ABSTRACT

A field experiment was conducted involving deer exclosures and planting of Quercus acutissima, a deciduous oak, to reveal forest recovery patterns and factors following clear-cutting at overcrowded conifer plantation sites. Sites were selected in a warm temperate region in western Japan, which is dominated by deciduous broad-leaved secondary forests and extensive conifer plantations. Thirteen years after clear-cutting in the study area, naturally regenerated stands were established with exclosures. The exclosures housed vegetation dominated by pioneer trees, such as Mallotus japonicus or Zanthoxylum ailanthoides. In contrast, naturally regenerated stands without exclosures had limited pioneer trees present. Vegetation dominated by pioneer shrubs (e.g. Aralia elata) was established in these stands. Reduced canopy height and total basal area were observed for vegetation outside the exclosures. In stands where Q. acutissima was planted immediately after clear-cutting, the vegetation that is dominated by this species in the canopy layer was established in both stands with and without exclosure. Most of tree species that emerged after clear-cutting across all stands were of the frugivore seed dispersal type. However, results from this study suggest that these frugivore seed dispersal type trees are more vulnerable to deer browsing than trees from the Fagaceae family. Natural forest recovery following plantation clear-cutting could be inhibited due to deer herbivory at relatively low deer density if a major source of tree regeneration in clear-cut plantations is non-Fagaceae trees.

摘要

进行了一项野外实验，涉及鹿的采伐和落叶栎栎栎的种植，以揭示在人满为患的针叶树人工林砍伐后的森林恢复方式和影响因素。选址是在日本西部一个温暖的温带地区进行的，该地区以落叶阔叶次生林和针叶树人工林为主。在研究区进行了整整13年的砍伐后，自然再生的林分被排除在外。避难所内有以先锋树为主的植被，例如日本绿头鸭或花椒。相比之下，没有遮挡的自然再生林分出现的先锋树数量有限。以先锋灌木为主的植被（例如在这些看台上建立了Aralia elata）。排泄物外的植被观察到冠层高度和总基底面积减小。在acutissima Q的看台上砍伐后立即种植，在有和没有遮盖的情况下，在该林分中都建立了以该物种为主的植被。在所有林分上进行清晰砍伐后出现的大多数树种都是节食种子传播型的。但是，这项研究的结果表明，这些节食种子散播型树木比菊科植物的树木更容易受到鹿的浏览。如果未砍伐的人工林中树木再生的主要来源是相对较低的鹿密度，则由于鹿为食草，可抑制砍伐后的天然林恢复。