黄河流域秦岭主要林分凋落物的水文生态功能

用水量平衡场和收获法研究了秦岭松栎林带主要林型凋落物在生态系统水分循环和营养循环中的功能。26龄锐齿栎林、24龄油松林和24龄华山松林凋落物现存量平均值为17.475t/hm₂,排序为华山松林>油松林>锐齿栎林。3种林分年凋落物平均值为4.179t/hm₂,前者是后二者的1.4倍,但凋落物现存量不及后二者一半。生长季节,3种林分凋落物层蓄留量平均值为44.81mm,占同期大气降水量的4.47%,阔叶林较针叶林高。地面蒸发量及其蒸发率为:无林裸地>阔叶林地>针叶林地,无凋落物覆盖>凋落物覆盖;针叶林地表蒸发季节变化相对稳定,阔叶树的变化较大。3种林分凋落物N、P、K、Ca和Mg含量平均值分别为1.08%、0.07%、0.37%、1.37%和0.21%,锐齿栎林较大,油松林和华山松林则差异不大。凋落物主要营养元素积累量平均值为502.5kg/hm₂,排序为:油松林>华山松林>锐齿栎林。锐齿栎林、油松林和华山松林5种营养元素年吸收量、归还量分别为334.4kg/hm₂和147.2kg/hm₂,195.5kg/hm₂和66.9kg/hm₂及138.8kg/hm₂和80.4kg/hm₂,不同林分营养元素的年吸收量和归还量也存在一定差异。锐齿栎林不仅对林地营养元素要求较高,而且循环较快。

Hydrological and ecological functions of litter layers for main forest-types in Qinling Mts.of Yellow River

By means of standard site-water balance fields and gathering baskets,the main func-tion s of litter layers for3forest-types of the Pine-oak forest belt in Qinling Mts.were examined,the result s are as follows:the average standing crop for sharptooth oak stand at age26,Ar mand pine stand at age24and Chinese pine stand at age24was17.475t/ha in the order of Armand pine>Chinese pine>sharptooth oak stand.The average annual falling litters for the3stands was4.179t/ha,of which the sharptooth oak stand was1.4times as high as the Armand pine or Chi-nese pine stand,but the accumulated litters for the former was less than half of the latter two.During the growth season the average retaining water for the3stands was44.81mm,being4.47% of the corresponding atmospheric precipitation.Among which the amount in broad-leaved stand was higher than in needle-leaved stand and changed with accumulated litters and tree species composition and so on.The orders of woodland evaporation and it's rate are put as naked land>broad-leaved woodland>needle-leaved woodland and naked woodland>litter-covered woodland,the seasonal variation for the woodland evaporation in needle-leaved stand was much more stable than in broad-leaved stand.The average percentage contents of N,P,K,Ca and Mg in the litters for the3stands was1.08,0.07,0.37,1.37and0.21respectively.In general,the average fig ure in sharp tooth oak stand was much higher than in Armand pine and Chinese pine stands,but there was no evident difference between that in Armand pine and Chinese pine stands.The average nutrient accumulated contents of the litters for the3stands was502.5kg/ha in the order of Chinese pine>Armand pine>sharptooth oak stand.The annual nutrient uptake and return of the sharptooth oak,Chinese pine and Armand pine stand were334.4and147.2,195.5and66.9,138.8and80.4kg /ha respectively with difference in the determined elements.The sharptooth oak stand not only required much more nutrient contents,but also had quicker bio-cycling rate than Chinese pine and Armand pine stand.