玉米农田土壤呼吸作用的空间异质性及其根系呼吸作用的贡献

基于4月底到9月底东北地区玉米农田土壤呼吸作用全生长季的观测,阐明了土壤呼吸作用的空间异质性特征,综合分析了水热因子、土壤性质、根系生物量及其测定位置对土壤呼吸作用空间异质性的影响,并对生长季中根系呼吸作用占土壤呼吸作用的比例进行了估算。结果表明,在植株尺度上,土壤呼吸作用存在着明显的空间异质性,较高的土壤呼吸速率通常出现在靠近玉米植株的地方。根系生物量的分布格局是影响土壤呼吸作用空间异质性的关键因素。在空间尺度上,土壤呼吸作用与根系生物量呈显著的线性关系,而土壤湿度、土壤有机质、全氮和碳氮比对土壤呼吸作用空间异质性的影响并不显著。通过建立土壤呼吸作用与玉米根系生物量的回归方程,对根系呼吸作用占土壤呼吸作用的比例进行了间接估算。玉米生长季中,根系呼吸作用占土壤呼吸作用的比例在43．1％～63．6％之间波动,均值为54．5％。     

施石灰对杉木人工林土壤呼吸及其温度敏感性的影响

我国酸沉降主要分布区域与杉木人工林主要分布区域重合,石灰添加是改良酸化土壤的有效措施。为探究酸沉降背景下施石灰对土壤呼吸及其温度敏感性的影响,本研究以杉木人工林土壤为对象,在2018年6月一次性添加0、1和5 t·hm^-2的氧化钙,于2020年6月开始进行为期一年的原位土壤呼吸速率观测。结果表明：与不施石灰相比,施石灰显著提高了土壤pH值和交换性Ca²⁺含量,不同石灰施用量之间无显著差异。杉木人工林土壤呼吸及其组分具有明显的季节差异,表现为夏季最高,冬季最低,施石灰未显著改变其季节动态特征。施石灰显著降低了土壤异养呼吸速率,提高了自养呼吸速率,最终导致施石灰对土壤呼吸无显著影响。土壤呼吸月动态变化与温度月动态变化基本保持一致,土壤呼吸与土壤温度呈显著的指数关系,施石灰后土壤呼吸及自养呼吸的温度敏感性(Q₁₀)呈上升趋势,土壤异养呼吸的Q₁₀呈下降趋势。综上,施石灰提高了杉木人工林土壤自养呼吸,显著降低了土壤异养呼吸,这有利于杉木人工林土壤固碳。     

东北地区落叶松人工林的根系呼吸

落叶松根系呼吸速率在6～9月期间逐渐升高,8月达到高峰,之后明显下降.幼林根系呼吸速率和根系呼吸占土壤总呼吸的比例均高于成熟林.根系呼吸速率与根生物量呈线性相关,与土温呈指数相关,与土壤含水量无明显相关关系,但温度较高时,土壤湿度的增加能促进根系呼吸.成熟林和幼林根系呼吸的Q10值分别为5.56和4.17.     

氮添加对沙质草地微生物呼吸与根系呼吸的影响

土壤呼吸可以细化为根系呼吸和微生物呼吸,二者对氮添加的响应有所不同.本文以科尔沁沙质草地为研究对象,探讨氮添加对土壤CO₂排放的影响,并细化为微生物呼吸和根系呼吸的响应特征.结果表明: 在观测期(5—10月),土壤呼吸、微生物呼吸月动态均呈先升高后降低的趋势;微生物呼吸是土壤呼吸的主要贡献者,占82.6%;观测期内根系呼吸贡献率随月份而变化,根系呼吸贡献率两个峰值分别出现在5月(占49.4%)和8月(占41.9%),6个月的平均贡献率为17.4%;在10 ℃条件下,根系呼吸较微生物呼吸对氮添加的响应更为敏感,微生物呼吸速率在氮添加后降低了3.9%,而根系呼吸降低了17.7%;氮添加提高了土壤呼吸、微生物呼吸温度敏感性Q₁₀值,也提高了二者对土壤水分变化的敏感程度.     

