Analysis On Structure And Quantity Dynamic Of Dominant Population In Different Succession Stages Of Karst Forest In Maolan Nature Reserve

(1)Species dominance and diversity of three succession stages in Maolan Karst forest were studied.The results showed that the total important value of Litsea verticillata Hance was the hightest at early succession stage and the second were followed by Viburnum henryi Hemsl ? Pittosporum crispulum Gagnep ? Machilus rehderi Allen ?Acercinn amomifolium ? Lindera communis Hemsl ? Sinosideroxylon wightianum ?Dendrobenthamia hongkongensis.The total important value of Litsea verticillata Hance was reduced to 44.2% at the middle succession stages,but the total value of Viburnum henryi Hemsl ? Pittosporum crispulum Gagnep ? Machilus rehderi Allen ? Acercinn amomifolium ? Lindera communis Hemsl ? Sinosideroxylon wightianum ?Dendrobenthamia hongkongens reduced to 30.6%,30.6%,19.4%,16.8%,23%,16.8% and 14.3% respectively.The total important value of Litsea verticillata Hance was still the highest at the late succession stage,the total important value of Cyclobalanopsis glauca(Thunb)Oerst ? Sinosideroxylon wightianum ? Dendrobenth amia japonica were more big,there were 29.912,25.266 and 20.33 respectively,but the total important value of Acer sycopseoides Chun?Decaspermum esquirolii and Choerospondias axillaris were lowest and started to decline.The maximum value of Shannon-Wiener index was 0.974,Simpson index was 1.446,ecological dominance index was 0.041 and the richness index of Margalef and Menhinick were 6.675 and 3.686 respectively.The species diversity was slightly lower,structure stability of plant community was weak,the distribution of plants was uneven and most species were seedlings or saplings at the early succession stage.Shannon-Wiener index and Simpson index were lower at early succession stage and they were the second at the middle succession stage,but they were the highest at late succession stage.Shannon-Wiener index and Simpson index were the same change trend with Margalef and Menhinick indexes.(2)For the structure of DBH,the distribution of 0 to 10 meters high level' were the most widely distributed entire succession series.They were mainly with Cinnamomum wilsonii Gamble,Ulmus castaneifolia Hemsl,Platycarya longipes Wu,Machilus rehderi Allen,Ilex latifolia Thunb,Brassaiopsis acuminata Li?Liquidambar formosana Hance?Sorbus pohuashanensis?Boniodendron minus(Hemsl.)T.Chen,etc.;The DBH in 20 to 30 meters height level were Lindera communis Hems?Cyclobalanopsis glauca(Thunb.)Oerst?Acer cinnamomifolium?Clausena dunniana Levl?Carpinus pubescens Burk,etc.,40-100 meters high level mainly were Litsea verticillata Hance ? Dendrobenthamia hongkongensis?Machilus rehderi Allen,etc..The DBH structure was L type including Lindera communis Hemsl ? Ulmus castaneifolia Hemsl ? Acer cinnamomifolium ?Sinosideroxylon wightianum(Hook.et Arn.)Aubr ? Cladrastis platycarpa(Maxim.)Makino;The DBH structure was inverse J type including Clausena dunniana Levl ?Mallotus repandus(Willd.)Muell.Arg?Celtis sinensis Pers;The intermittent type of DBH were mainly Litsea verticillata Hance?endrobenthamia japonica(DC.)Fang var.chinensis?Dendrobenthamia hongkongensis?Cyclobalanopsis glauca(Thunb.)Oerst?Diospyros kaki Thunb?Pittosporum crispulum Gagnep;A single column diameter at breast height structure were Machilus pingii Cheng ex Yang?Acer sycopseoides Chun?Choerospondias axillaris(Roxb.)Burtt et Hill.