Effect of gap size, aspect and slope on available light and soil temperature after patch-selection cutting in yellow birch-conifer stands, Quebec, Canada
- 作者：Marcel Pré ; vost ; marcel.prevost@mrnf.gouv.qc.ca ; Patricia Raymond
- 关键词：Solar radiation ; PPFD ; Soil temperature ; Hillslope site ; Patch-selection cutting ; Silvicultural gap
- 刊名：Forest Ecology and Management
- 出版年：2012
- 期刊代码：54_03781127
- 类别：abs
- 出版时间：15 June, 2012
- 卷：274
- 期：Complete
- 页码：210-221
- 文件大小：865 K
摘要
Solar radiation, photosynthetically active radiation (PAR) and soil temperature were monitored during three summers following establishment of silvicultural gaps (1-ha square patch clearcut, 20- and 30-m diameter circular gaps) in yellow birch-conifer stands, in eastern Quebec, Canada (47掳N latitude, 72掳W longitude). We assessed the effect of aspect, slope, opening size, and location within the opening on the microclimate in a foothill site characteristic of this forest type. Daily solar radiation averaged 9.7, 14.3, and 15.1 MJ/m2 in the patch clearcut, in 2001, 2002, and 2003, respectively, as compared to 1.7, 2.2, and 2.8 MJ/m2 in the understory of the uncut forest. We also determined that the ratio of PAR to broadband solar radiation was quite constant in the patch clearcut (1.67 mol/MJ), while it increased from 0.76 mol/MJ (June-September) to 1.49 mol/MJ (October) in the forest understory, as broadleaved trees in the main canopy lost their foliage. Circular gaps received intermediate levels of solar radiation (3.9, 6.3, and 7.3 MJ/m2) that were comparable for the 20- and 30-m gap diameters. Solar radiation was consistently lower in the southern portion of these gaps than in their central and northern portions, a relative shortfall of 40-50%on north-facing aspects, and 25%on east-southeast aspects. This microclimatic diversity among locations was confirmed by PAR measurements and soil temperature monitoring, which suggests that differing ecological niches may promote species coexistence in these mixedwood stands.