Data from: Habitat structure modifies microclimate: an approach for mapping fine-scale thermal refuge

1. Contemporary techniques predicting habitat suitability under climate change projections often underestimate availability of thermal refuges. Habitat structure contributes to thermal heterogeneity at a variety of spatial scales, but quantifying microclimates at organism‐relevant resolutions remains a challenge. Landscapes that appear homogeneous at large scales may offer patchily distributed thermal refuges at finer scales. 2. We quantified the relationship between vegetation structure and the thermal environment at a scale relevant to small, terrestrial animals using a new approach for mapping fine‐scale thermal heterogeneity. We expected that vegetation would create attenuated microclimates and that the influence of vegetation structure would vary seasonally. We measured shrub volume, horizontal cover, and operative temperature (Te) in a sagebrush‐steppe habitat in Idaho, USA, at 534 microsites across two study sites of approximately 1 km2 each. We modeled relationships between habitat structure and both mean daily maximum temperature (urn:x-wiley:2041210X:media:mee313008:mee313008-math-0001max) and mean diurnal temperature range (urn:x-wiley:2041210X:media:mee313008:mee313008-math-0002) for each study site during summer and winter. Aerial imagery from unmanned aerial systems was used to estimate shrub volume and canopy cover at 1‐m resolution, and we applied the best fit model to map thermal heterogeneity across broader extents. 3. Increasing shrub volume and cover was associated with lower urn:x-wiley:2041210X:media:mee313008:mee313008-math-0003max and (urn:x-wiley:2041210X:media:mee313008:mee313008-math-0004, but strengths of the relationships differed between study sites. There was considerable heterogeneity in availability of thermal refuges across sagebrush‐steppe rangelands that have traditionally been considered relatively homogeneous. 4. This technique can help ecologists and land managers identify critical thermal refuges that large‐scale climate modelling can overlook and thus contribute to an understanding of animal‐habitat relationships under changing climates and land uses.

1. 当前基于气候变化预测开展栖息地适宜性评估的主流技术，往往会低估热庇护所（thermal refuges）的可获得性。栖息地结构可在多种空间尺度上驱动热异质性（thermal heterogeneity）的形成，但以匹配生物体需求的分辨率量化微气候（microclimates）仍是一项核心挑战。宏观尺度上看似均质的景观，在精细空间尺度下可能存在斑块状分布的热庇护所。
2. 本研究针对小型陆生动物的适配尺度，采用全新的精细尺度热异质性制图方法，量化了植被结构与热环境之间的关联。我们推测植被可形成缓减极端温度的微气候，且植被结构的热调节效应存在季节差异。研究在美国爱达荷州的一处灌丛草原（sagebrush-steppe）生境中开展，在两个面积各约1 km²的研究样地内的534个微生境点位，测定了灌丛体积、水平覆盖度以及有效温度（operative temperature, Te）。针对每个样地的夏季与冬季数据，我们分别构建了栖息地结构与日最高均温（urn:x-wiley:2041210X:media:mee313008:mee313008-math-0001max）、平均昼夜温差（urn:x-wiley:2041210X:media:mee313008:mee313008-math-0002）之间的关联模型。本研究采用无人机系统（unmanned aerial systems）获取的航空影像，以1米分辨率估算灌丛体积与冠层覆盖度，并通过最优拟合模型在更大空间范围内绘制热异质性分布图。
3. 灌丛体积与覆盖度的提升与更低的日最高均温（urn:x-wiley:2041210X:media:mee313008:mee313008-math-0003max）以及平均昼夜温差（urn:x-wiley:2041210X:media:mee313008:mee313008-math-0004）相关，但这种关联的强度在两个研究样地间存在显著差异。传统上被认为相对均质的灌丛草原牧场，其热庇护所的可获得性存在显著的空间异质性。
4. 该技术可帮助生态学家与土地管理者识别大型气候模型所遗漏的关键热庇护所，进而助力理解气候变化与土地利用变化背景下的动物-栖息地关联机制。