Temporal and spatial responses of ecological resilience to climate change and human activities in the economic belt on the northern slope of the Tianshan Mountains, China

In the Anthropocene era,human activities have become increasingly complex and diversified.The natural ecosystems need higher ecological resilience to ensure regional sustainable development due to rapid urbanization and industrialization as well as other intensified human activities,especially in arid and semi-arid areas.In the study,we chose the economic belt on the northern slope of the Tianshan Mountains(EBNSTM)in Xinjiang Uygur Autonomous Region of China as a case study.By collecting geographic data and statistical data from 2010 and 2020,we constructed an ecological resilience assessment model based on the ecosystem habitat quality(EHQ),ecosystem landscape stability(ELS),and ecosystem service value(ESV).Further,we analyzed the temporal and spatial variation characteristics of ecological resilience in the EBNSTM from 2010 to 2020 by spatial autocorrelation analysis,and explored its responses to climate change and human activities using the geographically weighted regression(GWR)model.The results showed that the ecological resilience of the EBNSTM was at a low level and increased from 0.2732 to 0.2773 during 2010–2020.The spatial autocorrelation analysis of ecological resilience exhibited a spatial heterogeneity characteristic of"high in the western region and low in the eastern region",and the spatial clustering trend was enhanced during the study period.Desert,Gobi and rapidly urbanized areas showed low level of ecological resilience,and oasis and mountain areas exhibited high level of ecological resilience.Climate factors had an important impact on ecological resilience.Specifically,average annual temperature and annual precipitation were the key climate factors that improved ecological resilience,while average annual evapotranspiration was the main factor that blocked ecological resilience.Among the human activity factors,the distance from the main road showed a negative correlation with ecological resilience.Both night light index and PM2.5 concentration were negatively correlated with ecological resilience in the areas with better ecological conditions,whereas in the areas with poorer ecological conditions,the correlations were positive.The research findings could provide a scientific reference for protecting the ecological environment and promoting the harmony and stability of the human-land relationship in arid and semi-arid areas.

Evolution of economic linkage network of the cities and counties on the northern slope of the Tianshan Mountains,China

The exchanges between cities and counties in the northern slope economic belt of Tianshan Mountains(NSEBTM)are increasingly frequent and the economic linkages are increasingly close,but the spatial distribution of economic development and linkages among the cities and counties within NSEBTM is uneven.Therefore,it is of great significance to study the evolution of spatial-temporal pattern of the economic linkage network of cities and counties on NSEBTM to promote the coordinated and integrated development of the regional economy on NSEBTM.In this study,we used the modified gravity model and social network analysis method to analyze the spatio-temporal evolution characteristics of the economic linkage network structure of cities and counties on NSEBTM in 2000,2010,and 2020.The results showed that the comprehensive development quality level of cities and counties on NSEBTM increased from 2000 to 2020,its growth rate also increased,and its gap between cities and counties continued expanding.Both the spatial distribution patterns of the comprehensive development quality level of cities and counties on NSEBTM in 2000 and 2010 were presented as“high in the middle and low at both ends”,while the spatial distribution pattern of 2020 was exhibited as“high value and low value staggered”.The total amount of external economic linkages of cities and counties on NSEBTM showed an obvious upward trend,and its gap between cities and counties continued expanding,presenting a pattern of“a strong middle section and weak ends”.The direction of economic linkages of NSEBTM existed obvious central orientation and geographical proximity.The density of economic linkage network of NSEBTM increased from 2000 to 2020,and the structure of economic linkage network changed from single-core structure centered with Urumqi City to multicore structure centered with Urumqi City,Karamay City,Shihezi City,and Changji City,shifting from unbalanced development to balanced development.In the future,we should accelerate the construction of urban agglomeration on NSEBTM,cultivate a modern Urumqi metropolitan area,improve comprehensive development quality of the cities and counties at the eastern and western ends,strengthen the intensity of economic linkages between cities and counties,optimize the economic linkage network,and promote the coordinated and integrated development of regional economy.

