关键词: 集约经营, 粗放经营, 杨树人工林, 树冠结构

Abstract:

Crown structure (including vertical distribution of primary branches, crown form, vertical changes of branch inclinations, vertical distribution of leaf area and cumulative leaf area index) of intensively and extensively cultivated poplar plantations were studied here. The results showed that the layer with maximum branch length of trees in intensive management plantation was relatively lower than that of extensive ones. Most trees in intensive management plantation were with coniform crowns, but in extensive management plantation, crown form appeared parabolical cylinder crowns. The distribution pattern of primary branch of trees in intensive management benefit to light interception. Branch inclination angle was also varied significantly with crown length. The estimated LAI by destructive method was 3.0362 m²m^-2 for intensive management plantation, and 2.1786m²m^-2 for extensive management plantation. The CLAI for intensive and extensive management plantations can be simulated by the folowing models: I_CLAI=0.2 607*Z^1.8030e^-0.1643Z(R²=0.9919) and E_CLAI=0.0639*Z^{2.64 80}e^-0.2530(R²=0.9960) . If simulated by the crown length of standard trees in two plantations, the CLAI was 3.1221 m²m^-2 and 2 2619 m²m^-2 for intensive and extensive management plantations, which was only about 2\^8% and 3.8% difference compared with these by destructive method estimations respectively. There were high linear correlation relationship between the standard tree and simulated model for both plantations. The cultivation measures have significant effects on the crown structure. The conical\|shaped crown, large branch inclination and higher CLAI are contributed to the higher productivity for intensive management poplar plantation.

Key words: Intensive management, Extensive management, Poplar plantation, Crown structure