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Agroforestry (AF) is considered to be a sustainable land use practice as it combines agricultural production with multiple beneficial effects such as carbon sequestration, enhanced nutrient cycling and increased biodiversity. Quantification of these beneficial effects in temperate arable fields is still limited, however, and most studies focus on one sole parameter (i.e., impact on crop productivity, soil quality, biodiversity, etc.). Combined effects are only rarely considered, resulting in a lack of integrated quantification. Here we assess the effect of rows of walnut trees (Juglans regia L.) on soil organic carbon (SOC), soil nutrient status, the presence of potentially beneficial ground-dwelling arthropods and on the yield and quality of neighboring arable crops. Significantly higher SOC and soil nutrient concentrations were found near the trees, which is assumed to be primarily a result of tree leaf litter input. Abundance of macro-detritivorous arthropods was increased in and near the tree rows, whereas only limited effects of tree presence were found on the presence of the predatory arthropod taxa under study. The yield of all crops under study was reduced as a result of tree presence, with the strongest reductions observed for grain maize and sugar beet near the trees (

Ground dwelling arthropods present in agricultural systems regulate multiple ecosystem services (ES), such as nutrient and carbon cycling and biological pest control. The presence of semi-natural landscape features, such as the tree component of agroforestry systems (AFS), can contribute to functional agrobiodiversity and optimize the delivery of such ES in agricultural landscapes. In temperate AFS, however, potential patterns in abundance and diversity have scarcely been investigated for detritivorous soil dwelling arthropods and only to a limited extent for predatory arthropods. Therefore, we have assessed the abundance and diversity of woodlice (Isopoda), millipedes (Diplopoda), rove beetles (Coleoptera: Staphylinidae) and carabids (Coleoptera: Carabidae) as a function of the distance to the tree row in a set of temperate arable AFS. Abundance and diversity of woodlice and millipedes were significantly higher in the tree rows than in the arable zone. In the case of mature trees, a higher abundance of detritivores was also observed in the arable zone close to the trees. Tree presence did not consistently lead to higher abundance of predatory arthropods, but a limited increase in carabid diversity was observed in the arable zone close to the tree rows. These results indicate that in temperate AFS, the trees and the associated understory vegetation strip contribute to the preservation of arthropod biodiversity and the enhancement of associated ES in the tree rows and in the arable field zone.

Agroforestry systems (AFS) are considered to be a sustainable agricultural practice, as they deliver a wide range of ecosystem services (ES) while maintaining (agricultural) primary production. To optimize the productivity of AFS, the recommendation is to use well adapted tree-crop combinations, thereby limiting competition for resources and maximizing synergies. However, yield and quality data on arable crops in temperate AFS are scarce, in particular for AFS with a mature tree component. Here we assessed the influence of tree rows of contrasting age on yield and quality of key western European arable crops. We focused on (forage) maize, potato, winter wheat and winter barley during three consecutive years (2015–2017) on a set of 16 arable agroforestry fields in Belgium comprising 6 young (2–7 year old) alley cropping fields and 10 fields bordered by a row of deciduous trees of moderate to older age (15–48 years old). Both tree age and crop type were key determinants of yield and quality of the investigated arable crops. While effects on crop yield were limited for all crops near young tree rows, substantial yield reductions were observed near mature trees, in particular for maize and potato (both summer crops). Effects on crop quality were limited for all crops under study, with substantial effects only arising near the oldest tree rows. To optimize the provisioning service of AFS, the cultivation of winter cereals may be advisable over maize and potato towards the end of the rotation of an AFS. In addition, poplar trees should be harvested when they reach their target diameter for industrial processing. If tree rows are preserved for the delivery of other ES, however, substantial impacts on crop yield and quality should be taken into account.

