关中—天水经济区生态系统服务的权衡关系

关中—天水经济区是西部大开发规划中提出的需要重点发展的第三个经济区,经济迅速发展的同时带给生态环境巨大压力,因此研究关中—天水经济区的生态系统服务变化以及生态系统服务之间的关系,对经济区的可持续发展具有重要意义。本文测算了2000年至2010年关中—天水经济区的净初级生产力(NPP)、保水量以及土壤侵蚀量——反映狭义上的保土服务功能(减少土壤侵蚀),引入玫瑰图以及生产可能性边界方法研究这三种生态系统服务之间的权衡和协同关系,并对2030年关中—天水经济区的土地利用类型进行情景模拟,在不同情景下研究净初级生产力(NPP)保水以及土壤侵蚀三者的空间分布和相互之间权衡和协同关系。结果表明:NPP与保水之间存在协同关系,NPP的增加会促进保水量的提高,反过来,保水量的增加有利于NPP的积累;NPP与土壤侵蚀以及保水与土壤侵蚀之间为权衡关系,NPP、保水的增长有利于减少土壤侵蚀,增加土壤保持量;保护情景下获得的NPP与保水量最多,土壤侵蚀量最少,是最优的土地利用类型方案,最有利于生态环境;不同情景下NPP与土壤侵蚀以及保水与土壤侵蚀之间也存在权衡关系。     

关中—天水经济区路网空间通达性分析

通达性是人文地理学、城市与区域规划、交通运输经济学等学科的研究热点之一。随着应用需求的持续加大和技术研究的不断深入,通达性测度方法和度量体系正在逐步完善。以关中—天水经济区交通路网为例,本文试图将城市、交通和区域结合起来全面阐述区域通达性。采用空间句法模型、可达性相关指标和等时圈通过特征点算法,多视角综合测度经济区路网通达性的空间格局。研究结果表明：①区域路网体系较为完善,路网线段集聚明显;线段式空间伸展格局呈＂点—轴＂状发散,轴线式空间伸展格局呈＂干—枝＂状发散,初步形成核心圈、中间圈、外围圈三大等级圈层以及＂米＂字型路网骨架,区域交通运输与城镇发展水平表现出较强的共轭协同发展关系。②城镇区域可达性在较大程度上取决于区域中心性和周边路网发达程度,区域路网单中心极化现象比较明显,西安市对整个区域路网的控制作用过于突出。③区域通达度空间分布各异,核心板块连续性较好,外围板块破碎化明显。关中、天水两大梯度板块差异较大,天水与关中通达度中高值区出现断裂。鉴于区域中心偏于西安以西的现实,适度培育杨陵或宝鸡为区域路网的副中心城市;加快关中—天水高等级快速交通建设,推进关中—天水区域一体化进程。     

关中-天水经济区形成基础及空间结构优化

关中-天水经济区是国家西部大开发"十一五"规划中提出的重点建设的经济区之一,由陕西省的西安、咸阳、渭南、铜川、宝鸡、杨凌五市一区和甘肃省的天水市共同组成。经过两省长期的互补互动,各城市之间相互吸引辐射,空间地域毗邻相连,多种基础设施相通对接,从而形成了相对完整的产业带和经济区。从空间结构理论的角度审视,关中-天水经济区还存在核心不强,区内城市等级体系不完善,地区之间产业趋同、关联度弱等明显制约经济区健康发展的因素,因此,需要通过西安、咸阳两地一体化,建立区域副中心和实施大城市发展战略,城市间实施产业的有序转移和扩散等措施,使关中-天水经济区的空间结构进一步得到优化,以产生特有的结构效益。     

基于GIS的关中-天水经济区地形起伏度与人口分布研究

地形起伏度作为影响人口分布的重要因素之一,是人居环境自然评价的一个重要指标,在小尺度人居环境自然评价方面也具有较高的准确性和实际应用价值。基于关中-天水经济区栅格数字高程模型,采用窗口分析等方法,利用ArcGIS软件空间分析模块中的邻域分析,提取了基于栅格尺度的关中-天水经济区地形起伏度,并从比例结构、空间分布和高度特征3个方面系统分析了关中-天水经济区地形起伏度的分布规律及其与人口分布的相关性。研究结果为:①关中-天水经济区的地形起伏度以中低值为主,地形起伏度小于2.4的区域占总面积的96.66%,其中平地比例占总体的32.4%;地形起伏度越高的地区,平地比例越低,反之亦然。②关中-天水经济区的地形起伏度呈现南北高中间低的空间格局,最高值为宝鸡市太白县,最低值为关中平原;经度上的变化规律不是很明显,纬度上的地形起伏度无论从南到北还是从北到南都是先下降后增高的。③随着海拔高度的增加,地形起伏度呈现逐渐升高趋势,但变化幅度不大。④地形起伏度对区域人口分布有较强的影响,关中-天水经济区近90%的人口居住在地形起伏度小于1.5的地区,人口密度与地形起伏度的曲线拟合度非常高。     

