【作者】 姜艳；

【导师】 王兵；

【作者基本信息】 中国林业科学研究院 ， 生态学， 2010， 博士

【摘要】 土壤呼吸即土壤表面CO2释放量,包括植物根系呼吸、土壤微生物呼吸和土壤动物呼吸等三个生物学过程。土壤呼吸及其三个生物学过程变异机理将直接反应陆地生态系统土壤呼吸的强弱,并对植物生长及生态系统碳平衡产生影响。因此,森林生态系统土壤呼吸及组分分离、量化是当前碳循环研究中的热点和难点问题。本研究采用LI-Cor-8100开路式土壤碳通量测量系统,结合壕沟法排除根系,电棒+卫生球法排除土壤动物等,对毛竹(phyllostachys edulis)林200m、400m和700m海拔的土壤呼吸及其三个生物学过程的时空动态变化展开研究,精确区分、量化各组分呼吸在土壤总呼吸中的贡献率,同时测定空气温度、土壤温度及土壤含水率等环境因子,毛竹林地下根系生物量、土壤动物类群及微生物生物量(碳)等生物因子,确定土壤总呼吸及其三个生物学过程呼吸的影响因子,结果表明：(1)3个海拔毛竹林土壤总呼吸及组分呼吸昼夜变化均与空气温度、土壤温度昼夜变化相类似,呈单峰曲线,最小值均出现在晚间02：00左右,但最大值出现的时间有一定差异。总呼吸峰值出现在下午15：00左右,根系呼吸在中午11：00达到最大值,土壤微生物呼吸昼夜变化较为平缓,最大值出现在中午11：00～5：00,土壤动物呼吸最大值也出现在中午11：00～5：00。季节变化同样表明土壤总呼吸及组分呼吸与土壤温度、空气温度变化趋势一致,最大值出现在7、8月份,最小值在11、12月。空间变异表现为随着海拔升高,土壤总呼吸、根系呼吸及微生物呼吸均减小,而土壤动物呼吸为200m海拔最大,400m海拔最小。引起这种空间变异的原因,除了由于海拔变化引起的土壤温湿度变化外,生物因子(根系、微生物及动物生物量)及土壤因素也在一定程度上起到了关键作用。(2)3个海拔2008年8月土壤总呼吸日变化范围为3.89μmol·m-2·s-1～5.49μmol·m-2·s-1,3～12月变化范围为3.10μmol·m-2·s-1～3.60μmol·m-2·s-1;2009年三者日均值变化范围为3.36μmol·m-2·s-1～4.05μmol·m-2·s-13～11月年均值为2.58μmol·m-2·s-1～3.12μmol·m-2·s-1。由碳通量特征来看,2008年3个海拔土壤总呼吸碳释放量为881.61 g C m-2～1028.35 g Cm-2,比2009年碳通量增大了12.74%-18.03%,在热带、亚热带森林土壤呼吸年通量范围内(345 g C m-2～1520gC·m-2·a-1)。根系呼吸2008年日贡献率为51.73%～55.53%,年贡献率为33.51%-38.90%,2009年日贡献率为44.95%-48.97%,年贡献率34.79%～41.89%,3～12月碳通量为323.93 g Cm-2～431.48 g C m-2,占土壤总呼吸的36.74%～41.96%；2009年为277.24 g C m-2～401.25 gC m-2,占土壤总呼吸的37.05%～44.70%；200m海拔最大,总碳通量比400m和700m分别大3.40%和14.20%。2008年200m、400m和700m海拔土壤异养呼吸(微生物呼吸、动物呼吸)日贡献率为42.85%～47.87%(其中微生物呼吸为35.31%～39.45%,动物呼吸为7.54%～8.42%)；2009年为52.34%～53.43%(其中微生物呼吸为45.42%～45.52%,动物呼吸为6.92%～7.91%。)。从年贡献率来看,2008年3个海拔土壤异养呼吸年贡献率为59.02%～65.36%(其中微生物呼吸为52.07%～57.67%,动物呼吸为6.95%～7.69%),2009年异养呼吸年贡献率为54.60%～64.86%(其中微生物呼吸为47.41%～57.04%,动物呼吸为7.19%～7.82%)。从年碳通量来看,3个海拔2008年3～12月异养呼吸碳通量为557.68 gC m-2～626.63 g C m-2,占土壤总呼吸的57.36%～63.93%(土壤动物呼吸为69.42 g C m-2～87.94 g C m-2,占土壤总呼吸的7.87%～8.55%,微生物呼吸为488.26 g C m-2～544.75 g Cm-2,占土壤总呼吸的49.49%-55.38%)：2009年3-11月异养呼吸碳通量为470.90 g Cm-2～500.93 g C m-2,占土壤总呼吸的55.12%～63.63%(土壤动物呼吸为60.81 g C m-2～74.57g C m-2,占土壤总呼吸的8.13%～8.81%,微生物呼吸为410.18 g C m-2～429.12 g C m-2,占土壤总呼吸的46.99%～54.82%)。2008年毛竹林土壤根系呼吸比异养(微生物呼吸、动物呼吸)呼吸碳通量小195.15gC m-2～233.75 g C m-2;2009年小99.65 g C m-2～193.66 g C m-2,由此我们可以看出,土壤微生物和动物呼吸在很大程度上是土壤表面CO2通量的优势组成部分。(3)土壤温度与土壤总呼吸、根系呼吸、微生物呼吸和动物呼吸的相关性均达到极显著水平(P<0.01)。其中土壤总呼吸与土壤不同层温度(0～10cm,10～20cm和20～30cm)的相关性均达到显著水平(P<0.05),与10cm处土壤温度相关性最大,达到极显著水平(P<0.01)。Q10量化土壤呼吸的温度敏感性发现,土壤微生物呼吸温度敏感性比根系呼吸温度敏感性更高；土壤动物呼吸与温度相关性相(R2)比微生物呼吸稍有减小(R2),但从Q10值来看土壤动物的温度敏感性大于根系呼吸和微生物呼吸的温度敏感性。与土壤呼吸总与土壤温度之间的相关性比,土壤总呼吸与土壤含水量的相关性较小,但消除土壤温度的影响后,标准化的土壤呼吸与土壤含水率相关性显著增强(P<0.05)。土壤含水率是引起根系呼吸变化的重要因素之一,二者呈极显著线性相关性(P<0.01),而对土壤微生物和动物呼吸的影响不大。土壤水热双因子模型优于土壤温度或含水率单因子模型,土壤温度和土壤含水率的交互作用共同解释了不同海拔土壤总呼吸的50%以上,根系呼吸变化的77.10%～90.30%,土壤微生物呼吸的86.50%～88.90%,土壤动物呼吸的68.30%～76.20%,表明亚热带毛竹林土壤组分呼吸及土壤总呼吸均受土壤温度和土壤湿度的共同影响。土壤微生物呼吸与细菌、放线菌数量呈极限值正相关关系(P<0.01),而与真菌数量不存在相关关系(P>0.05),与微生物量碳存在显著相关性(P<0.05)。根系生物量、土壤动物区系的差异也会导致组分呼吸大小,毛竹林地下活根根系生物量解释了土壤呼吸的65.99%～70.26%,而土壤中的主要动物类群对土壤呼吸的影响大都达到显著水平,土壤各类群动物总数可以解释土壤表面CO2释放量的55.40%～60.10%。(4)健康,较健康,亚健康和不健康4种不同健康状况毛竹林土壤总呼吸大小为,健康林>较健康林>亚健康林>不健康林,多元方差分析表明4种健康状况土壤总呼吸之间差异极显著(P<0.01)。土壤微生物呼吸贡献率大小为健康林>较健康林>亚健康林>不健康林；根系呼吸贡献率大小为亚健康林>健康林>较健康林>不健康林；土壤动物呼吸贡献率为健康林>较健康林>亚健康林>不健康。更多还原

