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Sichuan Agricultural University (2007)

A Research On The Elevation Patterns Of Species Diversity And Bio-productivity For The Shrub Communities In Arid Valley In The Upper Reach Of Minjiang River

陈泓; Chen Zuo

Titre : A Research on the Elevation Patterns of Species Diversity and Bio-productivity for the Shrub Communities in Arid Valley in the Upper Reach of Minjiang River

Auteur : 陈泓; Chen Zuo

Grade : Master’s Theses 2007

Université : Sichuan Agricultural University

Résumé partiel
This research work focuses on natural shrub communities of Zagunao arid valley, which is the first-grade tributary of the upper reaches of the Minjiang river. This paper intend to find the critical environment factors which influence diversity and production of shrub communities on the basis of analysis of the plant characteristic, minimum species area, elevation patterns of species diversity, elevation patterns of bio-productivity, relationship between species diversity and bio-productivity and correlation between species diversity or bio-productivity and environment factors. This makes a detailed foundation and theoretical basis for vegetation restoration of arid valley region in the upper reach of Minjiang River. The results as follows:1. In this investigation region, there are 107 species of vascular bundle plant, which belong to 41 families and 88 genera separately. There are 45 shrub species, which belong to 20 families and 34 genera separately, and 62 herb species, which belong to 29 families and 56 genera separately. Thetype of plant is poor. There are obviously important families, including Leguminosae, Compositae, Rosaceae and Graminea.With the rising of elevation, the structure characteristic of shrub communities change from arid shrub communities to semi-moist shrub communities, and change from simple to complicated on the basis of analysis of the composition of dominant species, life-form spectrum, species frequency, and so on. It indicates that there is obvious pattern of species replacing along elevation gradients.2. Based on species-area curve, the minimum sampling areas (containing 60~90% species) are determined at different elevations.The sequences among 4 elevation gradients of shrub communities’ minimum species areas (MSA) are 2 165m>1 957m>1 558m>1 750m on north facing slope (NFS) and 2 200m>1 985m>1 578m>1 781m on south facing slope (SFS). The MSA decreases first, and then increases with the rising of elevation. At elevation below 2000 m, the MSA on NFS are larger than that on SFS. However at the elevation around 2200 m, there is no difference among different facing slopes.Hence the MSA are set as 100m 2 (10mxl0m) and 200m 2 (10mx20m) could be satisfied with different precision level, and could reduce the number of sampling plots and work load in field investigating.3. The sequences among 4 elevation gradients ofαdiversity of shrub communities are 2165m>1957m>1558m>1750m on NFS and 2200m>1985m>1578m>1781m on SFS. Theαdiversity decreases first, and then increases with the rising of elevation. The scopes ofαdiversity’s increasing and decreasing between elevation gradients are different. And it shows that : SFS>NFS, herb>shrub. At the elevation around 2200m, herb’sαdiversity on SFS are larger than NFS. Except for that, shrub and herb’sαdiversity on NFS are larger than that on SFS.4. Theβdiversities of shrub and herb between sampling sites at elevation around 1 550m and sampling sites at other elevations in NFS and SFS increase with the rising of elevation. Species and eco—environment have large difference between lower elevation and higher elevation. Between different communities, the species’ similarity decreases, the rate of species’ replacing increases with the rising of elevation.Theβdiversities of shrub between two bordering sampling sites increase first, and then decrease with the rising of elevation on NFS. But theβdiversities of shrub between two bordering sampling sites increase with the rising of elevation on SFS. Theβdiversities of herb between two bordering sampling sites decrease with the rising of elevation on NFS. But theβdiversities of herb between two bordering sampling sites decrease first, and then increase with the rising of elevation on SFS. The shrub species difference is very obvious from elevation 1750m to 1957m on NFS, and is very obvious from elevation 1985m to 2 200m on SFS. The herb species differences are very obvious from elevation 1578m to 1 750m on NFS, and is very obvious from elevation 1985m to 2200m on SFS. In these elevations, the species’ replacing rate is very quick.5. The shrub layer’s biomass takes the absolute proportion in shrub communities on NFS and SFS.

Mots clés : the arid valley in the upper reach of Minjiang River; shrub community; diversity; bio-productivity; elevation graduate; environment factor;

Présentation (CNKI)

Page publiée le 22 avril 2013, mise à jour le 22 octobre 2017