Regional Structure and Spatial Morphology Characteristics of Oasis Urban Agglomeration in Arid Area——A Case of Urban Agglomeration in Northern Slope of Tianshan Mountains,Northwest China

It is great important to the health development of urban agglomeration to correctly understand the formation and development law of regional structure of urban agglomeration.Employing the analysis methods like fractal theory and quantitative statistics,coupling with the use of remote sensing images and other spatial data,this article discusses the urban agglomeration of oasis on the northern slope of the Tianshan Mountains in an arid area,and conducts the researches on its city scale,spatial distribution and individual form from 1990 to 2005.The result shows that it has loose hierarchical scale structure and polarization trend of population distribution while its hierarchical scale structure tends to mature.Under the influence of natural conditions,the spatial layout of urban agglomeration of oasis has macro characteristics that suggest cities distributed along oasis edges(dense or sparse),spatially expand along rivers,and cluster around traffic branches.The connectivity among the cities is high and shows an internal organization form of a banding distribution.The whole spatial shape of the internal structure of cities presents a "dumbbell" form,with mononuclear phenomenon receding and multi-nuclear appearing gradually.Individual cities spatially expand along rivers,portraying a long strip appearance.It indicates that the urban agglomeration of oasis shows regular and close structure but with a tendency to be complicated form and the loose structure.In the development of urban agglomeration,the authors recommend that the development of the city with good economic development conditions should be strengthened,and more attention be put into regional planning.

Sustainable land-use patterns for arid lands: A case study in the northern slope areas of the Tianshan Mountains

Sustainable land use patterns are ecological and economic prerequisites of regional sustainable development. This is especially true for arid lands, where the environment is wholly fragile thanks to extremely limited precipitation, and where human activities have greatly transformed natural desert system by clearing natural vegetation, expanding oases and even building dams on inland rivers. However, the current studies on land use patterns are still characterized by field investigations and case studies, with almost no solid scientific basis. This paper holds that land types and their combination patterns are the principal basis for designing sustainable land use patterns, and that GIS and RS-based large-scale land type mapping and the study of their spatial combination structures should be coordinated with the demand of social development. The existing environmental problems induced by irrational land use mostly result from their deviation from the natural properties of land types. Taking the northern slope of the Tianshan Mountains （NSTM） as an example and considering land type patterns as the basis of land use patterns, this paper improves the vertical oa- sis-and-mid-mountain two-belts development model and the sustainable mountain land use model for arid lands put forward in recent years; and in terms of oases patterns, it outlines oasis development models, including intensive land use pattern in alluvial-diluvial fans, moderate agricultural development pattern in alluvial plains, and ecological land use pattern in river-end oases.

Response of ecosystem service value to land use/cover change in the northern slope economic belt of the Tianshan Mountains, Xinjiang, China

Land use/cover change(LUCC)is becoming more and more frequent and extensive as a result of human activities,and is expected to have a major impact on human welfare by altering ecosystem service value(ESV).In this study,we utilized remote sensing images and statistical data to explore the spatial-temporal changes of land use/cover types and ESV in the northern slope economic belt of the Tianshan Mountains in Xinjiang Uygur Autonomous Region,China from 1975 to 2018.During the study period,LUCC in the study region varied significantly.Except grassland and unused land,all the other land use/cover types(cultivated land,forestland,waterbody,and construction land)increased in areas.From 1975 to 2018,the spatial-temporal variations in ESV were also pronounced.The total ESV decreased by 4.00×10^(8) CNY,which was primarily due to the reductions in the areas of grassland and unused land.Waterbody had a much higher ESV than the other land use/cover types.Ultimately,understanding the impact of LUCC on ESV and the interactions among ESV of different land use/cover types will help improve existing land use policies and provide scientific basis for developing new conservation strategies for ecologically fragile areas.

