鼎湖山马尾松林凋落物及其对人类干扰的响应研究

LITTERFALL RESPONSE TO HUMAN IMPACTS IN A DINGHUSHAN PINE FOREST

通过处理 (根据当地习惯收割凋落物和林下层 )和保护 (无任何人类活动 )样地的比较 ,在 3年时间里研究了鼎湖山生物圈保护区马尾松 (Pinus massoniana)林凋落物、养分动态及其对人类干扰的响应。处理和保护样地年平均凋落物总量分别为 :2 .388和 2 .342 t· hm- 2 · a- 1 ,它们主要由针叶组成 (45 .4 %～ 78.8% ) ,皮 +枝占12 .4 %～ 14 .4 % ,杂物 8.6 %～ 4 0 .2 %。凋落物量具有明显的年、季和月变化规律。尽管为人工起源的马尾松林 ,但其凋落物的空间分布很不均匀 (变异系数 >2 2 % )。凋落物中主要营养元素浓度因组分和季节不同而异 ,但总的趋势以杂物和春季的浓度最高。凋落物主要营养元素的归还量亦随季节和组分不同而异 ,其年平均归还总量为 :处理样地 N 15 .85 kg· hm- 2 · a- 1 ,P 0 .6 3kg· hm- 2 · a- 1 ,K 2 .86 kg· hm- 2 · a- 1 ,Ca 6 .0 4 kg· hm- 2 · a- 1 和 Mg1.77kg· hm- 2 · a- 1 ;保护样地 N 16 .2 4 kg· hm- 2 · a- 1 ,P 0 .6 7kg· hm- 2 · a- 1 ,K 2 .6 1kg· hm- 2 · a- 1 ,Ca 5 .4 1kg· hm- 2 · a- 1 和 Mg 2 .0 9kg· hm- 2 · a- 1 。当停止人为干扰后 。

The response of litterfall to human impacts in a Pinus massoniana forest in the Dinghushan Biosphere Reserve was studied in an experiment comparing harvesting (according to local practice) and control (no harvest) plots over a three year period. Annual total litterfall in treatment and control plots was 2 39 and 2 34 t·hm -2 ·a -1 ,respectively. Pine needles accounted for 45 4%-78 8% of total litter, while bark+branches, and miscellaneous mostly reproductive parts components accounted for 12 4%-14 4% and 8 6%-40 2% of the total,respectively. Litterfall exhibited annual,seasonally and monthly variation,and,even though the studied forest was planted,the spatial distribution of litterfall was very uneven. Nutrient concentrations of litterfall also showed strongly seasonal variations depending on variation in the abundance of different components. Nutrient concentrations were generally highest in spring and in the miscellaneous litter type. The annual total nutrient contents of litterfall in treatment and control plots were: N 15 85 kg·hm -2 ·a -1 ,P 0 63 kg·hm -2 ·a -1 ,K 2 86 kg·hm -2 ·a -1 ,Ca 6 04 kg·hm -2 ·a -1 ,Mg 1 77 kg·hm -2 ·a -1 and N 16 24 kg·hm -2 ·a -1 ,P 0 67 kg·hm -2 ·a -1 ,K 2 61 kg·hm -2 ·a -1 ,Ca 5 41 kg·hm -2 ·a -1 ,Mg 2 09 kg·hm -2 ·a -1 ,respectively. After the cessation of human impacts,litterfall quantity and its nutrient content increased. Possible factors regulating litterfall and its nutrient composition are also discussed in the paper.