Environmental heterogeneity enhances species richness by creating niches and providing refugia. Spatial variation in climate has a particularly strong positive correlation with richness, but is often indirectly inferred from proxy variables, such as elevation and related topographic heterogeneity indices, or derived from interpolated coarse-grain weather station data. Our aim was to develop new remotely sensed metrics of relative temperature and thermal heterogeneity, compare them with proxy measures, and evaluate their performance in predicting species richness patterns. We analyzed Landsat 8's Thermal Infrared Sensor data, calculated two thermal metrics during summer and winter, and compared their seasonal spatial patterns with those of elevation and topographic heterogeneity. We fit generalized least squares models to evaluate each variable's effect in predicting seasonal bird richness using data from the North American Breeding Bird Survey. Generally speaking, neither elevation nor topographic heterogeneity were good proxies for temperature or thermal heterogeneity, respectively. Relative temperature had a non-linear relationship with elevation that was negatively quadratic in summer, but slightly positively quadratic in winter. Topographic heterogeneity had a stronger positive relationship with thermal heterogeneity in winter than in summer. The magnitude and direction of elevation–temperature and topographic heterogeneity–thermal heterogeneity relationships in each season also varied substantially across ecoregions. Remotely sensed metrics of relative temperature and thermal heterogeneity improved the predictive performance of species richness models, and both thermal variables had significant effects on bird richness that were independent of elevation and topographic heterogeneity. Thermal heterogeneity was positively related to total breeding bird richness, migrant breeding bird richness and resident bird richness, whereas topographic heterogeneity was negatively related to total breeding richness and unrelated to migrant or resident bird richness. Because thermal and topographic heterogeneity had contrasting seasonal patterns and effects on richness, they must be carefully contextualized when guiding conservation priorities.

中文翻译：

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对比相对温度和热异质性的季节性模式及其对美国本土繁殖和冬季鸟类丰富度模式的影响

环境异质性通过创造生态位和提供避难所来提高物种丰富度。气候的空间变异与丰富度有特别强的正相关，但通常是从代理变量间接推断的，例如高程和相关的地形异质性指数，或来自插值的粗粒气象站数据。我们的目标是开发新的相对温度和热异质性遥感指标，将它们与代理测量进行比较，并评估它们在预测物种丰富度模式方面的性能。我们分析了 Landsat 8 的热红外传感器数据，计算了夏季和冬季的两个热指标，并将它们的季节性空间模式与海拔和地形异质性的空间模式进行了比较。我们拟合广义最小二乘模型，以使用来自北美育种鸟类调查的数据来评估每个变量在预测季节性鸟类丰富度方面的效果。一般来说，海拔和地形异质性都不是温度或热异质性的良好代表。相对温度与海拔呈非线性关系，夏季呈负二次关系，冬季呈略正二次关系。冬季地形异质性与热异质性的正相关性强于夏季。每个季节的海拔-温度和地形异质性-热异质性关系的大小和方向在生态区之间也有很大差异。相对温度和热异质性的遥感指标提高了物种丰富度模型的预测性能，并且这两个热变量对鸟类丰富度都有显着影响，而这些影响与海拔和地形异质性无关。热异质性与总种鸟丰富度、候鸟丰富度和留鸟丰富度呈正相关，而地形异质性与总种鸟丰富度呈负相关，与候鸟或留鸟丰富度无关。由于热力和地形的异质性对丰富度具有截然不同的季节性模式和影响，因此在指导保护优先事项时必须仔细考虑它们的背景。并且这两个热变量对鸟类丰富度都有显着影响，而这些影响与海拔和地形异质性无关。热异质性与总种鸟丰富度、候鸟丰富度和留鸟丰富度呈正相关，而地形异质性与总种鸟丰富度呈负相关，与候鸟或留鸟丰富度无关。由于热力和地形的异质性对丰富度具有截然不同的季节性模式和影响，因此在指导保护优先事项时必须仔细考虑它们的背景。并且这两个热变量对鸟类丰富度都有显着影响，而这些影响与海拔和地形异质性无关。热异质性与总种鸟丰富度、候鸟丰富度和留鸟丰富度呈正相关，而地形异质性与总种鸟丰富度呈负相关，与候鸟或留鸟丰富度无关。由于热量和地形的异质性对丰富度有不同的季节性模式和影响，因此在指导保护优先事项时必须仔细考虑它们的背景。而地形异质性与总繁殖丰富度呈负相关，与候鸟或留鸟丰富度无关。由于热量和地形的异质性对丰富度有不同的季节性模式和影响，因此在指导保护优先事项时必须仔细考虑它们的背景。而地形异质性与总繁殖丰富度呈负相关，与候鸟或留鸟丰富度无关。由于热量和地形的异质性对丰富度有不同的季节性模式和影响，因此在指导保护优先事项时必须仔细考虑它们的背景。