Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark.
Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, 2100 Copenhagen Ø, Denmark.
Sci Total Environ. 2020 May 1;715:136793. doi: 10.1016/j.scitotenv.2020.136793. Epub 2020 Jan 18.
In the face of global climate change there is an increasing demand for biofuel, which exerts pressure on production and thus management of biofuel plantations. The intensification of whole-tree harvest from biofuel plantations increases export of nutrients. Returning ash from biofuel combustion to the forest plantations can amend the soil nutrient status and thus facilitate sustainable forest management. However, ash affects the forest floor decomposer food web, potentially changing organic matter turnover, carbon sequestration and nitrogen availability. Our aim was to examine the response of decomposer organisms, food web structure and nitrogen mineralization function after ash application. In a coniferous forest plantation amended with 0, 3, 4.5 or 6 t ash ha, we sampled in several depths of the forest floor for key organisms of the decomposer food web (fungal biomass, 0-12 cm; bacteria, protozoa, nematodes and enchytraeids, 0-3 cm and 3-6 cm; microarthropods and earthworms, 0-5 cm), 2, 14 and 26 months after ash application. We used structural equation modelling (SEM) to detangle the direct and indirect effects of ash application on organisms in the decomposer food web and on nitrogen availability. We found that ash increased the abundance of bacteria and protozoa, as well as the inorganic nitrogen pool at 0-3 cm depth, whereas the effect of ash was negligible at 3-6 cm depth. Earthworm abundance increased, whereas enchytraeid abundance decreased 2 years after ash application. The structural equation modelling showed that ash application stimulated the bacterial feeding pathway and increased nitrogen mineralization. Contrary, ash had a negative effect on fungal biomass at the first sampling, however, this effect subdued over time. Our results suggest that as the soil decomposer food web is resilient to ash application, this is a viable option for sustainable management of biofuel plantations.
面对全球气候变化，人们对生物燃料的需求不断增加，这给生物燃料种植园的生产和管理带来了压力。从生物燃料种植园中进行整树采伐会增加养分的输出。将生物燃料燃烧产生的灰分返回森林种植园，可以改良土壤养分状况，从而促进可持续的森林管理。然而，灰分会影响森林地被分解者的食物网，可能会改变有机物质的转化、碳固存和氮的有效性。我们的目的是研究灰分施入后对分解者生物、食物网结构和氮矿化功能的响应。在一个针叶林种植园中，我们在施灰 0、3、4.5 或 6 t/公顷的不同深度采集了森林地被层中的关键分解者生物（真菌生物量，0-12cm；细菌、原生动物、线虫和真蚓，0-3cm 和 3-6cm；微节肢动物和蚯蚓，0-5cm），并在施灰后 2、14 和 26 个月进行了采样。我们使用结构方程模型（SEM）来梳理灰分施入对分解者食物网中生物和氮有效性的直接和间接影响。我们发现，灰分增加了细菌和原生动物的丰度以及 0-3cm 深度的无机氮库，而在 3-6cm 深度的影响可以忽略不计。蚯蚓的丰度增加，而真蚓的丰度在施灰后 2 年减少。结构方程模型表明，灰分施入刺激了细菌食性途径并增加了氮矿化。相反，灰分对第一次采样时的真菌生物量有负面影响，但随着时间的推移，这种影响会减弱。我们的研究结果表明，由于土壤分解者食物网对灰分施入具有较强的恢复能力，因此这是生物燃料种植园可持续管理的可行选择。
