Qinling Mountains Fir Forest Community Characteristics, By Type And Productivity Studies

Abies fargesii natural forest, distributed at an altitude of 2450-3300m in the Mount Taibai of the Qingling Mountains, play an important role in water-source preservation, biodiversity conservation, subalpine fragile zone protection and natural forest conservation. The phytocoenological characteristics, stand-type classsification and productivity of Abies fargesii forest based on the investigative data of 41 phytocoenosis plots and 20 biomass plots are quantitatively analyzed. (1) Abies fargesii forest is composed of 221 species which belong to 136 genera and 64 families. There are only 21 eurychoric plant species in the undergrowth along with the living mulch, which cover 9.8%, and the 193 rare species make up the rest, account for 90.2%. (2) According to the features of plants in the shade-frigid ecotope, the plants of Abies fargesii belong to 8 different synusia in Raunkiear's plant life- form system, i.e. mesophonerophytes, microphanerophytes, nanophanerophytes, hemicryptophytes, geophytes, therophytes, the Sphagum teres synusia, and moderate-wet mosses synusia. Abies fargesii forest is classified into 3 types, i.e. shrubs-Abies fargesii stands, herbs-Abies fargesii stands and mosses-Abies fargesii stands in accordance with their synusia characteristics. (3) The a -diverse community features of shrubs-Abies fargesii forest, herbs-Abies fargesii forest and mosses-Abies fargesii forest are respectively studied by means of species richness indicator, Shannon-Wiener inside species diversity indicator and Simpson species dominance indicator as well as Pielou species evenness indicator. The results show that Shannon-Wiener inside species diversity indicator and Pielou species evenness indicator homologize the increasing tendency of community species. However the species dominance indicator dishomologizes the increasing tendency of community species. which means decreasing the indicator value while increasing the numbers of community species. (4) Through cluster analysis shrubs-Abies fargesii stands are classified into 12 stand types based on the similarity of the undergrowth along with the living mulch species. The NMDS ordination of shrubs-Abies fargeii forests indicates that altitude is the major factor affecting the distribution of its stand types, and illumination and site moisture are silmutaneously important factors limiting the distribution. Using cluster analysis, herbs-Abies fargesii communities are differentiated into 9 stand types on the basis of similarity of the living mulch species. The NMDS ordination of herbs-Abies fargesii communities manifests that the distribution of them has a close relation with altitude and site moisture of the communities, in which altitude is the main ecological factor influencing the distribution of stand types. Mosses-Abies fargesii stands are divided by cluster analysis into 5 subtypes based on the similarity of living mulch species. The NMDS ordination of mosses-Abies fargesii stands shows that the distribution of stand types is related with soil depth and site moisture. (5) The biomass and productivity of Abies fargesii stands depend on the stand types, and also on the altitude, slope-facing and soil depth. The accumulated biomass of shrubs-Abies fargesii stands are the highest with the average biomass 331 .47T1hm2 and the average productivity 2.22 T/hm2 a. followed by herbs-Abies fargesii stands with the average biomass 279.27 T/hni and the average productivity 2.54 T/hm2 a, whereas mosses-Abies fargesii stands are the low...