土壤跳虫在碳循环中的作用——^(13)C示踪研究  

Role of Collembola in Carbon Transformation——A ^(13)C-labelling Study

作　　者：徐国良[1] 王敏[2,3] 张卫信[2] 夏汉平[2] 王嘉珊 吴志峰[1] 

机构地区：[1]广州大学地理科学学院,广东广州510006 [2]中国科学院华南植物园,广东广州510650 [3]中国科学院大学,北京100039

出　　处：《生态环境学报》2015年第7期1103-1107,共5页Ecology and Environmental Sciences

基　　金：国家自然科学基金项目(31270560;41571247);973子课题(2011CB403205);广东省自然科学基金项目(2014A030313532);广州市属高校科研项目(1201410805)

摘　　要：土壤动物在土壤碳库中发挥着重要的作用,但长期以来受技术手段的限制,其作用过程及贡献程度仍不清楚。该研究通过室内微宇宙实验,利用稳定碳同位素标记凋落物和模式跳虫实验种(Folsomia Candida)探索了土壤动物在碳循环中的作用。试验设置了3个处理:对照土壤、土壤加标记凋落物、土壤加标记凋落物和跳虫,每处理设4个重复,分别在实验开始的第7、21、63天进行破坏性取样。研究结果发现,凋落物新碳可以很快进入土壤食物网。试验跳虫δ13C原始值为-9.91‰±0.08‰,经过7天的培养,跳虫体内的δ13C值达到522.70‰,表明跳虫能在短时间内高效同化来自凋落物的新碳;土壤微生物群落也显著地同化了凋落物新碳,添加凋落物后微生物PLFAsδ13C值极显著升高,这种效应在试验初期尤其显著;同时,研究发现在添加跳虫的处理中,微生物δ13C比无跳虫处理的极显著升高,反映跳虫的存在和活动对微生物有积极的能动作用,增加微生物对凋落物新碳的同化效率。虽然7 d后发现凋落物新碳明显进入了土壤,然而添加跳虫处理的土壤δ13C显著低于没有加跳虫的,说明跳虫的活动可能促使了更多新C释放出土壤,从而降低了土壤的δ13C值。不同处理之间累计呼吸量存在显著差异,有凋落物和跳虫存在的处理极显著高于对照处理,表明实验处理都显著地增加了系统CO2通量;通过对C来源的同位素解析,发现试验初期(21 d)有85%以上的C都来自凋落物新碳,表明初期凋落物新C大量释放;但随着凋落物分解的进行或跳虫活动的增强,土壤C的利用效率逐步增加,使得通量中土壤C的比例逐渐增加。本研究通过比较完善的控制实验明确证实,在土壤动物和微生物的作用下,凋落物新C可以很快进入碳循环,但新C也很容易通过呼吸作用释放回到大气,尤其在初期,绝大部分排放的CO2都源自新C。土壤跳虫在食物�Terrestrial carbon cycle is one of the key issues in the world. Soil fauna play essential roles in soil ecosystem which is the largest terrestrial carbon sink. However, both the contributions of soil fauna to carbon transformation and the underlying mechanisms are still unclear. The isotope technology provided an useful method to quantify the key processes in soil food web and material cycling. In this study,13C-labeled leaf litter was used to investigate the effect of the Collembola （Folsomia Candida） on carbon transformation in laboratory microcosms. Three treatments were set up： （1） soil （control, S）, （2） soil and labeled litter （SL）, and （3） soil, labeled litter and Collembola （SLC）. Each treatment has four replicates. These microcosms were destructively sampled on day 7, 21, 63 after the experiment initiation. The results showed that litter-derived C was incorporated into soil biota rapidly. The originalδ13C values of Collembola was -9.91‰±0.08‰, and it reached 522.70‰ after 7 days of incubation indicating that Collembola could efficiently assimilate this newly introduced litter-derived C. Similarly, theδ13C values in PLFAs increased significantly, especially at the initial experimental stage. In addition, the presence of Collembola significantly promoted the PLFAsδ13C suggesting that Collembola could accelerate the microbial assimilation of litter carbon. Unexpectedly, treatment SLC exhibited significantly lowerδ13C values than treatment SL. This may indicate that the presence of Collembola stimulated the release of newly metabolized litter C. Both of the treatments stimulated CO2 flux significantly. By C isotope analysis, over 85% of the mineralized C derived from litter at the initiation state （21 days）, demonstrating that new C from fresh litter tended to release back to atmosphere with active soil biota. Thereafter, the contribution of soil-derived C to the CO2 emission increased. This study proved that new C from litter could participate in soil C cycling ra

关 键 词：跳虫 同位素 碳循环 

分 类 号：X17[环境科学与工程—环境科学]