Carbon storage in biomass,litter, and soil of different native and introduced fast-growing tree plantations in the South Caspian Sea

Replantation of degraded forest using rapidgrowth trees can play a significant role in global carbon budget by storing large quantities of carbon in live biomass,forest floor,and soil organic matter.We assessed the potential of 20-year old stands of three rapid-growth tree species,including Alnus subcordata,Populus deltoides and Taxodium distichum,for carbon(C) storage at ecosystem level.In September 2013,48 replicate plots(16 m × 16 m) in 8 stands of three plantations were established.36 trees were felled down and fresh biomass of different components was weighed in the field.Biomass equations were fitted using data based on the 36 felled trees.The biomass of understory vegetation and litter were measured by harvesting all the components.The C fraction of understory,litter,and soil were measured.The ecosystem C storage was as follows: A.subcordata(626.5 Mg ha~(-1)) [ P.deltoides(542.9Mg ha~(-1)) [ T.distichum(486.8 Mg ha~(-1))(P \ 0.001),of which78.1–87.4% was in the soil.P.deltoides plantation reached the highest tree biomass(206.6 Mg ha~(-1)),followed by A.subcordata(134.5 Mg ha~(-1)) and T.distichum(123.3 Mg ha~(-1)).The highest soil C was stored in theplantation of A.subcordata(555.5 Mg ha~(-1)).The C storage and sequestration of the plantations after 20 years were considerable(25–30 Mg ha~(-1) year~(-1)) and broadleaves species had higher potential.Native species had a higher soil C storage while the potential of introduced species for live biomass production was higher.     

Carbon stocks and biomass production of three different agroforestry systems in the temperate desert region of northwestern China

Carbon sequestration potential of agroforestry systems has attracted worldwide attention following the recognition of agroforestry as a greenhouse gas mitigation strategy. However, little is known about carbon stocks in poplar–maize intercropping systems in arid regions of China. This study was conducted in the temperate desert region of northwestern China, a region with large area of poplar–maize intercropping systems. The objective of this study was to assess biomass production and carbon stock under three poplar–maize intercropping systems (configuration A, 177 trees ha^?1; configuration B, 231 trees ha^?1; and configuration C, 269 trees ha^?1). We observed a significant difference in the carbon stock of poplar trees between the three configurations, with the highest value of 36.46 t ha^?1 in configuration C. The highest carbon stock of maize was achieved in configuration B, which was significantly higher than configuration A. The grain yield was highest in configuration A, but there was no significant difference from the other two configurations. In the soil system (0–100 cm depth), the total carbon stock was highest in configuration C (77.37 t ha^?1). The results of this study suggest that configuration C is the optimum agroforestry system in terms of both economic benefits and carbon sequestration.     

Microbial biomass and nutrients in soil at the different stages of secondary forest succession in Ziwulin,northwest China

Microbial biomass, organic carbon, total nitrogen, and microbial quotient (MBC/Corg) in soil were determined during the secondary forest succession in north Ziwulin region in the middle of Loess Plateau, China. The results showed that with secondary forest succession organic carbon (Corg), total nitrogen (TN), microbial biomass carbon (MBC) and N (MBN) in soil increased quickly, and tended to be the highest contents under SF17 (17-year secondary forest), after that they decreased and gradually remained at quite a constant level, suggesting that accumulations of organic C, total N, MBC and MBN in soil occurred mainly at the early succession stages (before SF17). Soil microbial biomass was markedly correlated with the organic carbon and total nitrogen content of soil (p < 0.01), Furthermore, microbial quotient showed significant correlation not only with MBC and organic C, but also with succession duration during the secondary forest succession. Therefore, the results suggested that changes in microbial biomass in soil were relative not only to the quantity, but also to the quality of soil organic matter during secondary forest succession, and that changes in aboveground plant species during succession were critical to improve degradation soil physical, chemical and microbial properties in north Ziwulin of Loess Plateau, China.     

