Direct and Indirect Effects on Community Resilience in Oak Forests

Ostfeld，R.S.DEB-9615414 PIS建议测试对纽约州东南部橡树林的直接和间接影响的重要性。橡树间歇性地产生桅杆似乎会导致啮齿动物种群密度的短暂增加。反过来，啮齿动物似乎控制着低密度的吉普赛飞蛾种群，是携带莱姆病的扁虱的主要宿主。PI将模拟桅杆的生产，并测量啮齿动物数量水平的反应。小鼠种群密度的变化对吉普赛蛾蛹存活率和卵块密度、幼虫寄生率和若虫丰度的影响将被确定。PIS将进行灭鼠实验，以检验啮齿动物种群密度仅在飞蛾周期的低谷阶段调节吉普赛飞蛾种群动态的假设。对相互作用的建模将确定系统行为对啮齿动物捕食和橡子消费的功能反应的变化以及对肥大周期节奏的变化的敏感性。除了有助于更全面地了解决定生态系统结构和动态的因素外，这项研究的结果还将适用于落叶林的管理和影响东北地区生活质量的两个因素--吉普赛蛾落叶和莱姆病的迅速传播。

Ostfeld, R. S. DEB-9615414 The PIs propose to test the importance of direct and indirect effects in oak forests of southeastern New York State. Episodic mast production by oak trees appears to cause transient increases in the density of rodent populations. Rodents, in turn, appear to regulate low-density gypsy moth populations and are the primary reservoirs of the tick that carries Lyme disease. The PIs will simulate mast production and measure the response in rodent population levels. The effect of changes in mouse population densities will be determined for survival of gypsy moth pupae and density of egg masses, and parasitization rates of larval ticks and nymphal tick abundance. The PIs will conduct rodent removal experiments to test the hypothesis that rodent population density regulates gypsy moth population dynamics only during the low phase of the moth cycle. Modeling of the interaction will determine the sensitivity of system behavior to variation in the functional response of rodent predation and acorn consumption and to variation in the rhythm of the masting cycle. In addition to contributing to a more complete understanding of the factors determining the structure and dynamics of ecological systems, the results of this study will be applicable to the management of deciduous forests and to two factors affecting quality of life in the northeast - gypsy moth defoliation and the rapid spread of Lyme disease.