(3)In this study on static life table analysis to Maolan Karst forest tree species in different succession stages showed that mortality(qx)and disappear rate(kx)of Brachystegia spp ? Sinosideroxylon wightianum ? Machilus rehderi Allen ?Cyclobalanopsis glauca(Thunb)Oerst?Carpinus pubescens Burk,etc.Were downward trend after rising first in the whole succession.The average life expectancy of Litsea verticillata Hance?Brassaiopsis glomerulata var.longipedicellata?Ulmus castaneifolia Hemsl ? Cyclobalanopsis glauca(Thunb)Oerst ? Lindera communis Hemsl ? Clausena dunniana ? Brassaiopsis spinibracteata Hoo ? Machilus rehderi Allen ? Carpinus pubescens Burk,etc.had certain rising or felling trend in the early and mid succession stages,but they were eventually decline at late succession stage.The mortality and disappear rate change trend of Handeliodendron bodinieri?Carpinus turczaninowii Hance?Acercinn amomifolium ? Acer sycopseoides Chun ? Sinosideroxylon wightianum ?Cinnamomum tamala?Bothrocaryum controversum?Celtis sinensis Pers were basically accordant in the whole succession stages.The tree species survival analysis showed that the survival curve of Clausena dunniana?Litsea verticillata Hance?Machilus rehderi Allen were closed to Deevey ?type during the whole succession series.The survival curve of Celtis sinensis Pers,Cladrastis platycarpa Makino,Cyclobalanopsis glauca,Ulmus castaneifolia Hemsl and Lindera communis Hemsl nearly closed to Deevey II type distribution.The survival curve of Brachystegia spp?Brassaiopsis spinibracteata Hoo?Handeliodendron bodinieri?Dendrobenthamia japonica?Sinosideroxylon wightianum?Pittosporum crispulum Gagnep and Bothrocaryum controversum were not regular distribution in three periods of succession.No population were distributed in Deevey I type in the whole succession.(4)The distribution pattern of cluster distribution and congestion of Litsea verticillata Hance ?Lindera communis Hemsl,Dendrobenthamia hongkongensis were the biggest in the early succession stages,distribution pattern of Litsea verticillata Hance and Dendrobenthamia japonica were clumped and congestion were the largest at mid succession stage.The distribution pattern of Lindera communis Hemsl was random distribution in mid-succession stage and was cluster distribution in early and late succession stages.The distribution pattern of Diospyros kaki Thunb and Sinosideroxylon wightianum were nearly poisson's distribution and were cluster distribution at early and late succession stages.The distribution pattern of Celtis sinensis was random distribution at late succession stage and cluster distribution at early and middle succession stages.The distribution pattern of Clausena dunniana was nearly poisson's distribution at early succession stage and was cluster distribution at middle succession stage,but was random distribution at late succession stage.The distribution pattern of Cladrastis platycarpa was random distribution at early succession stage and nearly poisson's distribution at middle succession stage,but was cluster distribution at late succession stage.The distribution pattern of Mallotus repandus was poisson's distribution at early succession stage,was random distribution at middle succession stage and cluster distribution at late succession stage.(5)The dominant populations of tree layer in the three succession stages of Karst forest in Maolan Nature Reserve in Guizhou were studied,Through the typical samples survey,niche breadth and niche overlap of arbor population were calculated by using the Levins and Pianka formula.the results showed that the niche breadth of seven species such as Acercinn amomifolium,Sinosideroxylon wightianum,Cladrastis platycarpa Makino,mallotus repandus,Clausena dunniana,Pittosporum crispulum Gagnep and Machilus rehderi Allen were larger,and they were all appeared in three succession stages.Acercinn amomifolium,Sinosideroxylon wightianum and Cladrastis platycarpa Makino were the dominant species in early succession,mid-succession and late succession stages respectively,and had the highest niche breadths among all species.There were 55 species pairs,niche overlap were much than 0.7 in early succession stage,but there were 98 species pairs in the late succession stage.It indicated that niche overlap were intensify with the community succession.The relation between niche breadths and niche overlap was complex during the succession process.Niche breadths was on a declining curve but niche overlap was on the rise.There were no correlation between them.