Assessing ecological vulnerability in western China based on Time-Integrated NDVI data

Arid and semi-arid areas are the most vulnerable regions to climate change.Clear understanding of the effects of climate change on ecosystems in arid and semi-arid regions and the ecosystem vulnerability is important for ecosystem management under the background of climate change.In this study,we conducted a vulnerability assessment on various ecosystems from 1982 to 2013 in western China with large areas of arid and semi-arid lands based on the Time-Integrated Normalized Difference Vegetation Index(TINDVI)data and climate data.The results indicated that grasslands were the most vulnerable ecosystem to climate change in western China,especially for those in Tibetan Plateau.Croplands in oases were not vulnerable to climate change compared to rain-fed croplands in semi-arid regions(e.g.Gansu and Inner Mongolia),which was attributed to the well-developed drip irrigation technology in oases.Desert and Gobi ecosystems were slightly vulnerable to climate change during the past several decades.The assessment results,as revealed in this study,can provide a reference for taking appropriate actions to protect the ecosystems in western China.     

Meteorological impacts on evapotranspiration in different climatic zones of Pakistan

Arid regions are highly vulnerable and sensitive to drought. The crops cultivated in arid zones are at high risk due to the high evapotranspiration and water demands. This study analyzed the changes in seasonal and annual evapotranspiration(ET) during 1951–2016 at 50 meteorological stations located in the extremely arid, arid, and semi-arid zones of Pakistan using the Penman Monteith(PM) method. The results show that ET is highly sensitive and positively correlated to temperature, solar radiation, and wind speed whereas vapor pressure is negatively correlated to ET. The study also identifies the relationship of ET with the meteorological parameters in different climatic zones of Pakistan. The significant trend analysis of precipitation and temperature(maximum and minimum) are conducted at 95% confidence level to determine the behaviors of these parameters in the extremely arid, arid, and semi-arid zones. The mean annual precipitation and annual mean maximum temperature significantly increased by 0.828 mm/a and 0.014℃/a in the arid and extremely arid zones, respectively. The annual mean minimum temperature increased by 0.017℃/a in the extremely arid zone and 0.019℃/a in the arid zone, whereas a significant decrease of 0.007℃/a was observed in the semi-arid zone. This study provides probabilistic future scenarios that would be helpful for policy-makers, agriculturists to plan effective irrigation measures towards the sustainable development in Pakistan.     

内蒙农牧交错带家畜品种改良可行性分析——以克什克腾旗经棚镇为例

引入外来品种改良牲畜被作为干旱半干旱地区发展畜牧业的重要手段,但对其在生产基础差、严重依赖自然资源的小农户生产系统中的适用性却缺乏分析,因而,盲目推广改良可能危及牧民生计,进而导致生态破坏。以位于农牧交错带的内蒙古赤峰市克旗的家畜改良为案例,通过入户访谈,在识别其畜牧业生产系统约束条件的基础上,分析了家畜改良的效果、可行性条件及存在的问题。研究表明:在小农户生产系统中,家畜品种改良并不能提高限制性资源的生产率,而且增加了农户面临的生态风险和市场风险,改良是否可行取决于外部环境能否有效地改善其对限制性资源的利用及平衡风险,尤其是提供稳定的饲料和畜产品市场,以及良好的基础设施、技术及金融保障。     

Potential responses of vegetation to atmospheric aerosols in arid and semi-arid regions of Asia

Changes in atmospheric aerosols have profound effects on ecosystem productivity, vegetation growth and activity by directly and indirectly influencing climate and environment conditions. However, few studies have focused on the effects of atmospheric aerosols on vegetation growth and activity in the vulnerable arid and semi-arid regions, which are also the source areas of aerosols. Using the datasets of aerosol optical depth(AOD), normalized difference vegetation index(NDVI) and multiple climatic variables including photosynthetically active radiation(PAR), surface solar radiation(SSR), surface air temperature(TEM) and total precipitation(PRE), we analyzed the potential responses of vegetation activity to atmospheric aerosols and their associated climatic factors in arid and semi-arid regions of Asia from 2005 to 2015. Our results suggested that areas with decreasing growing-season NDVI were mainly observed in regions with relatively sparse vegetation coverage, while AOD tended to increase as NDVI decreased in these regions. Upon further analysis, we found that aerosols might exert a negative influence on vegetation activity by reducing SSR, PAR and TEM, as well as suppressing PRE in most arid and semi-arid regions of Asia. Moreover, the responses of atmospheric aerosols on vegetation activity varied among different growing stages. At the early growing stage, higher concentration of aerosol was accompanied with suppressed vegetation growth by enhancing cooling effects and reducing SSR and PAR. At the middle growing stage, aerosols tended to alter microphysical properties of clouds with suppressed PRE, thereby restricting vegetation growth. At the late growing stage, aerosols exerted significantly positive influences on vegetation activity by increasing SSR, PAR and TEM in regions with high anthropogenic aerosols. Overall, at different growing stages, aerosols could influence vegetation activity by changing different climatic factors including SSR, PAR, TEM and PRE in arid and semi-arid regions of Asia. This study not only clarifies the impacts of aerosols on vegetation activity in source areas, but also explains the roles of aerosols in climate.     