Three-dimensional modelling of soil organic carbon density and carbon sequestration potential estimation in a dryland farming region of China

Soil organic carbon density(SOCD) and soil organic carbon sequestration potential(SOCP) play an important role in carbon cycle and mitigation of greenhouse gas emissions. However, the majority of studies focused on a two-dimensional scale, especially lacking of field measured data. We employed the interpolation method with gradient plane nodal function(GPNF) and Shepard(SPD) across a range of parameters to simulate SOCD with a 40 cm soil layer depth in a dryland farming region(DFR) of China. The SOCP was estimated using a carbon saturation model. Results demonstrated the GPNF method was proved to be more effective in simulating the spatial distribution of SOCD at the vertical magnification multiple and search point values of 3.0×10~6 and 25, respectively. The soil organic carbon storage(SOCS) of 40 cm and 20 cm soil layers were estimated as 22.28×10~(11) kg and 13.12×10~(11) kg simulated by GPNF method in DFR. The SOCP was estimated as 0.95×10~(11) kg considered as a carbon sink at the 20–40 cm soil layer. Furthermore, the SOCP was estimated as –2.49×10~(11) kg considered as a carbon source at the 0–20 cm soil layer. This research has important values for the scientific use of soil resources and the mitigation of greenhouse gas emissions.     

Holocene lake carbon sequestration,hydrological status and vegetation change,China

Lakes have received considerable attention as long-term sinks for organic carbon(C) at regional and global scales. Previous studies have focused on assessment and quantification of carbon sinks, and few have worked on the relationship between millennial-scale lake C sequestration, hydrological status and vegetation, which has important scientific significance in improving our understanding of lake C stocks and storage mechanisms. Here, we present a comprehensive study of pollen records, organic geochemical proxies, lake-level records, sediment accumulation rate(SAR) and organic C accumulation rate(CAR) in China since the Holocene. We also include numerical climate classification and lake-level simulations, to investigate variations of lake C sequestration, hydrological status and vegetation during the Holocene. Results indicate that the evolution of lake C accumulation showed an out-of-phase relationship with hydrological status and vegetation in China. Lake C accumulation exhibited an overall trend of increasing from the early to late Holocene in response to gradually increasing terrestrial organic matter input. However, China as a whole experienced the densest vegetation cover in the middle Holocene, corresponding to the mid-Holocene optimum of a milder and wetter climate. Optimal hydrological conditions were asynchronous in China; for example, early Holocene in Asian monsoon dominated areas, and middle Holocene in westerlies controlled regions. Our synthesis indicated that climate change was the main factor controlling the long-term variability in lake C accumulation, hydrologic conditions, as well as vegetation, and human influences were usually superimposed on the natural trends.     

中国荒漠C4木本植物和土壤无机固碳研究回顾与展望

碳是贯穿自然和社会的首要元素之一,碳循环是自然和社会系统的重要纽带。陆地生态系统的自然固碳途径有2种,一种是植物碳同化,另一种是土壤碳同化,人们一直关注植物的有机固碳,对于土壤的无机固碳重视不够。本文回顾了中国荒漠区固碳能力强的C₄木本植物和土壤无机固碳研究进展。通过解剖结构观察、δ¹³C值和气体交换特征全面分析得出,荒漠植物梭梭（Haloxylon ammodendron）和沙拐枣（Calligonum mongolicum）为典型的C₄木本植物,梭梭同化枝有大量的含晶细胞,沙拐枣同化枝有大量的黏液细胞。干旱区荒漠的非生物固碳能力至今缺乏合理解释。通过对戈壁、沙漠和壤质荒漠土壤无机碳密度和碳储量分析,提出了土壤碳同化（soil carbon assimilation）概念,并给出了土壤碳同化途径的3个阶段,解释了土壤无机固碳这一现象;与植物碳同化比较,土壤碳同化是荒漠固碳的主要途径。最后,展望了荒漠C₄木本植物和土壤碳同化的研究方向及对中国2060年前实现碳中和目标的可能贡献。     

