【作者】 张靖乾；

【导师】 张卫国；

【作者基本信息】 兰州大学 ， 草业科学， 2008， 硕士

【摘要】 本文以甘南玛曲县典型的亚高山草甸为研究对象,一方面,在甘南州玛曲县典型高寒草甸区,不同利用频次下草地初级生产力基本特征的变化进行了研究。结果表明:莎草科和禾本科的物种对多次利用的耐受性较高;杂类草对多次利用较为敏感,其中,部分物种甚至会在高频次利用下消失;而毒害草则会在多次利用的干扰下得到促进。在生长季内,对草地实施适度、适法的多次利用(2次或3次)不仅不会对物种多样性造成不利影响,反而有利于物种多样性的提高,相反,若仅于生长季后期(9月中旬)利用1次或利用次数超过4次则可对物种多样性产生明显的负面影响。就地上生物量而言,最佳利用频次为2次(7月15日和9月15日)和3次(6月15日、7月30日和9月15日);就粗蛋白产量而言,最佳利用频次为3次,且显著高于利用2次的处理(16%,P＜0.05)。采用在牧草产量峰值期1次性测产的方法核定草地载畜量,必须考虑在实际利用方式下所产生的草地超补偿效应,并以相应的差异率对牧草产量进行校正。另一方面从群落的季节动态着手,对草地群落初级生产力的变化特征进行了研究,得出以下结论:1)群落在不同的季节动态变化影响到物种的多样性的变化,进而对初级生产力的测定产生较大影响;不同季节物种的多样性呈现近似单峰型增长的态势,所以初级生产力在某一时段的一次测定和估算有待改进,为准确的测定初级生产力提供理论支持;2)群落的物种组成在整个生长季的时间序列中始终处于一个动态变化的过程,因而任何时段的生物量组成都不能准确地反映群落的实际生产水平,即使是在现时物种数最大的时段,仍将有大约10%的物种对整体生物量的直接或间接贡献被忽略;3)在天然群落中,物种多样性,生境异质性和物种间作用关系的复杂性,必然导致种间和种内生长发育阶段在时间上的分异。这种情况对于平衡草地生产力的季节差异,特别是提高有效营养物质的均衡供应水平具有重要的意义。更多还原

【Abstract】 In this paper, changes of basic characteristics of grassland primary productivity under different utilizing frequencies were studied at a typical alpine meadow in maqu county, Gansu province. The results showed that: sedge and gramineous species have higher tolerance to frequent utilization, while forbs are more sensitive to frequent utilization, among which, some species even disappeared under high utilization frequencies, but poisonous species were promoted under frequent disturbances. During the growth season, moderate and frequent utilization (two or three times) in suitable ways to grassland would not cause adverse effects on species diversity, but would favor its increase. In contrast, it would lead to significantly negative effects on species diversity if utilization occurred only once during the late periods of growth season (mid - September) or over four times during the whole growth season. For aboveground biomass, two times (July 15 and September 15) or three times (June 15, July 30 and September 15) were the optimum utilization frequencies, and for output of protein, three times was the optimum utilization way and markedly higher than two times (16%, P < 0.05). Checking stocking capability of grassland in the way of assessing output once at peak period of forage productivity must take account in over-compensation effects produced in practice and revise forage productivity using corresponding variations.In addition ,we also focused on seasonal dynamics of community and studied change characteristics of the primary productivity in grassland community, the results showed that: 1) dynamic changes of communities in different seasons affect the variation of species diversity, further, affecting largely the determination of the primary productivity, species diversity in different seasons presented a growth trend close to single-peak type ,thus the determination and estimate of primary productivity in a period of time need to be improved to provide theory support for accurate determination of the primary productivity; 2) the species composition of communities throughout time series of the whole growing season has always been in a dynamic change process, So the biomass at any time could not accurately reflect the actual production level of community, even when the number of species was the largest, the direct or indirect contribution of about 10 percent of species to the total biomass could be ignored; 3) In natural communities, species diversity, habitat heterogeneity and complexity of interaction relationship among species are bound to lead to temporal differentiation of inter-species / intra-species growth and development stage. This situation has important significance for the balancing seasonal difference of grassland productivity and especially for increasing the balance supply level of available nutrients.更多还原