福建红壤侵蚀区马尾松林4种补植套种模式的水土流失阻控效益

Soil loss control effects of four interplanting modes in the Pinus massoniana stands of red soil erosion area in Fujian province

为筛选有效提升红壤侵蚀区低效马尾松生态林水土保持功能的补植套种阔叶树种,采用布设标准径流小区的方法,定位观测福建长汀红壤侵蚀区4种典型的低效马尾松改造林分,分析不同补植套种林分模式对马尾松林地坡面产流产沙及其养分流失的影响。结果表明:1)在降雨量和降雨次数较多的5—10月,马尾松林补植套种杨梅、无患子、油茶和黄栀子模式的产流量分别比马尾松纯林对照降低24.96%~42.19%、13.93%~53.68%、4.55%~26.45%和8.59%~32.98%;产沙量分别降低60.19%~84.86%、55.07%~87.14%、20.91%~67.06%和27.22%~72.66%;2)马尾松林补植套种杨梅和无患子模式的径流全氮、铵态氮、硝态氮流失量和侵蚀泥沙总碳流失量较接近,分别比马尾松纯林对照增加48.33%~48.79%、103.66%~139.05%、39.75%~42.29%和63.14%~66.57%;马尾松林补植套种油茶和黄栀子模式则分别增加19.96%~22.52%、74.89%~92.62%、15.44%~16.42%和25.24%~28.14%。其他养分流失量总体上与产流产沙的变化规律相似,表现为补植套种模式低于马尾松纯林对照;3)主成分分析表明,马尾松补植套种杨梅或无患子模式林分在降雨径流的作用下,较易引起土壤碳、氮的流失,而马尾松补植套种油茶或黄栀子模式林分则较易引起土壤磷、钾的流失。总体上看,补植套种杨梅或无患子在较短时间内改善低效马尾松林水土流失状况的效果较好。

[Background]The ecological public welfare forests in the south of China are mainly consisted of Pinus massoniana and Cunninghamia lanceolata pure forests.Because of lacking of diversity of vegetation species and simplicity of tree's structure,it is hard to harness the red soil erosion areas where the soil erosion is devastating.This research is aimed to analyze the influence on runoff and sediment and nutrient losses on slope gradient,after low-efficiency P.massoniana forest intercropping different native broad-leaved tree species,and to provide reference for red soil erosion harnessing and tree species selection of low-efficiency P.massoniana forest in similar areas.[Methods]Choosing the similar low-efficiency P.massoniana forests in Changting red soil erosion area of Fujian province and intercropping Myrica rubra,Sapindus mukorossi,Camellia oleifera and Gardenia jasminoides 4 typical reconstructed stands,the undisturbed low-efficiency pure P.massoniana in the same area was used as control.By setting up typical runoff plot we investigated the runoff,sediment yield and nutrient loss characteristics and screened out broad-leaved tree species which have better runoff and sediment reduction.[Results]1)In 2018,the rainfalls in the sample plots mainly occurred in May to October,accounting for 63.7%of the total annual rainfall,and the precipitation and frequency causing runoff and sediment yield accounted for 72.8%and 95.6%in the annual year.2)From May to October the yields of runoffs in 4 P.massoniana modes intercropping M.rubra,S.mukorossi,C.oleifera and G.jasminoides respectively decreased by 24.96%-42.19%,13.93%-53.68%,4.55%-26.45%,and 8.59%-32.98%,compared with the control group of pure P.massoniana forest,and sediment yield decreased by 60.19%-84.86%,55.07%-87.14%,20.91%-67.06%,and 27.22%-72.66%respectively.3)In contrast to the control plots of pure P.massoniana forest,the total nitrogen,ammonium nitrogen,nitrate nitrogen loss and total carbon loss in the erosion sediment of P.massoniana forest interplanting with M.rubra and S.mukorossi were almost similar,respectively increased 48.33%-48.79%,103.66%-139.05%,39.75%-42.29%,and 63.14%-66.57%,however the modes of intercropping C.oleifera and G.jasminoides increased by 19.96%-22.52%,74.89%-92.62%,15.44%-16.42%,and 25.24%-28.14%.In general,the loss pattern of other nutrients was similar to that of runoff and sediment yield,showing that the mode of intercropping was lower than that of pure P.massoniana forest.4)Principal component analysis showed that with the effect on rainfall and runoff,P.massoniana interplanting with M.rubra or S.mukorossi was more likely to cause the loss of soil carbon and nitrogen,while P.massoniana interplanting C.oleifera or G.jasminoides more easily caused the loss of soil phosphorus and potassium.[Conclusions]Low-efficiency P.massoniana forest intercropping indigenous broad-leaved tree species which are suitable for planting,constructing a multi-layer forest structure may result in the biomass increase of litter and root system,to a certain extent it even may improve the reduction of soil erosion on the slope of the low-efficiency P.massoniana forest land.Interplanting M.rubra or S.mukorossi will be more fruitful than that of C.oleifera or G.jasminoides,in the short term.