干旱半干旱地区农业生态环境系统优化调控研究

以松嫩平原西南部的长岭县为例,依据区域农业可持续发展理论、生态经济学、反馈控制理论和系统动力学原理,建立干旱半干旱区农业生态环境系统动力学模型。设计了“维持现状”、“生态建设”、“节水”、“偏畜牧业”、“偏种值业”和“农牧互促”等6种调控方案。经仿真模拟及其结果对比分析,“农牧互促”方案是研究区农业生态系统的优化调控方案。     

Change features of time-series climate variables from 1962 to 2016 in Inner Mongolia,China

Detecting change features of climate variables in arid/semi-arid areas is essential for understanding related climate change patterns and the driving and evolution mechanism between climate and arid/semi-arid ecosystems.This paper takes Inner Mongolia of China,a unique arid/semi-arid ecosystem,as the study area.We first detected trend features of climate variables using the linear trend analysis method and then detected their trend-shift features using the breaks for additive seasonal and trend method based on the time-series of monthly precipitation and monthly mean temperature datasets from 1962 to 2016.We analyzed the different change features of precipitation and temperature on a regional scale and in different ecological zones to discover the spatial heterogeneity of change features.The results showed that Inner Mongolia has become warmer-wetter during the past 54 years.The regional annual mean temperature increased 0.4°C per decade with a change rate of 56.2%.The regional annual precipitation increased 0.07 mm per decade with a slightly change rate of about 1.7%,but the trend was not statistically significant.The warmer trend was contributed by the same positive trend in each season,while the wetter trend was contributed by the negative trend of the summer precipitation and the positive trend of the other three seasons.The regional monthly precipitation series had a trend-shift pattern with a structural breakpoint in the year 1999,while the regional monthly mean temperature series showed an increasing trend without a periodical trend-shift.After the year 2000,the warmer-wetter trend of the climate in Inner Mongolia was accelerated.The late 20th century was a key period,because the acceleration of the wetter trend in some local zones(I and II)and the alleviation of the warmer trend in some local zones(Ⅶ,Ⅷand IX)occurred simultaneously.Moreover,the change features had a strong spatial heterogeneity,the southeastern and southwestern of Inner Mongolia went through a warmer-drier trend compared with the other areas.The spatio-temporal heterogeneity of the climate change features is a necessary background for various types of research,such as regional climate change,the evolution of arid/semi-arid ecosystems,and the interaction mechanisms between climate and arid/semi-arid ecosystems based on earth-system models in Inner Mongolia.     

宁夏旱地农业类型分区及评价研究

旱地农业是指干旱、半干旱区的雨养农业。类型分区是因地制宜布局农业生产,找出农业技术措施推广的合理区间和开发旱耕地生产潜力之重要条件。该文在指出宁夏干旱特点的基础上,提出旱地农业类型分类的原则与指标和分区方法,最后将宁夏划分为荒漠草原风沙干旱牧业区、半农半牧区、半干旱典型草原旱作农业区和半湿润森林草原农林区。同时也给每一区的资源条件以综合评价。     

基于GIS和RS的石羊河流域景观功能分区

景观功能分区是生态系统和自然资源科学管理及可持续利用的基础。干旱区内陆河流域生态系统组成要素和影响因素的区域差异性决定了不同区域具有不同的景观功能。对其进行科学划分,可为生态恢复与重建提供科学依据。针对目前生态功能区划仅从区域地貌单元、生态要素等方面考虑,而很少涉及景观能量循环运行与景观优化关注单元等景观生态学的内容。...     

Can climate change influence agricultural GTFP in arid and semi-arid regions of Northwest China?