喀斯特地区人工林凋落物及表层土壤水源涵养功能

以贵州省溶岩区4种人工林（桤木林、杜仲林、刺槐林、滇柏林）为对象,对其凋落物及表层土壤的水源涵养功能进行了初步研究。结果表明：4种人工林凋落物储量的大小顺序为桤木林〉杜仲林〉刺槐林〉滇柏林,凋落物持水量呈现桤木林〉杜仲林〉刺槐林〉滇柏林。凋落物持水量与浸泡时间的关系符合指数函数模型,凋落物吸水速率与浸泡时间的关系符合幂函数模型。人工林土壤持水量的大小关系为桤木林〉杜仲林〉刺槐林〉滇柏林。凋落物饱和含水时相对自由水面蒸发率桤木林为68.12%,刺槐林为76.84%,杜仲林为73.70%,滇柏林为80.41%。在环境一致条件下,滇柏林与其他3种人工林相比凋落物水分损失较易。     

典型黑土区水土保持林土壤结构性特征的对比研究(英文)

以典型黑土区水曲柳林、落叶松林、樟子松林、云杉林及撂荒地为对象,通过对土壤容重、非毛管孔隙/毛管孔隙(NCP/CP)、广义土壤结构指数(GSSI)的测定、计算与对比分析,研究了不同类型人工水土保持林对土壤结构性特征的影响。结果表明:在所研究的0-30cm土层范围内,水曲柳林和落叶松林在降低土壤容重方面略好于樟子松林和云杉林,降低幅度为8.04%-1 1.01%,落叶松林与云杉林和樟子松林之间差异均达显著水平(p0.05),而水曲柳林仅与云杉林差异显著(p0.05);林地土壤的平均NCP/CP值均显著高于撂荒地(p0.05),增加幅度范围为59.75%～128.82%,土壤透气性、透水性能力提高,并以落叶松林提高幅度最大;各林地的平均GSSI值均显著高于撂荒地(p0.05),增加幅度范围为2.98%-4.36%,说明林分可以有效改善土壤结构,使其能够更加接近旱地土壤理想结构,以水曲柳林和云杉林改良效果相对较强,但实现趋近理想土壤结构的途径、即相态的变化方式有所不同。研究结果可为科学评价典型黑土区植被恢复对土壤质量的影响和深入系统研究水土保持林构建提供理论依据。图3表2参17。     

滇中高原华山松人工林碳储量及固碳释氧效益

采用样方法和收获法,根据光合作用方程式、碳税法和人工制氧法,对云南玉溪磨盘山华山松人工林(16 a中龄林、26 a近成熟林、43 a成熟林)生物量、碳储量及其空间分布特征和固碳释氧进行了研究。结果如下:三种林龄华山松人工林的生物量分别为181.515 t·hm-2、284.679 t·hm-2、295.311 t·hm-2,碳储量分别为85.751 3t C·hm-2、139.934 4 t C·hm-2、132.508 6 t C·hm-2,净碳储量分别为:5.365 3 t C·hm-2·a-1、5.383 6 t C·hm-2·a-1和3.082 7t C·hm-2·a-1;三种林龄群落各层碳储量均为乔木层枯落物层灌木层草本层,三种林龄乔木层的碳储量分别占:91.37%、94.99%、93.70%;不同林龄相同器官(根、皮、叶、干、枝)之间变异系数在2.10%~7.33%之间,而同一林龄不同器官的变异系数在2.12%~5.82%之间;方差分析结果显示除成熟林乔木外,另两种林龄乔木各营养器官之间均存在显著差异;华山松中龄林、近成熟林、成熟林同化大气中CO2和释放出O2价值量分别是355 044.221 3 yuan·hm-2,216 003.386 1 yuan·hm-2,556 831.529 6 yuan·hm-2和338 767.648 4 yuan·hm-2、577 627.367 6 yuan·hm-2和351 419.513 0 yuan·hm-2。     

Carbon accumulation in aboveground and belowground biomass and soil of different age native forest plantations in the humid tropical lowlands of Costa Rica