An analysis of oasis stability in arid areas:a case study in the northern slope areas of the Tianshan Mountains

This paper discusses oasis stability at regional scale with a case study in the northern slope areas of the Tianshan Mountains (NSTM). The results showed certain significant aspects. (1) As long as water resources in the oasis keep stable and their utilization efficiency can be maintained or gradually increased, the primary productivity could be continuously increased and the natural primary productivity keeped relatively stable. In this case, it is considered that the oasis is stable and its sustainable development can be achieved at regional scale. (2) Considering the availability of water resources in the oases, the oases on the alluvial-diluvial fans are highly stable. In the alluvial plain downstream of the groundwater overflowing zones the oases are moderately stable and in the lacustrine deltas or dry lacustrine deltas the oases are lowly stable. (3) Enlargement of oases and the increase of water resources and vegetation coverage in the oasis will certainly enhance the 'cold-island effect' of the oasis and increase the stability of oases.

Spatiotemporal characteristics of the expansion of an urban agglomeration and its effect on the eco-environment: Case study on the northern slope of the Tianshan Mountains

Urban agglomerations, which are highly integrated urban groups, form during the advanced stages of industrialization and urban development. The urban agglomeration on the northern slope of the Tianshan Mountains is one of the 19 urban agglomerations promoted by China’s 13th Five-Year Plan and a key area of urbanization in Xinjiang. Based on remote sensing data, we analyzed the expansion of construction land in the urban agglomeration on the northern slope of the Tianshan Mountains and its effect on ecological value in 1980–2015. The results show that the expansion of construction land significantly affected ecological value in the study area over the past 35 years. Among land use types, grassland was the dominant contributor to changes in ecological value;its contribution rate reached 66.27% with an interannual variation of only 5%. The contribution rate of urban and rural residential land along with industrial and mining lands was very low(0.82%), while the interannual variation was large(86%). The area of construction land in the urban agglomeration expanded from 1,067 to 2,586 km^2, and the conversions of different land use types had different effects on ecological value. Among land use types, the conversions of lowcoverage grassland and dry land made the largest contributions to changes in ecological value. During the study period, a total of 1,685 km^2 of ecological land, 69.91% of which belonged to cultivated land and grassland, was converted into construction land.A total area of 1,082 km^2 of dry land and low-coverage grassland was converted into construction land, accounting for 64.21% of the total ecological land that was converted into construction land. In 2000–2015, the area of urban construction land increased significantly along with the proportion of unused land, including gobi(172 km^2), bare land(65 km^2), and salt-affected land(65 km^2), being converted into construction land. In contrast, the area of construction land that was converted into ecological land was less than 166 km^2. The areas with the largest expansions of construction land were concentrated in Urumqi, Karamay,and Changji, where the areas of construction land increased by 399, 186, and 126 km^2, respectively. The areas with the most rapid expansions in construction land were concentrated in Kuytun, Toksun, and Usu. The environmental effects of construction land expansion and land use change were more positive in the late stage of urban agglomeration(2000–2015) compared to in the early stage(1980–2000). Kuytun City, Shihezi City, and Wujiaqu City showed large changes in ecological value caused by the expansion of construction land, whereas the changes in ecological value in the 14 other cities were relatively small, and the expansion of construction land slowed in 2000–2015 compared to in 1980–2000. In the future, further development of the urban agglomeration on the northern slope of the Tianshan Mountains should fully consider the sensitivity and carrying capacity of the vulnerable ecological environment in this area. Population growth and industrial development in the urban agglomeration should be controlled based on the available water resources and ecological capacity to reduce the pressure on the environment and ensure sustainable development.

基于PLUS-InVEST模型的天山北坡生态系统碳储量时空变化与预测

土地利用变化作为影响陆地生态系统碳储量的重要因素,研究两者间的关系对维持区域碳平衡和实现双碳目标具有重要意义。基于第三次新疆综合科学考察背景,分析天山北坡1990年、2000年、2010年、2020年土地利用变化与碳储量的定量关系,结合PLUS和InVEST模型,模拟在历史趋势、水资源保护和经济发展3种情景下2030年区域碳储量的空间格局。结果表明:(1)草地和裸地是天山北坡主要土地覆被类型,1990—2020年耕地、林地、水域、建设用地和湿地面积增加,耕地面积增加最多,其余土地利用类型面积减少,草地减少最多。(2)1990—2020年天山北坡碳储量呈“先升后降”趋势,草地、裸地、耕地和林地间的转化是总碳储量变化的主要成因。(3)3种情景下碳储量均低于2020年水平,经济发展情景减幅最为显著,草地减少、裸地增加是碳损失的主要原因。

