erosion in Damaoqi grassland in Inner Mongolia was studied.The process and mechanism of soil erosion were studied.[Result]The results of runoff scouring experiment on inner Damaoqi steppe showed that the mean flow velocity of change slope increased with the discharge of flow and slope gradient.The mean silt content rate,the mean sediment transport rate and the mean sheer stress all increased when the discharge of flow increased,which changed in parabolic form with the increase of slope gradient and the critical gradient is 25°.The relationship between the mean sediment transport rate and the mean sheer stress was linear.[Conclusion]The study provided theoretic basis for the report of soil erosion in grassland in China.

Urgency and Necessity on Adjustment of China’s Current Agricultural Structure Based on the Stability and Developmental Trend Analyses of Pork Yield in China

With the development of economy, meat gradually plays an important role in Chinese people’s dietary pattern. As the most direct reflection of agricultural system, food system has always been the main output of agricultural system, and pork has occupied an important position in Chinese food system. We attempts to find the systematical disorder of current agricultural system by analyzing the meat output of the agricultural system. H-P Filter and Grey Prediction GM(1,1) Model was adopted to explore the inner rules between pork production and agricultural system in China. The results indicated that pork consumption ratio in Chinese urban residents’ dietary pattern constantly kept about 6%, the growth potential of grain yield is limited while the growth potential of pork yield is increased in China. By Grey Prediction GM(1,1) Model, we predicted the pork yield would reach 59.07 Mt in 2020, 110.25 Mt in 2060, 205.78 Mt in 2100, the demand of feed would reach 177.22 Mt in 2020, 330.75 Mt in 2060, 617.34 Mt in 2100. In China, agricultural system is traditional “pork-grain” mode, feed has been one of the biggest section that consumed grain. The present “pork-grain” agricultural system cannot meet the huge demand of grain from feed, adjusting the agricultural structure is imperative. Reforming the current agricultural system into grassland agricultural system which takes the beef and mutton as predominates would be a good choice for China in the future.

Relevant Analysis of Grassland Temperature and Ground Net Radiation in Guilin

[Objective] The aim was to study the relevance of grassland temperature and ground net radiation in Guilin.[Method] By dint of ground observation data and net radiation of national benchmark climate station in Guilin from 2007 to 2009,the changes of grassland temperature and ground net radiation were expounded and their relations were pointed out.[Result] The annual changes trends of grassland temperature and ground net radiation in Guilin were basically the same.Monthly average maximum value all appeared in summer(July to August).Monthly average lowest value appeared in winter(December to next January);monthly average grassland temperature and monthly average ground net radiation had positive relation.Grassland temperature and ground net radiation had basically same distribution in four seasons.The average largest value of ground net radiation in summer was the largest and average smallest value was the smallest;the average largest value of ground net radiation in cloudy days was the smallest and average minimum value was the largest;the daily difference was the largest in sunny day and daily difference was the smallest in cloudy day.The daily changes trend of grassland temperature and ground net radiation in different weather state were basically the same;when it was sunny or cloudy,the daily largest value of grassland temperature and ground net radiation occurred between 15:00 and 19:00;when it was overcast,there was no distinct peak and daily changes.The largest value of the daily extreme value of grassland temperature and ground net radiation took place from 12:00 to 15:00.The daily lowest value took place from 20:00 to 07:00 on the next day.[Conclusion] The study provided reference for the analysis of temperature changes in Guilin.

东北地区森林草原湿地生态系统外来入侵物种概况及对策

在对东北地区部分有害生物来源考证的基础上,筛选出56种外来入侵物种作为东北地区森林、草原、湿地生态系统的主要种类,并对其入侵特征进行分析。结果表明:原产地以北美洲种类最多,入侵东北种类总体呈不断增加势头,入侵途径以无意引入为主,入侵地以辽宁省种类居多,入侵生境在森林、草原、湿地生态系统均有代表性种类。进一步筛选出18种外来入侵物种作为东北地区森林、草原、湿地生态系统的重要种类,并对其重要性进行评述,根据每种在入侵过程的阶段性,分别提出防止入侵、阻止扩散和抑制危害的防控管理对策。针对完善入侵生物学理论提出3点建议,针对提升东北地区外来入侵物种防控能力提出4点建议。

