【作者】 杜满义；

【导师】 范少辉；

【作者基本信息】 中国林业科学研究院 ， 森林培育， 2013， 博士

【摘要】 竹林是我国南方重要的森林类型，到2008年第七次森林资源清查时已达538.10万公顷，其中毛竹（Phyllostachys edulis）林面积为386.83万公顷，约91.57亿株。竹林施肥是影响土壤质量演化及其可持续利用的重要林业措施之一，本文研究施肥对毛竹林生态系统碳平衡的影响，以期为现实竹林的科学经营提供理论指导。本项研究设置施用5年竹林专用肥（Ⅰ）、5年氮、磷、钾配方施肥（Ⅱ）、5年有机肥（Ⅲ）、1年竹林专用肥（Ⅳ）、1年有机肥（Ⅴ）、不施肥毛竹林（Ⅵ）6个试验水平，从生态系统碳输入和输出的角度出发，研究不同施肥措施下毛竹林生态系统碳储量及分配格局、土壤活性有机碳、呼吸及组分呼吸的变化规律，探讨其与土壤温/湿度、根系生物量、凋落物量及土壤质量因子等之间的关系，揭示不同施肥措施调控下土壤呼吸过程及影响机制，评估施肥措施调控下毛竹林碳汇/源的影响。主要研究结果如下：1.不同施肥处理毛竹林生态系统碳储量、碳分配格局及植被层碳素平均年净固定量（1）毛竹林Ⅰ～Ⅵ植被层碳储量分别为41.49、35.82、45.99、32.11、35.30、28.37tC·hm^-2，植被层碳储量在器官上的分配均以竹秆最大，毛竹林地施肥可以提高竹秆生物量及碳储量占总量的比例。（2）不同施肥处理及季节变化对土壤有机碳含量无显著影响，有机碳含量为：Ⅵ(13.70g·kg^-1)＞Ⅰ(13.61g·kg^-1)＞Ⅳ(12.11g·kg^-1)＞Ⅲ(11.95g·kg^-1)＞Ⅴ(11.57g·kg^-1)＞Ⅱ(11.43g·kg^-1)，Ⅰ～Ⅵ毛竹林土壤层（0～100cm）碳储量为111.34～122.36t C·hm^-2，平均值为117.41t C·hm^-2。（3）毛竹林Ⅰ～Ⅵ生态系统碳贮量分别为165.36、153.29、168.35、145.19、154.06、145.00t C·hm^-2。土壤层碳贮量所占比例最大，约为75%；其次是乔木层，枯落物层最低，仅为0.47%～1.73%。（4）毛竹林Ⅰ～Ⅵ植被层碳素平均年净固定量均为：Ⅲ＞Ⅰ＞Ⅱ＞Ⅴ＞Ⅳ＞Ⅵ，年固碳量分别为11.30、11.23、8.45、6.40、5.64、5.45t C·hm^-2·a^-1，相当于年同化CO2量41.41、41.17、30.99、23.47、20.69、20.00t CO₂·hm^-2·a^-1。2.不同施肥处理毛竹林活性有机碳变化规律（1）施肥降低土壤MBC含量，下降幅度为16.44%～28.69%。0-100cm土层MBC平均含量排列顺序为：Ⅵ(118.47mg·kg^-1)＞Ⅳ(98.99mg·kg^-1)＞Ⅰ(92.46mg·kg^-1)＞Ⅴ(91.06mg·kg^-1)＞Ⅱ(86.25mg·kg^-1)＞Ⅲ(84.48mg·kg^-1)。土壤微生物生物量碳表现出明显的季节动态，7月和10月MBC含量均显著高于1月和4月。（2）施肥降低土壤HWC含量，下降幅度为4.99%～23.54%。0-100cm土层HWC平均含量排列顺序为：Ⅵ(641.29mg·kg^-1)＞Ⅰ(609.30mg·kg^-1)＞Ⅳ(587.13mg·kg^-1)＞Ⅴ(562.88mg·kg^-1)＞Ⅲ(559.16mg·kg^-1)＞Ⅱ(490.35mg·kg^-1)。土壤热水浸提有机碳表现出明显的季节动态，但不同施肥处理之间规律性不一致。（3）施肥降低土壤ROC含量（除处理Ⅰ），降低幅度为-7.82%～20.08%。0-100cm土层ROC平均含量排列顺序为：Ⅰ(5.10g·kg^-1)＞Ⅵ(4.73g·kg^-1)＞Ⅲ(4.39g·kg^-1)＞Ⅱ(4.32g·kg^-1)＞Ⅳ(4.06g·kg^-1)＞Ⅴ(3.78g·kg^-1)。土壤易氧化态碳表现出明显的季节动态，均以10月份最高，1月份次之，4月和7月较低。（4）施肥有利于土壤中轻组有机质含量的积累，提高幅度为13.37%～59.30%。0-100cm土层LFOM平均含量排列顺序为：Ⅲ(2.74g·kg^-1)＞Ⅰ(2.22g·kg^-1)＞Ⅱ(2.20g·kg^-1)＞Ⅳ(1.95g·kg^-1)＞Ⅴ(1.72g·kg^-1)=Ⅵ(1.72g·kg^-1)。（5）不同土壤活性有机碳占总有机碳的比率为：ROC＞LFOM＞HWC＞MBC。其中ROC的比例介于29.00%～37.80%，LFOM介于11.01%～22.93%，HWC介于4.11%～4.84%，MBC介于0.68%～0.82%。不同形式活性有机碳均随土层加深呈现下降趋势，表层富集现象明显。土壤总有机碳、微生物量碳、热水浸提有机碳、易氧化态碳及轻组有机质之间均达到极显著相关水平，相关系数介于0.708～0.964。（6）以不施肥毛竹林各土层为参照土壤，计算出混交经营对毛竹林各土层土壤碳库指数（CPI）、碳库活度（L）、碳库活度指数（LI）、氧化稳定系数（KOS）和碳库管理指数（CMI），CPI介于0.83～0.99之间，LI介于0.92～1.15之间，KOS介于1.65～2.06之间，CMI介于77.32～112.36之间。表明处理Ⅰ对土壤具有培肥作用，处于良性管理状态。3.不同施肥处理毛竹林总呼吸及组分呼吸变化规律。（1）不同施肥处理毛竹林土壤总呼吸、根呼吸、凋落物呼吸、矿质呼吸均表现出一定的月动态特征，且呈单峰型曲线。（2）六种处理（Ⅰ～Ⅵ）毛竹林地土壤总呼吸、根呼吸、凋落物呼吸、矿质呼吸年平均速率为3.57～3.96、1.15～1.69、0.86～1.21、1.05～1.49μmol·m^-2·s-1。施肥处理增大了毛竹林土壤总呼吸、矿质呼吸，根呼吸（除处理Ⅲ），降低了凋落物呼吸。（3）根呼吸、凋落物呼吸、矿质呼吸对总呼吸的贡献率均具有一定的季节性变化。根呼吸年平均贡献率分别为42.14%、44.08%、31.40%、42.41%、39.76%、39.04%；凋落物呼吸年平均贡献率分别为23.48%、22.50%、29.06%、30.47%、26.69%、31.80%；矿质呼吸年平均贡献率分别为34.99%、33.59%、39.79%、27.12%、33.85%、29.17%。