Fluctuation of Picea timberline and paleoenvironment onthe northern slope of Tian-shan Mountains during the late Holocene

As a good indicator of Holocene climate, the fluctuation of alpine timberline is a synthetical result of impacts of many environmental factors dur-ing geological and historical periods and modern times. As the dominant tree species of mountainous conifer forests on the northern slope of Tianshan Mountains in Xinjiang, the distribution of Picea schrenkiana and its population size are sensitive to climatic change. The typical natural profile of Huashuwozi and the nearby Xiaoxigou archaeologi-cal profile, located in Quanzijie Township, Jimusaer County in Xinjiang, were chosen to analyze and compare the relative high-resolution pollen records, and to measure 14C dating and SEM (scanning elec-tron microscope) microstructure for charcoal frag-ments contained in Xiaoxigou profile’s cultural layers. The results show that in these two profiles, the high percentages of Picea (more than 20% and 35%, re-spectively) appeared in the stratum of the same pe-riod (2000-1300 a BP), which corresponds to the charcoal fragment’s age of Picea schrenkiana con-tained in Xiaoxigou cultural layers. These results convincingly revealed that during the period of 2000-1300 a BP, the timberline for Picea schrenkiana on the northern slope of Tianshan Mountains in Xinjiang declined by about 330m compared with the present.

不同牧压对天山北坡中段山地草甸植物群落特征及植物生活型的影响

【目的】研究天山北坡中段山地草甸植物群落特征在不同牧压条件下的变化,为建立合理放牧利用制度提供理论依据。【方法】通过对庙尔沟乡索尔巴斯陶夏、冬牧场的实际放牧强度和草场植被状况进行调查,选择重度(HG)、中度(MG)、轻度(LG)且具代表性地段的放牧场,设置3个不同牧压监测点,每个监测点设置3个重复。【结果】在不同牧压条件下,植物群落优势种略有差异,群落物种数随着放牧强度的增大而减少。随着牧压增大,禾本科、豆科等优良牧草的重要值下降,而杂类草及醉马草的重要值增大;不同牧压对植被生物量的影响最大,其次是植被的盖度和高度,对频度的影响较小,呈现出植被平均高度、总盖度和生物量随放牧强度增大而降低的趋势;不同放牧时期对山地草甸植被优势种和植物生活型有明显影响,在夏季放牧场中植株矮小、重要值很低的金露梅在冬季放牧场中却株型高大,重要值也极高。【结论】在不同牧压条件下,群落物种组成不同,HG、MG、LG物种数分别为26、22和33种,物种间数目相差明显。重度放牧降低了植物群落的高度、盖度和地上生物量,并增大了杂类草和醉马草的优势。随着放牧强度增大,植物的生活型和重要值发生了改变,这也是植物生长过程中适应环境变化的一种策略。

天山北坡经济带城乡聚落格局变化与影响因素分析

以天山北坡经济带城乡聚落为研究对象,采用景观格局指数、地理信息系统(GIS)空间分析、位序-规模法等分析1980-2020年间城乡聚落格局的变化,结合地理探测器从自然、区位及社会经济因素探究城乡聚落格局的影响因素。结果表明:1980-2020年间,城乡聚落数量、规模持续扩张且趋于集聚,前20 a扩张以耕地、草地为主,后20 a以未利用地为主;城乡聚落密度变化显著,高密度区主要集中在各绿洲呈现“多核集中分布”特征,中密度区沿高密度区周围扩张,低密度区沿绿洲边缘分布并在非绿洲区有扩张;首位聚落规模发展较好,趋于位序-规模曲线,中型聚落略微发育,小型聚落数量持续减少;交通等区位因素是天山北坡城乡聚落格局的首位影响因素,社会经济因素次之,自然地理因素影响较小,各影响因素差异显著。

