施肥对马尾松人工中龄林生物归还的影响

Biological Litterfall of Middle-aged Plantation of Masson Pine After Fertilization

生物归还是森林生态系统中物流和能流过程中的一环 ,对于快速育林具有极为重要的意义。马尾松Ⅰ类主产区枯枝落叶量 1年可达约 50 0 0kg/hm2 ,枯落物中以落叶所占比例最大 ,达75%～ 89% ,枯枝最少。不同时期枯落物多少差异较大 ,但枯枝差别较小 ;落叶每年 1 0月至次年2月间占总落叶量的 60 %多 ,花杂在 4～ 6月最多 ,均极显著差别于其它各个时期。施肥具有显著增加或减少枯落物量的作用 ,其中施N2 P2 K可显著减少落叶量 ,施P3 、N1 P1 、N2 可显著增加花杂量。然而施肥并未显著改变归还的营养元素量。 1年内归还的养分中 (平均值 )N为3 5.0 7kg/hm2 、P为 1 .77kg/hm2 、K为 6.3 6kg/hm2 、Ca为 1 8.3 0kg/hm2 、Mg为 6.99kg/hm2 。各类枯落物中枯枝归还的营养元素量最少 ,落叶最多 ,占归还元素总量的 80 .8%～ 87.6%。

Biological litterfall is a link of material fluxes and energy fluxes in forest ecosystem,which is important for forest fast growing.There was about 5 000 kg/hm 2 of biological litterfall in the Ⅰ 1 field of Masson pine stands every year,in which the percentage of the fallen leaves was the largest to 75%～89%,and branches the least.The amount of litterfall was significantly different in the different periods during one year(branches not involved):① more than 60% of litterfall came from fallen leaves from Oct to Feb(4 months);②flowers in the litterfall in the period of April to June were more than in other months of the year.Fertilization could significantly affect the amount of litterfall.N 2 P 2 K decreased the amount of leaves returned significantly while P 3,N 1P 1,N 2 obviously increased branches returned.The average N,P,K,Ca and Mg returned to soil from litterfall was 35.07,1.77,6.36,18.30 and 6.99 kg/hm 2 respectively .The amount of the elements from the different portions of litterfall was of the great difference.It was up to 80.8%～87.6% of the total amounts of elements from fallen leaves but only less than 20% from withered branches.