Palviainen Marjo, Peltomaa Elina, Laurén Ari, Kinnunen Niko, Ojala Anne, Berninger Frank, Zhu Xudan, Pumpanen Jukka
Department of Forest Sciences, University of Helsinki, Finland.
Department of Forest Sciences, University of Helsinki, Finland.
Sci Total Environ. 2022 Feb 1;806(Pt 4):150919. doi: 10.1016/j.scitotenv.2021.150919. Epub 2021 Oct 12.
Boreal peatlands are major sources of nitrogen (N), phosphorus (P) and dissolved organic carbon (DOC) to downstream aquatic ecosystems, and forest harvesting generally further increases the loading of DOC and nutrients. Continuous cover forestry (CCF) is proposed to be an environmentally more sustainable management option for peatland forests than conventional even-aged clear-cutting. However, the impacts of CCF on water quality, the biodegradability of DOC and consequent CO emissions from inland waters are poorly known. We studied the concentrations of N, P and DOC, the quality of DOC, and the mineralization of DOC to CO in ground water and ditch water in clear-cut, partially harvested, i.e. CCF, and uncut drained forests in Finland. Groundwater total N, NH-N and PO-P concentrations were significantly lower in CCF and uncut forest than in the clear-cut forest. Groundwater DOC concentrations were often highest in the clear-cut forest, where the water table was closer to the soil surface. Ditch water DOC and N concentrations were lowest next to the clear-cut area. DOC aromaticity in ground water was higher in the uncut forest than in the clear-cut and CCF, whereas ditch water aromaticity did not differ between the treatments. The biodegradation of DOC was studied by incubating water (at 15 °C for 24 h) 1, 3, 7 and 21 days after sampling. The results indicated that the majority of the CO production took place during the first three days, and CO fluxes were considerably higher from the ditch water than from the groundwater. The CO emissions were lower in summer than in the other seasons. Ditch water and groundwater CO production were generally significantly higher in the clear-cut than in the uncut forest. The results suggest that CCF can decrease the nutrient concentrations as well as CO emissions from inland waters compared to conventional clear-cutting.
北方泥炭地是下游水生生态系统中氮（N）、磷（P）和溶解有机碳（DOC）的主要来源，森林采伐通常会进一步增加DOC和养分的负荷。与传统的同龄皆伐相比，连续覆盖林业（CCF）被认为是泥炭地森林在环境方面更具可持续性的管理选择。然而，CCF对水质、DOC的生物降解性以及内陆水域随之产生的CO排放的影响却鲜为人知。我们研究了芬兰皆伐、部分采伐（即CCF）和未采伐排水森林中地下水和沟渠水中N、P和DOC的浓度、DOC的质量以及DOC矿化生成CO的情况。CCF和未采伐森林中的地下水总氮、NH-N和PO-P浓度显著低于皆伐森林。皆伐森林中的地下水DOC浓度通常最高，那里的地下水位更接近土壤表面。沟渠水DOC和N浓度在皆伐区附近最低。未采伐森林中地下水DOC的芳香性高于皆伐和CCF森林，而各处理之间沟渠水的芳香性没有差异。通过在采样后1、3、7和21天对水进行培养（在15℃下培养24小时）来研究DOC的生物降解。结果表明，大部分CO产生发生在前三天，沟渠水的CO通量远高于地下水。夏季的CO排放低于其他季节。皆伐森林中沟渠水和地下水的CO产生量通常显著高于未采伐森林。结果表明，与传统皆伐相比，CCF可以降低内陆水域的养分浓度以及CO排放。
