【摘要】 荒漠草原经过长期人为、自然等因素的干扰引起原始生境退化、破碎化,形成原生硬质灰钙土斑块并散布在广大沙化土地中,类似岛状的土被结构,我们称之为"土岛"。为研究不同大小"土岛"生境对优势种短花针茅种群空间格局的影响,2016年9月在宁夏盐池县杨寨子村选取大(200～300 m~2)、中(约100 m~2)、小(约50 m~2)"土岛"各3个,共9个"土岛",然后在每个"土岛"上选取一个2 m×2 m样方开展研究。结果表明:1)所有"土岛"上的短花针茅种群均处于老龄衰退阶段,幼龄小苗极少。2)随着"土岛"面积增大,"土岛"内部0～40 cm土层的土壤黏粉粒含量呈现增加趋势(P<0.05),细砂粒含量逐渐减少(P<0.05),土壤有机碳含量在不同土层均有所增加(P<0.05)。3)小"土岛"上的短花针茅种群主要表现为聚集分布,随着"土岛"面积的增大,短花针茅种群的生态对策发生转变,在大、中"土岛"上变成以随机分布为主。4)在各"土岛"上,短花针茅都为优势种,随着"土岛"面积增大,短花针茅种群密度表现为先增加后减小,推测短花针茅的最适"土岛"生境面积大约为100 m~2。此次研究表明,随着"土岛"生境不断缩小,短花针茅种群点格局从随机分布变为聚集分布,种群的生存状况受到极大威胁,说明荒漠草原典型植被的这种原始生境破碎化可能会引起种群的衰退甚至消失。今后在对荒漠草原的原始植被进行保护时,首先应当保障其生境的完整性、连续性,进而保障典型植被种群的规模。更多还原

【Abstract】 Through long-term natural factors and human disturbance, the natural habitats of desert steppe become degradation and fragmentation, forming natural hard sierozem patches which were similar to islands in the extensive sandy desertified land, which were named as"Soil Island". In order to study the influence of different"Soil Island"habitat areas on the spatial pattern of Stipa breviflora, we chose three large"Soil Island"(200-300 m~2), three middle"Soil Island"(about 100 m~2) and three small"Soil Island"(about 50 m~2) habitats,and set one 2 m×2 m sample plot in each"Soil Island"in September 2016. The results showed that: 1) S.breviflora population was in the aging and declining stage in the all of"Soil Island" habitats, with very few young seedlings. 2) With the increase of the area of"Soil Island", the content of clay silts in the 0-40 cm soil layer increased(P<0.05), and the content of fine sand in the 0-40 cm soil layer decreased(P<0.05), and the content of soil organic content(SOC) in different soil layers increased(P<0.05). 3) With the increase of the area of"Soil Island", the ecological strategy of S. breviflora population changed. In the small"Soil Island", the spatial patterns of S. breviflora aggregated mainly. But in the large"Soil Island"and middle"Soil Island", the spatial patterns of S. breviflora were mainly random. 4) In each"Soil Island", S. breviflora was the dominant species.With the increase of the area of"Soil Island", the density of S. breviflora population increased first and then decreased, so we guessed that the optimum area of"Soil Island"habitat was about 100 m~2. In summary, with the continuous reduce of the habitat areas of"Soil Island", the spatial pattern of S. breviflora population changes from a random distribution to an aggregated distribution, and its population size and survival are under great threat, which indicates that the fragmentation of typical vegetation habitat will make population decline or even disappear. In the future, the integrity and continuity of the habitat should be guaranteed first, and then the size of the typical vegetation population could be guaranteed for the protection of the native vegetation of desert steppe.更多还原