甘南亚高寒草甸恢复演替动态及其光合特性研究
发布时间：2019-05-31 22:13
【摘要】：生态恢复是当今人类面对的一个重要课题,尊重自然规律才能使得生态系统在功能上和景观水平上得到真正的恢复。演替是植物生态系统退化和发展的必然途径,演替理论对于解释生态退化及指导生态系统恢复具有很重要的实际意义。植物群落演替主要表现为物种相互替代导致的植物群落在组成、结构和功能方面的变化,而这些变化与植物在不同演替阶段的生理特征是分不开的。光合作用是绿色植物生存和发展的基本保证,演替梯度上植物光合生理特征的变化反映植物对不同生境地的适应机制,相关的研究对于植被恢复具有一定的理论意义。本文利用空间代替时间序列的方法,在甘南亚高寒草甸围封恢复地选取5个典型群落样带,通过样方调查法掌握了各群落物种组成,利用演替的一般规律及PCA排序法分别对5个群落演替阶段进行了定性和定量划分,之后对各群落中优势种及主要物种的一系列光合生理特征值进行了测定,结果表明:1)5个群落演替阶段可以表示为:杂草地→禾草地→豆科地→半灌木群落→灌丛的演替序列。随着演替进行,群落物种丰富度、Shannon多样性指数基本呈增长趋势,而最优种所占的比重在演替前期和后期比中期高。2)草本植物净光合速率(Aarea)、气孔导度(Gs)、蒸腾速率(Tr)、水分及氮素利用效率(WUEPNUE)均大于灌丛植物;叶片氮含量表现为豆科植物杂生草植物禾本科植物;5个群落优势种净光合速率呈单峰模式,峰值为B群落中的披碱草(Elymus dahuricus);PCA分析显示:光合生理特征在演替梯度上的变化大于物种间的差异,植物固定CO2的能力及水分、氮素利用效率随随演替进行呈单峰趋势。3)植物光合特性间有一定的相关性,物种获取物质能力及资源利用效率的指标(Aarea、PNUE、WUE)间,植物蒸腾密切相关的指标(Gs、Tr及WUE)间及净光合速率与叶片氮含量间均存在显著的正相关性;而叶片氮含量与光合氮利用效率间存在显著负相关;其他一些指标间也存在一定的相关关系,SPAD仅与Nmass存在显著正相关而与其他生理特征间的相关性不显著。4)不同结构及组成主要影响群落的养分及可获得光照资源,豆科植物的比重可以提升群落氮养分,但植物叶片氮还受到种间竞争的影响;而不同的群落高度产生了群落获得光照资源的空间异质性。自然状况中,植物的光合生理特征对于不同光照强度及养分条件的响应是不同的,与植物光合生理特征的变化相比,Aarea与Narea的正相关性在总体上和不同群落中却表现的比较稳定。这些结果表明,在恢复演替过程中,群落的结构组成趋于复杂,群落的氮素、水分及光照环境有所变化,物种光合生理特征在物种间及演替阶段间均发生了变化,反映了植物在演替过程中的竞争及适应机制。掌握围封地群落演替过程中的光合生理变化对于亚高寒退化草甸恢复具有一定的理论指导意义。
[Abstract]:Ecological restoration is an important subject faced by human beings nowadays. Only by respecting the laws of nature can the ecosystem be truly restored in terms of function and landscape level. Succession is the inevitable way of plant ecosystem degradation and development. Succession theory is of great practical significance to explain ecological degradation and guide ecosystem restoration. The succession of plant communities is mainly manifested in the changes of composition, structure and function caused by the substitution of species, and these changes are inseparable from the physiological characteristics of plants in different succession stages. Photosynthesis is the basic guarantee for the survival and development of green plants. The changes of plant photosynthetic physiological characteristics on succession gradient reflect the adaptation mechanism of plants to different living conditions, and the related research has certain theoretical significance for vegetation restoration. In this paper, five typical community transect zones were selected from the enclosed restoration site of alpine meadow in South Asia by using the method of space instead of time series, and the species composition of each community was mastered by sample investigation method. The succession stages of five communities were divided qualitatively and quantitatively by using the general law of succession and PCA sequencing method, and then a series of photosynthetic physiological characteristics of dominant species and main species in each community were determined. The results showed that: 1) the succession stages of the five communities could be expressed as the succession sequence of the semi-shrubs community in the legume field. With the succession, the species richness and Shannon diversity index of the community basically showed an increasing trend, while the proportion of the optimal species in the early and late stages of succession was higher than that in the middle stage. 2) the net photosynthetic rate of herbaceous plants, (Aarea), stomatal conductivity (Gs), was higher than that in the middle stage. 2) the net photosynthetic rate of herbaceous plants was increased by (Gs),. The water and nitrogen use efficiency (WUEPNUE) of transpiration rate (Tr), were higher than those of thickets. The nitrogen content in leaves was as follows: leguminous heterophytic grasses, gramineous plants, and the net photosynthetic rate of the dominant species in 5 communities was a single peak, with the peak value of (Elymus dahuricus); in B community. PCA analysis showed that the variation of photosynthetic physiological characteristics on succession gradient was greater than that among species. The ability of plants to fix CO2 and water, nitrogen use efficiency showed a single peak trend with succession. 3) there was a certain correlation between plant photosynthetic characteristics. There were significant positive correlation between plant transpiration index (Gs,Tr and WUE) and net photosynthetic rate and leaf nitrogen content among species acquisition ability and resource utilization efficiency index (Aarea,PNUE,WUE). There was a significant negative correlation between leaf nitrogen content and photosynthetic nitrogen utilization efficiency. There was also a certain correlation between other indexes. SPAD was only positively correlated with Nmass, but not with other physiological characteristics. 4) different structure and composition mainly affected the nutrients and available light resources of the community. The proportion of leguminous plants can increase the nitrogen nutrients of the community, but the nitrogen of plant leaves is also affected by interspecific competition. However, different community heights produce spatial heterogeneity of community access to light resources. In natural conditions, the response of plant photosynthetic physiological characteristics to different light intensity and nutrient conditions is different, compared with the changes of plant photosynthetic physiological characteristics. The positive correlation between Aarea and Narea was stable in general and in different communities. These results showed that in the process of restoration and succession, the structure and composition of the community tended to be complex, the nitrogen, water and light environment of the community changed, and the photosynthetic physiological characteristics of the species changed between species and between succession stages. It reflects the competition and adaptation mechanism of plants in the process of succession. Mastering the photosynthetic physiological changes during the succession of enclosed land community has certain theoretical guiding significance for the restoration of subalpine degraded meadow.
