Top-down and Bottom-up Mechanisms of Urban Edge and Fragmentation Effects

城市边缘与碎片化效应的自上而下和自下而上机制

• 批准号: 9981758
• 负责人: Douglas Bolger
• 金额: $ 14.98万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-05-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9981758&HistoricalAwards=false
• 关键词: Top; down; Bottom; up; Mechanisms

Bolger Abstract DEB-99-81758Top-down and bottom-up mechanisms of urban edge and fragmentation effectsHabitat fragmentation and edge effects due to urban and suburban development are among the principle threats to biological diversity. The effects of habitat fragmentation are complex, diverse and pervasive. They affect animal and plant populations through a number of interacting pathways. The PI's prior work has shown that predation and parasitism on Rufous-crowned sparrow do not increase along urban edges in coastal sage scrub habitat that is fragmented by urban development in coastal suouthern California. The research proposed here will investigate the generality of the previous findings by examining the rates of nest predation and brood parasitism in five focal species of birds that vary in nest placement (ground vs. shrub) and apparent sensitivity to fragmentation. Four landscape settings that vary in degree of exposure to edge and fragmentation effects will be considered. Rates of predation and parasitism will be compared across these landscape treatments. The proposed work will also address bottom-up (food-driven) effects on fragmentation and edge by quantifying foraging behavior, diet, and nestling provisinioning rates to determine if landscape-scale variation in arthropod (food) abundance affects higher trophic levels.

自上而下和自下而上的城市边缘和破碎化效应机制由于城市和郊区的发展，生境破碎化和边缘效应是对生物多样性的主要威胁之一。 栖息地破碎化的影响是复杂、多样和普遍的。 它们通过许多相互作用的途径影响动物和植物种群。 PI先前的工作表明，棕冠麻雀的捕食和寄生并没有增加沿着城市边缘在沿海鼠尾草灌木丛栖息地，这是分散的城市发展在沿海苏厄德加州。 这里提出的研究将调查的普遍性，通过检查巢捕食率和育雏寄生在五个焦点物种的鸟类，不同的巢的位置（地面与灌木）和明显的敏感性碎片。 将考虑四种受边缘和破碎化影响程度不同的景观环境。 捕食和寄生率将在这些景观处理进行比较。 拟议的工作还将解决自下而上（食物驱动）的碎片化和边缘的影响，通过量化觅食行为，饮食和雏鸟provisinioning率，以确定节肢动物（食物）丰度的规模变化是否影响更高的营养水平。