| The Wudalianchi has 14 new and old volcanic geological landforms,with complete preservation,centralized distribution,typical shape and complete types in the worldwhich has unique ecological characteristics of volcanic forest.It is a rare and ideal place to study many scientific problems such as primary succession and volcanic forest ecosystem.Betula Platyphylla is the main positive tree of temperate broad-leaved mixed forests in Northeast China.It is a pioneer species in the three heterogeneous habitats of lava platform(H1),volcanic kipuka(H2)and shankou lake(H3,non volcano),which is gradually weakened by volcanic eruption,and forms a large-area dominant community.It plays an indispensable role in the primary succession of Wudalianchi volcano.However,the systematic experimental research on the adaptability of B.platyphylla in volcanic heterogeneous habitats was rare.Therefore,field investigation and laboratory measurement were used,and the statistical analysis methods of traditional ecology and molecular ecology was used,the study on the phenotypic,physiological,nutritional and epigenetic adaptability of B.platyphylla in kipuka,lava platform and shankou lake to heterogeneous habitats were carried out,and the relationship between module traits and soil factors were analyzed.It can not only reveal the adaptation mechanism of different modules of B.platyphylla,but also explain the impact of special volcanic habitat on the plant adaptation,and for further reveal the divergent adaptive mechanism of plant in heterogeneous habitats,and provide a scientific reference for the study of plant succession and evolution in volcanio The results are as follows:(1)With the weakening of volcanic eruption,the leaf biomass,leaf number,stem biomass,stem length and twig biomass of B.platyphylla increased first and then decreased;lamina length,lamina thickness,leaf dry weight,petiole mass and leaf dry matter content of B.platyphylla decreased,but the specific leaf area increased.The twig biomass and leaf biomass of B.platyphylla showed isokinetic growth in lava platform,while it showed allometric growth in the kipuka and shankou lake.The leaf dry matter content and specific leaf area of B.platyphylla of B.platyphylla in three habitats showed the same growth law,and the same growth index.(2)With the weakening of effect of volcanic eruption,stomatal conductance and water use efficiency of B.platyphylla gradually increased,transpiration rate gradually decreased,and net photosynthetic rate first decreased and then increased.The maximum net photosynthetic rate,dark respiration rate,apparent quantum efficiency,light saturation point,light compensation point,leaf soluble sugar,leaf starch,proline and peroxidase all showed a decreasing trend.Stomatal conductance,chlorophyll a,chlorophyll b,leaf soluble sugar,leaf starch,stem starch,proline,peroxidase and root soluble sugar can be used as the main indexes of physiological characteristics.(3)With the weakening of effect of volcanic eruption,the leaf P content first decreased and then increased,leaf K content,C:P and N:P first increased and then decreased,leaf N content increased and leaf C:N decreased;stem C:N increased first and then decreased;the root N content,root P content and N:P increased first and then decreased,the root C root increased,and root C:N decreased first and then increased.The N content and K content in roots,stems and leaves of B.platyphylla showed the same law in three habitats,which was leaf>stem>root,while C:N was root>stem>leaf.The N contents and C:N,K content and C:N,K content and N:P in different organs showed allometric growth law in three habitats.(4)Methylation-susceptible loci accounted for about two-thirds in epigenetic analysis.With the weakening of effect of volcanic eruption,the number of observed alleles,Shannon index,polymorphic loci and the percentage of polymorphic loci gradually increased.According to the Nei distance of MSAP methylation sensitive locis,the epigenetic distance between lava platform and lava mound B.platyphylla is the largest.The leaf length and lamina mass of phenotypic traits were positively correlated with the number of alleles at each point,the number of effective alleles,Nei's gene diversity index,Shannon index and the percentage of polymorphic loci.(5)With the weakening of effect of volcanic eruption,the soil pH and TP decreased;Soil water content,TN,TN,AP,AK and Mg increased first and then decreased;soil TK and Fe in decreased first and increased.Basidiomycota and Ascomycota in three habitats of were the most dominant fungi groups,and Proteobacteria,Actinobacteria,Acidobacteria,Chloroflexi and Bacteroidetes were the most dominant bacteria groups.Soil TC,TN and AK are the main factors affecting soil fungal and bacterial groups.Soil TN is the main factor affecting soil fungal diversity,and TC is the main factor affecting soil bacterial diversity.(6)Soil water content and AN are the main factors affecting the twig characteristics,soil TN,AP,AN and NN are the main factors affecting the leaf traits of B.platyphylla.Soil water content is the main factor affecting physiological characteristics.Soil WC,TN,TP,TK,AP,AK,AN and NN are the main factors affecting leaf nutritional and stoichiometric characteristics,soil WC and AN are the main factors affecting stem nutritional and stoichiometric characteristics,soil TN,TC and TK are the main factors affecting root nutritional and stoichiometric characteristics.Soil TK is the main factor affecting the effective number of alleles,Nei's gene diversity index,Shannon information index and the percentage of polymorphic loci.This study will provide experimental cases for adaptation and epigenetics of plant in small spatial scale and extremely volcanic habitats.By comparing the differences between plant functional traits and soil characteristics in volcanic habitat,the influence of soil on plant traits were analyzed,which provided scientific thinking for further exploration of plant adaptation mechanism.It provides scientific basis for further study on the succession and evolution of plants in volcanic habitats. |
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