天山北坡经济带植被覆盖度动态变化研究

为探明天山北坡经济带植被覆盖度时空变化及其原因,本研究基于MODIS13Q1NDVI数据、气象数据、地形数据、人文数据,基于Google Earth Engine(GEE)平台,利用Theil-Sen Median趋势分析、Mann-Kendall显著性检验和稳定性分析方法,探究2000-2020年天山北坡经济带植被覆盖度(FVC)时空变化特征及其影响因子.结果表明:天山北坡经济带的FVC表现为两条平行的高覆盖度带.其中中部地区具有较高的植被覆盖度,而边缘地区的植被覆盖度相对较低.2000~2020年间,天山北坡经济带的FVC在时空上呈轻度变化,约占总变化的70%.植被改善区域主要呈现带状分布,集中在研究区的中部,而植被减少区域主要分布在研究区的南缘.整体上,天山北坡的植被覆盖度呈现出西北至东南的相间分布趋势,并且有逐渐上升的趋势.与东部地区相比,西部地区的植被改善更为明显.2000~2020年间,天山北坡经济带的FVC整体上表现出较高的稳定性和较小的波动,其变异程度介于弱变异和中等变异之间.但是,在克拉玛依市北部、乌鲁木齐市西南部以及研究区南缘的零星地区,FVC存在较强的变异.通过地理探测器模型对天山北坡经济带FVC影响因素的研究表明,人类活动(人口密度、夜间灯光和土地利用类型)是FVC空间分异的主要解释因素.从驱动因素来看,人口密度P值为0.283,对FVC影响最大,夜间灯光P值为0.125,土地利用类型P值为0.179.

1990—2022年天山北坡地区不同开垦年限耕层土壤盐分变化

近年来,随着频繁的土地利用变化和大量耕地的开垦,土壤盐渍化已成为导致天山北坡耕地质量退化、阻碍绿洲农业发展的环境因素。本研究基于翔实的调查数据资料、土壤实测数据和中国土地覆盖数据集(CLCD),比较传统插值模型和随机森林插值模型对耕层土壤(0~30 cm)含盐量插值的优缺点;选取精度最高的定量预测模型对天山北坡地区耕层土壤含盐量定量预测,得到耕层土壤含盐量分布变化特征;以空间换时间,将近30 a新开垦耕地耕层土壤含盐量进行比较,分析开垦年限对土壤含盐量的影响。结果表明:(1)与传统的插值方法相比,随机森林算法能够更准确地预测盐渍化土地的土壤盐分分布情况。(2)天山北坡地区,耕层土壤含盐量存在较大空间异质性,即高海拔地区土体中的盐分会随着径流的淋溶,在低海拔的河流下游尾闾或低洼区靠近沙漠一侧积聚。(3)随着开垦年限的延长,天山北坡地区耕层土壤含盐量总体呈现下降的趋势,且土壤盐渍化程度倾向于聚集在一个中等的水平上,趋向于平衡或“中心化”。本研究增进了对当前耕地盐渍化状况及从原始荒地开垦到耕地后耕层土壤盐分变化历程的理解。这为干旱区备用土地资源的开发、管理和有效利用提供了理论支撑,并为农业的持续发展提供了科学依据。

天山北坡城市群人居环境适宜性评价

基于人居环境自然和人文综合要素,构建了人居环境综合适宜性指数(HSCI),以天山北坡城市群为研究区,分析其2022年的空间分异规律。结果表明:(1)天山北坡城市群自然环境的空间适宜性受地形起伏度和温湿指数影响显著,整体为一般适宜区集中连片分布、高度适宜区零星分布在天山北坡山麓地带的绿洲。其中胡杨河市和乌鲁木齐县的自然环境适宜性最好;(2)人文环境的空间适宜性受夜间灯光指数和基础服务指数的影响较大,整体形成以乌鲁木齐市和石河子市为中心的“双核”空间特征,并有向周围递减的趋势;(3)天山北坡城市群人居环境综合适宜性指数最好的地方人口分布最多,充分体现了乌鲁木齐市作为区域极核的地位;(4)人居环境适宜性指数与天山北坡城市群的人口、经济和土地匹配程度不足。高质量和较高质量区土地面积仅占总量的2.62%,经济则占总量的54.69%,人口高达总量的59.06%。说明天山北坡城市群地区人口与经济在适宜性方面具有高度匹配性,但人居适宜性指数较高的土地存在过度集中和利用的情况。

