Contents lists available at ScienceDirect Agricultural and Forest Meteorology journal homepage: www.elsevier.com/locate/agrformet Forest and perennial herbland cover reduce microbial respiration but increase root respiration in agroforestry systems Mark Baah-Acheamfour a,1 , Cameron N. Carlyle b , Edward W. Bork b , Scott X. Chang a, ⁎ a Department of Renewable Resources, University of Alberta, 442 Earth Science Building, Edmonton, Alberta, Canada T6G 2E3 b Department of Agricultural, Food and Nutritional Science, University of Alberta, Agriculture/Forestry Centre, Edmonton, Alberta, Canada ARTICLE INFO Keywords: Agroforestry Climate change Greenhouse gas emissions Temperature sensitivity ABSTRACT Agricultural land management practices have the potential to reduce carbon emissions from soils, especially when a reduction in microbial (heterotrophic respiration, R H ) rather than root respiration (autotrophic, R A ) is achieved. Soil R A and R H and their sensitivity to temperature changes were determined in the forestland and neighboring herbland (area without trees) soils of three agroforestry systems (hedgerow, shelterbelt, and sil- vopasture) over two growing seasons (May through September in 2013 and 2014). Over the two growing sea- sons, mean R A from the forestland was 32% greater than that from the herbland, while the R H in the forestland was 22% lower than that in the herbland. The sensitivity of R A to temperature was consistently greater in the forestland (3.6) than in the herbland (3.4), though the opposite was found for R H .Effects of agroforestry system on R A and R H also varied seasonally. The contribution of R H to total soil respiration was greater in each of the hedgerow (59%) and shelterbelt (55%) systems than in the silvopasture system (51%), reflecting the high R H from annual cropland within the hedgerow and shelterbelt systems. We found stronger control of R H by tem- perature in the hedgerow and shelterbelt, suggesting that an increase in soil temperature in response to future climatic warming could reduce the amount of carbon held in these systems as compared to the silvopasture system. Overall, the inclusion or maintenance of perennial vegetation (forest and grassland) in an annually cropped agricultural landscape could result in a net reduction in soil R H , and thereby mitigate losses of carbon from agricultural soils. 1. Introduction Agroforestry systems, which integrate trees into the agricultural landscape, are common land uses across Canada and could play a substantial role in sequestering carbon (C) and mitigating increases in atmospheric greenhouse gas (GHG) concentrations (Albrecht and Kandji, 2003; Nair et al., 2009; Baah-Acheamfour et al., 2016, 2017). Contemporary agroforestry systems can take many forms, and across the Canadian landscape include shelterbelt, hedgerow, riparian buffer, and silvopasture systems (Thevathasan et al., 2012; Kort et al., 2014). Shelterbelt systems consist of trees and shrubs planted in one, two or multiple parallel rows, often along the edge of annual croplands, with many initially established to provide fuelwood to residents and wind- breaks to overwintering livestock. In contrast, hedgerow systems are made up of naturally regenerated perennial vegetation that include woody species (shrubs and/or trees) that are maintained along the edge of annual croplands due to the extended absence of mechanical disturbance. Riparian buffers consist of strips of trees, shrubs, and grasses between agricultural lands and water bodies (Korzekwa, 2019). Silvopasture systems contain trees growing in various configurations (i.e., forest patches of variable size and density) on otherwise open grasslands. These agroforestry systems are not unique to specific regions in Canada, but may be more widespread in some areas than others, de- pending on the soil conditions, climate, and land-use history. Within the Canadian prairies, hedgerows, shelterbelts, and silvopasture sys- tems have become a valuable addition to the agricultural landscape. Although fuelwood and shelter were of primary importance early on, they are now also recognized for many other ecological goods and services, which include soil conservation, water quality protection, snow management, nutrient cycling, and habitat for pollinators, pest suppressing insects, birds, and other wildlife (Kulshreshtha and Kort, 2009; Kort et al., 2012). For instance, the need for soil con- servation through windbreaks led to the widespread establishment of https://doi.org/10.1016/j.agrformet.2019.107790 Received 14 May 2019; Received in revised form 30 September 2019; Accepted 3 October 2019 ⁎ Corresponding author. E-mail addresses: mbaahach@ualberta.ca (M. Baah-Acheamfour), scott.chang@ualberta.ca (S.X. Chang). 1 Current address: Centre for Boreal Research, Northern Alberta Institute of Technology, Peace River, Alberta, Canada. Agricultural and Forest Meteorology 280 (2020) 107790 0168-1923/ © 2019 Elsevier B.V. All rights reserved. T