Browsing Promotes Drought Resistance of Wyoming Big Sagebrush in a Working Rangeland

IF 2.4 3区环境科学与生态学 Q2 ECOLOGY

Rangeland Ecology & Management Pub Date : 2025-02-25 DOI:10.1016/j.rama.2025.01.006

Ashley Tribitt , Lauren M. Porensky , Sally E. Koerner , Kimberly J. Komatsu , Kurt Reinhart , Kevin Wilcox

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Abstract

Droughts are projected to become more extreme and more frequent throughout the remainder of the 21st century. Our ability to sustain rangeland functioning relies on understanding the interactive effects of extreme drought and herbivory on vegetation. Here, we report on an experiment in northeast Wyoming, USA that simulated five levels of drought intercepting 0 %, 25%, 50%, 75%, or 99% of ambient rainfall for two years. These treatments were crossed with two grazing intensity (50%, 70% utilization) and two browsing intensity (background, +50% leader removal) treatments. We measured canopy volume changes, leader growth, and leaf water potential on a dominant shrub, Artemisia tridentata ssp. wyomingensis (Beetle & Young), to test three major predictions: (1) canopy volume and leader growth decline with greater drought magnitude, (2) heavy grazing reduces the effects of drought magnitude, and (3) heavy browsing amplifies effects of drought magnitude. Under ambient browsing intensity, extreme drought caused Wyoming big sagebrush (Beetle & Young) canopies to shrink. Interestingly, this effect went away in our heavy browsing treatment, despite overall negative effects of heavy browsing on shrub canopies and leader survival. We show that this drought-buffering effect may be driven by reduced leaf-level water stress in droughted, heavily browsed shrubs compared with droughted, ambiently browsed shrubs; this may have resulted from lower early-season leaf area leading to lower transpiration-related water loss. This potential mechanism for drought resistance in sagebrush steppe highlights the importance of maintaining intact food webs, despite perceived deleterious effects of herbivores for plant abundance and growth. To promote sustainability of sagebrush and other shrub-dominated ecosystems in face of extreme precipitation change, it may be necessary for land managers and policy makers to prioritize conservation of native herbivores within ecosystems.

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在工作牧场上，浏览提高了怀俄明州大山艾树的抗旱性

预计在21世纪余下的时间里，干旱将变得更加极端和频繁。我们维持牧场功能的能力依赖于了解极端干旱和草食对植被的相互作用。在这里，我们报告了在美国怀俄明州东北部进行的一项实验，该实验模拟了5个级别的干旱，在两年的时间里，干旱拦截了0 %、25%、50%、75%或99%的环境降雨量。这些处理与2个放牧强度（50%、70%利用率）和2个浏览强度（背景、+50% leader去除）处理杂交。以三叶蒿（Artemisia tridentata ssp）为研究对象，对其冠层体积变化、领导叶生长和叶片水势进行了测量。wyomingensis（甲虫）研究结果表明：(1)冠层体积和领导枝生长随干旱程度的增加而下降，(2)重度放牧会降低干旱程度的影响，(3)重度浏览会放大干旱程度的影响。在环境浏览强度下，极端干旱导致怀俄明大山艾树(Beetle &；年轻的)树冠收缩。有趣的是，尽管大量取食对灌木冠层和首领的存活率有负面影响，但这种影响在我们的大量取食处理中消失了。研究表明，这种干旱缓冲效应可能是由干旱、重度啃食的灌木与干旱、轻度啃食的灌木相比，叶片水平的水分胁迫减少所致；这可能是由于较低的季初叶面积导致较低的蒸腾相关水分损失。尽管食草动物对植物的丰度和生长有明显的有害影响，但山艾草草原抗旱的潜在机制强调了保持完整食物网的重要性。面对极端降水变化，为了促进山艾树和其他灌木为主的生态系统的可持续性，土地管理者和政策制定者可能有必要优先考虑生态系统中本地食草动物的保护。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Rangeland Ecology & Management 农林科学-环境科学

CiteScore

4.60

自引率

13.00%

发文量

审稿时长

12-24 weeks

期刊介绍： Rangeland Ecology & Management publishes all topics-including ecology, management, socioeconomic and policy-pertaining to global rangelands. The journal''s mission is to inform academics, ecosystem managers and policy makers of science-based information to promote sound rangeland stewardship. Author submissions are published in five manuscript categories: original research papers, high-profile forum topics, concept syntheses, as well as research and technical notes. Rangelands represent approximately 50% of the Earth''s land area and provision multiple ecosystem services for large human populations. This expansive and diverse land area functions as coupled human-ecological systems. Knowledge of both social and biophysical system components and their interactions represent the foundation for informed rangeland stewardship. Rangeland Ecology & Management uniquely integrates information from multiple system components to address current and pending challenges confronting global rangelands.