Generic or default values to account for biomass and carbon accumulation in tropical forest ecosystems are generally recognized as a major source of errors, making site and species specific data the best way to achieve precise and reliable estimates. The objective of our study was to determine carbon in various components (leaves, branches, stems, structural roots and soil) of single-species plantations of Vochysia guatemalensis and Hieronyma alchorneoides from 0 to 16 years of age. Carbon fraction in the biomass, mean (±standard deviation), for the different pools varied between 38.5 and 49.7% (±3 and 3.8). Accumulated carbon in the biomass increased with the plantation age, with mean annual increments of 7.1 and 5.3 Mg ha⁻¹ year⁻¹ for forest plantations of V. guatemalensis and H. alchorneoides, respectively. At all ages, 66.3% (±10.6) of total biomass was found within the aboveground tree components, while 18.6% (±20.9) was found in structural roots. The soil (0–30 cm) contained 62.2 (±13) and 71.5% (±17.1) of the total carbon (biomass plus soil) under V. guatemalensis and H. alchorneoides, respectively. Mean annual increment for carbon in the soil was 1.7 and 1.3 Mg ha⁻¹ year⁻¹ in V. guatemalensis and H. alchorneoides. Allometric equations were constructed to estimate total biomass and carbon in the biomass which had an R ²aj (adjusted R square) greater than 94.5%. Finally, we compare our results to those that could have resulted from the use of default values, showing how site and species specific data contribute to the overall goal of improving carbon estimates and providing a more reliable account of the mitigation potential of forestry activities on climate change.     

Variation of soil enzyme activity and microbial biomass in poplar plantations of different genotypes and stem spacings

To improve the productivity of poplar plantations, a field experiment of split-plot design with four tree spacings and three poplar clones was established, and four soil enzyme activities and microbial biomass were monitored in the trial.Soil enzyme activities, in most cases,were significantly higher in topsoil(0–10 cm) than in lower horizons(10–20 cm).Soil cellulase, catalase and protease activities during the growing season were higher than during the non-growing season, while invertase activity followed the opposite trend.Soil invertase, cellulase and catalase activities varied by poplar clone but soil protease activity did not.Cellulase and protease activities in the plantation at 5×5 m spacing were significantly higher than in the other spacings.The highest catalase activity was recorded at 6×6 m spacing.At the same planting density, invertase activity was greater in square spacings than in rectangular spacings.Soil microbial biomass was also significantly affected by seedling spacing and poplar clone.The mean soil MBC was significantly lower in topsoil than in the lower horizon, while MBN showed the opposite pattern.Significantly positive correlations were observed among soil cellulase, protease and catalase activities(p0.01), whereas soil invertase activity was negatively and significantly correlated with cellulase, protease and catalase activities(p0.01).Soil microbial biomass and enzyme activities were not correlated except for a significantly negative correlation between soil MBC and catalase activities.Variations in soil enzyme activity and microbial biomass in different poplar plantations suggest that genotype and planting spacing should be considered when modeling soil nutrient dynamics and managing for long-term site productivity.     

广西不同林龄桉树人工林叶—凋落物—土壤C、N、P生态化学计量特征

C、N、P元素的养分循环过程是影响森林生态系统结构与功能的关键因素。以广西不同林龄桉树人工林为研究对象,分析桉树幼龄林(1a)、中龄林(2a)、近熟林(3a)、成熟林(5a)、过熟林(8a)叶—凋落物—土壤的C、N、P化学计量特征及其内在联系,探讨林龄对桉树人工林生态化学计量的影响,为桉树人工林可持续经营提供参考。结果表明:1)桉树人工林叶、土壤呈现高C低N、P的元素格局,凋落物呈现高C、P低N的元素格局;叶的C、N、P含量从幼龄林到近熟林呈先增后减趋势,反映桉树人工林早期对养分需求旺盛,随年龄增大需求减小。2)不同林龄叶C、N、P差异显著(P<0.05),凋落物与土壤的N、P、C∶N、C∶P、N∶P均差异显著(P<0.05),凋落物C∶P与叶N∶P、C∶P显著正相关(P<0.05),凋落物N∶P与叶的C∶P、N∶P之间呈极显著正相关(P<0.01),说明凋落物养分源自叶,土壤与叶的C、N、P均不相关。3)与叶相比,凋落物中N、P含量偏低,C∶N、C∶P偏高;土壤C∶P、N∶P偏低,说明土壤P素分解较快,可适时施以磷肥来弥补土壤速效磷的不足;土壤C∶N偏高表明土壤有机质具有较慢的矿化作用。中龄林、近熟林和成熟林叶N∶P<14,生长过程受N限制;中龄林、近熟林和成熟林凋落物分解的主要限制性元素是N,而幼龄林凋落物分解的主要限制性元素是P。     

