荒漠草原区柠条固沙人工林地表草本植被季节变化特征

研究荒漠草原人工林固沙区地表草本植被季节变化特征及其和柠条林龄的关系,对于分析柠条人工林地表草本植物的季节适应性和制订合理的人工林管理措施均具有重要的科学意义。选择6、15、24年生和36年生柠条人工林为研究对象,通过调查每个样地5月、8月和10月地表草本植物密度、物种数、盖度和高度,分析了荒漠草原区柠条人工固沙林生长过程中地表草本植被季节变化特征及其影响因素。结果表明,地表草本植物物种数在柠条林龄6和15a时受季节改变的影响较小,在24a之后受到季节变化的显著影响(P0.05)。地表草本植物密度在柠条林龄6a时受季节改变的影响较小,但在15a之后季节变化显著影响地表草本植物个体数分布(P0.05),而且在10月具有最多的地表草本植物个体数。地表草本植被盖度和高度均受到季节变化的显著影响(P0.05),而受林龄的影响较小;不同年龄林地地表草本植被盖度和高度均表现为10月和8月较高,5月较低。研究表明,荒漠草原柠条人工林固沙区,柠条林发育生长和灌木形态的改变不仅影响土壤营养条件,而且还可以调控由于季节改变而引起的土壤温湿度变化,柠条林龄和季节更替二者交互作用,共同影响地表草本植被的季节变化特征。

Seasonal changes of ground vegetation characteristics under artificial Caragana intermedia plantations with age in desert steppe

It is a very valuable study on seasonal changes of ground vegetation characteristics under artificially plantations and its relation to stand age in desert steppe. These results will be beneficial to understand the adaptation of ground vegetation under artificial plantations to seasonal changes, and to give rational management on these artificial plantations. An investigation on ground vegetation characteristics including herbaceous plant species richness, density, cover and height, was carried out in May, August and October, in four artificial plantations (C. intermedia) at age of 6, 15, 24 and 36 yeas respectively. The seasonal changes of ground vegetation under artificial plantations during stand development were discussed, together with the related affecting factors. As the results were shown, there were marked different seasonal adaptations of ground vegetation to varying artificial plantations with age. There was a significant impact of seasonal changes on herbaceous plant species richness, not at age of 6 or 15 years but at age of 24 and 36 years (P<0.05). When (at age of 24 and 36 years), herbaceous plant species were significantly lower in May than in October (P<0.01). There was also a significant impact of seasonal changes on herbaceous plant density not at age of 6 years but at age of 15, 24 and 36 years (P<0.05), when there was a significantly higher herbaceous plant density in October than in May (P<0.05). Whiles ground vegetation cover and height were not affected by stand age, but by seasonal changes (P<0.05). There was a significantly higher ground cover and height in October and August than in May (P<0.05), irrespective of stand age. Pearson correlation analysis implied that the main forces were shrub height and basal diameter on herbaceous plant species richness, and shrub morphological characteristics and soil moisture on herbaceous plant density. While soil moisture and temperature with seasonal changes was the main limiting factors on ground vegetation cover and height, respectively. It was suggested that the changing shrub characteristics during stand development not only facilitated soil nutrient conditions, but regulated soil moisture and temperature due to seasonal changes in these artificial plantations. The interaction between stand age and seasonal changes (soil moisture and temperature) co-affected the seasonal dynamics of ground vegetation under artificial plantation in desert steppe.