【Abstract】 Soil respiration (Rs) is the process that soil releases CO2 to atmosphere (also called soil surface CO2 flux), and is the important part of carbon cycling in terrestrial ecosystems. Soil respiration includes plant root respiration, soil microbial and fauna respiration. The respiration and the variation mechanism of the three components will be direct response to the intensity of soil respiration and will affect plant growth and ecosystem carbon balance. Thus separate and quantify the different components (root respiration, soil microbial and fauna respiration) of soil respiration is critical to learn the carbon cycling of forest ecosystem and is the focal point in current. In this study, using infrared gas exchange analyzer (Li-Cor-8100), we combined with trench method excluded roots, naphthalene combining with electric bar(220V) exclude soil faunas measuring the soil respiration and its three biological processes (root respiration, soil microbial respiration and fauna respiration) from spatial and temporal scale in Mao bamboo plantations. Soil temperature, moisture, the biomass of he microbe, root and fauna were measured at the same time. Main objective was to estimate the contribution of root respiration, soil microbial and soil fauna respiration to soil respiration and determine the control factor of the total soil respiration and the respiration from different components, the results showed that:(1)Total soil respiration and the three components at the three elevations had similar diurnal variation trend (single peak curve) with those of air temperature and soil temperature. The minimum values always occurred at 02:00 at night, neither did the maximum values. Total soil respiration peaked in the afternoon around 15:00, root respiration peaked at 11:00, both soil microbial respiration and fauna had gentle diurnal variation and the maximum occurred at 11:00-15:00. Seasonal variation showed that total soil respiration and the three components respiration consistent with soil temperature and air temperature, had a maximum in 7-8 months and minimum in 11-12 months. Spatial variation showed that soil respiration, root respiration and microbial respiration reduced with elevation increased, while fauna respiration had the maximum at 200m altitude,400m had the smallest respiration. The reasons for this spatial variability are due to soil temperature and humidity, the biological factors (roots, microbes and animal biomass) and soil factors.