黄河三角洲湿地柽柳林生长动态对密度结构的响应特征

The Response Characteristic of Growth Dynamics of Tamarix Chinensis Stand to Density Structure in Wetlands of Yellow River Delta

为了阐明滨海湿地不同密度柽柳(Tamarix chinensis)林的生长动态,探索滨海湿地柽柳林的密度合理性,在黄河三角洲莱州湾南岸的山东昌邑海洋生态特别保护区内,利用标准木树干解析法,对10a生的3种密度(2400株/hm2、3600株/hm2和4400株/hm2)的柽柳林地上生物量、林木生长动态和基径分布特征进行研究。结果表明,3种密度林分的地上生物量、树高生长量和林木基径生长过程差别较大。随着林分密度增大,林木单株生物量和基径减小,但单位面积林分生物量增加;树高、基径的速生期都出现滞后现象。3种密度林分基径分布的偏度系数(SK)差别较大;密度为3600株/hm2林分的SK值为0.085,接近正态分布,林分密度结构和基径分布较为合理;密度为2400株/hm2和4400株/hm2林分的SK值分别为-0.842和0.303,偏离正态分布,林分密度结构不合理。密度为2400株/hm2林分的峰度系数(K)为0.017,林木生长相对整齐;密度为3600株/hm2和4400株/hm2林分的K值相差不大;密度因素对林木分化作用较小。若不考虑10a间的林木间伐利用,该区柽柳人工造林合理的初植密度建议为3600株/hm2(株行距约2.0m×2.0m)。

To discover the growth dynamics and suitable forest density of Tamarix chinensis as coastal protection forest in coastal wetland under different forest density,we carried on the study,which offers references and theory basis for density management of windbreak and sand-fixation forests of T.chinensis in coastal wetlands of der Bohai-golf region.Using trunk analysis method,the aboveground biomass,growth process of tree height and diameter at 30 cm height,and basal diameter distribution characteristics of 10-year-old of T.chinen sis forests were investigated under densities of 2 400 trees/hm 2（lower density）,3 600 trees/hm 2（middle density）and 4 400 trees/hm 2（high density） in National Marine Ecology Special Reserve,Changyi Count of south coast of the Laizhou Bay,Yellow River Delta of China.The results showed that there were distinct differences in the indexes,aboveground biomass,tree height increment,the growth process of basal diameter in three density forest.With the increase of forestry density,the biomass of individual tree and the basal diameter were declined while unit stand biomass was increased.The aboveground biomass of dry weight in individual tree under lower and middle density forests increased 38.48%,4.29%,respectively,which compared with high density forest.The aboveground biomass of dry weight in unit stand under high and middle forests was 1.25 times and 1.08 times,respectively,larger than that of lower forest density,meanwhile the fast growing period of tree height and basal diameter were delayed.With the increase of stand age,the growth rate and annual increment of tree height decreased year by year,meanwhile the annual increment of tree height in middle and high density stand was 0.007 m/a,0.014 m/a,respectively.Using the tree diameter at 30 cm height as an independent variable,the S K of basal diameter distribution had great distinction in three density structures.The S k（was 0.085） of middle density forest approached to normal distribution,the density structure and basal diameter distribution were reasonable.While the S k（was-0.842） of middle density forest and the S k（was 0.303） of high density forest were partial to normal distribution,and the low and heigh density structure were unreasonable.The kurtosis（K） of lower density forest was 0.017,trees growth was relatively tidy and concentrative.Meanwhile,the K of middle and high density forests had little distinction and the density factor had little function to forest polarization.The utilization of double cutting was not considered,the reasonable planting density was 3600 trees/hm^2（proposing the space is 2.0 m×2.0 m）,and could be regarded as the density of initial planting.