Department of Biological Sciences, Eastern Illinois University, 600 Lincoln Avenue, Charleston, Illinois 61920-3099 USA;
Am J Bot. 2002 Mar;89(3):466-71. doi: 10.3732/ajb.89.3.466.
Forest edges affect many aspects of plant communities, causing changes in microclimate, species composition, and community structure. However, the direct role of edges in regulating forest regeneration is relatively unknown. The pattern of tree establishment across a forest-old field edge was experimentally examined to determine the response of three tree species to the edge gradient. We placed 100 1-m(2) plots in a 90 × 90 m grid that began 30 m inside the forest, extended across the edge, and ended at 60 m into the old field. Into each plot, we planted seeds of Acer rubrum, Acer saccharum, and Quercus palustris. Emergence increased with distance into the field for both A. saccharum and Q. palustris. Emergence for A. rubrum increased from forest to field, reaching a maximum near 20 m into the field, and then declined with further distance. Nearly all A. rubrum seedlings died shortly after emergence. Survival of A. saccharum increased with distance into the old field, while survivorship of Q. palustris did not respond to the edge gradient. Establishment probabilities increased with distance into the old field for both A. saccharum and Q. palustris. Growth of Q. palustris and allocation patterns of A. saccharum also varied across the edge gradient. These results suggest that edges have complex, species-specific effects on tree establishment and growth that can influence the spatial pattern and species composition of regenerating forests.
森林边缘影响植物群落的许多方面，导致微气候、物种组成和群落结构发生变化。然而，边缘在调节森林更新方面的直接作用还相对未知。本研究通过实验检验了森林-农田边缘树木建立的模式，以确定三种树种对边缘梯度的响应。我们在 90×90 m 的网格中放置了 100 个 1 m2 的样方，样方从森林内部开始，延伸到边缘，然后延伸到 60 m 进入旧农田。在每个样方中，我们种植了红枫、糖枫和沼泽栎的种子。对于糖枫和沼泽栎来说，种子的萌发随着进入农田的距离而增加。红枫的萌发从森林到农田增加，在进入农田 20 m 左右达到最大值，然后随着距离的进一步增加而下降。几乎所有的红枫幼苗在萌发后不久就死亡了。糖枫的存活率随着进入旧农田的距离而增加，而沼泽栎的存活率则没有响应边缘梯度。对于糖枫和沼泽栎来说，建立概率都随着进入旧农田的距离而增加。沼泽栎的生长和糖枫的分配模式也沿着边缘梯度发生变化。这些结果表明，边缘对树木的建立和生长有复杂的、特定于物种的影响，这可能会影响到再生林的空间格局和物种组成。