土地利用方式对内蒙古典型草地生态系统碳氮固持的影响(英文)

To explore the optimal land-use for soil carbon(C) sequestration in Inner Mongolian grasslands,we investigated C and nitrogen(N) storage in soil and soil fractions in 8 floristically and topographically similar sites which subjected to different land-use types(free-grazing,grazing exclusion,mowing,winter grazing,and reclamation).Compared with free-grazing grasslands,C and N storage in the 0-50 cm layer increased by 18.3%(15.5 Mg C ha-1) and 9.3%(0.8 Mg N ha-1) after 10-yr of grazing exclusion,respectively,and 21.9%(18.5 Mg C ha-1) and 11.5%(0.9 Mg N ha-1) after 30-yr grazing exclusion,respectively.Similarly,soil C and N storage increased by 15.3%(12.9 Mg C ha-1) and 10.2%(0.8 Mg N ha-1) after 10-yr mowing,respectively,and 19.2%(16.2 Mg C ha-1) and 7.1%(0.6 Mg N ha-1) after 26-yr mowing,respectively.In contrast,soil C and N storage declined by 10.6%(9.0 Mg C ha-1) and 11.4%(0.9 Mg N ha-1) after 49-yr reclamation,respectively.Moreover,increases in C and N storage mainly occurred in sand and silt fractions in the 0-10 cm soil layer with grazing exclusion and mowing.Our findings provided evidence that Inner Mongolian grasslands have the capacity to sequester C and N in soil with improved management practices,which were in the order:grazing exclusion > mowing > winter grazing > reclamation.     

关中—天水经济区协调发展进程的社会网络分析

对城市间经济联系的分析能了解区域的协调发展状况.用修正后的引力模型分别计算出关中—天水经济区中6个城市在1999,2002,2005,2008年的经济联系值,采用社会网络分析软件Ucinet对关中—天水经济区各城市间经济联系值进行了网络密度、点的中心度、中心势、凝聚子群、凝聚子群密度、核心—边缘结构等指标分析.结果表明,关中—天水经济区的经济协调发展程度不高,有向着协调发展的趋势.因此,提出了关中—天水经济区早日实现成为全国内陆型经济开发区目标的一些建议.第一,加快推进西成一体化建设,着力打造西安国际化大都市,进一步做大增长极.第二,边缘区域中城市应充分发挥自己的角色,以实现经济区协调发展.第三,经济区内各城市要突破地理位置的束缚,形成网络开发的模式.     

Modeling the effects of land-use optimization on the soil organic carbon sequestration potential

Increasing soil organic carbon (SOC) sequestration is not only an efficient method to address climate change problems but also a useful way to improve land productivity. It has been reported by many studies that land-use changes can significantly influence the sequestration of SOC. However, the SOC sequestration potential (SOCP, the difference between the saturation and the existing content of SOC) caused by land-use change, and the effects of land-use optimization on the SOCP are still not well understood. In this research, we modeled the effects of land-use optimization on SOCP in Beijing. We simulated three land-use optimization scenarios (uncontrolled scenario, scale control scenario, and spatial restriction scenario) and assessed their effects on SOCP. The total SOCP (0–20 cm) in Beijing in 2010 was estimated as 23.82 Tg C or 18.27 t C/ha. In the uncontrolled scenario, the built-up land area of Beijing would increase by 951 km² from 2010 to 2030, and the SOCP would decrease by 1.73 Tg C. In the scale control scenario, the built-up land area would decrease by 25 km² and the SOCP would increase by 0.07 Tg C from 2010 to 2030. Compared to the uncontrolled scenario, the SOCP in 2030 of Beijing would increase by 0.77 Tg C or 0.64 t C/ha in the spatial restriction scenario. This research provides evidence to guide planning authorities in conducting land-use optimization strategies and estimating their effects on the carbon sequestration function of land-use systems.     