短期增温和增加降水对内蒙古荒漠草原土壤呼吸的影响

利用红外辐射增温装置模拟短期持续增温和降水增加交互作用对内蒙古荒漠草原土壤呼吸作用的影响, 结果表明: 土壤含水量对月土壤呼吸的影响显著大于土壤温度增加的影响, 生长旺季的月土壤呼吸显著大于生长末季; 土壤温度和水分增加都显著影响日土壤呼吸, 但二者的交互作用对土壤呼吸无显著影响。荒漠草原7‒8月平均土壤呼吸速率为1.35 μmol CO₂·m ^-2·s ^-1, 7月份为2.08 μmol CO₂·m ^-2·s ^-1, 8月份为0.63 μmol CO₂·m ^-2·s ^-1。土壤呼吸与地下各层根系生物量呈幂函数关系, 0‒10 cm土层的根系生物量对土壤呼吸的解释率(79.2%)明显高于10‒20 cm土层的解释率(31.6%)。0-10 cm土层的根系生物量是根系生物量的主体, 根系生物量对土壤呼吸的影响具有层次性。在未来全球变暖和降水格局变化的情景下, 荒漠草原土壤水分含量是影响生物量的主导环境因子, 而根系生物量的差异是造成土壤呼吸异质性的主要生物因素, 土壤含水量可通过影响根系生物量控制土壤呼吸的异质性。     

万木林保护区毛竹林土壤呼吸特征及影响因素

2009年1-12月,利用Li-Cor 8100开路式土壤碳通量系统测定福建省万木林自然保护区毛竹林土壤呼吸速率,分析毛竹林土壤呼吸动态变化及其与凋落物量的关系.结果表明:毛竹林土壤呼吸月变化呈明显的双峰型曲线,峰值分别出现在6月(6.83 μmol·m-2·s-1)和9月(5.59μmol·m-2·s-1).土壤呼吸速率的季节变化较明显,最大值出现在夏季,最小值出现在冬季;土壤呼吸速率与土壤5 cm温度呈显著正相关关系(P＜0.05),与土壤含水量无显著相关性(P＞0.05);毛竹林凋落物量月变化呈单峰型曲线.毛竹林土壤呼吸速率与当月凋落物归还量呈显著正相关(P＜0.05).土壤温度和凋落物量的双因素模型可以解释土壤呼吸速率变化的93.2%.     

种植密度对东北玉米农田土壤呼吸时空动态的影响

基于东北地区玉米生态系统土壤呼吸的观测数据,阐明了玉米常规密度种植和低密度种植土壤呼吸的日变化特征及其空间差异性,分析了温湿度对土壤呼吸的影响。结果表明:土壤呼吸日动态呈单峰型曲线,土壤呼吸日动态最大峰值出现的时间随测定位置不同而变化;玉米常规密度种植土壤呼吸速率最大峰值出现在12:00—15:00;低密度种植土壤呼吸速率最大峰值出现在11:00—16:00;在生态系统尺度上,测定位置距离玉米植株越远,土壤呼吸速率则越低;玉米常规密度种植土壤呼吸速率高于玉米低密度种植;测定位置不同,土壤呼吸速率与土壤温度、空气相对湿度的相关系数不同,均达到显著相关(P0.01),其中土壤呼吸速率与土壤温度呈正相关,与近地表的空气相对湿度呈负相关。     

环境因子和生物因子对黄河三角洲滨海湿地土壤呼吸的影响

采用Li-8150多通道土壤呼吸自动测量系统对黄河三角洲滨海湿地土壤呼吸进行全年连续测定,同步测量了温度、土壤含水量、地上生物量以及叶面积指数等环境因子和生物因子.结果表明: 土壤呼吸日动态在全年尺度上多呈单峰型,但在受到土壤封冻和地表积水干扰时,土壤呼吸日动态呈多峰型.土壤呼吸具有明显的季节动态特征,总体呈单峰型,年平均土壤呼吸速率为0.85 μmol CO₂·m^-2·s^-1,生长季平均土壤呼吸速率为1.22 μmol CO₂·m^-2·s^-1.在全年尺度上,土壤温度是滨海湿地土壤呼吸的主要控制因子,可解释全年土壤呼吸87.5%的变化.在生长季尺度上,土壤含水量和叶面积指数对土壤呼吸的协同影响达到85%.     

万木林保护区柑橘和锥栗园土壤呼吸的比较

采用Li-8100开路式土壤碳通量系统,对福建省万木林保护区内柑橘和锥栗两果园土壤呼吸进行1年的定位观测,分析了土壤水热因子及人为管理措施对土壤呼吸的影响.结果表明:柑橘和锥栗园样地土壤的呼吸速率月变化均呈单峰型曲线,峰值分别出现在7月(3.76 μmol·m-2·s-1)和8月(2.69 μmol·m-2·s-1);柑橘和锥栗园样地土壤呼吸速率的年均值分别为2.68和1.55 μmol·m-2·s-1,且柑橘园土壤呼吸速率极显著高于锥栗园;土壤温度是影响土壤呼吸的主要因素,可以解释土壤呼吸速率月动态变化的73％～86％;锥栗园土壤含水量与土壤呼吸速率呈显著正相关,但柑橘园两者关系不显著;指数方程计算的柑橘和锥栗园土壤呼吸的Q10值分别为1.58和1.75;柑橘和锥栗园土壤呼吸年通量值分别为10.01和5.77tC·hm-2 ·a-1.     

