WSL-Swiss Federal Institute for Forest, Snow and Landscape Research, Zürcherstrasse 111, 8903, Birmensdorf, Switzerland.
Environ Monit Assess. 2011 Mar;174(1-4):47-63. doi: 10.1007/s10661-010-1759-y. Epub 2010 Nov 4.
At Swiss long-term forest ecosystem research sites, ground vegetation was assessed during the period 1994-2003/2008 following two approaches: (1) visual assessment of the cover of species occurring in sixteen 1 m(2) quadrats, distributed over a 43 × 43 m area, and (2) phytosociological relevés in concentric circular plots of 30, 200, and 500 m(2). We first compared the two approaches with respect to diversity assessment. The number of species recorded in the 16 quadrats was in general higher than in the 30 m(2) plot and it represented 42% to 108% of the number of species recorded in the 500 m(2) plot. In a second step, we tested whether any temporal trends were apparent. In a few cases, a decrease or increase in Landolt's mean indicator values for light, nitrogen availability, soil pH, soil moisture, or temperature was found to be significant. However, these changes were usually restricted to one approach or one area. The only clear trend was detected in an unmanaged former coppice beech stand, for which all survey approaches indicated canopy closure. At another site, vegetation reacted to the local opening of the canopy following windthrow. In a third step, we compared the leaf area index (LAI), measured with an LAI-2000 instrument (Licor, Inc.) over each quadrat, with the indicator value of the vegetation for light (L). Within a site, there was no clear relationship between LAI and L values per quadrat. In contrast, across all sites, the relationship between LAI and L, averaged per site for all available years, was highly significant.
在瑞士的长期森林生态系统研究站点，于 1994-2003/2008 年期间采用两种方法评估了地面植被：(1) 在 43×43 m 区域内的 16 个 1 m²样方中，对出现的物种的盖度进行视觉评估；(2) 在 30、200 和 500 m²的同心环形样地中进行植物社会学样方记录。我们首先比较了这两种方法在多样性评估方面的差异。在 16 个样方中记录的物种数量通常高于 30 m²样方，且其记录的物种数量分别占 500 m²样方记录的 42%至 108%。在第二步中，我们测试了是否存在任何时间趋势。在少数情况下，光、氮可用性、土壤 pH 值、土壤水分或温度的 Landolt 平均指示值的下降或增加被发现具有显著意义。然而，这些变化通常局限于一种方法或一个区域。唯一明显的趋势是在一个未管理的前萌生山毛榉林中发现的，所有调查方法都表明树冠闭合。在另一个地点，植被对因风倒而导致的局部树冠开放做出了反应。在第三步中，我们将每个样方上用 LAI-2000 仪器（Licor，Inc.）测量的叶面积指数（LAI）与植被的光指标值（L）进行了比较。在一个站点内，LAI 值与每个样方的 L 值之间没有明显的关系。相反，在所有站点中，LAI 值与平均每个站点所有可用年份的 L 值之间的关系具有高度显著性。