Carbon and nitrogen storage in agroforests, tree plantations, and pastures in western Oregon, USA

Pastures store over 90% of their carbon and nitrogen below-ground as soil organic matter. In contrast, temperate conifer forests often store large amounts of organic matter above-ground in woody plant tissue and fibrous litter. Silvopastures, which combine managed pastures with forest trees, should accrete more carbon and nitrogen than pastures or timber plantations because they may produce more total annual biomass and have both forest and grassland nutrient cycling patterns active. This hypothesis was investigated by conducting carbon and nitrogen inventories on three replications of 11 year-old Douglas-fir (Pseudotsuga menziesii)/perennial ryegrass (Lolium perenne)/subclover (Trifolium subterraneum) agroforests, ryegrasss/subclover pastures, and Douglas-fir timber plantations near Corvallis, Oregon in August 2000. Over the 11 years since planting, agroforests accumulated approximately 740 kg ha^–1 year ^–1 more C than forests and 520 kg ha^–1 year^–1 more C than pastures. Agroforests stored approximately 12% of C and 2% of N aboveground compared to 9% of C and 1% of N above ground in plantations and less than 1% of N and C aboveground in pastures. Total N content of agroforests and pastures, both of which included a nitrogen-fixing legume, were approximately 530 and 1200 kg ha^–1 greater than plantations, respectively. These results support the proposition that agroforests, such as silvopastures, may be more efficient at accreting C than plantations or pasture monocultures. However, pastures may accrete more N than agroforests or plantations. This apparent separation of response in obviously interrelated agroecosystem processes, points out the difficulty in using forest plantation or pasture research results to predict outcomes for mixed systems such as agroforests. This revised version was published online in June 2006 with corrections to the Cover Date.     

Carbon content in vegetation,litter, and soil under 10 different land-use and land-cover classes in the Central Highlands of Michoacan,Mexico

In this study we estimated the carbon content in vegetation, litter, and soil, under 10 different classes of land-use and land-cover classes (LU/LC) in the Purepecha Region, located in the Central Highlands of México. Forests in this area are representative of the montane forests of Central and Southern Mexico and are subject to rapid degradation and deforestation by human pressure.     

Litterfall and litter chemistry change over time in an old-growth temperate forest, northeastern China

? Litterfall and litter chemistry are key factors for the assessment of forest floor properties. A long-term study on litterfall, litter chemistry and forest basal areas was carried out in an old-growth temperate forest, northeastern China.

? The objective of this study was to test whether forest floor properties in the old-growth forest remain relatively constant.

? Litterfall increased significantly over the past 27 y but litterfall of various litter components showed different temporal trends. Changes in proportions of various litter components, combined with the inherent chemistry differences among them, made litter carbon (C): nitrogen (N) and lignin:N ratios increase at an average rate of 0.19 and 0.16 per year, respectively, suggesting a decreasing trend in the forest floor C and N cycling rates. Changes in dominant tree species biomass significantly affected their corresponding foliar litter production and proportions in the total litterfall and therefore played a dominant role in regulating the developing trends of litter chemistry and quantity in this forest floor.

? Our study indicated that forest floor properties in the old-growth forest still showed a directional change and this was mainly caused by the intrinsic changes rather than yearly climatic fluctuation.

     

Factors influencing biomass and carbon storage potential of different land use systems along an elevational gradient in temperate northwestern Himalaya

We observed the influence of five different altitudes and prevailing agro ecosystems on biomass and carbon sequestration potential in Kullu district of Himachal Pradesh, India. The study area had five prevailing land uses viz., agriculture, agro-horticulture, horticulture, silvi-pasture, and forest at four elevations representing about 1 °C temperature change. The results showed that maximum total biomass of 404.35 Mg C ha^?1 was accumulated by forest landuse and followed a decreasing trend in the order as forest > silvi-pasture > agro-horticulture > horticulture > agriculture. Similar trends were also seen with respect to biomass carbon (C) density and C-sequestration potential of different land uses. Biomass and carbon density potential enhanced with the increase in the altitudinal ranges from 1100–1400 to 2000–2300 m a.s.l. But, the rate of C-sequestration potential enhanced from 1100 to 2000 m and declined at 2000–2300 m a.s.l. Maximum carbon density (393.29 Mg C ha^?1) of both plant as well as soil was displayed by the forest-based land use systems situated at an altitudinal gradient of 2000–2300 m a.s.l. The rate of C-sequestration was maximum (2.17 Mg ha^?1) in the agro-horticulture at 2000–2300 m a.s.l. This study brings out the potential of different land use systems influenced by varying factors on their C-sequestration potential in western Himalayan elevation gradient, thereby providing useful information for effective management in a climate change mitigation and carbon budget.     