（4）土壤呼吸及组分呼吸与5cm土壤温度、土壤湿度均呈指数相关，土壤总呼吸，矿质呼吸相关性要高于根呼吸与凋落物呼吸。土壤呼吸及组分呼吸Q10介于1.30-2.13。处理Ⅰ增强了土壤呼吸与根呼吸的敏感性，处理Ⅱ-Ⅴ降低了土壤呼吸与根呼吸的敏感性，施肥处理均降低了凋落物呼吸和矿质呼吸的敏感性。4.不同施肥处理毛竹林生态系统碳平衡处理Ⅰ～Ⅵ土壤总呼吸年释放量分为13.67、14.18、14.41、14.96、14.10、13.51tC·hm^-2·a^-1，相当于年CO2释放量为49.55～54.84t CO2·hm^-2·a^-1，其中根呼吸年释放量为18.20～23.36t CO2·hm^-2·a^-1，凋落物呼吸年释放量为11.96～16.82t CO2·hm^-2·a^-1，矿质呼吸年释放量为14.53～20.61t CO2·hm^-2·a^-1。年初级净生产力（NPP）分为12.60、9.79、12.86、6.31、7.13、6.25t C·hm^-2·a^-1。不同施肥处理下生态系统净生产力（NEP）不同，Ⅰ～Ⅵ生态系统净生产力分别为4.71、1.47、2.79、-2.28、-1.21、-2.29t C·hm^-2·a^-1，表现为：Ⅰ＞Ⅲ＞Ⅱ＞Ⅴ＞Ⅳ＞Ⅵ,施肥毛竹林高于不施肥毛竹林，施肥5年毛竹林优于施肥1年毛竹林，且以施用5年毛竹林专用肥效果最佳。更多还原

【Abstract】 Bamboo forest is a critical type of forest in South China, until the7thnational forestinventory in2008, bamboo forest has an area of5.381million hectare, among which, Mosobamboo （Phyllostachys edulis） forest accounts for3.8683million hectare, about9.157billionstems. Fertilization in bamboo forest is one of the most impressive forest measures affectingsoil quality evolution and sustainable use, In this study, the effect of fertilization on carbonbalance in Moso bamboo forest was conducted to supply theoretical guidance to scientificallysustainable management in bamboo forest. In this research, bamboo forests with six treatments,5-year application of specialized fertilizer for bamboo, formula NPK-fertilizer, organicfertilizer, and1-year application of specialized fertilizer for bamboo, organic fertilizer, andnon-fertilization application were selected to study the carbon stock, stock distribution patterns,change laws of soil active organic matter, soil respiration and source components underdifferent fertilization measures from the point of ecosystem carbon input and output. The studyalso discussed the relationships between these changes patterns and soil respiration/moisture,root biomass, litter biomass and soil quality factors, and revealed the influence of fertilizationon soil respiration processes and influence mechanism, further assessed the influence offertilization on carbon sink/source in Moso bamboo forest. The main results were following:1. Carbon stock, carbon distribution patterns and annual net carbon sequestration ofvegetation layer in Moso bamboo forest ecosystems under different fertilization treatments（1）Vegetation carbon stock of stand Ⅰ～Ⅵ were41.49,35.82,45.99,32.11,35.30,28.37t C.hm^-2. Considering the distribution of vegetation carbon stock to different organs, thedistribution was highest in stem, and fertilization could increase the proportion of stembiomass and carbon stock to total biomass and carbon stock.