Hydrological effects of litter layers in different forest types in the Bashang region
[Objective]This study,with an investigation of the water conservation capacity of litter layers in different forest types in the Bashang region,an important water conservation functional area in the Beijing-Tianjin-Hebei region,is aimed to provide a basis for the restoration,management and improvement of water and soil conservation in this region.[Method]With four types of forests,including Larix gmelinii var.principis-rupprechtii(PL),Betula platyphylla(NP),Populus davidiana and B.platyphylla mixed forest(NBP),L.gmelinii var.principis-rupprechtii and B.platyphylla mixed forest(PBL),selected as research objects in the Heping Forest Farm in Zhangjiakou City,field investigations and indoor immersion methods were employed to measure the ecological hydrological indicators of litter layers.[Result](1)The thickness of litter layers in different forests ranged from 32.0 to 62.0 mm,with the PBL mixed forest having the thickest litter layer,followed by PL forest,NBP mixed forest,and NP forest.(2)The maximum water holding rate,maximum retention rate,and effective retention rate of litter layers were higher in NP forest and NBP mixed forest than PBL mixed forest and PL forest,with NP forest having the highest values of 231.15％,207.60％,and 172.94％,respectively,and PL forest having the lowest values of 208.92％,170.29％,and 138.95％,respectively.(3)The biomass,maximum water holding capacity,maximum retention capacity,and effective retention capacity of litter layers in the four types of forests ranged from 8.27 to 23.33 t·hm-2,18.96 to 49.71 t·hm-2,16.73 to 39.05 t·hm-2,and 13.90 to 31.56 t·hm-2,respectively,and the general trend was PL＞PBL mixed forest＞NBP mixed forest＞NP forest.(4)The water holding capacity of litter layers in the four types of forests showed a logarithmic function relationship with the immersion time(R2＞0.94)while the water absorption rate showed a power function relationship with the immersion time(R2＞0.92).[Conclusion]The water absorption performance of litter layers per unit mass in PL forest was weaker than that in NP forest,but when considering the biomass,the total water holding and retention capacity of PL forest was significantly higher than NP forest,indicating a strong comprehensive water conservation capacity.[Ch,5 fig.3 tab.38 ref.]
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