Pearse Ian S, Funk Kyle A, Kraft Thomas S, Koenig Walter D
Cornell Lab of Ornithology, 159 Sapsucker Woods Road, Ithaca, NY, 14850, USA,
Oecologia. 2015 Jun;178(2):361-8. doi: 10.1007/s00442-014-3193-2. Epub 2015 Jan 8.
The seasonal match between folivore and leaf phenology affects the annual success of arboreal folivore populations because many folivores exploit developing leaves, which are an ephemeral resource. One strategy for folivores to exploit early-season leaves is to anticipate their emergence. The consequence of this behavior for trees is that individuals that set leaves earlier may experience greater rates of folivore damage, with potential negative fitness consequences. To test this hypothesis, we surveyed the early-season phenology, insect folivore damage, and acorn crop of a population of valley oaks (Quercus lobata) over a 3-year period. We found that trees that set leaves earlier experienced greater rates of folivore damage than trees that set leaves later in the season. In addition, we observed a lagged effect of folivore damage on acorn production, whereby trees with greater leaf damage produced fewer acorns in the subsequent year. These results indicate potential negative fitness consequences of earlier leaf phenology. Our study suggests that folivore pressure may be one factor that affects the optimal timing of leaf set in oaks.
食叶动物与叶片物候的季节性匹配会影响树栖食叶动物种群的年度繁殖成效，因为许多食叶动物以正在发育的叶片为食，而这些叶片是一种短暂的资源。食叶动物利用早季叶片的一种策略是预测叶片的出现。这种行为对树木的影响是，较早长出叶子的个体可能遭受更高比例的食叶动物损害，从而可能对适合度产生负面影响。为了验证这一假设，我们在三年时间里对一群山谷橡木（Quercus lobata）的早季物候、昆虫食叶动物损害情况以及橡子产量进行了调查。我们发现，较早长出叶子的树木比在季节后期长出叶子的树木遭受食叶动物损害的比例更高。此外，我们观察到食叶动物损害对橡子产量有滞后效应，即叶片损害更严重的树木在次年结出的橡子更少。这些结果表明，较早的叶片物候可能对适合度产生负面影响。我们的研究表明，食叶动物压力可能是影响橡树最佳展叶时间的一个因素。