(2)The average daily respiration of the total CO2 efflux of 200m,400m and 700m altitude varied from 3.89μmol·m-2·s-1 to 5.49μmol·m-2·s-1 in August 2008 and 3.36μmol·m-2·s-1-4.05μmol·m-2·s-1 in August 2009. During the periods from Mar to Dec in 2008 the average annual respiration of this three elevations was 3.10μmol·m-2·s-1-3.60μmol·m-2·s-1,2009 years was 2.58μmol·m-2·s-1-3.12μmol·m-2·s-1. Carbon (C) flux were 881.61 gC m-2-1028.35 g C m-2 in 2008, increased 12.74%-18.03% than in 2009 and in the range in tropical and subtropical forest (345 gC m-2 a-1-1520 gC m-2 a-1).The daily contribution rate of root respiration to total soil respiration was 51.73%-55.53% and annual contribution rate was 33.51%-38.90% in 2008, while in 2009 the daily contribution rate was 44.95%-48.97% and annual contribution rate was 34.79%-41.89%.200m altitudes had the highest root respiration contribution,700m was the minimum. Different regions, ecosystems and methods all had an impact on root respiration. C flux from root respiration during Mar to Dec varied between 323.93 g C m-2-431.48 g C m-2, accounting for 36.74%-41.96% of the total C flux in 2008; C flux varied from 277.24 g C m-2-401.25 g C m-2, accounting for 37.05%-44.70% of total soil respiration in 2009; 200m altitude had the largest C flux and more 3.40% than 400m and 14.20% than 700m.The daily contribution rate of heterotrophic respiration(microbial respiration, fauna respiration) to total soil respiration of 200m,400m and 700m varied from 42.85%-47.87%(of which microbial respiration was 35.31%-39.45%, fauna respiration was 7.54%-8.42%) in 2008; while in 2009, the contribution rate was 52.34%-53.43%(of which microbial respiration was 45.42%-45.52%,6.92% animal breathing 7.91%). The annual contribution rate of heterotrophic respiration of the three altitudes were 59.02%-65.36%(of which microbial respiration was 52.07%-57.67%, fauna respiration was 6.95%-7.69%),2009 was 54.60%-64.86%(of which microbial respiration was 47.41%-57.04%, fauna respiration was 7.19%-7.82%). C flux from heterotrophic respiration during Mar to Dec was 557.68-626.63 g C m-2, accounting for 57.36%～63.93% of total C flux (of which soil fauna respiration was 69.42 g C m-2-87.94 g C m-2, accounting for 7.87%-8.55% of total soil respiration, microbial respiration was 488.26 g C m-2-544.75 g C m-2, accounting for of total soil respiration 49.49%-55.38%) in 2008; while in 2009, C flux from heterotrophic respiration was 470.9 g C m-2-500.93 g C m’2, accounting for 55.12%-63.63%of total soil respiration (fauna respiration was 60.81 g C m-2-74.57 g C m-2, accounting for 8.13%-8.81% of total soil respiration, microbial respiration was 410.18 g C m-2-429.12 g C m-2, accounting for 46.99%-54.82% of total soil respiration).Heterotrophic respiration are the main components of soil surface CO2 flux.C flux from root respiration was 195.15 g C m-2-233.75 g C m-2 smaller than heterotrophic respiration in 2008 and 99.65 g C m-2-193.66 g C m-2 in 2009.