天山北坡城市群国土空间格局识别与时空变化分析

气候变化和人类活动大环境下,探索国土空间格局演化特征及其规律对进一步缓和绿洲地区人地矛盾有着重要的意义。以天山北坡城市群为例,选取2000、2010年和2020年3期土地利用数据及DEM数据,基于“三生”空间理论对天山北坡城市群国土空间结构数量与空间分布进行分析。结果表明:(1)20 a间天山北坡城市群“三生”空间类型面积呈不同程度的增减,其中水域和林地生态空间的转出量最多,牧草和其他生态空间两者间相互的转换数量最大;(2)研究区除阜康市、木垒哈萨克自治县、奇台县、石河子市及乌鲁木齐市的国土空间利用程度综合指数呈小幅度增加和递减外,其他县域呈逐年提高趋势;(3)生产空间的核密度高值区呈东南-西北条带状,连片分布于研究区的中部,而生态空间的核密度高值区则分布于研究区外围;生活空间的核密度高值区以乌鲁木齐市为中心呈点状分布,周围衍生出许多零碎的中值点,总体分布较为破碎,空间连接性较低。

天山北坡中段放牧草地生态系统功能权衡关系的研究

草地生态系统功能保障着人类的生存发展,是草地畜牧业的重要基础。以天山北坡中段草地为研究对象,设置轻牧(LG),重牧(HG)和禁牧(CK)3种处理,基于野外植被调查和室内分析及高通量测序技术,利用单功能法和平均值法得到草地生产力、土壤碳贮存、土壤养分循环、生物多样性和土壤微生物量5种草地生态系统功能以及生态系统多功能性(EMF),并使用均方根偏差法(RMSE)分析放牧干扰下草地生态系统功能及多功能性之间的权衡关系。结果表明,相较于CK,HG显著降低草地生态系统功能及多功能性(P<0.05)。放牧可以改变生态系统功能之间原有的权衡关系,但土壤养分循环功能与土壤碳贮存功能的权衡关系对放牧响应不敏感。根据多项功能权衡协同分析的结果显示,生态系统功能ERMSD值为LG(E_(RMSD)=0.07)<HG(E_(RMSD)=0.10)<CK(E_(RMSD)=0.12),这意味着在LG处理下的草地生态系统功能间的均衡性和协调性最优。综上,本研究区最适宜放牧强度为LG,有利于最大程度地提高草地生态系统功能间的协同效应。

近60a天山北坡经济带天然径流量时空变化及归因识别

天山北坡经济带地处干旱的亚洲腹地,厘清天然径流量(NR)时空变化及成因对统筹区域发展、维持生态安全至关重要。为此,采用Sen’s斜率估计法、Mann-Kendall趋势检验等分析径流量时空变化,基于Budyko假设的水热耦合平衡方程定量评价降水、潜在蒸散发及下垫面对NR变化的贡献。结果表明:(1)近60a天山北坡经济带NR总体呈显著增加趋势,年变化率0.68mm·a-1。1961—1986年波动较大,1987—2012年波动变小且NR增加明显,2013年后NR显著减少。(2)NR大小与海拔变化在空间上高度叠合,天山北坡经济带西部和南部NR较大,西南部与西北部增长幅度大。(3)NR突变点为1980年与2013年,降水一直是NR变化的主导因素,但下垫面影响不断加大,近60a贡献率从31.5%增至45.5%。(4)2012年前天然径流量主要受降水主导,但不同区域影响不同。2013年,西部、东部与中南部下垫面对径流量的影响已超过降水成为主导因素。研究成果深化了天山北坡经济带NR变化的认识,为天山北坡经济带高质量发展提供科学支撑。

