半干旱区荒漠化演变趋势研究*——以科尔沁左翼后旗为例

RESEARCH ON THE EVOLUTION TREND OF DESERTIFITION IN SEMI ARID AREA*——A CASE STUDY OF KEZUOHOUQI COUNTY

关键词:  遥感荒漠化演变趋势土地利用变化半干旱区

Key words:  remote sensing  desertification  evolution trend  land use change  semi arid area

摘要:

［目的］干旱半干旱地区荒漠化防治是该区域关注的重大环境问题，开展荒漠化现状的综合评价和演变趋势研究，可为荒漠化防治提供数据支持和参考。［方法］文章在内蒙古通辽市科尔沁左翼后旗，基于2000年， 2007年和2014年3期的遥感解译数据，选取评价因子，采用熵值法，划分适宜的荒漠化等级，进而对其荒漠化演变趋势进行分析。［结果］（1）研究选择了土壤调整植被指数、地表反照率、氧化铁质量分数、归一化植被指数和地表温度5个评价指标作为荒漠化演变趋势评价因子，对研究区荒漠化状况进行评价，划分为4个级别，即轻度荒漠化，中度荒漠化，重度荒漠化与极重度荒漠化。（2）科尔沁左翼后旗荒漠化状况得到了有效的治理，生态环境较大改善，但整体情况仍然不容乐观，荒漠化防治任务依然艰巨。2014年极重度荒漠化面积占比仅为294%，比2000年减少2506%； 2014年轻度荒漠化，中度荒漠化的面积占比分别为2337%和3565%，比2000增加1194%和1374%。重度荒漠化的占比2000年， 2007年和2014年分别为3865%， 4371%和3804%，未发生显著变化。（3）不同地类的荒漠化程度与演变趋势有所差异，对于各地类的荒漠化程度而言，耕地＞未利用地＞林地＞草地。因而在同等条件，各地类不变的前提下，草地抵御荒漠化的能力最强，耕地相对较弱。［结论］基于研究结果，冬季大风与干旱同季的气候条件和长期过度的放牧和开垦耕地，两者相互叠加是造成荒漠化的主要原因。对于科尔沁左翼后旗后续荒漠化的治理与防范，需要合理进行退耕还林还草工程，加大农业配套设施建设和农业技术升级的投入，将低产耕地和荒地退为草地和林地。

Abstract:

Desertification controlling is a major environmental issue of concern in arid and semi arid regions. Meanwhile, taking the comprehensive evaluation and evolution trend research on desertification can provide data support and reference for desertification combating. Based on the remote sensing interpretation data of 2000, 2007 and 2014 in Kezuohouqi county, Tongliao city, Inner Mongolia, this paper selected certain evaluation factors and adopted the entropy method to classify the appropriate desertification grade and then analyzed the desertification evolution trend. The results showed that: (1) Five evaluation indexes including MSAVI, Surface Albedo, Fe2O3, NDVI and LST were finally selected as the evaluation indicators of desertification evolution trend. Then the desertification status of the study area can be assessed and divided into four grades which were mild desertification, moderate desertification, severe desertification and extremely severe desertification. (2) The desertification status of Kezuohouqi county had been effectively managed, and the ecological environment had been greatly improved. However, the overall situation was still not optimistic and the task of desertification combating was still arduous. In 2014, the proportion of extremely severe desertification was only 2.94%, which was 25.06% lower than that in 2000. In 2014, mild desertification and medium desertification accounted for 23.37% and 35.65%, which increased by 11.94% and 13.74 % respectively. The proportion of severe desertification which did not change significantly was 38.65%, 43.71% and 38.04% in 2000, 2007 and 2014, respectively. (3) The degree of desertification and evolution trend of different land types were different. As for the degree of desertification in various land types, cultivated land>unused land>forest land>grassland. Therefore, under the same conditions and without the land use practice changing, the grassland showed the strongest power to resist desertification. But this ability of cultivated land was relatively weak. Based on the research results, it can be found that the climatic conditions which included gale and drought in the same season, long term excessive grazing and reclamation of cultivated land were the main causes of desertification. In terms of the treatment and prevention of desertification in Kezuohouqi county, it is essential to rationally conduct the project of returning farmland to forests and grasslands, increase the investment of agricultural supporting facilities and agricultural technology upgrading, and change low yield cultivated land and wasteland to grassland and woodland.