(3)The correlation between soil temperature and total soil respiration, soil microbial respiration and soil fauna respiration is significant exponent function(P<0.01). The relationship between total soil respiration and soil temperature at different depth (soil surface,0-10cm,10-20cm and 20-30cm) reached a significant level (P<0.05) and the correlation with soil temperature at 10cm depth reached the very significant level (P<0.01). Soil microbial respiration had higher Q10 than root respiration, while compared with microbial respiration, the relationship between soil fauna respiration and soil temperature was slightly, but Q10 values bigger than Q10 of root and microbial respiration.Compared with the correlation between soil temperature and soil respiration, the correlation between soil respiration and soil water content was less apparent, but there was an apparent improvement in the correlation between standardized soil respiration (Rio) and soil water content(P<0.05) when the effect of soil temperature was removed. Soil water content had significant effect on root respiration and had very significant linear correlation (P<0.01), but the relationship between soil water content and fauna, microbial respiration was not significant.Compared with the one-dimensional (soil temperature and soil water content) equation, the R2 of the two-dimensional equation increased to some extent. The combination effect of soil temperature and soil water content could explained more 50% of soil respiration at different altitudes, root respiration could explained 77.1%-90.3%, soil microbial respiration explained 86.5%-88.9% and soil fauna explained 68.3%-76.2%, indicating that soil respiration and its components are affected by both soil temperature and soil water content in Mao bamboo forest in subtropical.Microbial respiration showed a significantly positive correlation with the biomass of bacteria, actinomycetes (P<0.01) and microbial biomass C (P<0.05), while had no correlation (P>0.05) with fungi. Biomass of root and soil fauna components can also lead to differences in soil respiration, live underground root biomass could explain 65%-70% of soil respiration. The total numbers of the soil faunas could explained 55.4%-60.1% of soil respiration in Mao bamboo forest(4) The total soil respiration of health, general health, sub-health and poor healthy Mao bamboo forest were healthy forest>the general healthy forest>sub-health forest>poor healthy forest and there was very significant difference between them (P< 0.01). Contribution of soil microbial respiration were health forest>general healthy forest>Sub-health forestpoor healthy forest; root respiration contribution rate was sub-health forest>health forest>general healthy forest>poor healthy forest; contribution of soil fauna respiration rate was healthy forest>general healthy forest>sub-health forest>poor healthy forest.更多还原