长期频繁的火灾和牛放牧改变了干森林的低层植被
Becky K Kerns1, Michelle A Day2
1USDA Forest Service, Pacific Northwest Research Station, Corvallis, Oregon, USA.
概括
在西部森林中,规定的火灾和牛放牧可以减少地下植被覆盖面,特别是在频繁的秋季烧伤的情况下. 需要更长的火灾间隔等管理策略来提高森林的弹性.
科学领域:
- 森林生态森林生态学
- 牧场管理管理的牧场管理.
- 干扰生态学 干扰生态学
背景情况:
- 火灾和大型食草动物是西部森林中普遍存在的干扰.
- 了解它们的相互作用对于森林的弹性,保护和恢复至关重要.
- 对这些相互作用的操纵性研究在森林牧场中很少见.
研究的目的:
- 调查长期的地下植被对规定的火灾 (春季和秋季) 的反应,以及 ponderosa松树种群中的牛放牧排除.
- 分析火灾和放牧对植被覆盖面和构成的相互作用影响.
- 评估对草 (Bromus tectorum) 等入侵物种的影响.
主要方法:
- 在近二十年的时间里,对春季和秋季的实验性操纵规定了大火和牛放牧的排除.
- 监测底层植被覆盖面,植物功能群和入侵物种.
- 燃烧与未燃烧以及放牧与未放牧地区的植被反应的比较.
主要成果:
- 秋季燃烧与牛放牧相结合,与除放牧之外的秋季燃烧相比,低木覆盖率减少了12%.
- 这种相互作用似乎是数值介导的,草食动物可能会集中在烧伤的区域.
- 秋季的火灾和放牧增加了年度的草和重新生长的灌木,但也促进了草的入侵,特别是在初始传播压力高的地区.
结论:
- 频繁的秋季火灾和牛放牧可能会降低干松松树林的底层树木弹性.
- 春季燃烧的影响很小,与牧场没有相互作用.
- 管理策略,如较长的火灾返回间隔,火灾后放牧休息或全牧场烧伤等可能是必要的,以减轻负面影响.
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