天山北坡城市群高质量测度与障碍因子诊断研究

通过熵权TOPSIS方法,测度2020年天山北坡城市群高质量发展水平,并采用障碍因子模型和耦合协调模型,判定影响高质量发展的障碍因子和城市内部协调度。结果表明:高质量综合得分排名为乌鲁木齐市>克拉玛依市>石河子市>吐鲁番市>五家渠市>昌吉市>阜康市;影响乌鲁木齐市主要障碍因子是建成区绿化覆盖率、每万人图书馆数量、人均城市道路面积、建成区排水管道密度;其余城市的主要障碍因子是进出口贸易额、城市GDP、每万人专利授予量、参加基本养老保险的人数;乌鲁木齐市属于轻度失调,石河子市、克拉玛依市和昌吉市属于严重失调,吐鲁番市、五家渠市和阜康市属于极度失调。天山北坡城市群高质量发展水平与内部耦合协调水平低且呈非均衡的空间分布格局,未来应充分发挥各市的区位、资源和产业优势,着力补齐短板,注重全方位协调发展,提升发展质量。

天山北坡经济带经济韧性与生态韧性的时空耦合

如何平衡经济-生态间的关系,以应对外部扰动和冲击,成为促进区域可持续发展的关键。借鉴韧性理论,构建了生态韧性和经济韧性评价指标体系,基于多源数据,利用耦合协调度模型和核密度方法分析了天山北坡经济带经济韧性与生态韧性的时空耦合特征,并探索了各要素对二者耦合协调度的影响。结果发现:①2000—2020年天山北坡经济带经济韧性总体以中等水平为主,呈现天山北坡“中段>西段>南部>东段”的空间分异特征;②生态韧性则总体处于低水平,呈现“西北高东南低”“低值集聚、高值分散”的空间分布特征;③经济韧性和生态韧性一直处于“失调”状态,但逐渐由轻度失调向濒临失调转变,且西段和中段的耦合协调度高于东段和南部;④经济韧性与生态韧性各要素对耦合协调度的影响存在差异,其中经济潜力韧性和生态系统抵抗力对经济韧性和生态韧性耦合协调关系的阻滞作用最强,经济结构韧性和生态系统恢复力对经济韧性和生态韧性耦合协调关系的推动作用最强。通过时空动态分析和关键影响因素的识别,本研究为可持续发展政策提供了综合视角。平衡这两个方面不仅对该地区当前的稳定至关重要,也是确保其在未来挑战中长期生存的关键所在。

天山北坡典型草地施肥阈值及不确定性分析

在全球气候变化的背景下,干旱半干旱区草地作为陆地生态系统中重要且非常脆弱的组分之一,显现出一系列生态问题。探究气候变化及人类活动对于该区草地生态系统净初级生产力(NPP)的影响,对于合理利用自然资源,保持农牧业可持续发展具有重要的意义。施肥作为促进作物生长的一种方式,合理施肥也可以提高退化草地的NPP。基于此,本研究拟以天山北坡沿海拔梯度分布的4种草地类型:高山草甸(AM)、中山森林草甸(MMFM)、低山干草原(LMDG)和平原荒漠草原(PDG)为研究对象,基于反硝化-分解模型(DNDC)分析该区典型草地生态系统净初级生产力对施加不同氮肥的响应,并揭示施肥阈值及最优施肥方式。结果表明:1)适度氮肥添加促进了各个类型草地生态系统NPP的增长,但草地NPP对施肥量的响应存在阈值,且不存在适用于4种草地类型的统一最优施肥方式。LMDG草地生态系统对施氮肥的响应最敏感。2)PDG草地NPP达到最大的施肥方式为一年分两次施加100 kg·hm^(-2)硝酸盐,NPP的最大值为68.72 g C·m^(-2)·a^(-1)。LMDG草地NPP最大的施肥方式为一年分两次施加尿素260 kg·hm^(-2),NPP的最大值为263.28 g C·m^(-2)·a^(-1)。MMFM草地生态系统达到NPP最大的施肥方式为一年一次施尿素80 kg·hm^(-2),NPP的最大值为171.22 g C·m^(-2)·a^(-1)。无水氨作为在AM草地中反应最好的氮肥,以最小的施肥量(60 kg·hm^(-2))达到了NPP的最大值(114.62 g C·m^(-2)·a^(-1))。3)通过蒙特卡洛不确定分析的结果显示,施肥时间对PDG和LMDG的影响更为明显,施肥量波动对LMDG和MMFM的影响较其他两种草地更为明显。