摘要
对不同封育时间、不同坡向的蒙古栎(Quercusmongolica)林主要乔木树种的分布格局与径级结构进行了分析,结果表明:蒙古栎、黄榆(Ulmuslaciniata)种群均为聚集型分布;蒙古栎和黄榆种群的聚集强度在不同封育时间内表现不同的变化,总体上看种群聚集强度均呈下降趋势.在封育初期,黄榆种群比蒙古栎种群的聚集强度更大,随着封育时间的延长,黄榆种群的聚集强度下降,呈扩散趋势.在封育5年样地内,蒙古栎、糠椴(Tiliamandshurica)和黄榆种群的数量均随着径级的增加而单调下降,表明均为增长型种群;在封育16年以后,由于林内乔木层的盖度较大,糠椴和黄榆种群均呈不同程度的衰退,逐步成为蒙古栎的伴生种群;封育24年样地中蒙古栎种群明显成为优势树种.在阳坡随封育时间延长乔木层盖度增长较快,而阴坡乔木层盖度增长较慢;糠椴和黄榆种群随封育时间延长逐步衰退的现象在阳坡比阴坡表现明显.
The spatial patterns and structures of diameter grades of main arbor populations in Quercus mongolica forest by different aspects and times of forest conservation were studied. The results showed that Q. mongolica and Ulmus laciniata populations were aggregated distribution; they displayed different degrees of aggregation intensity during different times of forest conservation; aggregation intensity of populations inclined as a whole. During initial stages of forest conservation, the aggregation intensity of U. laciniata population was greater than that of Q. mongolica, and the aggregation intensity of U. laciniata population declined and diffused gradually with prolong times of forest conservation. The quantities of Q. mongolica, Tilia mandshurica and U. laciniata populations declined with raising diameter grades on 5 years forest conservation, which indicated they were evolving populations. After 16 years forest conservation, T. mandshurica and U. laciniata populations were retrogressive to some extent for greater coverage in arbor layer and they became associated species of Q. mongolica population. Q. mongolica population became dominant species as a result of 24 years forest conservation. Coverage of arbor layer increased more rapidly on positive slope then on negative slope with longer time of forest conservation. The decline phenomenon of T. mandshurica and U. laciniata populations manifested more clearly on positive slope than on negative slope with longer time of forest conservation.
出处
《华南农业大学学报》
CAS
CSCD
北大核心
2003年第4期17-20,共4页
Journal of South China Agricultural University
