Tree strips on agricultural production sites offer many economic, ecological and social advantages. However, the introduction of trees creates a transition zone between tree strips and crop land. Here, trees and crop plants compete for resources such as space, nutrients, water and light, which causes stress in the low-competitive system. On the other hand, facilitation such as additional nutrient input through tree leaf litter and fine roots are possible. This study aims to provide indications for competition and benefits that can arise for plants growing in the transition zone of a temperate short rotation alley cropping agroforestry system (SRACS). Various climatic and plant-growth parameters were investigated between 2013 and 2019 at different positions of an SRACS with fast-growing poplars in northern Germany. Reduced yield of wheat, oilseed rape and silage maize close to the tree strip was associated with greater soil water tension in 30 and 60 cm soil depth due to the presence of poplar roots, reduced solar radiation due to tree shading and leaf litter coverage. In contrast, poplars growing in the outer rows produced more biomass than those in the inner rows due to the additional availability of space, light and nutrients taken from the crop field. Trees in the transition zone seem to be competitive with arable crops, but without effect on the average long-term yield of arable crops.

中文翻译：

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竞争、压力和收益：温带短轮作农林系统过渡区的树木和作物

农业生产场地上的林带提供了许多经济、生态和社会优势。然而，树木的引入在林带和农田之间创造了一个过渡区。在这里，树木和农作物争夺空间、养分、水和光等资源，这给低竞争系统带来了压力。另一方面，诸如通过树叶凋落物和细根的额外营养输入等促进是可能的。本研究旨在为生长在温带短轮作农林业系统 (SRACS) 过渡区的植物提供竞争和利益的迹象。2013 年至 2019 年期间，在德国北部快速生长的杨树的 SRACS 的不同位置调查了各种气候和植物生长参数。小麦减产，由于杨树根的存在，靠近树带的油菜和青贮玉米与 30 厘米和 60 厘米土壤深度的土壤水分紧张有关，树木遮蔽和落叶覆盖导致太阳辐射减少。相比之下，生长在外排的杨树比内排的杨树产生更多的生物量，因为从农田中获取的空间、光照和养分更多。过渡区的树木似乎与可耕作物具有竞争力，但对可耕作物的平均长期产量没有影响。由于从农田中获取的额外空间、光照和养分，外排的杨树比内排的杨树产生更多的生物量。过渡区的树木似乎与可耕作物具有竞争力，但对可耕作物的平均长期产量没有影响。由于从农田中获取的额外空间、光照和养分，外排的杨树比内排的杨树产生更多的生物量。过渡区的树木似乎与可耕作物具有竞争力，但对可耕作物的平均长期产量没有影响。