基于中国水土保持区划的江苏省植被盖度监测点布局

Layout of vegetation coverage monitoring sites based on the soil and water conservation region in China

植被盖度是土壤侵蚀监测与评价的重要因子。植被空间分异性是影响植被盖度分布的主要因素。以江苏省为研究区,以全国水土保持区划的三级区为控制单元,采用多源数据空间分析、分层抽样和野外调查相结合的方法,分析植被类型、林种与树种的空间分异性,提出植被盖度监测点布局方案。结果表明:1)鲁中南低山丘陵土壤保持区(Ⅲ-4-2t)、黄泛平原防沙农田防护区(Ⅲ-5-3fn)及淮北平原岗地农田防护保土区(Ⅲ-5-4nt)地带性植被为栎类落叶林;江淮丘陵岗地农田防护保土区(V-1-2nt)、江淮下游平原农田防护水质维护区(V-1-1ns)、沿江丘陵岗地农田防护人居环境维护区(V-1-5nr)以及太湖丘陵平原水质维护人居环境维护区(V-1-4sr)北部地带性植被从含有常绿灌木的落叶阔叶林演变为常绿落叶阔叶混交林;V-1-4sr南部地带性植被为常绿阔叶林;2)研究区用材林占53.45%,其次为防护林和经济林,分别占26.06%和13.10%,各水土保持三级区林种、树种的比例结构差异较大,自北向南用材林和防护林由杨树、侧柏等转变为马尾松、杉木、香樟以及以麻栎、栓皮栎、枫香、青冈等为优势树种的阔叶混交林等,经济林由苹果、梨、板栗、银杏等转变为茶、桃、柑橘等;3)基于水土保持三级区林种与树种的空间分异性,以17个县(区)为抽样区获取96个抽样监测点,通过野外调查确定49个植被盖度监测点,涵盖各区划的主要林种与树种。研究结果可为江苏省开展植被盖度监测提供技术支撑,也可为其他区域布设植被盖度监测点提供借鉴。

[Background]Vegetation coverage is an essential factor in monitoring and assessing soil erosion.It is critically impacted by the spatial heterogeneity of vegetation characters such as vegetation types,forest category and tree species.Although remote sensing is considered as an effective way to monitor the dynamic change of vegetation coverage in large area,field survey at fixed monitoring site is still necessary especially for understory vegetation.[Methods]The purpose of this study is to localize a set of vegetation coverage monitoring sites in Jiangsu province.Multi-source data was used including map of vegetation regionalization,map of tree species,map of soil and water conservation,remote sensing images and digital elevation model.Spatial heterogeneity of vegetation characters was analyzed by taking the third-level soil and water conservation regions as the control units.On the basis of this,monitoring sites were sampled through stratified sampling and flitted according to observations through field survey.[Results]1)Ⅲ-4-2t,Ⅲ-5-3fn andⅢ-5-4nt belongs to the warm-temperate deciduous broad-leaved forest,with oak deciduous forest as zonal vegetation.V-1-2nt,V-1-1ns,V-1-5nr and the north V-1-4sr belongs to north-subtropical mixed evergreen and deciduous broad-leaved forest,the zonal vegetation of which changes from deciduous broad-leaved forest with evergreen shrubs to mixed evergreen and deciduous broad-leaved forest.The south of V-1-4sr belongs to the mid-subtropical evergreen broad-leaved forest,with evergreen broad-leaved forest as zonal vegetation.2)Timber forests,shelter forests and economic forests are predominant in the study area.However,the proportion of each forest category and tree species varies among different soil and water conservation regions.From the north to the south,the dominant tree species of timber forests and shelter forests change from Populus spp.and Platycladus orientalis to Pinus massoniana,Cunninghamia lanceolata,Cinnamomum camphora and broad-leaved forest,while the dominant tree species of economic forests change from Malus pumila,Pyrus spp.,Castanea mollissima and Ginkgo biloba to Camellia sinensis,Amygdalus perisica and Citrus reticulata.3)Considering the spatial heterogeneity of forest category and tree species among the third level of soil and water conservation regions,96 monitoring sites were sampled from 17 sampling area.According to field survey,49 vegetation coverage monitoring sites were located,which including the dominant forest categories and tree species in each soil and water conservation region.[Conclusions]Vegetation category,forest category and tree species exhibit significant spatial heterogeneity in Jiangsu Province.The proposed layout of monitoring sites provides a technical support for vegetation coverage monitoring in Jiangsu province.It also provides useful reference for the layout of vegetation coverage monitoring sites in other similar regions.