Keystone Interactions: Salmon, Bear, and Riparian Vegetation in Riverine Corridors of the Pacific Northwest

摘要提案#：DEB-9806575研究员(S)：奈曼研究所：华盛顿大学标题：基石相互作用：太平洋西北地区河流走廊的鲑鱼、熊和河岸植被太平洋鲑鱼(Oncorhynchus spp.)和熊(Ursus spp.)似乎在影响太平洋西北部河岸植被的高度和动态方面发挥了重要作用。初步数据表明，来自海洋的营养物质在河岸植被中积累，熊可能通过杀死和消耗鲑鱼以及随后在河岸森林中沉积身体和粪便，成为将营养物质从溪流转移到河岸地带的重要媒介。来自海洋的营养物质的输入可能会提高河岸树木的生长速度，影响大型木质废弃物的产生，进而可能影响河流走廊内的结构生境和生产力。该项目的目标是发现河岸植被从产卵的鲑鱼中获取海洋来源的氮的程度；评估海洋来源的营养物质对河岸生长和群落组成的影响；评估熊的活动(例如，身体和粪便分布)和海流作为N从河流向河岸系统转移的途径的相对重要性；以及评估鲑鱼与熊的相互作用对河岸植被生长的重要性。用于评估这些目标的主要方法是测量稳定同位素(15N)以及对鲑鱼身体和熊的粪便进行实验操作。这项研究的意义在于发现海洋、鲑鱼和熊之间的协同作用如何影响河岸森林，以及来自这些森林的物质如何影响鲑鱼种群强度。

ABSTRACT PROPOSAL # : DEB-9806575 INVESTIGATOR(S) : NAIMAN INSTITUTION: UNIVERSITY OF WASHINGTON TITLE: Keystone Interactions: Salmon, Bear and Riparian Vegetation in Riverine Corridors of the Pacific Northwest Interactions between Pacific salmon (Oncorhynchus spp.) and bear (Ursus spp.) appear to play an important role in influencing the stature and dynamics of riparian vegetation in the Pacific Northwest. Preliminary data suggest that marine-derived nutrients accumulate in riparian vegetation, and that bears may act as an important vector for moving nutrients from the stream to the riparian zone through the killing and consumption of salmon and subsequent deposition of carcasses and feces within the riparian forest. Inputs of marine-derived nutrients may enhance growth rates of riparian trees and influence the production of large woody debris, which may in turn affect structural habitat and productivity within the stream corridor. The objectives of this project are to discover the extent to which riparian vegetation acquires marine-derived nitrogen from spawning salmon; to assess the impacts of marine-derived nutrients on riparian growth and community composition; to assess the relative importance of bear activity (e.g., carcass and feces distribution) and hyporheic flow as pathways for transfer of N from stream to riparian systems; and to assess the community importance of salmon-bear interactions with regard to the growth of riparian vegetation. The principal methods used in the evaluation of these objectives are the measurement of stable isotopes (15N) and experimental manipulation of salmon carcasses and bear feces. The significance of this research lies in the discovery of how synergistic interactions between the ocean, salmon and bear can act to influence riparian forests, and how materials from those forests act to influence salmon population strength.