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

为了对沿海松林进行治理，研究了沿海松林的植被结构、人工林阔叶树种在沙丘上的建立和生长以及树苗对沙埋的耐受性。主要研究结果如下：对鸟取县36个沿海黑松林的植被结构进行了研究。红壤型土壤上的黑松林中常绿阔叶乔木种类较多。相反，沙丘上的黑松林中几乎没有常绿阔叶树。为了探讨常绿阔叶树在沙丘上的适宜建立和生长条件，在沿海沙丘上受松材枯萎病破坏的黑松林周围，在不同的环境条件下，种植了黑松林和东北栲幼苗。很少有幼苗能在树冠缝隙和光秃秃的沙丘上存活。相反，许多幼苗在黑松树冠下存活了下来。青松幼苗的成活率高于东北栗幼苗。黄连木的水分利用效率高于东北栗，这可能影响了两种植物在沙丘上的幼苗存活率差异。以黄松（Pinus thumbergii）、黄松（Machilus thunbergii）和东北栲（Castanopsis cuspidate）幼苗为试验材料，研究了其对砂埋的耐受性。3种树种中，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.