（2）Different fertilization treatments and seasonal changes had no significant effect on soilorganic matter, and the soil organic carbon content were: Ⅵ (13.70g·kg^-1)＞Ⅰ(13.61g·kg^-1)＞Ⅳ(12.11g·kg^-1)＞Ⅲ(11.95g·kg^-1)＞Ⅴ(11.57g·kg^-1)＞Ⅱ(11.43g·kg^-1). In layer of0～100cm, the soil organic carbon stock of standⅠ～Ⅵ was111.34～122.36t C·hm^-2with average of117.41t C·hm^-2.（3）Ecosystem carbon stock of Moso bamboo forest of stand Ⅰ～Ⅵ were165.36,153.29,168.35,145.19,154.06,145.00t C·hm^-2, respectively. Soil layer accounted for thehighest rate of about75%, followed by tree layer, but litter layer was lowest of only0.47%～1.73%.（4）Annual average carbon sequestration of vegetation layer of stand Ⅰ～Ⅵ was inorder of Ⅲ＞Ⅰ＞Ⅱ＞Ⅴ＞Ⅳ＞Ⅵ, which were11.30,11.23,8.45,6.40,5.64,5.45tC·hm^-2·a^-1, equaling41.41,41.17,30.99,23.47,20.69,20.00t CO2·hm^-2·a^-1.2. Changes patterns of different types of active organic matter in Moso bamboo forestecosystem under different fertilization treatments（1）Fertilization decreased soil MBC content by16.44%～28.69%. In0-100layer, theMBC was in order of Ⅵ (118.47mg·kg^-1)＞Ⅳ (98.99mg·kg^-1)＞Ⅰ(92.46mg·kg^-1)＞Ⅴ(91.06mg·kg^-1)＞Ⅱ(86.25mg·kg^-1)＞Ⅲ (84.48mg·kg^-1). Seasonal changes were observedin MBC, the content of MBC in July and October were significant higher than that in Januaryand April.（2）Fertilization decreased soil HWC content by4.99%～23.54%. In0-100layer, theHWC was in order of Ⅵ (641.29mg·kg^-1)＞Ⅰ(609.30mg·kg^-1)＞Ⅳ (587.13mg·kg^-1)＞Ⅴ(562.88mg·kg^-1)＞Ⅲ (559.16mg·kg^-1)＞Ⅱ(490.35mg·kg^-1). The HWC content showedobvious seasonal changes, however the change laws of different fertilization treatments werenot uniform.（3）Fertilization decreased soil ROC content by-7.82%～20.08%, except treatment Ⅰ. In0-100layer, the ROC was in order ofⅠ(5.10g·kg^-1)＞Ⅵ(4.73g·kg^-1)＞Ⅲ (4.39g·kg^-1)＞Ⅱ(4.32g·kg^-1)＞Ⅳ(4.06g·kg^-1)＞Ⅴ(3.78g·kg^-1). Seasonal changes were observed in ROCcontent, peaking in October followed by January, but bottomed in April and July.（4）Fertilization was good to LFOM accumulation, increased by13.37%～59.30%. In0-100layer, the LFOM was in order of Ⅲ (2.74g·kg^-1)＞Ⅰ(2.22g·kg^-1)＞Ⅱ(2.20g·kg^-1)＞Ⅳ (1.95g·kg^-1)＞Ⅴ (1.72g·kg^-1)=Ⅵ (1.72g·kg^-1).（5）The proportions of different types of organic matter to total soil organic matter were inorder of ROC＞LFOM＞HWC＞MBC. The rates of ROC, LFOM, HWC and MBC were in range of29.00%～37.80%,11.01%～22.93%,4.11%～4.84%,0.68%～0.82%,respectively. Different types of active organic matter decreased along with the increase of soildepth, showing obvious surface enrichment. The relationships between total soil organic matterand MBC, HWC, ROC and LFOM were significantly related, the coefficients were0.708～0.964.