【作者】 陈雷；

【导师】 曹福亮；

【作者基本信息】 南京林业大学 ， 森林培育， 2013， 博士

【摘要】 农林经营措施对系统碳固定有着显著影响。开展复合经营系统固碳和碳循环的研究，对全面分析和评价银杏复合经营生态系统的固碳价值有着重要的意义。本文以江苏省泰兴市不同银杏（Gingko biloba L.）复合经营方式和传统农业经营方式（银杏-桑树（GM），银杏-小麦-花生（GWP），银杏-油菜-花生（GRP）模式、林下抛荒模式（GNT）和小麦-花生模式（WP））为研究对象，对其碳储量、土壤碳循环过程及其影响因素等进行5年的跟踪研究（2008-2012年），采用通径分析方法对银杏复合系统碳储量和碳循环影响因子进行分析，为揭示银杏复合经营碳循环机理、全面分析和评价复合系统的固碳价值奠定基础。主要研究结果如下：1、银杏复合经营系统和经营时间显著影响了系统银杏和林下作物碳储量。复合系统中生物碳储量显著高于农地，并随着复合时间延长显著上升，持续经营5年之后，不同复合系统中生物碳储量并不存在显著差异，但是仍然高于农地。可见，银杏复合经营促进了系统生物碳储量。2、银杏复合系统模式下在0-20cm层次中土壤碳储量随着经营时间呈现上升趋势；而不同复合模式下凋落物碳储量随经营时间变化各不相同；不同复合系统下土壤碳储量和凋落物碳储量存在显著差异，且均显著高于农地；GM模式下土壤碳储量均显著高于其它复合模式；经过5年持续经营之后，GNT模式凋落物碳储量显著高于其它模式。长期银杏复合经营在促进土壤碳储量的同时，也促进了系统凋落物碳储量。3、银杏复合系统总碳储量随着复合经营时间呈现上升趋势。银杏复合系统总碳储量显著高于WP模式，GM模式中总碳储量显著高于其它银杏复合模式。所有模式中，土壤碳储量比例最高。长期银杏复合经营提升了系统总碳储量。通径分析表明，土壤碳储量是影响总碳储量的主要因素。4、不同凋落物及其组成显著影响了凋落物的分解速度。不同复合系统中凋落物残留率随着经营时间而发生变化，均显著低于农业模式。复合系统下凋落物碳释放量显著高于农地。不同模式间凋落物碳释放量变化趋势各不相同，其中，GM和GNT模式中，凋落物碳释放量随着复合时间显著增加。持续经营5年之后，GNT模式下凋落物碳释放量显著高于其它模式。银杏复合系统促进了凋落物的分解，同时促进了凋落物碳释放。5、银杏复合系统显著影响了土壤总呼吸、微生物呼吸和根系呼吸。不同年份间，复合系统下这些指标均显著高于农地。银杏复合系统中土壤总呼吸和微生物呼吸碳损失随着复合经营时间普遍呈现增加趋势。而不同复合系统中根系呼吸在不同年份间变化趋势存在一定差异。经过5年持续经营之后，GNT模式下土壤总呼吸、根系呼吸和微生物呼吸碳释放均最高。可见，银杏复合经营促进了林下土壤总呼吸、根系呼吸和微生物呼吸碳排放。6、银杏复合系统土壤中每年均能固定大量的碳，而且随着林分生长，系统的土壤固碳能力和土壤碳截留能力进一步得到了提升。但是在开始抛荒的初始阶段会导致系统土壤碳流失；GM模式中，土壤碳截留能力优秀，并能促进了系统碳储量。长期复合经营可以进一步提升系统土壤固碳和碳截留能力。7、银杏复合模式间土壤有机碳组分变化趋势各不相同。在GNT模式下，有机碳和及其组分则呈现先下降后上升趋势；除了易氧化碳外，GRP和GWP模式下复合系统下土壤有机碳和有机碳组分均呈现上升趋势；在经过长期银杏复合经营之后，除了无机碳和重组有机碳组分外，复合系统下其它有机碳组分均显著高于WP模式。8、银杏复合经营土壤中，酶活性在5年持续经营过程中变化趋势各不相同。GWP、GRP和GM模式下内切葡聚糖酶、漆酶和木聚糖酶活性均呈现上升趋势；GNT模式下，外切葡聚糖酶、木质素过氧化物酶、锰过氧化物酶、漆酶和木聚糖酶活性均呈现上升趋势，但是内切葡聚糖酶和β-葡萄糖苷酶活性则呈现先下降后上升趋势。可见，长期银杏复合经营促进了纤维素分解相关酶、木质素分解相关酶和木聚糖酶活性。9、银杏复合经营土壤中，微生物活性在5年持续经营过程中变化趋势各不相同。GWP和GRP模式中，这3个指标均呈现显著上升趋势；在GNT模式中，则呈现先下降后上升趋势。到了2012年，GNT模式下土壤微生物碳和土壤基础呼吸显著高于其它模式。农地中土壤代谢熵显著高于复合系统，而微生物熵和变化规律较差。总的来说，长期银杏复合经营促进了系统中的土壤微生物碳、土壤基础呼吸和可矿化碳等微生物活性。综上所述，长期银杏复合经营可以有效的提升系统中生物、凋落物和土壤碳储量，并能够促进系统中凋落物分解碳释放和微生物呼吸碳释放；此外，银杏复合系统也促进了土壤中与碳循环密切相关的碳组分、凋落物分解过程相关酶活性和土壤微生物活性。从系统碳储量来说，GM模式下复合系统固碳能力最强；而在GNT模式中，系统凋落物碳释放高，同时，微生物呼吸碳损失也高。在银杏复合系统中，影响土壤凋落物碳释放的因素主要是：轻组有机碳、木质素过氧化物酶和微生物生物量碳；影响土壤微生物呼吸的主要因素为：可溶性有机碳、漆酶活性和微生物生物量碳；影响土壤碳截留的因素为：易氧化碳、木聚糖酶活性和累积可矿化碳含量。更多还原