Agroforestry systems (AFS) have a large potential to deliver a wide range of ecosystem services (ES). In field and crop management, changes to factors such as regulatory ES delivery are rarely taken into account, in part due to the paucity of detailed quantification of how trees affect biophysical field characteristics. This is especially true for arable systems in temperate climates. We have therefore assessed the influence of rows of trees of varying size on the prevailing soil characteristics in arable AFS. Spatial variability of soil organic carbon, acidity and nutrient status (N, P, K, Ca, Mg and Na) of the plough layer were analysed on a set of 17 arable agroforestry fields comprising 6 young (

Environmental measures in an agricultural context often lead to extra constraints in current farming. This suggests trade-offs between the environmental objectives and profitability. Whether trade-offs exist, or may be turned into win-win, depends on creative farm options to comply new constraints. This paper concentrates on Ecological Focus Areas as a new EU Common Agricultural Policy greening requirement, and investigates profitability changes of two greening options with permanent woody elements, hedgerows and alley cropping. We predicted discounted gross margins for a hedgerow and alley cropping greening option and four market scenarios on a representative arable farm in Flanders (Belgium). Starting from the tree row, over a distance of 1.64 times the tree height, relative crop yield is 70% as compared to a treeless situation. Between 1.64 and 9.52 times the tree height, relative yield is 107%. Beyond that point, the effect is considered negligible. Discounted gross margins are calculated to account for the time horizon. Relative discounted gross margins at farm level, compared to the business as usual option, vary between 91% and 108%, depending on market conditions and policy support. The calculations show that fulfilment of the 5% ecological focus area greening requirement on arable farms with hedgerows and alley cropping only becomes economically competitive to the traditional cropping systems with extra financial stimuli (e.g. greening payments). We also show and discuss how the calculations can be fine-tuned and used in policy making, e.g. by i) getting better insights in the tree-crop interactions, ii) including the effect of e.g. crop type, tree species, tree line space and tree line orientation in the meta-information, iii) evaluating this conditional competitiveness and suggesting a better linking between subsidy level and ecological value and ecosystem services and iv) exploring novel valorization channels for wood products.

There is a renewed interest in temperate agroforestry systems because of their potential to increase biodiversity, sequester carbon and diversify the landscape while maintaining productivity. Little quantitative information is available about the interaction between trees and the crop for water, especially in temperate climate and for tree ages towards the end of an agroforestry cycle. With this study, we quantified the effect of mature poplar trees on soil moisture dynamics in space and time in an agricultural field sown with maize during one growing season. We confirmed the ability of electrical resistivity tomography to study tree-crop interactions for water under field conditions and we delimited an area of influence of the 40-year old trees on the crop of about 15 m. In order to do this, we installed four 30 m electrode transects perpendicular to the field border. Three transects were located next to a tree-bordered part of the field and one reference transect was located along the same border, but without any tree present. We performed seven electrical resistivity tomography (ERT) measurements during the maize growing season and compared the soil moisture distribution and dynamics with and without tree border as a proxy for a mature agroforestry system. We showed that the ERT tomograms in a tree-bordered zone are significantly different from a reference zone without trees along the 30 m of the transect using a single and segmented linear regression analysis. This article shows the potential of ERT to quantify tree-crop-soil interactions for water in agroforestry systems.

The importance of semi-natural vegetation elements in the agricultural landscape is increasingly recognized because they have the potential to enhance multiple ecosystem service delivery and biodiversity. However, there is great variability in the observed effects within and between studies. Also, little is known about the simultaneous delivery of multiple ecosystem services and biodiversity because most studies focus on monitoring one service at a time and in conditions specifically suited to observe this one service. In this study, the results are presented of 1 year of monitoring of a set of parcel-level and simplistic ecosystem service and biodiversity indicators on parcels with grass strips or hedgerows. In the grass strips, an increase in soil organic carbon stock, a decrease in soil mineral nitrogen content, a different carabid species composition and a higher spider activity density were found, compared to the adjacent arable parcel. These results indicate a contribution of grass strips to climate regulation, the regulation of water quality, an increase of beta diversity and potential for pest control. Next to hedgerows, crop yield was reduced and winter wheat thousand kernel weight, soil organic carbon stock and spider activity density were increased. These indicators show an effect of the hedgerow on food production, climate regulation and potential for pest control. The study concludes that both grass strips and hedgerows have the potential to increase multiple ecosystem service delivery, but that an increase of every service is not assured and that multifunctionality is affected by management choices. Also, an improved experimental setup in order to enhance ecosystem service monitoring is suggested.