Enhanced understory carbon flux components and robustness of net CO2 exchange after thinning in a larch forest in central Japan
Enhanced understory carbon flux components and robustness of net CO2 exchange after thinning in a larch forest in central Japan
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DOI：
10.1016/j.agrformet.2019.04.008
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发表时间：
2019-08
影响因子：
6.2
通讯作者：
Munemasa Teramoto;N. Liang;Yoshiyuki Takahashi;J. Zeng;N. Saigusa;R. Ide;Xin Zhao
中科院分区：
文献类型：
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作者：
Munemasa Teramoto;N. Liang;Yoshiyuki Takahashi;J. Zeng;N. Saigusa;R. Ide;Xin Zhao
间伐是人工林可持续经营的必要步骤。间伐对森林碳平衡有显著影响；然而，目前有限的研究表明，利用长期监测数据综合评估了间伐对几种林下碳通量组分的影响。为了了解2014年5月和2015年3月进行的森林间伐对林下碳平衡的影响，并阐明短期气候变化对日本中部落叶松林下碳平衡的影响，我们使用自动化室连续测量了12年的林下通量成分。虽然间伐（树干减少39%）使年平均土壤湿度增加16.5%，生长季土壤温度增加2.4%，但降水和土壤温度的年际变化在很大程度上掩盖了间伐对土壤呼吸（Rs）和土壤异养呼吸（Rh）的影响。年平均土壤温度与各年外排分量呈显著正相关。间伐还使林下光合光子通量密度（PPFDu）在生长季节（5 ~ 10月）增加了63.1%。间伐后林下3年平均光合作用（GPPu）、林下植物呼吸（Rp）和林下总呼吸（Ru）分别显著增加59.5%、99.7%和26.9%。净林下co2交换（NUE =Ru−GPPu）仅在2015年发生了显著变化（13.8%）。还检测到基于后间伐年三年平均值的NUE略有显著变化（14.4%）。结果表明，各通量组分（尤其是GPPu、Rp和ru）在减薄后变化显著。相比之下，该森林的NUE相对于其他增强的林下通量组分更为稳健。然而，NUE的边际显著增加（疏林后3年平均值）意味着疏林后NUE略有增加。
Thinning is a necessary procedure for the sustainable management of plantation forests. Thinning has a remarkable influence on forest carbon balance; however, there are limited studies showing the integrated assessment of the effects of thinning on several understory carbon flux components using long-term monitoring data. We measured understory flux components using automated chambers continuously over 12 years to understand the effects of forest thinning conducted in May 2014 and March 2015 and to elucidate the effect of short-term climate change on understory carbon balance in a Japanese larch (Larix kaempferiSarg.) forest in central Japan. Although thinning (39% decrease in tree stems) increased the mean annual soil moisture by 16.5% and growing season soil temperature by 2.4%, large inter-annual variations in precipitation and soil temperature largely masked the effects of thinning on both soil respiration (Rs) and soil heterotrophic respiration (Rh). Annual mean soil temperature was positively related to all annual efflux components. Thinning also increased the understory photosynthetic photon flux density (PPFDu) by 63.1% during the growing season (May to October). In post-thinning years, the average three-year understory photosynthesis (GPPu), understory plant respiration (Rp), and total understory respiration (Ru) increased significantly by 59.5%, 99.7%, and 26.9%, respectively. The net understory CO2exchange (NUE =Ru− GPPu) changed significantly only in 2015 (13.8%). A marginally significant change in NUE based on the three-year average in post-thinning years was also detected (14.4%). Our results indicated each flux component (especially GPPu,Rp, andRu) changed dramatically after thinning. In contrast, the NUE of this forest was relatively more robust than other enhanced understory flux components. However, the marginally significant increase of NUE (3-year average in post-thinning years) implied a slight increase in NUE after thinning.