Variations in the biomass of Eucalyptus plantations at a regional scale in Southern China

We quantified deviations in regional forest biomass from simple extrapolation of plot data by the biomass expansion factor method(BEF) versus estimates obtained from a local biomass model,based on large-scale empirical field inventory sampling data.The sources and relative contributions of deviations between the two models were analyzed by the boosted regression trees method.Relative to the local model,BEF overestimated accumulative biomass by 22.12%.The predominant sources of the total deviation (70.94%) were stand-structure variables.Stand age and diameter at breast height are the major factors.Compared with biotic variables,abiotic variables had a smaller overall contribution (29.06%),with elevation and soil depth being the most important among the examined abiotic factors.Large deviations in regional forest biomass and carbon stock estimates are likely to be obtained with BEF relative to estimates based on local data.To minimize deviations,stand age and elevation should be included in regional forest-biomass estimation.     

间伐对华北落叶松人工林凋落物和土壤理化性质的影响研究

为了了解间伐对华北落叶松人工林凋落物和土壤理化性质的影响,利用试验测定和定量统计的方法,分析比较了河北省塞罕坝机械林场间伐和未间伐华北落叶松人工林凋落物层和土壤层(0~10cm、10~20cm)的理化性质,结果显示:与未间伐林分相比,50%强度间伐6a后林分内凋落物层生物量、质量含水量、有机质含量和全氮含量分别提高了17.25%、6.05%、9.08%、31.94%;土壤层的质量含水量、土壤容重和有机质含量有所上升(0~10cm土壤层分别增加4.84%、11.11%、15.67%;10~20cm土壤层分别增加10.25%、12.50%、28.97%),而全氮含量呈下降趋势(0~10cm土壤层减少20.83%;10~20cm土壤层减少16.67%);土壤pH值亦有所下降。研究进一步证实,通过间伐能够增加地表凋落物生物量,改变有机质分解速率,从而在一定程度上影响土壤的理化特性。     

Soil animals and nitrogen mineralization under sand-fixation plantations in Zhanggutai region,China

The effects of soil animals on soil nitrogen （N） mineralization and its availability were studied by investigating soil animal groups and their amounts of macro-faunas sorted by hand, and middle and microfaunas distinguished with Tullgren and Baermann methods under three Pinus sylvestris var. mongolica Litv. plantations in Zhanggutai sandy land, China. In addition, soil N mineralization rate was also measured with PVC closed-top tube in situ incubation method. The soil animals collected during growing season belonged to 13 orders, 5 groups, 4 phyla, whose average density was 86 249.17 individuals-m^-2. There were significant differences in soil animal species, densities, diversities and evenness among three plantations. Permanent grazing resulted in decrease of soil animal species and diversity. The average ammonification, nitrification and mineralization rates were 0.48 g：m^-2·a^-1, 3.68 g·m^-2·a^-1 and 4.16 g·m^-2·a^-1, respectively. The ammonification rate in near-mature forest was higher than that in middle-age forests, while the order of nitrification and net mineralization rates was： middle-age forest without grazing 〈 middle-age forest with grazing 〈 near-mature forest with grazing （P〈0.05）. Soil N mineralization rate increased with soil animal amounts, but no significant relationship with diversity. The contribution of soil animals to N mineralization was different for different ecosystems due to influences of complex factors including grazing, soil characteristics, the quality and amount of litter on N mineralization.     

