中文摘要：

木质的碎片(WD ) 是混合的 Pinus tabulaeformis 承受的天赋的重要部分，并且它影响森林生态系统稳定性和发展。WD 空间模式是能提供卓见进森林动力学的特别重要的结构的特征。在这份报纸， WD 存储， WD 空间模式和 WD，在主要种类之中的协会在西北中国在黄土高原上在自然第二等的森林里被检验。数据被收集在一 1 哈(100 m ??  ??????? 甠獮獵慴湩 'L 敬吗？？

英文摘要：

Woody debris（WD） is an important par of natural Pinus tabulaeformis mixed stands, and i affects the forest ecosystem stability and developmen The WD spatial patterns are especially importan structural characteristics that can provide insights into forest dynamics. In this paper, the WD storage WD spatial patterns and WD associations among the main species were examined in the natural secondary forest on Loess Plateau in northwest China. Data were collected in a 1 ha（100 m × 100 m） permanent plot and all the trees with a diameter at breast height o more than 3 cm were measured and stem-mapped Ripley＇s K functions from the spatial-point-pattern analysis method were used to analyze the spatia distribution and associations. The results showed tha（1） The total storage of WD was 10.73 t/ha, fallen wood was the main source of WD, and the majority diameters were greater than 20 cm, and in intermediate levels of decay;（2） The overall spatia pattern was closely related to the spatial scale, which exhibited an aggregated pattern on a small scale, and a random pattern on a large scale. The spatia patterns of coarse woody debris also gradually transitioned from an aggregated pattern in fine scales to a random pattern in broader spatial scales, which matched the overall spatial pattern. The spatial intensity was gradually decreased with the increasing diameters, and increased with the decomposition classes;（3） The WD of Pinus tabulaeformis species was negatively associated with Betula platyphylla and Populus davidiana on a small scale but positively associated with these species on a large scale. The spatial pattern and interspecies relations were the results of long-term interactions between the natural secondary forest community and the surrounding natural environment. These findings would provide a scientific basis for the sustainable management and protection of natural secondary forest ecosystems on Loess Plateau.