Centre for Forest Research, Université du Québec à Montréal, PO Box 8888, Centre-Ville Station, Montréal, H3C 3P8, Canada.
Sci Total Environ. 2013 Oct 1;463-464:51-60. doi: 10.1016/j.scitotenv.2013.05.071. Epub 2013 Jun 19.
Agroforestry is increasingly viewed as an effective means of maintaining or even increasing crop and tree productivity under climate change while promoting other ecosystem functions and services. This study focused on soil biochemical properties and resilience following disturbance within agroforestry and conventional agricultural systems and aimed to determine whether soil differences in terms of these biochemical properties and resilience would subsequently affect crop productivity under extreme soil water conditions. Two research sites that had been established on agricultural land were selected for this study. The first site included an 18-year-old windbreak, while the second site consisted in an 8-year-old tree-based intercropping system. In each site, soil samples were used for the determination of soil nutrient availability, microbial dynamics and microbial resilience to different wetting-drying perturbations and for a greenhouse pot experiment with wheat. Drying and flooding were selected as water stress treatments and compared to a control. These treatments were initiated at the beginning of the wheat anthesis period and maintained over 10 days. Trees contributed to increase soil nutrient pools, as evidenced by the higher extractable-P (both sites), and the higher total N and mineralizable N (tree-based intercropping site) found in the agroforestry compared to the conventional agricultural system. Metabolic quotient (qCO2) was lower in the agroforestry than in the conventional agricultural system, suggesting higher microbial substrate use efficiency in agroforestry systems. Microbial resilience was higher in the agroforestry soils compared to soils from the conventional agricultural system (windbreak site only). At the windbreak site, wheat growing in soils from agroforestry system exhibited higher aboveground biomass and number of grains per spike than in conventional agricultural system soils in the three water stress treatments. At the tree-based intercropping site, higher wheat biomass, grain yield and number of grains per spike were observed in agroforestry than in conventional agricultural system soils, but in the drought treatment only. Drought (windbreak site) and flooding (both sites) treatments significantly reduced wheat yield and 1000-grain weight in both types of system. Relationships between soil biochemical properties and soil microbial resilience or wheat productivity were strongly dependent on site. This study suggests that agroforestry systems may have a positive effect on soil biochemical properties and microbial resilience, which could operate positively on crop productivity and tolerance to severe water stress.
农业林业正日益被视为在气候变化下维持甚至提高作物和树木生产力的有效手段，同时促进其他生态系统功能和服务。本研究侧重于农业林业和常规农业系统内受干扰后的土壤生物化学特性和弹性，并旨在确定这些生物化学特性和弹性方面的土壤差异是否会随后影响极端土壤水分条件下的作物生产力。本研究选择了两个建立在农业用地上的研究点。第一个研究点包括一个 18 年的防风林，而第二个研究点由一个 8 年生的混农林业系统组成。在每个研究点，土壤样本用于测定土壤养分供应、微生物动态以及微生物对不同干湿扰动的弹性，并进行了一项温室盆栽小麦实验。干旱和水淹被选为水分胁迫处理，并与对照进行比较。这些处理在小麦开花期开始时启动，并持续 10 天。树木有助于增加土壤养分库，这表现在农业林业中比在常规农业系统中提取的 P 更高（两个研究点），以及总 N 和矿化 N 更高（混农林业研究点）。农业林业中的代谢商（qCO2）低于常规农业系统，表明农业林业系统中的微生物对基质的利用效率更高。与常规农业系统的土壤相比，农业林业土壤的微生物弹性更高（仅防风林研究点）。在防风林研究点，在三种水分胁迫处理中，在农业林业系统土壤中生长的小麦的地上生物量和每穗粒数均高于常规农业系统土壤。在混农林业研究点，农业林业土壤中的小麦生物量、籽粒产量和每穗粒数均高于常规农业系统土壤，但仅在干旱处理中。干旱（防风林研究点）和水淹（两个研究点）处理均显著降低了两种系统中的小麦产量和千粒重。土壤生物化学特性和土壤微生物弹性或小麦生产力之间的关系强烈依赖于研究点。本研究表明，农业林业系统可能对土壤生物化学特性和微生物弹性产生积极影响，这可能对作物生产力和对严重水分胁迫的耐受性产生积极影响。