基于CMIP6的中国北方草地生态系统年总初级生产力时空格局

[目的]揭示我国北方草地年总初级生产力未来时空变化规律,为草地恢复及保护的政策制定提供重要依据。[方法]基于CMIP6中9个地球系统模式总初级生产力(Gross Primary Productivity,GPP)模拟数据,采用多模式集合平均(MME)的方法,在SSP1-2.6,SSP2-4.5,SSP3-7.0和SSP5-8.5未来情景下预估了21世纪我国北方草地生态系统AGPP的时空变化。[结果](1)多模式集合(MME)模拟的准确性和年度趋势相关系数达到0.83,较其他单个模式更准确。(2)1982—2100年,4个情景均得出我国北方草地AGPP整体呈现上升趋势,温室气体高排放情景下的上升趋势大于温室气体低排放情景下的上升趋势。(3)空间上,我国北方草地平均AGPP在历史及未来情景下均呈西北到东南递增的趋势,SSP1-2.6情景下AGPP年均值最低〔308.03 g C/(m^(2)·a)〕,SSP5-8.5情景下最高〔389.63 g C/(m^(2)·a)〕。(4)在4个未来情景下的不同草地类型中,温性草原AGPP年均值最高〔SSP1-2.6情景下为445.44 g C/(m^(2)·a),SSP2-4.5情景下为474.53 g C/(m^(2)·a),SSP3-7.0情景下为532.42 g C/(m^(2)·a),SSP5-8.5情景下为558.14 g C/(m^(2)·a)〕,稀疏灌丛最低〔SSP1-2.6情景下为128.51 g C/(m^(2)·a),SSP2-4.5情景下为141.31 g C/(m^(2)·a),SSP3-7.0情景下为155.38 g C/(m^(2)·a),SSP5-8.5情景下为167.29 g C/(m^(2)·a)〕。[结论]我国北方草地AGPP未来呈显著增长趋势,不同情景下AGPP的增长趋势各不相同,排放情景越高增长越显著,未来应加强对我国北方草地AGPP变化的研究。

三江源区高寒草地生态恢复措施及效果评价

基于文献计量法整理了2005—2020年三江源区生态保护、恢复和建设的文献,梳理了三江源区主要生态保护、恢复和建设措施,提出恢复与建设效果评价指标体系,运用Meta分析评估不同恢复措施在高寒退化草地生态系统恢复中的效果.结果表明:高寒轻度退化草地最适合的技术措施是短期、中期围栏封育和N、P添加,不适合长期禁牧和大量施肥.中度退化草地最适合的技术措施是休牧、追加N、P或大量氮肥,不适合施有机肥或低氮肥.重度退化草地最适合的技术措施是休牧,不适合采用短期围栏封育和低氮量施肥.

放牧对中国天然草地土壤有机碳含量影响的Meta分析

草地土壤碳库贮存着丰富的有机碳储量,在全球碳循环中占有重要地位,土壤有机碳(Soil organic carbon,SOC)作为碳在土壤中的主要储存形式,对调节全球气候至关重要。放牧作为最广泛的草地利用方式影响着草地SOC含量,然而有关研究结果不尽相同。本研究全面检索了放牧对我国草地SOC含量影响的文献,利用Meta分析开展定量评估。结果表明,放牧使我国草地SOC含量显著降低20.78%。在中度和重度放牧条件下,草地SOC含量分别显著降低14.62%,45.5%,轻度放牧无显著影响。气候因素(降水、气温)、环境因素(海拔、土壤深度)和管理方式(放牧持续时间)分别不同程度地影响草地SOC含量对放牧的响应。本研究通过定量分析放牧对我国草地SOC含量的影响,为我国草地放牧管理、应对气候变化提供科学依据和理论参考。

林草援外培训线上与线下模式的比较研究——基于SWOT分析法

林草援外培训在构建人类命运共同体、筑牢全球伙伴关系的进程中,扮演着日益重要的角色。新冠疫情后,线上培训逐步取代线下培训成为援外培训首选的培训形式。结合对13期线下培训学员和148名线上培训学员的调查,用SWOT比较分析的方法,对比援外培训线上和线下两种模式的优势、劣势、机遇和挑战,提出林草援外培训线上、线下优势互补的具体策略,以及二者融合发展的建议,即根据学员不同需求和培训教学需要,充分挖掘线下培训和线上培训的优势,合力促进林草援外培训高质量发展,为促进发展中国家在生态保护与修复领域的绿色、普惠、包容发展作出贡献。

管理措施对我国草地土壤有机碳的影响

基于中国期刊网和外文数据库以及《中国土种志》和《中国草地资源》等文献中有关我国草地管理措施及其土壤有机碳的数据,分析不同管理措施下草地土壤表层有机碳变化量。结果表明：由于各草地类型土壤质地、气候条件有所不同,因此在不同管理措施下土壤有机碳的年际变化量也存在着差异。其中,高寒草甸各管理措施下土壤有机碳变化范围最大为-5.62～1.26 t/（hm^2·a）,温性荒漠草原最小为-0.85～0.68t/（hm^2·a）,而其他草地类型有机碳年变化范围分别为温性草甸草原-3.74～0.68 t/（hm^2·a）,高寒草原-3.62～0.04 t/（hm^2·a）,温性草原-2.4～1.07 t/（hm^2·a）,暖性灌草丛-1.94～0.64 t/（hm^2·a）;同时,利用Meta分析法估算中国主要草地类型各管理措施下土壤碳年际变化量可以得出：过牧管理措施下土壤有机碳的年减少量最大[-2.34 t/（hm^2·a）],重牧[-1.52 t/（hm^2·a）]〉轻牧[-0.54 t/（hm^2·a）]〉中牧[-0.49 t/（hm^2·a）],而补播管理下土壤有机碳的年增加量最大[0.9 t/（hm^2·a）],围封、禁牧2种管理措施次之,分别为0.48和0.19 t/（hm^2·a）。可见,我国草地表层土壤有机碳年变化量在不合理管理方式下对草地土壤有机碳的积累具有不利影响,而补播、禁牧则有益于中国草地的固碳作用。