Maize yield patterns on the leeward side of tree windbreaks are site-specific and depend on rainfall conditions in eastern Canada

摘要

Tree windbreaks may offer a range of potential advantages in terms of increased crop productivity and stability under climate change while providing multiple external benefits to society. The effects of windbreak on maize yields have not been assessed in a well-documented manner in eastern Canada, which is a major influential barrier limiting their adoption by farmers. In this study, we investigated the spatial distribution of maize grain yield in the leeward side of mature (average age, 30-years-old) single-tree row windbreaks that were located on four farm sites in southern Québec, Canada. We determined whether the sign and magnitude of windbreak effects on spatial patterns of maize yield varied across contrasting years with respect to rainfall conditions. The greatest yield variation was observed at the tree-crop interface (within 0.5–1H, where H = tree height), where substantial yield reductions occurred. In two sites, the magnitude of negative windbreak effects on maize yield at the tree-crop interface decreases in the wetter years. We found important maize yield variation among sampling positions between 2H and 20H (here considered as the shelter zone), with yield values often significantly higher than at 24H (here considered as a control zone with negligible tree shelter effects). The magnitude of this yield variation in the shelter zone generally decreased in the wetter years. In most cases, we estimated that the net effect of windbreak on maize yield (0.5–20H vs. 24H) was negligible. Significant net positive (16 %) or negative (−6 %) effects of windbreaks on maize production were found at one site only and occurred on two different years. We conclude that the sign and magnitude of windbreak effects on spatial patterns of maize grain vary considerably across farms and depend upon temporal variation in rainfall conditions in eastern Canada.