There are eight provinces and autonomous regions (Gansu Province, Ningxia Hui Autonomous Region, Xinjiang Uygur Autonomous Region, Inner Mongolia Autonomous Region, Tibet Autonomous Region, Qinghai Province, Shanxi Province, and Shaanxi Province) in Northwest China, most areas of which are located in arid and semi-arid regions (northwest of the 400 mm precipitation line), accounting for 58.74% of the country's land area and sustaining approximately 7.84×10⁶ people. Because of drought conditions and fragile ecology, these regions cannot develop agriculture at the expense of the environment. Given the challenges of global warming, the green total factor productivity (GTFP), taking CO₂ emissions as an undesirable output, is an effective index for measuring the sustainability of agricultural development. Agricultural GTFP can be influenced by both internal production factors (labor force, machinery, land, agricultural plastic film, diesel, pesticide, and fertilizer) and external climate factors (temperature, precipitation, and sunshine duration). In this study, we used the Super-slacks-based measure (Super-SBM) model to measure agricultural GTFP during the period 2000-2016 at the regional level. Our results show that the average agricultural GTFP of most provinces and autonomous regions in arid and semi-arid regions underwent a fluctuating increase during the study period (2000-2016), and the fluctuation was caused by the production factors (input and output factors). To improve agricultural GTFP, Shaanxi, Shanxi, and Gansu should reduce agricultural labor force input; Shaanxi, Inner Mongolia, Gansu, and Shanxi should decrease machinery input; Shaanxi, Inner Mongolia, Xinjiang, and Shanxi should reduce fertilizer input; Shaanxi, Xinjiang, Gansu, and Ningxia should reduce diesel input; Xinjiang and Gansu should decrease plastic film input; and Gansu, Shanxi, and Inner Mongolia should cut pesticide input. Desirable output agricultural earnings should be increased in Qinghai and Tibet, and undesirable output (CO₂ emissions) should be reduced in Inner Mongolia, Xinjiang, Gansu, and Shaanxi. Agricultural GTFP is influenced not only by internal production factors but also by external climate factors. To determine the influence of climate factors on GTFP in these provinces and autonomous regions, we used a Geographical Detector (Geodetector) model to analyze the influence of climate factors (temperature, precipitation, and sunshine duration) and identify the relationships between different climate factors and GTFP. We found that temperature played a significant role in the spatial heterogeneity of GTFP among provinces and autonomous regions in arid and semi-arid regions. For Xinjiang, Inner Mongolia, and Tibet, a suitable average annual temperature would be in the range of 7°C-9°C; for Gansu, Shanxi, and Ningxia, it would be 11°C-13°C; and for Shaanxi, it would be 15°C-17°C. Stable climatic conditions and more efficient production are prerequisites for the development of sustainable agriculture. Hence, in the agricultural production process, reducing the redundancy of input factors is the best way to reduce CO₂ emissions and to maintain temperatures, thereby improving the agricultural GTFP. The significance of this study is that it explores the impact of both internal production factors and external climatic factors on the development of sustainable agriculture in arid and semi-arid regions, identifying an effective way forward for the arid and semi-arid regions of Northwest China.     

干旱半干旱区地下水引起的表生生态效应及其评价指标体系研究

干旱半干旱地区地下水具有重要的生态价值.本文从这一地区地下水与生态环境之间关系出发,以地下水资源永续利用并与社会经济和生态环境协调发展为目标,探讨了地下水生态价值的定义,分析了地下水引起的表生生态效应及其驱动力,建立了地下水引起的表生生态效应递阶层次评价指标体系.这些研究不仅丰富了水资源生态价值理论,而且对这一地区水资源合理开发利用并与社会经济、生态环境协调发展具有参考价值.     

宁夏半干旱偏旱区苜蓿引进品种在不同立地及干旱胁迫下抗旱性研究

连续3年对引进的14个紫花苜蓿品种在半干旱偏旱区的缓坡耕地、台地和川旱地三种不同立地类型区,分别布设旱地组和补充灌溉组进行田间试验,对同一苜蓿品种在不同立地类型和不同水分胁迫下的苗期抗旱性生理指标进行测定分析.结果表明,苜蓿品种叶片失水速率以补充灌溉最高,旱地次之,坡耕地最低;离体叶片失水速率(RWL)与保水力(HAW)、抗旱性指教(ID)之间呈负相关,HAW与ID呈显著正相关.对主要抗旱指标进行了多元回归预测和聚类分析.     

