大清河流域山丘区大兰小流域立地分类与评价

Site classification and evaluation of Dalan small watershed in the hilly area of Daqing river basin

为推进“十四五”规划对于白洋淀大清河流域综合治理的实施,以大清河流域上游的大兰小流域为研究对象,通过野外调查和室内试验,选取地形、土壤等8个立地因子,采用相关性分析、主成分分析和ArcGIS叠置分析等方法,筛选出影响立地类型划分的主导因子,划分并制作立地类型图;利用均方差与层次分析法相结合确定指标权重,利用克里金插值将单指标样点数据由点及面,经模糊隶属度对栅格数据标准化后,指标权重叠加形成立地质量等级图。结果表明:1)海拔、坡度、坡向和土壤类型为主导立地因子;2)大兰小流域共划分26种立地类型,以丘陵缓阳坡褐土立地类型为主,占16.37%;3)小流域内无“优”等级立地类型,“良”等级占50.47%,“中”等级占48.48%;“差”等级占1.05%。在“适地适树”原则下营造水源涵养林时,应重视立地类型划分和质量评价,针对不同类型和质量的立地选取适宜的造林树种及空间配置方案,提高林地生产力。

[Background]The Daqing river basin is an important component of the water resource security system in Xiong′an New Area and a key area for governance in the 14th Five-Year Plan.However,due to arid climate and severe soil erosion,the upstream of the basin has experienced flow interruption and frequent river dry-ups,resulting in low vegetation coverage and poor water conservation function.Therefore,comprehensive basin governance is urgently needed,with a focus on providing technical support for“appropriate tree species in appropriate areas”and“scientific forest management”to the upstream water conservation forests.[Methods]The present study was carried out in the Dalan small watershed located in the upper reaches of the Daqing river basin.Through field surveys and indoor experiments,eight site factors,including topography and soil,were obtained for research.By employing correlation analysis,principal component analysis,and ArcGIS overlay analysis,the primary factors that impacted the site type division were identified and site type maps were generated.The index weight was determined using the mean square deviation and analytic hierarchy process.Kriging interpolation was used to convert the sample point data into surface data,which was then standardized using the fuzzy membership method.The site quality grade map was generated by overlaying the index weight using raster calculator,and subsequently,reclassified and graded.[Results]1)Elevation,slope,aspect and soil type are the dominant site factors.2)Dalan small watershed is divided into 26 site types,and the site type of hilly gentle sunny slope cinnamon soil is the main one,accounting for 16.37%.3)There is no“excellent”site in the small watershed,with“good”site types accounting for 50.47%and“medium”site types accounting for 48.48%.The“poor”site type accounts for 1.05%.[Conclusions]When constructing water source conservation forests based on the principle of“suitable land and suitable trees,”attention should be paid to the classification and quality evaluation of the site types.For different types and qualities of sites,appropriate afforestation tree species and spatial allocation schemes should be selected to improve the productivity of forest land.This can provide theoretical guidance for the scientific afforestation of the relatively tree-poor regions in the Beijing-Tianjin-Hebei area in northern China.