期刊
FOREST ECOLOGY AND MANAGEMENT
卷 259, 期 10, 页码 1870-1879出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.foreco.2010.01.049
关键词
Climate change; Tree encroachment; Festuca campestris; Fire suppression; Grazing; Pinus contorta
类别
资金
- Alberta Tourism, Parks, Recreation and Culture
- Alberta Conservation Association
- National Sciences and Engineering Research Council of Canada
- University of Calgary
Tree encroachment into rough fescue (Festuca campestris) grassland has been identified as an ecological concern on the Cypress Hills plateau in southeastern Alberta, Canada. A combination of field sampling (109 transects), a dendrochronological assessment (1361 trees), and a time series analysis of remotely sensed images from five different time periods (1950-2002) were used to determine the extent and rate of tree encroachment and forest development. Tree cover increased by 768 ha (similar to 51%) between 1950 and 2007, representing 10% of the study area, from 1502 ha of pre-1950 forest. Post-1950 tree invasion also created an ingress zone of 750 ha (similar to 10% of study area) based on field transects. Forest cover increased at a consistent rate of 14.3 ha/year. Lodgepole pine (Pinus contorta var. latifolia) was the most common tree species associated with encroachment. Invasion based on the number of established trees occurred at an exponential rate of 3.1%/year after 1890, with density increased by filling spaces adjacent to and between trees within the grassland vegetation. The rate of tree establishment increased to 4.4%/year after 1980, suggesting a change occurred in environmental conditions. Annual atmospheric temperatures increased 0.55 degrees C from 1929 to 2005 (P < 0.001), with winter (December-February) and spring (March-May) temperatures accounting for most of the increase (P < 0.001), whereas summer (June-August) temperatures slightly decreased (P < 0.050, 0.34 degrees C) and precipitation increased (P < 0.005, 30 mm). Cattle and elk (Cervus elaphus) grazing was not considered a primary factor for explaining tree encroachment. Based on multidimensional scaling, lodgepole pine establishment was associated with warmer spring temperatures and greater fall (October-November) precipitation. A landscape devoid of wildfires, combined with greater moisture availability, and a longer frost-free season is likely conducive to the sustained establishment of coniferous trees and forest development within the Cypress Hills fescue grassland ecosystem. Long-term conservation of the fescue grasslands could be possible by reintroducing fire. (C) 2010 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据