马尾松和青冈凋落物对紫茎泽兰生长的影响

为了探究紫茎泽兰在马尾松林下较多，青冈林下很少的原因。笔者以种子萌发性状参数（发芽率、芽长、根长和鲜重）和幼苗生长性状参数（株高、最大叶面积）为评价指标，野外模拟与室内盆栽研究了2 种林下凋落物覆盖及水浸液对紫茎泽兰种子萌发及幼苗生长的影响。结果表明：（1）马尾松林下覆盖，紫茎泽兰种子发芽和幼苗生长优于无覆盖但不显著；（2）青冈林下覆盖严重抑制种子发芽和幼苗生长；无覆盖对种子发芽率无影响，但对芽后生长和幼苗生长有明显抑制作用；（3）马尾松水浸液对种子发芽和幼苗生长基本无影响，青冈水浸液除种子发芽率外对其他指标都具有极显著抑制作用。紫茎泽兰密度差异显著的原因：马尾松林下松针凋落物覆盖保湿效果好、透气性好，凋落物分解提供了适宜的紫茎泽兰生长的土壤养分，青冈阔叶凋落物覆盖透气性差，凋落物分解释放出抑制紫茎泽兰生长的化感物质。

Litters of Pinus massoniana and Quercus glauca: Effect on Eupatorium adenophorum Growth

The paper aims to explore the reason that Eupatorium adenophorum is more under Pinus massoniana forests and less under Quercus glauca forests in field. Taking seed germination parameters (germination rate, bud length, root length and fresh weight) and the seedling growth parameters (plant height, maximum leaf area) as evaluation index, the authors studied the effects of the litter cover and water extract on the seed germination of Eupatorium adenophorum and the growth of its seedlings on the basis of indoor potted tests and field simulation. The results showed that: (1) the influence of the cover under Pinus massoniana forests on the seed germination and the growth of Eupatorium adenophorum seedlings was greater than that of uncover, but with no significant difference; (2) the cover under Quercus glauca forests seriously inhibited the seed germination and the growth of Eupatorium adenophorum seedlings; uncover had no influence on the germination rate but obviously inhibited the growth of the seedlings; (3) the water extract of Pinus massoniana had almost no influence on the seed germination and seedling growth, and the water extract of Quercus glauca intensely inhibited the seed germination and seedling growth except the seed germination rate. The main reasons for the significant density differences of Eupatorium adenophorum under Pinus massoniana forests and Quercus glauca forests are: the needle litter cover of the former can keep soil moisture and permeability and litter decomposition provides soil nutrients suitable for the growth of Eupatorium adenophorum; the broadleaved litter cover of the latter cannot keep permeability and litter decomposition releases allelochemicals that inhibit the growth of Eupatorium adenophorum.