Soil Seed Bank Research In Different Geochemistry Background In Karst Area

Karst region in Southwest China is one of the biodiversity distributing centers of China. With the ecosystem guadually degenerating, some species exterminate and the biodiversity is being destoried. The study contrasts on characteristics of element geochemistry, soil seed bank reserving , the composition of species diversity in soil seed bank , soil seed bank density, the components of life form and the coefficient of similarity in three kinds of karst environment which are pure limestone, pure dolomite and impure carbonate rock. Main points are as follows:1. Maolan karst area1) By the Shannon-Wiener diversity index computation showing: In Maolan grassland of soil seed bank research, pure dolomite soil seed bank species diversity index > impure carbonate rocks soil seed bank > pure calcareous rock soil seed bank; In Maolan forest soil seed bank research, pure calcareous rock soil seed bank species diversity index > pure dolomite soil seed bank > impure carbonate rocks soil seed bank. This indicated : in the process of vegetation succession, the influence of different geochemistry background to the soil seed bank of different vegetation succession stage are different.2) In Maolan,the main species of soil seed bank herbaceous regardless of whether forest or grassland. .The species compositions of Soil seed bank are consistent with the compositions of early vegetation succession , Moreover in Maolan all kinds soil seed bank reserves size order was: pure calcareous rock soil seed bank sample > impure carbonate rocks sample > pure dolomite rocks sample. The predominant ingredient of soil seed bank in the different succession stage is also different.3)By the Jaccard index showing, In Maolan ,the soil seed band of forest and grassland are the same. The similar coefficient between the pure calcareous rock soil seed bank and the impure carbonate rocks soil seed bank is lowest; The different lothological soil seed bank density order was A > B > C. The seed concentrates on the upper lever; From the top to the down, the number of seeds decrease obviously. But in same lothological soil seed bank, the soil seed bank density of grassland is bigger than the soil seed bankdensity of forest.2. Nongla karst area1)Using the Shannon-Wiener diversity index, in the soil seed bank of grassland researching , in October, pure dolomite soil seed bank species diversity index < impure carbonate rocks soil seed bank < pure calcareous rock soil seed bank. But in May, three kinds of lithological characters soil seed banks diversity index are not very different .In Nongla of the soil seed bank of forest researching, The October of grassland species diversity is bigger than the May, The pure calcareous rock soil seed bank species diversity and the pure dolomite soil seed bank species diversity in the same time in not very different, but They are bigger than the impure carbonate rocks.2)The soil seed bank reserves in secondary forest and the grassland whatever October or May was the impure carbonate rocks > the pure calcareous rock > the pure dolomite. But in May the secondary forest and the lawn of the soil seed bank reserves nearly is bigger than in October, but the grassland impure dolomite soil seed bank in October is bigger than in May. Moreover herb is the predominant species components of soil seed band The superiority ingredient of soil seed bank in different rocks in the different succession stage is also different.3) Using the Jaccard index, in the secondary forest soil seed bank research, the similar coefficient between pure calcareous rocks soil seed bank and the impure carbonate rocks soil seed bank >the similar coefficient between the pure dolomite soil seed bank and the pure calcareous rock soil seed bank >the similar coefficient between the pure dolomite soil seed bank and the impure carbonate rocks soil seed bank; Moreover in the October the similar coefficient of different lithological character soil seed bank is smaller than in the May. Obviously in the same succession stage, the influence of similar coefficient in the soil seed bank of different geochemistry background is similar. In the grassland soil seed bank research, the similar coefficient of October in various lithological characters soil seed bank is bigger than in the May.4) In Nongla the different lothological soil seed bank density order was A > B > C. The seeds concentrate on the upper lever, from the top to the down, the number of seeds decrease obviously. This article about the soil seed bank, generally speaking, with depth deepening, the seed density by 0-2cm, 2cm-5cm, 5cm-10cm gradually reduces. But generally speaking, the grassland in Nongla in October in each lothological soil seed bank density is higher than in May. But in Nongla all lothological soil seed bank density in secondary forest in May is bigger than in October.The above mentioned is needed further study and discussion. But we may draw a conclusion: The karst mountainous region, because of the special hydrography characteristic and the vulnerable ecological environment, after the primary vegetation suffered the destruction, is very difficulty to restore. Some researchs indicated, at present the way that takes natural forest conservation method without man-made-interference, is most economical, the most effective way for the restoration of karst mountainous region vegetation. We must pay attention to matches between the introduction cultivation tree seed and the indigenous plant , enhance ecology function and the benefit of the artificial forest , improve the ecological environment of the local area , protect this local'speculiar plantdiversity.