关中-天水经济区土地利用变化模拟预测及景观格局动态变化

利用2000年和2010年两期TM影像,应用遥感和GIS技术获取关中-天水经济区2000-2010年土地利用变化数据,对研究区土地利用时空状态进行分析,并借助CA-Markov模型对该地区土地利用变化趋势进行情景模拟,深入分析了10 a来和2020年研究区土地利用变化的数量和空间特征以及由此所引起的一系列生态环境效应,主要表现在：过去10 a来城镇建设用地面积增加迅速,耕地和草地面积则减少,城镇建设用地的扩展是通过占用大量城郊的农田来实现的,通过这10 a间的快速城市化进程看出,研究区的城市扩张和基本农田保护之间已经开始产生矛盾;研究区土地利用实际变迁面积约占全区总面积的24.39%,也就是说全区约1/4的土地在这10 a间都发生了变化,从而反映出人类活动之强烈;未来10 a耕地和草地面积将持续下降,耕地面积的减少速度变快,城镇建设用地面积仍然迅速增加,且主要有耕地和草地转化而来,未来10 a研究区土地利用实际变迁面积约占全区总面积的11.43%。景观指数的分析结果表明了研究区内的景观趋向破碎化、复杂化和均匀化发展,景观的稳定性和抗干扰性减小。     

Tree biomass and soil organic carbon densities across the Sudanese woodland savannah: A regional carbon sequestration study

Mean tree biomass and soil carbon (C) densities for 39 map sheet grids (1° lat. × 1.5° long.) covering the Acacia woodland savannah region of Sudan (10–16° N; 21–36° E) are presented. Data from the National Forest Inventory of Sudan, Harmonized World Soil Database and FAO Local Climate Estimator were used to calculate C densities, mean annual precipitation (MAP) and mean annual temperature (MAT). Above-ground biomass C and soil organic carbon (SOC, 1 m) densities averaged 112 and 5453 g C m⁻², respectively. Below-ground biomass C densities, estimated using root shoot ratios, averaged 33 g C m⁻². Biomass C densities and MAP increased southwards across the region while SOC densities were lowest in the centre of the region and increased westwards and eastwards. Both above-ground biomass C and SOC densities were significantly (p < 0.05) correlated with MAP (r_s = 0.84 and r_s = 0.34, respectively) but showed non-significant correlations with MAT (r_s = −0.22 and r_s = 0.24, respectively). SOC densities were significantly correlated with biomass C densities (r_s = 0.34). The results indicated substantial under stocking of trees and depletion of SOC, and potential for C sequestration. Up-to-date regional and integrated soil and forest inventories are required for planning improved land-use management and restoration.     

根系水分胁迫响应函数对土壤水及作物生长动态和产量模拟影响的研究

为探究根系水分胁迫响应函数对农田水分动态及产量模拟的影响,基于Richards方程和PS123作物生长模型分别进行了土壤水分动态和小麦产量的模拟,对比分析了VG(S型曲线)、MP(凹凸型曲线)及LS(S型曲线)3种水分胁迫响应函数.采用山西省霍泉站(3 a)及潇河站(2 a)的试验资料对模型中的土壤水力特征参数、水分胁...     

关中-天水经济区土地利用变化对净第一性生产力影响测评

净第一性生产力是表现陆地生态过程的关键参数,土地利用变化深刻影响区域的净第一性生产力。选取关中-天水经济区为研究区域,尝试对30 m精度的1980-2011年4期9月份左右Landsat 7的遥感影像以及CASA模型来估算关中-天水经济区的净第一性生产力,并用2011年遥感图像解译获得该年的土地利用数据,以及土地利用变化情况。在此基础上分析土地利用变化对净第一性生产力的影响,并且对关天经济区各县市净初级生产力进行了对比和分析。结果表明：1980-2011年,关中-天水经济区土地利用耕地、林地、居民建筑用地变化明显,南部秦岭山区多为林地与草地,净第一性生产力高达625.37 g C·m-2·a-1,而关中平原与天水地区人口居住区与开垦区净第一性生产力明显下降,最低达47.78 g C·m-2·a-1,人为的开发与利用土地降低了区域的净第一性生产力。所以,要继续施行落实退耕还林政策,控制城镇用地较大速度的扩增,以保持好区域的生态服务功能。     

Estimation of soil organic carbon reservoir in China

The paper respectively adopted physio-chemical properties of every soil stratum from 2473 soil profiles of the second national soil survey. The corresponding carbon content of soils is estimated by utilizing conversion coefficient 0.58. In the second soil survey, the total amount of soil organic carbon is about 924.18×108t and carbon density is about 10.53 kgC/m2 in China according to the area of 877.63×106 hm2 surveyed throughout the country. The spatial distribution characteristics of soil organic carbon in China is that the carbon storage increases when latitude increases in eastern China and the carbon storage decreases when longitude reduces in northern China. A transitional zone with great variation in carbon storage exists. Moreover, there is an increasing tendency of carbon density with decrease of latitude in western China. Soil circle is of great significance to global change, but with substantial difference in soil spatial distribution throughout the country. Because the structure of soil is inhomogeneous, it could bring some mistakes in estimating soil carbon reservoirs. It is necessary to farther resolve soil respiration and organic matter conversion and other questions by developing uniform and normal methods of measurement and sampling.     