【学位授予单位】：西北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q948
本文编号：2490048
[Abstract]:Ecological restoration is an important subject faced by human beings nowadays. Only by respecting the laws of nature can the ecosystem be truly restored in terms of function and landscape level. Succession is the inevitable way of plant ecosystem degradation and development. Succession theory is of great practical significance to explain ecological degradation and guide ecosystem restoration. The succession of plant communities is mainly manifested in the changes of composition, structure and function caused by the substitution of species, and these changes are inseparable from the physiological characteristics of plants in different succession stages. Photosynthesis is the basic guarantee for the survival and development of green plants. The changes of plant photosynthetic physiological characteristics on succession gradient reflect the adaptation mechanism of plants to different living conditions, and the related research has certain theoretical significance for vegetation restoration. In this paper, five typical community transect zones were selected from the enclosed restoration site of alpine meadow in South Asia by using the method of space instead of time series, and the species composition of each community was mastered by sample investigation method. The succession stages of five communities were divided qualitatively and quantitatively by using the general law of succession and PCA sequencing method, and then a series of photosynthetic physiological characteristics of dominant species and main species in each community were determined. The results showed that: 1) the succession stages of the five communities could be expressed as the succession sequence of the semi-shrubs community in the legume field. With the succession, the species richness and Shannon diversity index of the community basically showed an increasing trend, while the proportion of the optimal species in the early and late stages of succession was higher than that in the middle stage. 2) the net photosynthetic rate of herbaceous plants, (Aarea), stomatal conductivity (Gs), was higher than that in the middle stage. 2) the net photosynthetic rate of herbaceous plants was increased by (Gs),. The water and nitrogen use efficiency (WUEPNUE) of transpiration rate (Tr), were higher than those of thickets. The nitrogen content in leaves was as follows: leguminous heterophytic grasses, gramineous plants, and the net photosynthetic rate of the dominant species in 5 communities was a single peak, with the peak value of (Elymus dahuricus); in B community. PCA analysis showed that the variation of photosynthetic physiological characteristics on succession gradient was greater than that among species. The ability of plants to fix CO2 and water, nitrogen use efficiency showed a single peak trend with succession. 3) there was a certain correlation between plant photosynthetic characteristics. There were significant positive correlation between plant transpiration index (Gs,Tr and WUE) and net photosynthetic rate and leaf nitrogen content among species acquisition ability and resource utilization efficiency index (Aarea,PNUE,WUE). There was a significant negative correlation between leaf nitrogen content and photosynthetic nitrogen utilization efficiency. There was also a certain correlation between other indexes. SPAD was only positively correlated with Nmass, but not with other physiological characteristics. 4) different structure and composition mainly affected the nutrients and available light resources of the community. The proportion of leguminous plants can increase the nitrogen nutrients of the community, but the nitrogen of plant leaves is also affected by interspecific competition. However, different community heights produce spatial heterogeneity of community access to light resources. In natural conditions, the response of plant photosynthetic physiological characteristics to different light intensity and nutrient conditions is different, compared with the changes of plant photosynthetic physiological characteristics. The positive correlation between Aarea and Narea was stable in general and in different communities. These results showed that in the process of restoration and succession, the structure and composition of the community tended to be complex, the nitrogen, water and light environment of the community changed, and the photosynthetic physiological characteristics of the species changed between species and between succession stages. It reflects the competition and adaptation mechanism of plants in the process of succession. Mastering the photosynthetic physiological changes during the succession of enclosed land community has certain theoretical guiding significance for the restoration of subalpine degraded meadow.
【学位授予单位】：西北师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q948
【参考文献】
相关期刊论文 前1条
1 邱扬;张英;韩静;王军;孟庆华;;生态退耕与植被演替的时空格局[J];生态学杂志;2008年11期
，本文编号：2490048
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