Land‐use legacies and present fire regimes interact to mediate herbivory by altering the neighboring plant community
Land‐use legacies and present fire regimes interact to mediate herbivory by altering the neighboring plant community
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土地利用遗产和当前的火灾状况相互作用，通过改变邻近的植物群落来调节食草性
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
John L. Orrock
中科院分区：
文献类型：
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作者：
P. Hahn;John L. Orrock
过去和现在的人类活动，如历史上的农业和灭火，是广泛的，可以创建depaderate植物群落。虽然许多研究表明，食草动物对焦点植物依赖于食草动物的密度或周围的植物群落的组成，目前还不清楚是否人为改变植物群落改变食草动物。我们测试的假设，人类活动，改变植物群落导致随后的变化，草食动物。在20个站点分布在80 300公顷，我们进行了一项实地实验，操纵昆虫草食动物访问（全封闭和伪封闭）的四个焦点植物物种在长叶松林地不同的土地利用历史（后农业用地或非农业用地）和火灾频率（频繁和罕见）的程度。植物覆盖，特别是草本植物覆盖，是较低的后农业和火抑制林地。我们地点的优势食草昆虫（蚱蜢）的密度与植物覆盖呈正相关。食草动物访问减少了可口的杂类草一枝黄花的生物量经常烧毁后的农业用地和不经常烧毁的非农业林地和死亡率增加的另一个杂类草（Pityopsis graminifolia），但没有影响其他两个不太可口的物种（Schizachyrium scoparium和山毛豆virginiana）。草食性在S. odora表现出一个驼峰形的反应，植物覆盖，低水平和高水平的植物覆盖与低草食动物。草食动物密度对草食动物有微弱的负向影响。这些研究结果表明，与过去和现在的人类活动有关的植物覆盖的变化可以改变病灶S的损害率。odora植物通过改变蝗虫觅食行为，而不是通过改变当地蝗虫密度。由此产生的草食动物的变化可能会限制自然恢复或恢复的努力，减少可口的植物物种的建立或性能。
Past and present human activities, such as historic agriculture and fire suppression, are widespread and can create depauperate plant communities. Although many studies show that herbivory on focal plants depends on the density of herbivores or the composition of the surrounding plant community, it is unclear whether anthropogenic changes to plant communities alter herbivory. We tested the hypothesis that human activities that alter the plant community lead to subsequent changes in herbivory. At 20 sites distributed across 80 300 hectares, we conducted a field experiment that manipulated insect herbivore access (full exclosures and pseudo-exclosures) to four focal plant species in longleaf pine woodlands with different land-use histories (post-agricultural sites or non-agricultural sites) and degrees of fire frequency (frequent and infrequent). Plant cover, particularly herbaceous cover, was lower in post-agricultural and fire suppressed woodlands. Density of the dominant insect herbivore at our site (grasshoppers) was positively related to plant cover. Herbivore access reduced biomass of the palatable forb Solidago odora in frequently burned post-agricultural sites and in infrequently burned non-agricultural woodlands and increased mortality of another forb (Pityopsis graminifolia), but did not affect two other less palatable species (Schizachyrium scoparium and Tephrosia virginiana). Herbivory on S. odora exhibited a hump-shaped response to plant cover, with low herbivory at low and high levels of plant cover. Herbivore density had a weak negative effect on herbivory. These findings suggest that changes in plant cover related to past and present human activities can modify damage rates on focal S. odora plants by altering grasshopper foraging behavior rather than by altering local grasshopper density. The resulting changes in herbivory may have the potential to limit natural recovery or restoration efforts by reducing the establishment or performance of palatable plant species.