生态环境学报
生態環境學報
생태배경학보
ECOLOGY AND ENVIRONMENT
2013年
11期
1846-1852
,共7页
CO2升高%碳循环%碳输入%碳输出
CO2升高%碳循環%碳輸入%碳輸齣
CO2승고%탄순배%탄수입%탄수출
elevated CO2%carbon cycle%soil carbon input%soil carbon output
土壤有机碳是陆地碳库的重要组成部分，其积累和分解的变化直接影响全球的碳平衡。据估计，全球土壤（表层1 m）有机碳积累总量相当于大气中碳总量的2~3倍。土壤是温室气体的源或汇，土壤碳库的变化将影响大气CO2的浓度，因此，土壤碳库对人类活动的响应也是全球碳循环和全球变化研究的热点。在全球变化的大背景下，大气 CO2升高导致植被生态系统碳平衡的改变进而对土壤碳循环产生影响。总结了陆地生态系统碳循环对大气 CO2浓度升高响应的主要生物学机制及过程，简述了大气 CO2浓度升高对影响土壤碳输入和输出的各因素的研究进展，并指出未来研究的主要方向。在大气 CO2浓度升高条件下，陆地生态系统碳循环的变化主要反映在以下几个方面：1）不同类型植物群落的净初级生产力（NPP）显著增加，但湿地植物的净初级生产力也有可能降低；2）光合产物向根系分配的数量增加，地上/地下生物量降低，根系形态发生变化，根系周转速率和根系分泌等过程的碳流量提高；3）植物含氮量降低，C/N 提高，次生代谢产物增加，微生物生长受到抑制，植物残体分解速率降低；4）土壤呼吸速率显著增加，提高幅度受植物类型与土壤状况的影响；5）进入土壤的植物残体及分泌物的数量和性质影响土壤酶的活性，脱氢酶和转化酶活性增加，酚氧化酶和纤维素酶受植物类型与环境条件的影响；6）土壤中真菌的数量的增加幅度要高于细菌；7）CH4释放量增加，在植物的生长期表现更为明显。由于陆地生态系统碳循环的复杂性，研究结果仍有很大的不确定性。大气 CO2浓度升高与全球变化的其它表现间的交互作用将是今后研究的重点，同时由于土壤碳循环是一个由微生物介导的生物地球化学循环过程，因此，加强陆地生态系统碳循环的微生物机制研究也将为全面理解碳循环的过程提供更加准确的研究理论基础。
土壤有機碳是陸地碳庫的重要組成部分，其積纍和分解的變化直接影響全毬的碳平衡。據估計，全毬土壤（錶層1 m）有機碳積纍總量相噹于大氣中碳總量的2~3倍。土壤是溫室氣體的源或彙，土壤碳庫的變化將影響大氣CO2的濃度，因此，土壤碳庫對人類活動的響應也是全毬碳循環和全毬變化研究的熱點。在全毬變化的大揹景下，大氣 CO2升高導緻植被生態繫統碳平衡的改變進而對土壤碳循環產生影響。總結瞭陸地生態繫統碳循環對大氣 CO2濃度升高響應的主要生物學機製及過程，簡述瞭大氣 CO2濃度升高對影響土壤碳輸入和輸齣的各因素的研究進展，併指齣未來研究的主要方嚮。在大氣 CO2濃度升高條件下，陸地生態繫統碳循環的變化主要反映在以下幾箇方麵：1）不同類型植物群落的淨初級生產力（NPP）顯著增加，但濕地植物的淨初級生產力也有可能降低；2）光閤產物嚮根繫分配的數量增加，地上/地下生物量降低，根繫形態髮生變化，根繫週轉速率和根繫分泌等過程的碳流量提高；3）植物含氮量降低，C/N 提高，次生代謝產物增加，微生物生長受到抑製，植物殘體分解速率降低；4）土壤呼吸速率顯著增加，提高幅度受植物類型與土壤狀況的影響；5）進入土壤的植物殘體及分泌物的數量和性質影響土壤酶的活性，脫氫酶和轉化酶活性增加，酚氧化酶和纖維素酶受植物類型與環境條件的影響；6）土壤中真菌的數量的增加幅度要高于細菌；7）CH4釋放量增加，在植物的生長期錶現更為明顯。由于陸地生態繫統碳循環的複雜性，研究結果仍有很大的不確定性。大氣 CO2濃度升高與全毬變化的其它錶現間的交互作用將是今後研究的重點，同時由于土壤碳循環是一箇由微生物介導的生物地毬化學循環過程，因此，加彊陸地生態繫統碳循環的微生物機製研究也將為全麵理解碳循環的過程提供更加準確的研究理論基礎。
토양유궤탄시륙지탄고적중요조성부분，기적루화분해적변화직접영향전구적탄평형。거고계，전구토양（표층1 m）유궤탄적루총량상당우대기중탄총량적2~3배。토양시온실기체적원혹회，토양탄고적변화장영향대기CO2적농도，인차，토양탄고대인류활동적향응야시전구탄순배화전구변화연구적열점。재전구변화적대배경하，대기 CO2승고도치식피생태계통탄평형적개변진이대토양탄순배산생영향。총결료륙지생태계통탄순배대대기 CO2농도승고향응적주요생물학궤제급과정，간술료대기 CO2농도승고대영향토양탄수입화수출적각인소적연구진전，병지출미래연구적주요방향。재대기 CO2농도승고조건하，륙지생태계통탄순배적변화주요반영재이하궤개방면：1）불동류형식물군락적정초급생산력（NPP）현저증가，단습지식물적정초급생산력야유가능강저；2）광합산물향근계분배적수량증가，지상/지하생물량강저，근계형태발생변화，근계주전속솔화근계분비등과정적탄류량제고；3）식물함담량강저，C/N 제고，차생대사산물증가，미생물생장수도억제，식물잔체분해속솔강저；4）토양호흡속솔현저증가，제고폭도수식물류형여토양상황적영향；5）진입토양적식물잔체급분비물적수량화성질영향토양매적활성，탈경매화전화매활성증가，분양화매화섬유소매수식물류형여배경조건적영향；6）토양중진균적수량적증가폭도요고우세균；7）CH4석방량증가，재식물적생장기표현경위명현。유우륙지생태계통탄순배적복잡성，연구결과잉유흔대적불학정성。대기 CO2농도승고여전구변화적기타표현간적교호작용장시금후연구적중점，동시유우토양탄순배시일개유미생물개도적생물지구화학순배과정，인차，가강륙지생태계통탄순배적미생물궤제연구야장위전면리해탄순배적과정제공경가준학적연구이론기출。