改变C源输入对油松人工林土壤呼吸的影响

2010年生长季,采用不同处理（去凋切根、去除凋落物、对照、切除根系、加倍凋落物）研究土壤C源输入方式对油松人工林土壤呼吸速率及5 cm土壤温湿度的影响。结果表明：改变C源输入对土壤温度产生的差异不显著（P>0.05）,而对土壤湿度和土壤呼吸速率产生的差异显著（P<0.05）。整个观测期去凋切根、去凋、对照、切根及加倍凋落物处理的土壤呼吸速率平均值分别为1.54,1.71,2.71,2.47和3.39 ?mol m-2 s-1。相比对照样方土壤呼吸,去凋切根处理使油松人工林整个观测期土壤呼吸速率平均降低（44.27 2.31）%;去除凋落物使土壤呼吸速率平均降低（36.03 2.64）%;切除根系使土壤呼吸速率平均降低（10.76 3.26）%,但试验初期切除根系表现为增加土壤呼吸,6月下旬和7月中旬分别使土壤呼吸增加25.91%和0.29%,此后,切除根系使土壤呼吸速率显著降低。如果排除6月和7月的数据,则切除根系使土壤呼吸速率平均降低21.90%;加倍凋落物使土壤呼吸速率平均增加（21.01 3.21）%。去凋切根、去凋、切根和加倍凋落物处理土壤呼吸的温度敏感系数Q10值分别为1.75,1.65,2.32和3.10,四者之间差异均显著（P<0.05）,对照样方土壤呼吸的Q10值为2.23。不同处理土壤呼吸速率与土壤温度均呈显著指数相关（P<0.001）,而与土壤湿度的相关性并不显著（P>0.05）。土壤温度和水分的双变量模型均可以很好地解释土壤呼吸的季节变化,拟合方程的R2值范围为0.49—0.83。     

Soil Respiration under Different Land Uses in Eastern China

Land-use change has a crucial influence on soil respiration, which further affects soil nutrient availability and carbon stock. We monitored soil respiration rates under different land-use types (tea gardens with three production levels, adjacent woodland, and a vegetable field) in Eastern China at weekly intervals over a year using the dynamic closed chamber method. The relationship between soil respiration and environmental factors was also evaluated. The soil respiration rate exhibited a remarkable single peak that was highest in July/August and lowest in January. The annual cumulative respiration flux increased by 25.6% and 20.9% in the tea garden with high production (HP) and the vegetable field (VF), respectively, relative to woodland (WL). However, no significant differences were observed between tea gardens with medium production (MP), low production (LP), WL, and VF. Soil respiration rates were significantly and positively correlated with organic carbon, total nitrogen, and available phosphorous content. Each site displayed a significant exponential relationship between soil respiration and soil temperature measured at 5 cm depth, which explained 84–98% of the variation in soil respiration. The model with a combination of soil temperature and moisture was better at predicting the temporal variation of soil respiration rate than the single temperature model for all sites. Q₁₀ was 2.40, 2.00, and 1.86–1.98 for VF, WL, and tea gardens, respectively, indicating that converting WL to VF increased and converting to tea gardens decreased the sensitivity of soil respiration to temperature. The equation of the multiple linear regression showed that identical factors, including soil organic carbon (SOC), soil water content (SWC), pH, and water soluble aluminum (WSAl), drove the changes in soil respiration and Q₁₀ after conversion of land use. Temporal variations of soil respiration were mainly controlled by soil temperature, whereas spatial variations were influenced by SOC, SWC, pH, and WSAl.     

