Diversity Pattern And Coexistence Mechanisim Of Deciduous Broad-leaved Forests In Huangcangyu Reserves Of Anhui Province, East China

As a famous area for vegetation protection in Huaibei Plain, Huangcangyu nature reserve is an ideal place for the study of the vegetation flora and development. This study analysis the structure and dynamics of communities and dominant populations by investigating the floristic composition, structure characteristics and diversity pattern of plant communities at different micro-landform units. It would reveal the differentiation pattern and regeneration of vegetation in this area and clarifies the coexistence mechanisms of plant species. Thus, it would provide the evidence for vegetation conservation and recovery and reconstruction for damaged ecosystem. The main conclusions are as follows:(1) There were81seed plant species belonging to69genera and41families, including1gymnosperm species and69dicotyledonous species belonged to58genera,35families, and11monocotyledon species belonged to10genera,5families.68.49%of the flora was temperate geographical element while31.51%of them were tropical component without considering the cosmopolitan type. Especially the north temperate component was dominated in this area that reflected the characteristics of flora. Besides, it also showed the transitional characteristics in floristic geographical clement due to the common species in subtropical zone such as Tilia miqueliana and Pyrus calleryana which were the principal accompany species in plant community.(2) There were Pistacia chinensis community, Pteroceltis tatarinowii-Quercus variabilis community, Q. variabilis-P. chinensis community, P. tatarinowii community,Q. variabilis-Q. aliena community which can be regard as natural secondary forests in this area. The distribution of these communities presented alternative at different micro-landform units. Pistacia chinensis community and Q. variabilis community mainly distributed on relatively stable habitats while P. tatarinowii community on frequently interference habitats. The artificial Robinia pseudoacacia and Platycladus orientalis forests in the periphery of the mountain were also distributed widely which intruded by deciduous trees such as P. chinensis, Q. variabilis and Firmiana simplex when abandoned management.(3) These dominant populations taken different regeneration strategy to adapt different micro-landform units. The regeneration of P. chinensis populations appeared the shape of single peak type and presents a recession tendency for lack of seedings.Q. variabilis populations presented a development tendency in the P. chinensis community located on the foot slope while a stable tendency on the lower sideslope and crest slope. The population spatial distributions were mainly aggregation type and different diameter individuals were continuity. P. tatarinowii population took a dominant position on river bed and upper sideslope. It presented a growth type development tendency by regenerating through seeding bank and sprouter bank. Different diameter individuals have significant positive correlation in spatial. T. miqueliana and F. simplex recruited through intermittent regeneration.(4) By considering the community development tendency,Q. variabilis population would gradually replace P. chinensis population in P. chinensis community due to the lack of follow-up individuals. And Q. variabilis population would also maintain the stability of community through a small amount of regenerate individuals. As a dominant species, P. tatarinowii occupied advantage position through the trade-off of seeding and sprouteres in P. tatarinowii communities. Otherwise, the other populations maintained population size through intermittence regeneration and became the principal accompany species.(5) Q. variabilis communities can be recognized as the zonal vegetation types in this region by inferring from the community types, distribution area, community dynamics and population regeneration strategies. P. chinensis and P. tatarinowii became the main composition of azonal vegetation due to the characteristics of pioneer species. P. chinensis constitutes the pioneer stage of community succession, but P. tatarinowii constitutes the climax stage of community succession on account for its feature of long lifetime, giant size and strong ability of sprouting. P. tatarinowii is identified as climax-pioneer species and constitutes the topography-climax community on river bed.