Impact of planting trees on abandoned farmlands on diversity and carbon sequestration

在废弃农田上建立人工林为植物生物量和土壤固碳提供了良好的机会。与耕地相比，建立在废弃农田上的种植园有利于生物多样性，因为它加速了原生植物的入侵和种植，而植物演替的生态障碍可以阻止或减缓殖民化。然而，人工林履行其正在取代的生态系统（休耕地、耕地或森林）中通常存在的生态服务的潜力在很大程度上是未知的。本研究旨在确定建立杨树和白云杉杂交人工林对维管植物和非维管植物功能多样性、物种组成、土壤微生物组和碳含量的影响，并将其与以前的利用情况进行比较，并与周围森林和未种植的废弃农田进行比较。我们还打算沿着种植（白云杉）和类似的未种植的休耕地的时间顺序比较生物多样性。最后，本研究旨在确定在深层土壤中以稳定形式增加碳固存的功能性根系性状，以及土壤微生物群如何与这些性状相互作用。已经建立的白云杉和杂交杨树种植园将根据其以前的土地用途（杨树）和年龄（云杉）进行采样，以便与未种植的废弃农田和周围森林进行比较，确定其植物组成和土壤微生物组的特征。在杂交杨树人工林中，对几个生长速度慢或快的无性系的根系功能性状和土壤碳进行了测定，以便将这些性状与长期固碳联系起来。最后，该项目将有助于根据生态标准做出明智的决策和造林投资，并优化结果，更好地针对加拿大利用树木补偿二氧化碳排放和管理景观多样性的目标。

The establishment of plantations on abandoned farmland offers good opportunities to sequester carbon into plant biomass and soils. Plantations established on abandoned farmlands can be beneficial to biodiversity compared to cultivated lands, by accelerating the invasion and installation of native plants where ecological barriers to plant succession can halt or slow down colonisation. The potential for plantations to fulfill ecological services typically found in the ecosystems they are replacing (fallow lands, cultivated lands or forests) is however largely unknown. This study aims to determine the effects of establishing hybrid poplar and white spruce plantations on vascular and non-vascular plant functional diversity and species composition, soil microbiome and carbon content, in relation to the previous use of the sites and in comparison with surrounding forests and unplanted abandoned farmlands. We also aim to compare biodiversity along a chronosequence of planted (white spruce) and comparable unplanted fallow lands. Finally, this study aims to identify functional root traits that increase carbon sequestration in deep soil layers and in stable forms, and how the soil microbiome interacts with these traits.Already established white spruce and hybrid poplar plantations will be samples according to their previous land use (poplar) and age (spruce), in order to characterize their plant composition and soil microbiome, in comparison with unplanted abandoned farmland and surrounding forest. Soil carbon will be measured in the hybrid poplar plantations along with root functional traits of several clones that have slow to rapid growth rates, in order to link these traits with long term carbon sequestration. In the end, this project will contribute to make informed decisions and silviculture investments into plantations, according to ecological criteria and optimize outcomes better targeted to Canada's objectives of using trees to compensate CO2 emissions and manage diversity over the landscape.