脆弱生态区适度经济开发的评价与调控

脆弱生态区的适度经济开发及其调控模式 ,是实现脆弱生态区可持续发展的理论基础。在生态承载力与生态弹性力研究的基础上 ,采用脆弱生态区的演化模型 ,可对经济开发活动影响下脆弱生态区的动态变化进行研究 ,并进而提出脆弱生态区适度经济开发模式及其调控措施。本文首先讨论了经济开发活动对脆弱生态区的影响以及脆弱生态区主要经济开发活动的类型及其驱动因子 ,然后在此基础上探讨了脆弱生态区的适度经济开发的评价模型及其调控手段 ,最后以内蒙古翁牛特旗和敖汉旗脆弱生态区为例 ,通过对其 4个状态变量演化趋势的模拟 ,认为它们现有的经济开发模式都是不可持续的 ,并分别提出了它们的最佳调控方式     

黄土高原生物气候分区与该区生态系统的恢复

根据不同的生物气候状况 ,可将黄土高原分成五个生物气候区 :暖温带湿润半湿润森林区、暖温带半湿润半干旱森林草原区、中温带半干旱典型草原区、中温带干旱半干旱荒漠草原区以及中温带干旱草原化荒漠区。紧密结合上述生物气候区域特征 ,将生态学的有关原理引入到该区的治理与生态恢复中 ,提出了治理黄土高原的新模式 :正确实施生物措施 ,人工模拟天然生态系统。该区的生态恢复应从系统的角度考虑 ,并严格遵守生态学的有关规律在不同的生物气候区构建与该区大环境一致的不同的生态系统 ,改变过去那种在黄土高原全面造林而又成效不佳的做法     

Community structure and carbon and nitrogen storage of sagebrush desert under grazing exclusion in Northwest China

Overgrazing is regarded as one of the key factors of vegetation and soil degradation in the arid and semi-arid regions of Northwest China.Grazing exclusion(GE)is one of the most common pathways used to restore degraded grasslands and to improve their ecosystem services.Nevertheless,there are still significant controversies concerning GE’s effects on grassland diversity as well as carbon(C)and nitrogen(N)storage.It remains poorly understood in the arid desert regions,whilst being essential for the sustainable use of grassland resources.To assess the effects of GE on community characteristics and C and N storage of desert plant community in the arid desert regions,we investigated the community structure and plant biomass,as well as C and N storage of plants and soil(0-100 cm depth)in short-term GE(three years)plots and adjacent long-term freely grazing(FG)plots in the areas of sagebrush desert in Northwest China,which are important both for spring-autumn seasonal pasture and for ecological conservation.Our findings indicated that GE was beneficial to the average height,coverage and aboveground biomass(including stems,leaves and inflorescences,and litter)of desert plant community,to the species richness and importance values of subshrubs and perennial herbs,and to the biomass C and N storage of aboveground parts(P<0.05).However,GE was not beneficial to the importance values of annual herbs,root/shoot ratio and total N concentration in the 0-5 and 5-10 cm soil layers(P<0.05).Additionally,the plant density,belowground biomass,and soil organic C concentration and C storage in the 0-100 cm soil layer could not be significantly changed by short-term GE(three years).The results suggest that,although GE was not beneficial for C sequestration in the sagebrush desert ecosystem,it is an effective strategy for improving productivity,diversity,and C and N storage of plants.As a result,GE can be used to rehabilitate degraded grasslands in the arid desert regions of Northwest China.     

西北地区生态建设中的水资源容量问题

本文依据生态系统中水分平衡理论 ,针对西北干旱、半干旱地区水资源短缺的特点 ,较详细地探讨了区域生态建设中水资源特点以及对植被建设的影响 ,提出应依据西北地区水资源时空分布的特点来建设不同类型的植被 ,并以此做为区域生态建设可持续发展的基础     

干旱半干旱地区地下水问题

对干旱半干旱地区地下水资源的特征，地下水的水文地质条件及相关的水文地质问题进行了分析，阐述了干旱半干旱地区地下水资源的利用现状及地下水资源管理的内容和意义。     

石羊河流域生态系统的气候变化脆弱性评估

选取石羊河流域生态系统作为研究对象,简要分析影响其生态系统气候变化脆弱性的主要因子。在此基础上,选取4类共13项指标,构建了生态系统脆弱性评价指标体系。通过层次分析法确定了指标权重,最后采用综合指标分析方法,对石羊河流域生态系统气候脆弱性现状进行了定量评价;结合气候变化情景,定量分析了未来该流域的脆弱性变化趋势,并给出减缓不利影响的对策和建议。     

Effects of climate change and human activity on lake shrinkage in Gonghe Basin of northeastern Tibetan Plateau during the past 60 years

