摘要:我国北方农牧交错带为典型生态脆弱带，对其科学合理的界定对基于资源利用的区域可持续发展具有重要意义。北方农牧交错带界定的最基本条件是水分条件，但是前人的界定均以降水作为水分条件，均没考虑灌溉对农牧交错带形成的影响。本研究在传统界定方法的基础上，增加了灌溉条件订正，以订正后的水分条件作为界定指标，并结合水分变率和干燥度指标，运用模糊综合评判法，对北方农牧交错带进行界定，并进一步结合行政边界进行农牧交错带县域的划分。结果显示，我国北方农牧交错带呈东北—西南走向的带状分布，总面积65.90万km2；北方农牧交错带县（市、旗）共有123个，总面积66.08万km2，分布于北方的9个省（自治区），农牧交错带县数量以内蒙古自治区、山西省和青海省居多，农牧交错带县总面积以内蒙最大。本研究的界定结果在位置上比农业部指定范围略向西北方向偏移，范围上分别向东北和西南扩展，增加了黑龙江、吉林、青海3个省份，去掉了辽宁省；在县域总数上有所减少，黑龙江、吉林、内蒙古、青海的农牧交错带县域（市、旗）总数有所增加，而河北、山西、陕西、甘肃、宁夏的农牧交错带县域（市）总数有所减少；部分位于内蒙河套灌区和宁夏河套灌区的县域被划入。由对农牧交错带水热条件的分析可知，农牧交错带大部分地区的年积温为2000~3500℃，空间上呈中间高，东北、西南低的趋势；大部分地区的水分条件（降水和灌溉）为300~450 mm，空间上沿东南—西北方向递减；大部分地区的表层土壤有机碳含量为0~1%，空间上呈中间低，东北、西南高的趋势。本研究将灌溉指标纳入农牧交错带的界定指标系统，弥补了传统气候界定方法的缺陷，是对农牧交错带界定工作的科学补充和发展，得到的县域尺度的农牧交错带结合农牧交错带水热条件分布研究，可为农牧交错带区域农牧结构调整和精准可持续发展提供科学借鉴。
关键词:中国北方/
农牧交错带/
界定/
灌溉订正/
水分条件/
河套灌区
Abstract:The agro-pastoral ecotone in North China is a typical ecologically fragile zone. Scientific and reasonable definitions are important for the sustainable development of regions based on resource utilization. The water conditions are the most basic conditions to define the agro-pastoral ecotone in North China. Previous studies used precipitation as the water condition and did not consider the impact of irrigation. Based on the traditional method, this study incorporated irrigation corrections and used the corrected water condition, combined with the water variability and dryness indicators and with support of the fuzzy comprehensive evaluation method, to define the agro-pastoral ecotone in North China. Subsequently, this study also combined the administrative boundaries to divide the counties in the agro-pastoral ecotone. The results show that the agro-pastoral ecotone in North China presents a banded distribution in the northeast-southwest direction, with a total area of 659 000 km2. There are 123 counties (cities, banners) in the agro-pastoral ecotone, with a total area of 660 800 km2, distributed across nine provinces (autonomous regions) in North China. The number of counties is highest in the Inner Mongolia Autonomous Region, Shanxi Province, and Qinghai Province, and the total area of the counties is the largest in the Inner Mongolia Autonomous Region. The results of this study shift slightly northwest of the range designated by the Ministry of Agriculture and extend northeast and southwest, respectively, in scope. Three provinces, Heilongjiang, Jilin, and Qinghai, were added, while Liaoning Province was removed. There has been a decrease in the total number of counties. The total number of counties (cities, banners) in the agro-pastoral ecotone in Heilongjiang, Jilin, Inner Mongolia, and Qinghai increased, while the total number of counties (cities) in the agro-pastoral ecotone in Hebei, Shanxi, Shaanxi, Gansu, and Ningxia decreased. Some counties in the Inner Mongolia Hetao Irrigation District and Ningxia Hetao Irrigation District were included. Analysis of the hydrothermal conditions in the agro-pastoral ecotone show that the annual accumulated temperature in most areas is between 2000-3500 ℃, with high temperatures in the middle and low temperatures in the northeast and southwest. The water conditions (precipitation and irrigation) in most areas of the agro-pastoral ecotone are in the range of 300-450 mm, decreasing in the southeast-northwest direction. The content of topsoil organic carbon in most areas is between 0 and 1%, with low values in the middle and high values in the northeast and southwest. This study incorporates irrigation indicators into the definition index system of the agro-pastoral ecotone, which compensates for the shortcomings of the traditional climate definition method and is a scientific supplement to the definition of the agro-pastoral ecotone. The obtained county-scale agro-pastoral ecotone can provide a scientific reference to adjust the agricultural-pastoral structure for precise sustainable development of the agro-pastoral ecotone if combined with the hydrothermal conditions.
Key words:North China/
Agro-pastoral ecotone/
Definition/
Irrigation corrections/
Water condition/
Hetao Irrigation District
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