Abstract Windbreaks modify microclimatic conditions within agricultural systems, however these affects are altered by temporal, environmental and spatial factors often resulting in variation in the reported agricultural benefits. Understanding the climatic conditions and times when windbreaks are most effective will increase our ability to predict impacts of windbreaks on agricultural yields and returns. We examined the effects of windbreaks on paddock microclimate (windspeed, temperature, relative humidity and vapor pressure deficit (VPD)) at fine temporal scales and described the temporal and spatial patterns in the effectiveness of windbreaks in moderating microclimate. We also assessed the climate conditions under which windbreaks have the biggest impact on paddock microclimates to determine the climate conditions where windbreaks are most effective. Microclimate variables were monitored at six distances away from established windbreaks across four pasture/grazing paddocks in the Tasmanian midlands, Australia. Results showed that the effect of windbreaks on paddock microclimate varied; spatially, temporally and with environmental conditions. Temperature, relative humidity and VPD exhibited highly diurnal and seasonal trends in their response to windbreaks, with the largest effects observed in summer and during the afternoon. Environmental conditions also impacted on the magnitude of windbreak effects observed. Windbreaks were most effective at reducing wind when speeds were high, although under these conditions the impact of windbreaks on temperature and relative humidity was reduced. Wind direction was also a key factor, with the largest microclimate changes observed when wind originated from directly behind the windbreak, although plots closely adjacent to windbreaks had microclimate changes when wind came from all directions. This study highlights that when predicting the benefits of windbreaks, it is important to consider spatial and temporal dynamics as well as the environmental conditions of the site.

中文翻译：

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防风林对牧场小气候影响的时间、环境和空间变化

摘要 防风林改变了农业系统内的小气候条件，但这些影响会受到时间、环境和空间因素的影响，通常会导致报告的农业效益发生变化。了解防风林最有效的气候条件和时间将提高我们预测防风林对农业产量和回报影响的能力。我们在精细的时间尺度上研究了防风林对围场小气候（风速、温度、相对湿度和蒸汽压差 (VPD)）的影响，并描述了防风林在调节小气候方面的有效性的时间和空间模式。我们还评估了防风林对围场小气候影响最大的气候条件，以确定防风林最有效的气候条件。在澳大利亚塔斯马尼亚中部地区的四个牧场/放牧围场距离已建防风林六距离处监测微气候变量。结果表明，防风林对围场小气候的影响各不相同；空间、时间和环境条件。温度、相对湿度和 VPD 在对防风林的反应中表现出高度的昼夜和季节性趋势，在夏季和下午观察到的影响最大。环境条件也影响了观察到的防风效果的程度。当速度很高时，防风林最有效地减少风，尽管在这些条件下，防风林对温度和相对湿度的影响减少了。风向也是一个关键因素，当风直接来自防风林后面时观察到的小气候变化最大，尽管当风来自各个方向时，紧邻防风林的地块会发生小气候变化。这项研究强调，在预测防风林的好处时，重要的是要考虑空间和时间动态以及场地的环境条件。尽管当风从四面八方吹来时，紧邻防风林的地块会发生小气候变化。这项研究强调，在预测防风林的好处时，重要的是要考虑空间和时间动态以及场地的环境条件。尽管当风从各个方向吹来时，紧邻防风林的地块会发生小气候变化。这项研究强调，在预测防风林的好处时，重要的是要考虑空间和时间动态以及场地的环境条件。