【Abstract】 There is a widespread interest in increasing carbon sequestrations by forest andagricultural production operations. Agroforestry systems are very important to carbonsequestrations and cycle. We compared the impacts of four Ginkgo agroforestry systems and areference system (a conventional agrosystem with a sequential rotation of wheat and peanuts;WP), on a variety of total carbon stocks, soil carbon cycle systems, and some factors of cycleprocesses, then analyzed the factors of soil cycle processes and carbon stocks by path analysis.The objectives of this study were to investigate the processes of carbon cycle, and evaluate thepotential carbon sequestration of Ginkgo agroforestry systems. The four agroforestry systemswere: Gingko, wheat and peanut (GWP); Gingko, rapeseed and peanut (GRP); Gingko andmulberry (GM); and Ginkgo fallow system (GNT). The results showed that:1The different Ginkgo agroforestry systems and ages significantly affected Ginkgo andcrops biomass and carbon stocks. The biomass carbon stocks in agroforestry systems weresignificantly higher than WP systems, and increased with the system age. In2012, there was nosignificantly different biomass carbon stock among Ginkgo agroforestry systems, and they stillhigher than agriculture systems.2Significant soil carbon stocks and litter carbon stocks were found in different Ginkgoagroforestry systems, and they were both significantly higher in agroforestry systems than WPsystems. GM systems had significantly higher soil carbon stocks than other Ginkgoagroforestry systems. In soil0-20cm layer, soil carbon stocks in Ginkgo agroforestry systemsincreased with the system age, while the trends of litter carbon stocks were different inagroforestry systems. After5years, the litter carbon stocks in GNT systems were significantlyhigher than other systems.3The total carbon stocks in Ginkgo agroforestry systems increased with the system age.Significantly higher total carbon stocks were found in agroforestry systems than WP systems.The proportion of soil carbon stocks was highest in all systems. From the path analysis, the soilcarbon stock is the key factor of total carbon stock.4Different litter types and compositions significantly affected the litter decomposition rate.The litter residual rates in different agroforestry systems were changed with the system age, butthey all significant lower than WP systems. Significantly higher litter carbon releases werefound in agroforestry systems than WP systems. The trends of litter carbon releases weredifferent in different systems, while they increased with system age in GM and GNT systems.In2012, GNT systems had significantly higher litter carbon releases than other systems.5The different agroforestry systems significantly affected soil total respiration, microbialrespiration, and roots respiration, and these indexes were significantly higher in agroforesteysystems than in WP system during the year of2008-2012. Soil total respiration and microbial respiration increased with system age in Ginkgo agroforestry systems. However, the trends ofroots respiration were different among different Ginkgo agroforestry systems. After5years, theGNT system had the highest soil total respiration, microbial respiration, and roots respiration.6A lot of soil carbon was sequestrated in Ginkgo agroforestry systems every year. The soilcarbon sequestration and carbon retention of agroforestry systems also grew with growth ofGinkgo. However, in the early years of fallow, a lot of soil carbon was lost in Ginkgoagroforestry systems. GM systems had the best soil carbon retention, and these systems alsoincreased carbon stocks.7Within5year, the trends of soil organic carbon and fractions were different amongdifferent systems. They were decreased in early years, and then increased. Except readyoxidized carbon fractions, soil organic carbon and other carbon fractions were increased withsystem age. After18agroforestry system, except soil inorganic carbon and heavy fractionsorganic carbon, other organic carbon and fractions were significantly higher in Ginkgoagroforestry systems than in WP systems.8The enzyme activity of cellulose and lignin, and xylanase activity were significantlyhigher in Ginkgo agroforestry systems than in WP systems. Within5years, endo-1,4-β-D-glucanase, laccase, and xylanase activity in GWP, GRP and GM systems were increasedwith systems age, while exo-1,4-β-D-glucanase, lignin peroxidase, Manganese peroxidase,laccase and xylanase activity in GNT systems were also increased with systems age. However,the endo-1,4-β-D-glucanase and β-D-glucosidase activity were decreased in early years, andthen increased.9Significant higher soil microbial biomass carbon, soil basal respiration, and totalmineralized carbon were found in Ginkgo agroforestry systems than WP systems, and theysignificantly increased with the system age in GWP and GRP systems. Besides, In GNTsystems, they decreased at early years, and then increased. After5years, GNT had thesignificantly higher soil microbial biomass carbon and soil basal respiration than other systems.The WP systems had significantly higher metabolic quotient than other systems, but themicrobial quotient was lacked regularity.In summy, Ginkgo agroforestry systems increased biomass carbon stocks, litter carbonstocks, and soil carbon stocks, and it also increased litter compositions and microbialrespiration, soil organic carbon fractions, enzyme activity, and soil biological activity. InGinkgo agroforestry systems, the light fraction organic carbon, lignin peroxidase activity, andsoil microbial biomass carbon are the the key factor of litter carbon releases; the dissolvedorganic carbon, laccase activity, and soil microbial biomass carbon are the key factor of soilmicrobial respiration; the ready oxidized carbon, xylanase activity, and total mineralized carbonare the key factor of soil carbon retention.更多还原