Soil respiration in Pinus tabulaeformis forest during dormant period at Huoditang forest zone in the Qinling Mountains, China

Soil CO₂ efflux in forest ecosystems during dormant season is one of the key components of the forest ecosystem carbon balance. Little work has been done to quantify soil CO₂ efflux in most forests in China in special time because of difficulty in taking measurements. Soil respiration in a natural secondary Pinus tabulaeformis forest at Huoditang in the Qinling Mountains was measured from October to December in 2006 by means of open-path dynamic chamber technique. Relationships of soil respiration rate (R_s) with mean soil temperature (MST) and mean volumetric soil moisture content (MVSC) in different depths (0-5 cm and 5-10 cm) were examined in the current study. We found that (1) At the same observation site (upper-part, middle-part or under-part), there were tremendous temporal and spatial variations in R_s with variation coefficients of 48.38%, 82.51% and 81.88% in October, November and December, respectively; (2) There was a significant exponent relationship between diurnal mean soil respiration rate (F_c) and diurnal mean soil temperature (DMST) when DMST > 8.5°C for both soil depths (0-5 cm and 5-10 cm) examined. The temperature sensitivity of soil respiration, known as the Q₁₀ value, was 1.297 and 1.323 in soil depths of 0-5 cm and 5-10 cm, respectively; (3) Relationship between R_s and MVSC was complex in soil depths of 0-5 cm and 5-10 cm; (4) Soil CO₂ efflux from October to December in 2006 in the experimental area was (977.37 ± 88.43) to (997.19 ± 80.73) gCm⁻² (p = 0.005).     

西双版纳山地三种土地利用方式的旱季土壤呼吸

为了解西双版纳山地不同土地利用方式土壤呼吸旱季变化特征,本研究对古树茶园、台地茶园和次生林中土壤呼吸速率及其相关因素进行定位观测。结论如下：三种土地利用方式土壤呼吸速率日变化有显著的差异性（P<0.05）;土壤呼吸速率日最高值大多出现在14∶00-16∶00;旱雨季交错期是土壤呼吸速率和土壤湿度变化最剧烈的阶段;土壤呼吸速率日均值表现为古树茶园（2.62μmol·m-2s-1）<台地茶园（2.73μmol·m-2s-1）<次生林（3.01μmol·m-2s-1）;土壤湿度过高和过低都会阻碍土壤呼吸的进行;三种土地利用方式土壤呼吸速率均与土壤湿度(0~10cm)和空气日均温具有相关关系;降水会引起土壤呼吸较大的波动。     

Seasonal Changes in Soil Respiration with An Elevation Gradient in <i>Abies nephrolepis</i> (Trautv.) Maxim. Forests in North China

Soil respiration (Rs) plays an important role in regulating carbon cycle of terrestrial ecosystems and presents temporal and spatial heterogeneity. Abies nephrolepis is a tree species that prefers the cold and wet environment and is mainly distributed in Northeast Asia and East Asia. The Rs variations of Abies nephrolepis forests communities are generally environmental-sensitive and can effectively reflect the adaptive responses of forest ecosystems to climate change. In this study, the growing-seasonal variations of Rs, soil temperature, soil water content and soil properties of Abies nephrolepis forests were analyzed along an altitude gradient (2000, 2100, 2200 and 2300 m) over two years on Wutai Mountain in North China. As the main results showed, soil respiration keeps the same change trend as soil temperature and reached peaks in July at 2000 m in 2019 and 2020. During 26^th July to 25^th October in 2019 and 27^th May to 23^rd October in 2020, on the whole, the soil temperature independently explained 76.2% of Rs variations while the soil water content independently explained 26.8%. Soil temperature and soil water content jointly explained 81.8% of Rs variations. Soil properties explained 61.8% and 69.6% of Rs variation in 2019 and 2020, respectively. Soil organic carbon content and soil enzyme activity had the signifi- cant (P < 0.01) negative and positive relationships, respectively, with Rs variation. With altitudes evaluated from 2000 to 2300 m, soil respiration temperature sensitivity (Q₁0) and the soil organic carbon content increased by 12.4% and 10.4%, respectively, while invertase activity, cellulase activity and urease activity dropped by 41.2%, 29.45% and 38.19%, respectively. The results demonstrate that (1) soil temperature is the major factor affecting Rs variations in Abies nephrolepis forests; (2) weakened microbial carbon metabolism in high-altitude areas results in the accumulation of soil organic carbon; (3) with a higher Q₁, forest ecosystems in high-altitude areas might be more easily affected by climate change; (4) climate warming might accelerate the consumption of soil organic carbon sink in forest ecosystems, especially in high-altitude areas.     

