Resilience and resistance in sagebrush ecosystems are associated with seasonal soil temperature and water availability
Resilience and resistance in sagebrush ecosystems are associated with seasonal soil temperature and water availability
复制标题
山艾树生态系统的恢复力和抵抗力与季节性土壤温度和可用水量有关
DOI：
10.1002/ecs2.2417
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发表时间：
2018
期刊：
影响因子：
2.7
通讯作者：
Trevor Gruell
中科院分区：
文献类型：
--
作者：
B. Roundy;J. Chambers;D. Pyke;Richard Miller;R. Tausch;E. Schupp;B. Rau;Trevor Gruell
外来牧草的入侵和主导地位以及火灾频率的增加威胁着世界各地的本土生态系统。在美国西部的大盆地地区，木本和草本燃料处理被实施，以减少野火的影响，增加鼠尾草(Artemisia spp.)生态系统对干扰的恢复能力和对外来一年生草本植物的抗性。经过处理的外来一年生雀麦(Bromus Tectorum)的高盖度增加了精细燃料，这反过来又增加了越过生物阈值进入野火频率增加并转变为麦草优势的状态的风险。鼠尾草生态系统对野火的适应能力和对牧草的抵抗力取决于气候条件和与牧草竞争的多年生草本植物的丰富程度。在这项研究中，我们使用较长期的数据来评估在燃料管理处理后土壤气候条件、多年生草本植物覆盖和牧草覆盖之间的关系，这些环境梯度是大流域鼠尾草生态系统的特征。本文研究了木本植物和草本植物燃料处理对土壤温度、土壤水分有效性(13-30和50 cm深)以及本地和外来植物盖度的影响。或刺柏(Juniperus spp.)树木扩展和11个带有树木扩展的鼠尾草站点。规定的火和机械处理都增加了林地土壤水分的有效性，并增加了一些林地和山艾灌木地的多年生草本盖度。与不处理和机械处理相比，处方火还略微提高了土壤温度，特别是增加了牧草覆盖率。非度量尺度排序和决策树分割分析表明，晚春较暖、瀑布较暖、较潮湿的地点，其雀麦盖度较高。冬季较潮湿、春季较早的地点(3-4月)多年生草本植物的盖度较高。我们的研究结果表明，在火灾和燃料控制处理后，随着气候变暖和变干，场地对作业草的抵抗力降低。这强调需要采取管理行动来维持和加强多年生草本植物的覆盖，例如实施适当的放牧管理，并结合燃料控制处理恢复多年生草本植物丰度较低的地点。
Invasion and dominance of exotic grasses and increased fire frequency threaten native ecosystems worldwide. In the Great Basin region of the western United States, woody and herbaceous fuel treatments are implemented to decrease the effects of wildfire and increase sagebrush (Artemisia spp.) ecosystem resilience to disturbance and resistance to exotic annual grasses. High cover of the exotic annual cheatgrass (Bromus tectorum) after treatments increases fine fuels, which in turn increases the risk of passing over a biotic threshold to a state of increased wildfire frequency and conversion to cheatgrass dominance. Sagebrush ecosystem resilience to wildfire and resistance to cheatgrass depend on climatic conditions and abundance of perennial herbaceous species that compete with cheatgrass. In this study, we used longer-term data to evaluate the relationships among soil climate conditions, perennial herbaceous cover, and cheatgrass cover following fuel management treatments across the environmental gradients that characterize sagebrush ecosystems in the Great Basin. We examined the effects of woody and herbaceous fuel treatments on soil temperature, soil water availability (13–30 and 50 cm depths), and native and exotic plant cover on six sagebrush sites lacking pi~ non (Pinus spp.) or juniper (Juniperus spp.) tree expansion and 11 sagebrush sites with tree expansion. Both prescribed fire and mechanical treatments increased soil water availability on woodland sites and perennial herbaceous cover on some woodland and sagebrush sites. Prescribed fire also slightly increased soil temperatures and especially increased cheatgrass cover compared to no treatment and mechanical treatments on most sites. Non-metric dimensional scaling ordination and decision tree partition analysis indicated that sites with warmer late springs and warmer and wetter falls had higher cover of cheatgrass. Sites with wetter winters and early springs (March–April) had higher cover of perennial herbs. Our findings suggest that site resistance to cheatgrass after fire and fuel control treatments decreases with a warmer and drier climate. This emphasizes the need for management actions to maintain and enhance perennial herb cover, such as implementing appropriate grazing management, and revegetating sites that have low abundance of perennial herbs in conjunction with fuel control treatments.