Studies On Plant Species Diversity And Stand Structural Diversity Of Typical Forest Types And Cutting Effects On Them In Over-logged Forests In Northeastern China

Four typical forest types are selected, which include mixed coniferous andbroad-leaved forests, mixed broad-leaved forests, Mongolian oak forests and OlgaBay Larix plantation in Wangqing forestry bureau Jili province, one representative ofover-logged forest areas in Northeastern China. Plant species diversity, standstructural diversity and cutting effects on them are studied from forest managementaspect. The main methodologies include intrinsic community diversity ordering,variance analysis, Detrended Correspondence Analysis (DCA), Detrended CanonicalCorrespondence (DCCA), canonical correlation analysis and two-way stepwiseregression. The conclusions are as follows: 1 ) Species richness, Shannon index and Simpson index of diversity cangenerally represent the intrinsic diversity among communities. The community withhigh intrinsic diversity has really high diversity. Therefore, community intrinsicdiversity ordering can precisely reflect differences in species diversity of communities.It is suggested that the three indices should be used in sustainable forest management; 2)Diversity of woody species in mixed coniferous and broad-leaved forests is themost intrinsically in the four forest types, and that of Mongolian oak forests is the lest.Mixed broad-leaved forests and Larix plantation are not intrinsically comparable inwoody species diversity. However, grass species diversity in Larix plantation isintrinsically higher than other types; 3)Stand variables which mainly affect understory species diversity in naturalforests are Shannon index of tree species, stand closure and tree numbers per hectare.They are all controllable by forest management. Of the variables, Shannon index oftree species diversity has significant positive correlation with understory speciesdiversity, stand closure and tree numbers per hectare have negative correlation withunderstory species diversity;4) Cultivation cutting is useful for the maintenance and conservation ofunderstory species diversity in mixed coniferous and broad-leaved forests and mixedbroad-leaved forests. Understory species diversity indices are slowly increased afterthinning in Mongolian oak forests, so closing the mountain for afforestation orthinning is recommended for biodiversity conservation;5)Thinning from below with other tree species remained improves the understoryspecies diversity in Olga Bay Larix plantation, but the result is not significantstatistically. Both Shannon index of tree diameter diversity and integrated species anddiameter diversity increase with the years after thinning. But the thinning has nosignificant effects on vertical structural diversity in the 7th year after thinning.However, the distribution pattern of trees significantly changed after thinning. Treesin controls are close to random distribution and that of thinning stands to regulardistribution.