邵阳县石漠化植被恢复湿地松人工林林分结构的研究

Stand structure of Pinus elliottii plantation in rocky desertification area in Shaoyang county,Hunan province

石漠化植被恢复已受到人们的广泛关注。湿地松前期生长快,是湘西南石漠化植被恢复的首选树种之一。以邵阳县石漠化植被恢复湿地松人工林为研究对象,采用随机标准地法对湿地松林分进行调查,分别研究了不同石漠化程度下湿地松人工林的群落结构、胸径和树高结构。结果表明:湿地松人工林林下植被共有21科27种,其中灌木6科,6种,草本15科,21种;3类石漠化程度下湿地松林下植被种类从高到低排序为:轻度(59.0%)>中度(37.0%)>重度(25.9%)。轻度石漠化湿地松林直径分布呈正态分布,生长状况良好,其余两个立地条件下的直径分布不规则,不符合一般人工林径级分布规律。树高分布中,轻度石漠化人工林分布曲线呈正态分布,长势良好;中度石漠化林分树高分布较集中,主要在6～7 m,小树较少;重度石漠化树高分布范围广,且尖峭,树高生长主要受土壤等立地条件的影响,受林分密度的影响较小;中度和重度树高生长呈现散生木的生长特征;立地条件的优劣决定了整个林分的树高和胸径结构。

Vegetation restoration in rock desertification land is attracting people＇s widespread concern. As a pioneer tree species in the southwest of Hunan province, Pinus elliottii grows quickly in the early growth stage. Based on the of sample investigation in standard plots of different rocky desertification degree of P. elliottii forest, theirs community structure, DBH and tree height distribution were compared and analyzed. The results show that there were 27 species of 21 families in the understory vegetation, including 6 shrub species of 6 families and 21 herbaceous species of 15 families; The species ofP. elliottii forests under three different rocky desertification degrees were： slight （59.0%）〉 moderate （37.0%）〉intense desertification （25.9%）; The diameter distribution of slight degree was close to normal distribution which indicated the trees grows well; The diameter distribution of the other two site distributed irregularly and were inconformity with the general diameter distribution of plantation; In the tree height structure, the distribution curve of stand of intense rock desertifieation was similar to diameter distdbution~ The H-distribution of moderate rocky intense desertifieation degree was relatively coneentratedly and mainly distributed between 6 meters and 7 meters with less sapling; The range of H-distribution of moderate rocky desertifieation degree was widely and the curve was very sharp; Tree height was more affected by the site conditions （the soil） than stand density; Trees showed a scattered distribution in the moderate and intense desertification stands; Height and DBH distribution of the study stands were determined by the quality of site conditions.