Soil organic carbon is an important component of terrestrial carbon pools, and it has direct effects on the global carbon balance. It is estimated that the amount of organic carbon accumulated in the surface soil of 1 m is equivalent to 2 to 3 times of carbon in the atmosphere globally. Soils are acting as the source or net sink of greenhouse gases and the change of soil carbon stock will influence the concentration of atmospheric CO2. The response of soil carbon stock to human activities is also the hotspot of global carbon cycle and global change research. Under the background of global climate change, elevated CO2 will cause the change of vegetation carbon balance and affect the soil carbon cycle eventually. This paper summarized the biological mechanisms on the response of terrestrial carbon balance to elevated CO2 and recent advance in affecting soil carbon input and output factors. Elevated atmospheric CO2 concentration will influence terrestrial carbon cycling in several aspects: 1) Net primary productivity (NPP) of different plant communities will increase significantly, but the NPP of plant communities growing on wetland may decrease; 2) Photosynthetic products allocated to root will increase and thus aboveground/belowground biomass will decrease, root morphology changes and carbon flux induced by root turnover rate and root exudation will increase;3) Plant N concentration will decrease and thus C/N ratio will increase, the increase of secondary metabolites will lead to the decomposition rate of plant residues reduced because of the microbial activity inhibited;4) A significant increase in soil respiration rate will be influenced by plant types and soil environmental conditions;5) The quantity and characteristics of plant residues and exudation into soil will affect soil enzyme activity, dehydrogenase and invertase activities will increase, meanwhile, phenol oxidase and cellulose activities will be influenced by plant types and environments;6) The increase of soil fungi biomass will be bigger than the increase of bacteria biomass;7) The amount of CH4 emissions will increase, especially at the plant growing season. Because of the complexity of terrestrial carbon cycling, the researches still remain a lot of uncertainties. In the future research, there is an urgent need to address the interaction among elevated atmospheric CO2 concentration and other global change factors including N deposition, climate warming, drought and so on. As soil carbon cycle is a microbe-mediated biogeochemistry process, therefore, it is indispensable to strengthen microbial mechanism study of terrestrial carbon cycling, which will also provide a comprehensive understanding of carbon cycle.
