摘要
研究了阿拉善荒漠飞播建植的不同密度人工白沙蒿 (Artemisia sphaerocephala)种群的生长、繁殖与土壤水分的关系 ,主要结果是 :(1)不同密度白沙蒿人工种群的生长与繁殖特征存在明显差异 ,它反映在白沙蒿单株地上生物量、根量、生殖枝数和种子产量随着种群密度的增加而下降。 (2 )不同密度白沙蒿种群的存活率明显不同 ,当种群密度超过 3.1株 /m2时 ,个体植物生长发育不良 ,并出现密度制约死亡 (自疏 )现象 ,植株死亡率急剧上升。(3)不同密度白沙蒿草地不同深度土壤含水量存在明显差异 ,特别是 0～ 2 0和 2 0～ 4 0 cm两个土层的土壤含水量随种群密度的增加显著下降 ,与水资源容量相适应的白沙蒿种群密度约为 2 .1株 /m2 ,在该密度下土壤水分含量基本上能够满足白沙蒿的生理生态需水。 (4 )回归分析显示 ,白沙蒿单株地上生物量与0～ 2 0和 2 0～ 4 0 cm的土壤含水量呈显著正相关 ,而与 4 0 cm以下土层的土壤含水量无显著相关性 ,表明白沙蒿种群的生长主要受 0～ 4 0
At the southeastern edge of Tengger Desert in Inner Mongolia of northern China, grassland degradation usually occurs primarily due to improper management regimes in fragile environmental conditions. Over the last several decades, most sandy grasslands in this region have turned into shifting, semi-shifting and semi-fixed sandy lands, corresponding to severe, moderate and light degradation. To curb degradation and alleviate the impacts of degradation on environment and human life in this region, the central and local governments have implemented a variety of measures to restore vegetation on degraded grasslands since the mid 1990s. One of these measures is revegetation by planting indigenous shrubs and semi-shrubs (e.g. Artemisia sphaerocephala) through air seedling on severely degraded areas. As a result, artificial communities of A. sphaerocephala have been established in many parts of the Tengger desert. Little is known, however, about the effects of different densities of artificially established A. sphaerocephala communities on patterns of growth and reproduction of the plants in relation to soil water content. In this paper, we examined the patterns of growth and reproduction of artificially established A. sphaerocephala populations with different densities as well as the relationship between standing biomass per plant and soil water content at different depths over the growing season in 2001. Several important conclusions can be drawn from this study. (1) There were striking differences in the patterns of growth and reproduction of A. sphaerocephala plants among populations of different densities, and above-ground biomass, root biomass, number of flowering shoots and seed yield per plant tended to decrease significantly with increasing density of A. sphaerocephala populations. Among the 5 density treatments, greatest values of the above performance measures were found in population with the lowest density of 1.1 plants/m^(2) and lowest values of these measures occurred in population with the highest density of 5.3 plants/m^(2).(2)There was a very low mortality rate of the plants in both the density treatments of 1.1 and 2.1 plants/m^(2) compared with the other treatments. When density of the A. sphaerocephala populations was more than 3.1 plants/m^(2), however, growth and reproduction of the plants were significantly limited and their mortality rate increased greatly.(3)There were also large differences in soil water contents at different depths among density treatments. This is particularly the case for soil water contents at the depths of 0～20和20～40cm decreasing significantly with increasing density of the population. The optimal density of A. sphaerocephala populations was found to be approximately 2 plants/m^(2), because of greatest growth and reproduction of A. sphaerocephala plants in this density treatment. (4) Regression analyses indicated that standing biomass per plant had a strong positive relationship with soil water content in either the 0～20cm layer or the 20～40cm layer, but the relationship between standing biomass per plant and soil water content at depths below 40cm tended to be much weaker. This suggests that growth and reproduction of A. sphaerocephala plants were strongly related to soil water conditions within the 40cm layer.
出处
《生态学报》
CAS
CSCD
北大核心
2004年第5期895-899,共5页
Acta Ecologica Sinica
基金
国家重点基础研究发展规划资助项目 ( G2 0 0 0 0 4870 5 )
国家自然科学基金重点资助项目 ( 3 973 0 10 0 )
国家自然科学基金西部环境研究资助项目计划 ( 90 10 2 0 11)
中国科学院寒区旱区环境与工程研究所创新工程资助项目 ( 2 10 0 97)~~
关键词
白沙蒿
荒漠草地
生长与繁殖
种群密度
灌木
土壤水分
Artemisia sphaerocephala
desert steppe
growth and reproduction
population density
shrubs
soil moisture