（6）Considering the soil of different layers of non-fertilized Moso bamboo stand asreference, the carbon pool index （CPI）, carbon pool activity（L）, carbon pool activity index（LI）,coefficient of oxidation stability （KOS） and carbon pool index were calculated, the CPI, LI, KOSand CMI were in range of0.92～1.15,1.65～2.06,77.32～112.36. Results showed thattreatment Ⅰ was functioned by improving soil fertility, which was in good managementstatus.3. Change patterns of total soil respiration and source components under differentfertilization treatments（1）Total soil respiration （RS）, root respiration （RR）, litter respiration （RL） and mineralrespiration （RM） were characterized by monthly changes with single peak curve.（2）Among the six treatments （Ⅰ～Ⅵ）, annual rates of RS, RR, RL, RMwere ranged from3.57～3.96,1.15～1.69,0.86～1.21,1.05～1.49μmol·m^-2·s-1. Fertilization increase total RS,RM, and RR（except treatment Ⅲ）, decreased RL.（3）Contributions RR, RL, RMto total RSshowed seasonal changes. RRcontributed42.14%,44.08%,31.40%,42.41%,39.76%,39.04%, RLcontributed23.48%,22.50%,29.06%,30.47%,26.69%,31.80%and RMcontributed34.99%,33.59%,39.79%,27.12%,33.85%,29.17%.（4）Soil respiration and source components were exponentially related with soiltemperature and moisture at depth of5cm, and the correlation efficient of RSand RMwerehigher than that of RRand RL. Q10values of soil respiration and source components were inrange of1.30-2.13. TreatmentⅠincreased temperature sensitivity of RSand RR, but treatmentsⅡ-Ⅴdecreased temperature sensitivity of RSand RR. However, fertilization treatmentdecreased temperature sensitivity of RLand RM.4. Carbon balance in Moso bamboo forest ecosystem under different fertilizationtreatment Annual C release from RSwere13.67,14.18,14.41,14.96,14.10,13.51t C·hm^-2·a^-1,respectively, in treatmentⅠ～Ⅵ, equalling49.55～54.84t CO2·hm^-2·a^-1, among which, annualC release from RR, RLand RMwere18.20～23.36,11.96～16.82and14.53～20.61tCO2·hm^-2·a^-1, respectively. Annual net primary productivity （NPP） were12.60,9.79,12.86,6.31,7.13,6.25t C·hm^-2·a^-1. Net ecosystem productivity （NEP） varied among differentfertilization treatments, and NEP of Ⅰ～Ⅵ were4.71,1.47,2.79,-2.28,-1.21,-2.29tC·hm^-2·a^-1and in order of Ⅰ＞Ⅲ＞Ⅱ＞Ⅴ＞Ⅳ＞Ⅵ. NEP of fertilized bamboo stand washigher than that of unfertilized bamboo stand, and duration of5-year fertilization was betterthan that of1-year fertilization, further bamboo forest with5-year specialized fertilizationapplication was best.更多还原