Malan Forest Liaodong Oak Gap Characteristics And Their Communities

The Loess Plateau is the largest accumulative loess area in the world.It is imperative under the situation to accelerate the recovery and restoration of degenerative ecosystem on the Loess Plateau,because the ecosystem is seriously degraded due to soil and groundwater depletion by human disturbed.Malan forest region,a relative intact natural secondary forest on the Loess Plateau,is important water conversation and ecological availability forest for loess plateau central area.It has crucial effect on adjusting regional climate,maintaining ecological balance and promoting agricultural yield in the north of Shaanxi province.Quercus wutaishanica Blume around Malan forest region,is usually pure forest,and is the first dominant forest community.So the research of Q.wutaishanica forest community regeneration and community structure has significant ecological meaning for recovery and restoration of degenerative ecosystem.In this paper,the whole types of communities and thirty Q.wutaishanica gaps were investigated completely in Malan forest region.The results as follow:1.Quantitative studies on Q.wutaishanica gaps in Malan Forest Area on the Loess Plateau have shown that small gaps(20-40 m~2) and middle gaps(40-60 m~2) were the most numerous.Most of forest gaps' age structures were metaphase and anaphase.The standing die and truncal basal breakage were the most important manner in forest gaps formatting and accounted for 70.31%of total gaps.The numbers of gap border tree mostly were 41-52 a Q.wutaishanica,the forest gap maker were 1-3,which shows the forest gaps were mainly formed by natural disturbance in this area.2.The abundance of Q.wutaishanica seedlings has significant difference between in Canopy and in gaps(P＜0.05),but the abundance of Q.wutaishanica saplings has no significant difference between in canopy and in gaps.The abundance of adult trees supplied later in Q.wutaishanica forest gaps and adult trees in forest canopy have extremely significant difference(P＜0.01).The abundance has extremely significant difference between Q.wutaishanica seedlings and Q. wutaishanica sprouts in gaps(P＜0.01).Between shady slope and sunny slope,the abundance of Q. wutaishanica seedlings has extremely significant difference(P＜0.01);Comparing different within-gap position of shady slope and sunny slope respectively,they all have no significant difference. 3.The abundance of Q.wutaishanica seedlings decreases gradually as increasing of age,and there is a death fastigium at the age grade of 4-8 a and 8-12 a.The abundance of Q.wutaishanica sprouts is relatively stable,and reach a peak at the age grade of 4-8 a and 8-12 a.The regeneration of Q.wutaishanica populations in forest gaps is able to achieve by seedling crops,the special sprouts make Q.wutaishanica forests to be larger sprout populations when regenerating or being disturbed, what makes Q.wutaishanica saplings older to make up quickly,regenerate successfully through bottleneck,which can keep community to be balanced.4.The abundance of Q.wutaishanica seedlings were highly correlated with the area of gap and the mean height of gap border tree(R~2=0.429,P＜0.01),and abundance of saplings were highly correlated with Indirect Site Factor solely(R~2=0.286,P＜0.01).But adults abundance were correlated only with sapling abundance(R~2=0.175,P＜0.05).5.Environmental factors which have significant influence on the composition of plant communities in different layer were selected by forward selection and Monte Carlo tests.The relationship between the distribution pattern of plant communities in different layer and environmental factors was identified by canonical correspond analysis(CCA).Altitude(P=0.042) is the significant factor related to tree layer distribution,and 53%environmental information was extracted from it.Altitude(P=0.024),slope aspect(P=0.028) and mean height of gap border tree (P=0.002) are the significant factors related to shrub distribution,and 62%environmental information was extracted from them.Mean height of gap border tree(P=0.008) is significant factor related to herbage distribution,and 26%environmental information was extracted from it.To sum up,the Q.wutaishanica forest gaps were mainly formed by natural disturbance in Malan Forest Area on the Loess Plateau,its micro-environmental conditions has significant influence on Q.wutaishanica forest community regeneration and community composition.Therefore, by means of thinning or man-made gaps in the process of forest management,we can promote the forest communities regeneration.