Study On Mathematical Models Of Species Diversity Pattern Of Mountain Flora

The distribution pattern of species richness along the altitudinal gradient and its relationship with environmental factors was one of the hotspots in biodiversity research.In this paper,we selected Wenshan Nature Reserve in the subtropical zone,Taibai Mountain Nature Reserve in the edge of warm temperate zone,and Helan Mountain Nature Reserve in the mid-temperate zone as three study sites.Based on the distribution records of seed plants in the scientific investigation reports of the nature reserves and the digital elevation model(DEM),combined with the energy hypotheses and the information of seed plant flora,the altitudinal patterns of seed plants and their different distribution types(the wide spread,the tropical elements and the temperate elements)were explored.The influences of three energy hypotheses(Currie productivity hypothesis,PHC;water-energy dynamic hypothesis,WED;metabolic hypothesis of ecology,MTE)on species richness patterns were evaluated.The main results were shown as follows:1)The species richness of seed plants and their distribution types in Wenshan Nature Reserve decreased with the increase of altitude.The first-order polynomial regression model of elevation explained a large proportion of the variance in species richness of seed plants,tropical elements and temperate elements(adjust R~2 > 0.9).PHC,WED and MTE explained the altitudinal patterns of species richness of seed plants,tropical elements and temperate elements(adjust R~2 > 0.85).However,the explanatory effect of the three models is slightly weaker(adjust R~2 = 0.65-0.85)in interpreting the altitudinal patterns of wide spread.The reason is that the wide spread has a wide range of ecological adaptation,and made a single model could not explain its altitudinal pattern very well.Compared to the other floristic distribution types,the relative abundance of the tropical elements was most affected by energy in the subtropical zone.2)The species richness of seed plants and their distribution types in Taibai Mountain Nature Reserve decreased with the increase of altitude.The first-order polynomial regression model of elevation explained a large proportion of the variance in species richness of seed plants and their different distribution types(adjusted R~2 > 0.9).PHC,WED and MTE could explain the altitudinal patterns of seed plants and their different distribution types(adjusted R~2 > 0.85).Taibai Mountain was located at the edge of warm temperate zone,and its hydrothermal conditions were more moderate than Wenshan and Helan Mountain,so the results of three energy models were very well.Compared to the other floristic distribution types,the relative abundance of the temperate elements was most affected by energy in the warm temperate zone.3)The species richness of seed plants and their distribution types in Helan Mountain Nature Reserve showed a single peak pattern with altitude distribution.PHC,WED and MTE had better result on the altitudinal pattern in species richness of wide spread than other distribution types(adjusted R~2 > 0.75).Compared to the other floristic distribution types,the relative abundance of the wide spread was most affected by energy in the mid-temperate zone.4)The species richness of Helan Mountain was the least one at the same elevation in the three nature reserves which located in different temperature zones.With the increase of latitude,the species richness of seed plants decreased gradually in three nature reserves,and the relative abundance of temperate elements increased gradually.5)The comparative analyses of all the models indicated that PHC and WED have the effect on the species richness patterns of plants,and WED seem better.Although MTE can explain the altitudinal pattern of plant species richness to some extent,its effect is often not the strongest.The MTE results shown that,the activation energy of seed plants,tropical elements and temperate elements decreased with increasing latitude,but the activation energy of wide spread increased with increasing latitude.The aim of this paper was to study the altitudinal patterns of mountain plants,to explore the effects of the energy hypotheses on these patterns,and to provide the ideas and methods for the future biodiversity research.This study would be useful for understanding the mechnisms behind species richness patterns,biodiversity conservationand vegetation restoration.