Studies on afforestation of hardwood in Pine forests damaged by pine wilt disease on coastal sand dunes

为治理沿海沙丘黑松林，研究了黑松枯梢病危害区的植被结构、沙丘黑松枯梢病危害区人工阔叶树种的建群与生长以及黑松枯梢病危害区人工阔叶树种苗木对沙埋的耐受性。主要研究结果如下：1.对鸟取县36个黑松枯萎病受害林的植被结构进行了研究。在土壤类型上的黑松林中发现了许多万年青阔叶树种。沙丘上的黑松林中万年青阔叶树种较少.为探讨沙丘万年青阔叶树的适生条件，在滨海沙丘黑松枯萎病危害林周围的几种环境条件下，栽植了红楠和东北锥幼苗。在林隙和裸露沙丘上，很少有幼苗能够存活。相反，许多幼苗在黑松的树冠下存活。结果表明，在相同的造林条件下，红楠幼苗的成活率高于苦槠幼苗。润楠的水分利用效率高于苦槠，这可能影响了两种树种在沙丘上幼苗存活的差异.以白皮松、润楠和东北锥幼苗为材料，研究了其对沙埋的耐性。在3种树种中，白松对沙埋的耐受性最强。

Vegetation structure of coastal black pine forests damaged by pine wilt disease, establishment and growth of planted broad-leaved tree species in black pine forests damaged by pine wilt disease on sand dunes and tolerance of tree seedlings to sand burial were studied in order to manage the black pine forests damaged by pine wilt disease on coastal sand dunes. The main results are as follows.1. Vegetation structure was studied in 36 coastal black pine forests damaged by pine wilt disease in Tottori prefecture. Many evergreen broad-leaved tree species were found in the black pine forests on andsol type soils. On the contrary, few evergreen broad-leaved trees were found in the black pine forests on sand dunes.2. In order to investigate the suitable conditions for the establishment and growth of evergreen broad-leaved trees on sand dunes, seedlings of Machilus thunbergii and Castanopsis cuspidate were planted under several environmental conditions around black pine forest damaged by pine wilt disease on coastal sand dunes. Few seedlings could survive in canopy gaps and on bare sand dunes. Many seedlings, on the contrary, survived under canopy of black pine. Survival rate of Machilus thunbergii seedlings was higher than that of Castanopsis cuspidate seedlings. Water use efficiency of Machilus thunbergii was higher compared with Castanopsis cuspidate, and it was considered that this affect the difference in seedling survival on sand dunes between two species.3. Tolerance to sand burial was investigated using seedlings of Pinus thumbergii, Machilus thunbergii and Castanopsis cuspidate. Among three species, Pinus thumbergii was the most tolerant to sand burial.