Leu Matthias, Hanser Steven E, Knick Steven T
U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Snake River Field Station, 970 Lusk Street, Boise, Idaho 83706, USA.
Ecol Appl. 2008 Jul;18(5):1119-39. doi: 10.1890/07-0480.1.
Anthropogenic features such as urbanization, roads, and power lines, are increasing in western United States landscapes in response to rapidly growing human populations. However, their spatial effects have not been evaluated. Our goal was to model the human footprint across the western United States. We first delineated the actual area occupied by anthropogenic features, the physical effect area. Next, we developed the human footprint model based on the ecological effect area, the zone influenced by features beyond their physical presence, by combining seven input models: three models quantified top-down anthropogenic influences of synanthropic predators (avian predators, domestic dog and cat presence risk), and four models quantified bottom-up anthropogenic influences on habitat (invasion of exotic plants, human-caused fires, energy extraction, and anthropogenic wildland fragmentation). Using independent bird population data, we found bird abundance of four synanthropic species to correlate positively with human footprint intensity and negatively for three of the six species influenced by habitat fragmentation. We then evaluated the extent of the human footprint in relation to terrestrial (ecoregions) and aquatic systems (major rivers and lakes), regional management and conservation status, physical environment, and temporal changes in human actions. The physical effect area of anthropogenic features covered 13% of the western United States with agricultural land (9.8%) being most dominant. High-intensity human footprint areas (class 8-10) overlapped highly productive low-elevation private landholdings and covered 7% of the western United States compared to 48% for low-intensity areas (class 1-3), which were confined to low-productivity high-elevation federal landholdings. Areas within 1 km of rivers were more affected by the human footprint compared to lakes. Percentage human population growth was higher in low-intensity human footprint areas. The disproportional regional effects of the human footprint on landscapes in the western United States create a challenge to management of ecosystems and wildlife populations. Using footprint models, managers can plan land use actions, develop restoration scenarios, and identify areas of high conservation value at local landscapes within a regional context. Moreover, human footprint models serve as a tool to stratify landscapes for studies investigating floral and faunal response to human disturbance intensity gradients.
随着美国西部人口的快速增长，城市化、道路和电力线等人为特征在美国西部景观中不断增加。然而，它们的空间效应尚未得到评估。我们的目标是对美国西部的人类足迹进行建模。我们首先划定了人为特征实际占用的面积，即物理影响面积。接下来，我们通过组合七个输入模型，基于生态影响面积（受特征实际存在之外的区域影响的区域）开发了人类足迹模型：三个模型量化了伴人捕食者（鸟类捕食者、家犬和家猫存在风险）自上而下的人为影响，四个模型量化了自下而上的人为对栖息地的影响（外来植物入侵、人为引发的火灾、能源开采和人为导致的荒地破碎化）。利用独立的鸟类种群数据，我们发现四种伴人物种的鸟类丰度与人类足迹强度呈正相关，而在受栖息地破碎化影响的六种鸟类中的三种呈负相关。然后，我们评估了人类足迹相对于陆地（生态区）和水生系统（主要河流和湖泊）、区域管理和保护状况、物理环境以及人类活动的时间变化的范围。人为特征的物理影响面积覆盖了美国西部13%的区域，其中农业用地（9.8%）最为占主导。高强度人类足迹区域（8 - 10级）与高产的低海拔私人土地高度重叠，覆盖了美国西部7%的区域，相比之下，低强度区域（1 - 3级）占48%，这些区域局限于低产的高海拔联邦土地。与湖泊相比，河流1公里范围内的区域受人类足迹的影响更大。低强度人类足迹区域的人口增长率更高。人类足迹在美国西部景观上的区域影响不均衡，给生态系统和野生动物种群的管理带来了挑战。利用足迹模型，管理者可以规划土地利用行动、制定恢复方案，并在区域背景下确定当地景观中具有高保护价值的区域。此外，人类足迹模型可作为一种工具，对景观进行分层，用于研究动植物对人类干扰强度梯度的响应。
