Effects of Farmland Shelterbelts on Microclimate, Crop Yield, and Edge-Zone Yield Loss in China: A Meta-Analysis

Farmland shelterbelts can provide broad microclimatic and production benefits, but these benefits may coexist with localized competition near the tree–crop interface. Their effects also vary with environmental conditions, shelterbelt attributes, and crop type. We searched Web of Science and China National Knowledge Infrastructure for field studies conducted in China and published between 1980 and 2023. A total of 120 studies were retained, providing 1377 treatment–control comparisons. Log response ratios and random-effects models were used to quantify shelterbelt effects on wind speed, summer air temperature, air relative humidity, crop yield, thousand-grain weight, and crop yield in study-defined edge zones. Subgroup analyses examined the moderating effects of mean annual precipitation, shelterbelt structure, main−belt spacing, shelterbelt height, stand age, orientation, and crop type. Shelterbelts reduced wind speed and summer air temperature by 35.80% and 4.01%, respectively, and increased air relative humidity by 13.45%. Crop yield and thousand−grain weight increased by 16.57% and 12.28%, respectively, whereas crop yield in study−defined edge zones decreased by 20.47%. Shelterbelt height and stand age significantly moderated microclimatic responses and edge-zone yield loss, while crop type significantly moderated crop yield and thousand−grain weight. These results demonstrate that broad protective and production benefits can coexist with localized near−tree yield penalties. The findings provide evidence for context−specific shelterbelt management and highlight the need to account for spatial variation in tree–crop interactions.