中国科学院新疆生态与地理研究所机构知识库

蒸散发作为干旱区农田最敏感的水分支出项，是绿洲生态系统中水量和能量平衡的关键组成部分，而防护林作为干旱区绿洲农田重要的生态屏障，对绿洲农田蒸散发过程有着不可忽视的影响，但农田防护林体系的防护效益不是单条林带的简单叠加，而是整个林网综合作用的结果。因此，传统的小尺度上的观测或模拟难以科学合理的评估农田防护林网对绿洲生态过程的影响，只有在宏观尺度上基于防护林网空间格局进行评价，才能客观揭示不同林网格局的整体效益。 本研究以新疆天山北坡典型流域——三工河流域绿洲为研究区， 以ZY-1 02C 和 Landsat 8 影像为数据源，分别解译了流域的农田防护林和反演了作物生长季三个时期（5 月 25 日、 6 月 26 日和 7 月 12 日）不同作物的日蒸散量， 研究农田防护林网分布格局及其对绿洲蒸散发的影响。 并基于防护林网对农田蒸散量的影响结合合理状态下防护林网的空间格局，对流域防护林网布局进行优化。 结果表明：（1）三工河流域农田防护林在空间上分布不均匀。 防护林网空间格局等级由南至北不断提升。 流域北部兵团农场所辖区域农田防护林网布局相对较好，林网面积充足，林带较为完整，网格成型程度也较高； 位于流域中部的六运湖农场防护林网格局差异较大，既存在布局较好的农田小区，也存在布局较差的农田小区； 而位于流域南部地方政府所辖区域防护林空间格局整体较差。（2） 防护林不仅能够有效降低绿洲农田蒸散量， 而且能够在一定程度上维持蒸散量在较低水平上的相对稳定；在防护林网的格局功能上， 防护林网带斑比指数与农田蒸散量呈极显著负相关（P<0.01），环度指数与农田蒸散量呈显著负相关（P<0.05），而防护林网连接度指数与蒸散量的相关性不明显（P>0.05），说明防护林网的分布密度和林网结构的成型程度对农田蒸散量具有明显的影响，而在网格基本成型的防护林网络中其连通性对蒸散发的影响不明显。在景观水平上研究防护林网格局对蒸散发的影响，对于农田防护林网的规划管理具有一定的参考价值。（3） 防护林网格局指数与农田蒸散量呈现负相关的关系，表明防护林网格局指数越大越能降低农田蒸散量， 因此对于流域绿洲防护林网的规划， 根据兵团防护林网建设标准， 尽可能的增加防护林的面积条带数，保持林带的完整性和闭合程度。

As the most sensitive component of farmland in arid lands, evapotranspiration isthe key component of the balance of water and energy in oasis ecosystems. Andshelterbelt is an important ecological barrier to oasis farmland in arid area, and has anundeniable impact on the evapotranspiration of oasis farmland. But its function is notonly the simple sum of that of the separate belts, it is the result of the interaction ofthe shelterbelt network.The ecological processes of shelterbelt network in arid oasesare so complicated that the observation and modeling at single scale was hard toassess the effects scientifically, and only the observation and modeling at multi-scalescould help toassess the spatial and temporal pattern of the ecological processes ofshelterbelt network objectively. In this study, taking the oasis in the typical watershedof the north slope of the Tianshan Mountains in Xinjiang as an example, and ZY-102Cand Landsat 8 images were used as data sources to interpret the farmland shelterbeltof the basin and the data of different crops in the three periods of crop growth (May25, June 26 and July 12) daily evapotranspiration, studied the distribution patterns offarmland shelterbelts and the impact on oasis evapotranspiration. The results showedthat :(1) The farmland shelterbelts in Sangong river basin are unevenly distributed in space.Shelterbelt spatial pattern level from south to north continuously improve. Thedistribution of farmland shelterbelt in the area under the management of the Corpsfarm in the northern part of the basin is relatively good, the area of the shelterbeltis adequate, the forest belt is more complete, and the degree of grid formation isalso higher. The distribution pattern of the shelterbelt in the six-round lake farmsin the middle part of the basin is quite different, Good farmland, but also thelayout of poor farmland; and located in the southern basin of the local governmentunder the jurisdiction of the overall spatial pattern of shelterbelt overall poor.(2) The shelterbelts can not only effectively reduce the evapotranspiration of oasisfarmland, but also maintain the relatively stable evapotranspiration at a relativelylow level at a certain extent. In the pattern function of the shelterbelts, there was a significant negative correlation between the ratio of belt to patch and theevapotranspiration of shelterbelts (P <0.01), the ring degree and farmlandevapotranspiration were negatively correlated (P<0.05), while the connectivityand evapotranspiration was insignificant（P>0.05） .Showing that the distributiondensity of shelterbelts and the degree of formation of forest network structure hada significant effect on farmland evapotranspiration. However, the connectivity ofthe shelterbelt network with basic grid shape has no obvious effect onevapotranspiration. Studying the impact of shelterbelts pattern onevapotranspiration at the landscape level has some reference value for theplanning and management of farmland shelterbelts.(3) There is a negative correlation between the shelterbelts index of the shelter forestand the evapotranspiration of farmland, indicating that the larger the index of theshelterbelt grid bureau, the more the evapotranspiration can be reduced. Therefore,for the planning of the oasis shelterbelt network, the area of the shelterbelt forestshould be increased as much as possible according to the construction standards ofthe forestry protection forest network. Number of strips to maintain the integrityand closure of the forest belt.