短期模拟氮沉降对兴安落叶松林土壤呼吸及其组分的影响OA

Forest soil respiration is the second largest carbon flux in the global carbon cycle,following vegetation photosynthesis.Its small fluctuations can not only change the CO2 concentration in the atmosphere,but also affect the forest carbon storage capacity.The increase in atmospheric nitrogen deposition has significantly impacted the carbon cycle of forest ecosystems.As climate change intensifies,understanding the mechanisms by which simulated nitrogen deposition affects soil respiration has garnered considerable attention from researchers.This study focused on the Larix gmelinii forest and set three nitrogen deposition levels from May to October 2023,namely 0 g·m-2·a-1(CK),5 g·m-2·a-1(N1)and 10 g·m-2·a-1(N2).The soil respiration and its components,as well as soil environmental factors,were measured to explore the mechanism of short-term nitrogen deposition on the soil respiration and its com-ponents in Larix gmelinii forest.The results showed that,the soil respiration and its components showed significant monthly variations under CK,N1 and N2 treatments.Compared to CK,N1 and N2 treatments significantly increased soil respiration and its components in the Larix gmelinii forest(P＜0.05),with N2＞N1＞CK,the promoting effects of nitrogen deposition were Ra>Rs>Rh.Compared with the soil autotrophic respiration,the soil heterotrophic respiration accounted for the largest proportion of total soil respiration,with CK,N1 and N2 accounted for 72.39%,72.25%and 71.48%,respectively.The soil respiration and its components in Larix gmelinii forest showed a significant exponential relationship with the soil temperature,and short-term nitrogen deposition reduced soil respiration and its component Q10,both showing CK>N1>N2.Except for the N2 treatment,there was a significant correlation be-tween the soil respiration and its components and soil moisture in all other treatments(P<0.05),but the correlation was smaller than that between the soil temperature and soil respiration and its components.The composite model of soil respiration and its components with soil temperature and moisture was superior to the single-factor model.The redundancy analysis results indicated that the soil mi-crobial biomass carbon(MBC)was the main factor that influencing soil respiration and its components under short-term simulated ni-trogen deposition.This study revealed the response characteristics and mechanisms of soil respiration and its components to short-term nitrogen deposition in the Larix gmelinii forest,and provided basic data and theoretical basis for accurately evaluating the re-sponse of carbon cycling in forest ecosystems in the region to the global nitrogen deposition increase.