Changes in the status of freshwater resources are a topic of major global,regional and local concern.This is especially so in the arid and semi-arid regions of China,where shortage of water resources plays a crucial role in limiting sustainable socioeconomic development,as well as in sustaining natural ecosystems.Recent climate change,as well as the effects of localized human activity,such as the use of water for irrigation agriculture,may have significant effects on the status of the water resources in the region.Here,we report the results of a study of changes in the areas of lakes in Gonghe Basin,northeastern Tibetan Plateau of China,over the last 60 years.The data were acquired from optical satellite images and demonstrate that the total water area of lakes in Gonghe Basin decreased significantly from the 1950 s to 1980 s.The cause is ascribed mainly to human activity including exploitation of farmland,against a background of increasing population;in addition,climatic data for the region demonstrate a minor drying trend during this period as the temperature increased slightly.After the construction of several reservoirs,significant amounts of water were redistributed to promote irrigation agriculture and we conclude that this caused a significant shrinkage of the natural lakes.However,both the area of farmland and the population size remained approximately constant after 1990.We conclude that the variation of the total area of lakes during the second period was mainly controlled by climatic factors(precipitation and temperature).As the regional temperature reached a new high,the area of some of the lakes decreased sharply before finally maintaining a relatively steady state.We emphasize that anthropogenic climate change and human activity have both significantly influenced the status of water resources in the arid and semi-arid regions of China.     

Effects of grazing intensity on seed production of Caragana stenophylla along a climatic aridity gradient in the Inner Mongolia Steppe,China

As the increases of climatic aridity and grazing intensity,shrubs play an increasingly important role in grassland ecosystem in arid and semi-arid regions,and its abundance also generally increases.However,the effects of climatic aridity and grazing intensity on sexual reproduction of shrubs in grassland remain largely unclear.In order to understand the effects of grazing intensity and climatic drought stress,and their interaction on seed production of shrub species,we examined the seed number,seed weight and seed yield of Caragana stenophylla under three grazing intensities(fenced,mild grazing and severe grazing) across a climatic aridity gradient(semi-arid,arid,very arid and intensively arid zones) in the Inner Mongolia Steppe,northern China during 2012–2013.The seed number,seed weight and seed yield gradually increased from the semi-arid to the very arid zones,but decreased from the very arid to the intensively arid zones in fenced plots.The seed number and seed yield decreased from the semi-arid to the intensively arid zones in mild and severe grazing treatment plots,therefore,grazing enhanced the suppression effect of climatic aridity on seed production of C.stenophylla.The seed number and seed yield gradually decreased as grazing intensity increased.The seed weight was highest in severe grazing plots,followed by the mild grazing plots and then the fenced plots.Precipitation varied interannually during the study period.We observed that the seed number,seed weight and seed yield were lower in the low precipitation year(2013) than in the high precipitation year(2012).As climatic drought stress increased,the negative effects of grazing on seed production of C.stenophylla also gradually increased.Our results indicated that climatic drought stress may contribute to the encroachment of C.stenophylla shrub in arid zones by promoting its seed production.However,grazing had negative effects on sexual reproduction of C.stenophylla,and the combined effects of drought stress and grazing seriously suppressed sexual reproduction of C.stenophylla in the intensively arid zone.     

Assessing the response of dryland barley yield to climate variability in semi-arid regions,Iran

Precipitation and temperature are the most abiotic factors that greatly impact the yield of crop, particularly in dryland. Barley, as the main cereal is predominantly cultivated in dryland and the livelihood of smallholders depends on the production of this crop, particularly in arid and semi-arid regions. This study aimed to investigate the response of the grain yield of dryland barley to temperature and precipitation variations at annual, seasonal and monthly scales in seven counties of East and West Azerbaijan provinces in northwestern Iran during 1991-2010. Humidity index (HI) was calculated and its relationship with dryland barley yield was evaluated at annual and monthly scales. The results showed that the minimum, maximum and mean temperatures increased by 0.19°C/a, 0.11°C/a and 0.10°C/a, respectively, while annual precipitation decreased by 0.80 mm/a during 1991-2010. Climate in study area has become drier by 0.22/a in annual HI during the study period. Negative effects of increasing temperature on the grain yield of dryland barley were more severe than the positive effects of increasing precipitation. Besides, weather variations in April and May were related more to the grain yield of dryland barley than those in other months. The grain yield of dryland barley was more drastically affected by the variation of annual minimum temperature comparing with other weather variables. Furthermore, our findings illustrated that the grain yield of dryland barley increased by 0.01 t/hm² for each unit increase in annual HI during 1991-2010. Finally, any increase in the monthly HI led to crop yield improvement in the study area, particularly in the drier counties, i.e., Myaneh, Tabriz and Khoy in Iran.