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利用 PVC顶盖埋管原位培育法测定了北京东灵山地区一个油松纯林和一个油松 -辽东栎落叶阔叶混交林生态系统土壤无机氮库、氮素净矿化 /硝化速率的季节动态以及年度净矿化 /硝化量。结果发现 :1)两个生态系统的土壤无机氮库和氮素净矿化 /硝化速率都存在比较明显且比较一致的季节动态 ,但个别时期也存在较大差异 ;2 )纯林与混交林土壤 NH+ 4 - N浓度在各月都没有显著差异 ,而 NO- 3 - N浓度 ,除了 1995年 11月和 1996年 8月纯林显著高于混交林外 ,其它月份也都差异不显著 ;3)无论是年度净矿化总量 (纯林 ,2 2 .7kg· hm- 2 ;混交林 ,5 5 .5 kg·hm- 2 )及其占总全 N量的百分比 (纯林 ,0 .6 94% ;混交林 ,2 .12 8% ) ,还是年度净硝化总量 (纯林 ,2 6 .7kg· hm- 2 ;混交林 ,44 .6 kg· hm- 2 )及其占总全 N量 (纯林 ,0 .815 % ;混交林 ,1.70 7% )的百分比 ,油松针阔混交林生态系统均显著大于油松纯林 ,高达后者的两倍左右 ,而净硝化氮占净矿化氮的百分比则相反 ,油松纯林 (10 0 % )显著高于油松 -辽东栎混交林 (80 .2 % )。上述结果表明 :油松 -辽东栎针阔混交林生态系统土壤的氮素有效性 (即土壤的供氮能力 )以及维持土壤中植物可利用氮素的能力都显著高于油松纯林。物种构成及在其影响下所产生的林下微?
In situ incubation of PVC top-cap was used to determine the season of soil inorganic nitrogen pool, net nitrogen mineralization / nitrification rate in a pure Pinus tabuleaana forest and a Pinus tabulaeformis-Quercus liaotungensis deciduous broad-leaved mixed forest ecosystem in Beijing Dongling Mountain. Dynamic and annual net mineralization / nitrification. The results showed as follows: 1) There were obvious and consistent seasonal dynamics of soil inorganic nitrogen pools and N net mineralization / nitrification rates in both ecosystems, but there were also significant differences in individual periods; 2) Pure and mixed forests The concentration of NH + 4 - N in soil did not show significant difference in each month, while the concentration of NO - 3 - N was not significantly different in other months except that the pure forests in November 1995 and August 1996 were significantly higher than other mixed forests. ) Both annual net mineralization (pure forest, 27.7 kg · hm-2; mixed forest, 55.5 kg · hm-2) and their percentage of total N (pure forest, 694%; mixed forest, 2.128%), or the annual total amount of net nitrification (pure forest, 26.7 kg · hm-2; mixed forest, 44.6 kg · hm-2) The percentage of N (pure forest, 0.885%; mixed forest, 1.707%) and Pinus tabulaeformis mixed forest ecosystem was significantly higher than that of Pinus tabulaeformis forest, up to twice that of the latter, while the net N On the contrary, the percentage of mineralized nitrogen was significantly higher than that of Pinus tabulaeformis-Quercus liaotungensis (80.2%). The above results show that the availability of nitrogen (ie nitrogen-supplying ability of soil) to Pinus tabulaeformis-Quercus liaotongica coniferous-broad-leaved mixed forest ecosystem is significantly higher than that of pure Pinus tablaeformis forest. Species composition and under the influence of the forest under micro?