气候变化情景下中国陆地生态系统碳吸收功能风险评价

气候变化会对陆地生态系统的碳吸收产生影响,从而改变其碳的源汇功能.因此,评估未来气候变化下陆地生态系统碳吸收功能面临的风险,可以为中国应对气候变化措施的制定和国际碳排放谈判提供科学依据.本文采用大气-植被相互作用模型对气候变化情景下净生态系统生产力进行模拟,运用线性倾向估计方法确定碳吸收功能风险评估标准,对中国陆地生态...     

Estimation of soil organic carbon reservoir in China

1 IntroductionResearch on global change has aroused many scientists' attention to the balance, storage and spatial distribution of carbon in the terrestrial ecosystem. The carbon stored in soil is 2.5-3 times as much as that stored in plants[1,2], so the distribution and conversion of carbon in humus has become one of the global research foci on organic carbon at present[3]. Organic carbon and nitrogen contents in soils are not only important components of soils but also the most important eco…     

基于TETIS模型的黑土区乌裕尔河流域径流与侵蚀产沙模拟研究

为科学地认识中国东北黑土区流域土壤侵蚀特征,探讨TETIS模型在该区的适用性,本文以乌裕尔河流域为例,利用1971-1987年日径流与泥沙实测数据对TETIS模型进行了校正与验证,进而分析了流域土壤侵蚀强度特征及其与坡度、土地利用方式的关系。研究结果表明：TETIS模型在乌裕尔河流域适用性好,日径流与日输沙量的纳什效率系数在0.52~0.70之间,决定系数在0.60~0.71之间,体积误差均不超过15%。流域平均侵蚀模数为397.2 t/(km²·a),流域以微度和轻度侵蚀为主,约90%的产沙来自于坡面。平均土壤侵蚀模数随坡度的增大而增大,流域侵蚀量主要来自于0°~5°坡面。不同土地利用方式具不同的土壤侵蚀模数,耕地土壤侵蚀模数最大,达556.3 t/(km²·a)。坡度较大的耕地和植被覆盖度较低的区域是水土流失治理的重点。研究表明,TETIS模型在黑土区模拟土壤侵蚀产沙应用前景好,可为研究区制定水土保持措施提供科学依据。     

A review of soil and water conservation in China

The preservation and sustainable development of soil and water resources is one of the basic principles for the development of China. Throughout the course of history, all the social improvement and economic development are deeply concerned with soil loss and ecological environmental protection. It is now a common sense that soil and water conservation is the safety insurance for national ecology and its development. For the past long period of time, soil and water loss has been recognized as "the No.1 killer" to the ecological environment. The nation is on the stage of the critical conditions for its development. China has massive mountain and upland area with complicated geological conditions and accelerated human destruction and serious soil and water loss. Based on rich historical documents, renovating experience and detailed analysis of the data collected in field experiments and field surveys for soil and water conservation, this paper aims to review the general characteristics of soil and water loss, to explore the relationship between soil and water conservation and sustainable economic development, and to provide relevant strategies for soil and water conservation in China.     

中国水土保持研究回顾

The preservation and sustainable development of soil and water resources is one of the basic principles for the development of China. Throughout the course of history, all the social improvement and economic development are deeply concerned with soil loss and ecological environmental protection. It is now a common sense that soil and water conservation is the safety insurance for national ecology and its development. For the past long period of time, soil and water loss has been recognized as “the No. 1 killer“ to the ecological environment. The nation is on the stage of the critical conditions for its development. China has massive mountain and upland area with complicated geological conditions and accelerated human destruction and serious soil and water loss.Based on rich historical documents, renovating experience and detailed analysis of the data collected in field experiments and field surveys for soil and water conservation, this paper aims to review the general characteristics of soil and water loss, to explore the relationship between soil and water conservation and sustainable economic development, and to provide relevant strategies for soil and water conservation in China.