中国东部亚热带森林土壤呼吸的时空格局

土壤呼吸是陆地碳循环中仅次于全球总初级生产力的第二大碳通量途径, 揭示土壤呼吸的时空格局对整个陆地碳循环具有重要意义。该文在中国东部亚热带季风气候区, 按纬度梯度由南向北选取深圳梧桐山、杨东山十二度水保护区、宁波天童山3个区域作为研究对象, 于2009年8月至2010年10月测定了不同季节各个区域内代表性植被类型的土壤呼吸速率及地下5 cm处土壤温度, 旨在初步了解中国东部亚热带森林地区土壤呼吸的时空格局及其影响因素。结果显示: 3个区域的土壤呼吸速率均存在显著的季节变化, 其变幅为2.64-6.24 μmol CO₂·m ^-2·s^-1, 总体趋势和地下5 cm处土壤温度的季节变化一致, 均为夏季最高冬季最低; 土壤温度的变化可以解释不同样地土壤呼吸季节变化的58.3%-90.2%; 各样地全年的Q₁₀值从1.56到3.27; 通过离样地最近的气象站点的日平均气温与试验样地地下5 cm处土壤温度之间的线性正相关关系推算出日土壤温度的变化, 利用土壤呼吸速率和地下5 cm处土壤温度之间的指数关系, 估算出各样地全年的土壤CO₂通量为1 077-2 058 g C·m^-2·a^-1, 在全球所有生态系统类型中处于较高水平。     

Soil Respiration under Three Land use Categories of Mountainous Region in Xishuangbanna,Yunnan

In order to study the difference of the soil respiration under different land uses in Xishuangbanna, field observations were conducted on the soil respiration rate from November 2010 to May 2011 under forest tea plantations, terrace tea plantations and secondary forests. Daily variations of soil respiration and its influence factors were analyzed. The results showed that there are different daily change patterns of soil respiration rate and soil moisture under different land uses, with statistically insignificance of soil respiration rate (P<0.05). The daily maximum soil respiration rate is almost at 14∶00-16∶00. The soil respiration rate and soil moisture vary most during the dry rainy transition season. The average soil respiration rate: forest tea plantations (2.62μmol·m-2s-1)相似文献   

秦岭火地塘林区油松(Pinus tabulaeformis)林休眠期的土壤呼吸

林木休眠期林地土壤CO2释放是森林生态系统碳平衡关键组成部分之一.由于绝大多数森林生态系统林木休眠期土壤CO2释放过程测定困难,国内有关林木休眠期CO2释放,量化方面的研究开展较少.采用动态开路气室法对秦岭火地塘林区天然次生油松(Pinus tabulaeformis)林土壤呼吸的日变化进行了测定,分析了土壤呼吸速率(mgCO2m-2h-1)与土壤温度和体积含水率的关系,基于土壤日均呼吸速率和土壤日均温度指数方程与观测季的总天数,估算了林木休眠期林地土壤CO2释放量.结果表明:(1)研究区林地土壤呼吸速率存在较大的时、空变异.不同观测部位土壤呼吸速率的峰值出现时间各异,呼吸作用较弱的时段也不一致.同一观测部位不同观测月中,土壤日均呼吸速率变异系数分别为48.38%,82.51%和81.88%;(2)当土温＞8.5 ℃时,0～5 cm和5～10 cm土层,土壤日均温与土壤日均呼吸速率间存在极显著(p＜0.001)的指数关系,Q10分别为1.297和1.323;(3)0～5 cm和5～10 cm土层,土壤体积含水率与土壤呼吸速率间关系复杂;(4) 林木休眠期研究区林地土壤CO2释放量变化于(977.37±88.43)～(997.19±80.73) gCm-2(p=0.005)间.     

Soil plus root respiration and microbial biomass following water, nitrogen, and phosphorus application at a high arctic semi desert

In order to investigate the effects of anticipated increased precipitation and changing soil nutrient levels on soil CO₂ efflux from high arctic semi desert, a field experiment was carried out in Northeast Greenland. Water, phosphorus, and nitrogen were added to plots in a fully factorial design. Soil microbial biomass carbon was analysed after one year, and respiration from soil plus roots was measured in situ throughout the third growing season after initiation of the experiment. Soil plus root respiration was enhanced by up to 47%, and the microbial biomass by 24%, by the weekly water additions, but not by nutrient additions. The direct effect of increased soil moisture on CO₂ efflux suggests that future changes of precipitation levels and patterns may strongly affect below-ground respiration in arctic semi deserts, with direction of responses depending upon amounts and frequencies of precipitation events. Morover, low CO₂ emission at low light intensities regardless of treatment suggests that the major part of the below-ground respiration originated from turnover of recently fixed C. Hence, the more recalcitrant soil organic matter C pool may not change in proportion to changes in below-ground respiration rate.