Potassium,calcium, and magnesium dynamics during litter decomposition in a cool temperate forest

The dynamics of K, Ca, and Mg were investigated during the decomposition of 14 litter types over a 3-year period on the upper and lower parts of a forest slope in a cool temperate forest in Japan. Potassium dynamics were divided into initial leaching phase and late phase. Initial K concentrations for the initial phase were correlated with the rate of decrease in K concentration during the initial phase. The late phase was characterized by seasonal fluctuations in concentration: K concentration increased from April to November and decreased during the winter period. The pattern of change in Ca concentration was divided into initial increase phase and late decrease phase in some litter types, or consisted of the late phase only in other litters. Calcium concentration of the initial litter was not predictable for the pattern of change in Ca concentration nor the rate of change in Ca concentration during the initial phase. Initial Ca concentration for the late phase was correlated with the rate of change in Ca concentration during the late phase. The pattern of change in Mg concentration was divided into initial leaching phase and late immobilization phase. Initial Mg concentration for the initial phase was correlated with the rate of change in Mg concentration during the initial phase. At the lower site, initial Mg concentration for the late phase was correlated with the rate of change in Mg concentration during the late phase, while such a relationship was not observed at the upper site. Concentrations of K, Ca, and Mg showed a convergent trend at the end of the study period. The final concentration differed between the upper and lower sites.     

Comparison of minirhizotron and soil core methods for quantifying root biomass in a temperate alley cropping system

A study was carried out in southern Indiana, USA with the objective of comparing soil core sampling and the minirhizotron technique in quantifying fine root biomass and root distribution patterns in an alley cropping system with black walnut (Juglans nigra L.), northern red oak (Quercus rubra L.) and maize (Zea mays L.). Spatial variation in tree rooting pattern was investigated prior to planting maize. Tree fine root biomass was quantified at distances of 0, 1.1, 2.3, 3.5, and 4.3 m where 0 m represents the tree row and 4.3 m represents the middle of the alley. Root samples were collected to a depth of 90 cm using a hydraulic auger. Maize rooting pattern was determined 65 days after planting to the same depth. Using plexiglass access tubes installed near the actual soil core locations and a minirhizotron camera root images were recorded on a VHS tape. These images were later analyzed using a raster based GIS software (ERDAS-IMAGINE). Regression analysis revealed significant relationships between root surface area measurements from minirhizotron observations and fine root biomass data from soil coring for all species. Predicted fine root biomass data were also in close agreement with actual fine root biomass for all species examined. Maize root biomass was slightly, but not significantly, underestimated by the minirhizotron technique in the top 30 cm soil layer. No significant underestimation or overestimation of root biomass in surface or deeper soil layers was observed for the tree species. The results indicate that minirhizotron can be used in quantifying fine root biomass if site and species specific predictive models can be developed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Characteristics of carbon and nitrogen of soil microbial biomass and their relationships with soil nutrients in Cunninghamia lanceolata plantations

The soil microbial biomass and nutrient status under the native broadleaved forest and Cunninghamia lanceolata plantations at the Huitong National Research Station of Forest Ecosystem (in Hunan Province, midland of China) were examined in this study. The results showed that after the native broadleaved forest was replaced by mono-cultured C. lanceolata or C. lanceolata, soil microbial biomass and nutrient pool decreased significantly. In the 0–10 cm soil layer, the concentrations of soil microbial carbon and nitrogen in the broadleaved forest were 800.5 and 84.5 mg/kg, respectively. These were 1.90 and 1.03 times as much as those in the first rotation of the C. lanceolata plantation, and 2.16 and 1.27 times as much as those in the second rotation of the plantation, respectively. While in the 10–20 cm soil layer, the microbial carbon and nitrogen in the broadleaved forest were 475.4 and 63.3 mg/kg, respectively. These were 1.86 and 1.60 times as much as those in the first rotation, and 2.11 and 1.76 times as much as those in the second rotation, respectively. Soil nutrient pools, such as total nitrogen, total potassium, NH₄ ⁺-N, and available potassium, also declined after the C. lanceolata plantation replaced the native broadleaved forest, or Chinese fir was planted continuously. Less litter and slower decay rate in pure Chinese fir plantation were the crucial factors leading to the decrease of soil microbial biomass and nutrient pool in this area. Human disturbance, especially slash-burning and site preparation, was another factor leading to the decrease. There were significant positive correlations between soil microbial carbon and nitrogen and soil nutrients. To improve soil quality and maintain sustainable productivity, some measures, including planting mixed conifer with hardwood, preserving residues after harvest, and adopting scientific site preparation, should be taken. Translated from Chinese Journal of Applied Ecology, 2006, 17(12): 2,292–2,296 [译自: 应用生态学报]