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1.
Using China's ground observations, e.g., forest inventory, grassland resource, agricultural statistics, climate, and satellite data, we estimate terrestrial vegetation carbon sinks for China's major biomes between 1981 and 2000. The main results are in the following: (1) Forest area and forest biomass carbon (C) stock increased from 116.5×106 ha and 4.3 Pg C (1 Pg C = 1015 g C) in the early 1980s to 142.8×106 ha and 5.9 Pg C in the early 2000s, respectively. Forest biomass carbon density increased form 36.9 Mg C/ha (1 Mg C = 106 g C) to 41.0 Mg C/ha, with an annual carbon sequestration rate of 0.075 Pg C/a. Grassland, shrub, and crop biomass sequestrate carbon at annual rates of 0.007 Pg C/a, 0.014―0.024 Pg C/a, and 0.0125―0.0143 Pg C/a, respectively. (2) The total terrestrial vegetation C sink in China is in a range of 0.096―0.106 Pg C/a between 1981 and 2000, accounting for 14.6%―16.1% of carbon dioxide (CO2) emitted by China's industry in the same period. In addition, soil carbon sink is estimated at 0.04―0.07 Pg C/a. Accordingly, carbon sequestration by China's terrestrial ecosystems (vegetation and soil) offsets 20.8%―26.8% of its industrial CO2 emission for the study period. (3) Considerable uncertainties exist in the present study, especially in the estimation of soil carbon sinks, and need further intensive investigation in the future. 相似文献
2.
尽管凝结水在干旱生态系统中所发挥的重要作用已被广泛关注,但对其在固沙灌丛下时空变化特征的研究仍然比较薄弱。为探明固沙灌丛对地表凝结水的影响,在毛乌素沙地南缘沙区选择3种典型固沙灌丛（沙柳Salix psammophila、柠条Caragana korshinskii和油蒿Artemisia ordosica）,以无固沙灌丛影响的裸沙作为对照,用微型蒸渗仪测定了固沙灌丛下不同位置（根部、1/2冠幅和外缘）和不同方向（东、南、西、北）上地表凝结水的形成和蒸发特征。结果表明：（1）与对照相比,固沙灌丛的存在显著降低了地表凝结水量,沙柳、油蒿和柠条灌丛下凝结水量分别降低了29%、32%和33%;(2)不同类型固沙灌丛下地表凝结水量由里向外均呈显著增加的趋势,但不同方向上地表凝结水量差异不显著;（3）固沙灌丛的存在减缓了凝结水的形成和蒸发过程,即凝结水自19:00开始形成,到次日08:00基本结束,至13:00—15:00蒸发殆尽,其形成过程整体上表现出增加—平缓—增加的趋势,柠条和油蒿灌丛下地表凝结水在03:00—05:00甚至有少量蒸发,而蒸发过程呈稳定下降趋势;（4）凝结水的形成过程与空气... 相似文献
3.
The effects of elevated atmospheric CO2 concentrations on plant polyphenolic, tannin, nitrogen, phosphorus and total nonstructural carbohydrate concentrations were investigated in leaves of subtropical grass and fynbos shrub species. The hypothesis tested was that carbon-based secondary compounds would increase when carbon gain is in excess of growth requirements. This premise was tested in two ecosystems involving plants with different photosynthetic mechanisms and growth strategies. The first ecosystem comprised grasses from a C4-dominated, subtropical grassland, where three plots were subjected to three different free air CO2 enrichment treatments, i.e., elevated (600 to 800 μmol mol−1), intermediate (400 μmol mol−1) and ambient atmospheric CO2. One of the seven grass species, Alloteropsis semialata, had a C3 photosynthetic pathway while the other grasses were all C4. The second ecosystem was simulated in a microcosm experiment where three fynbos species were grown in open-top chambers at ambient and 700 μmol mol−1 atmospheric CO2 in low nutrient acid sands typical of south western coastal and mountain fynbos ecosystems. Results showed that polyphenolics and tannins did not increase in the grass species under elevated CO2 and only in Leucadendron laureolum among the fynbos species. Similarly, foliar nitrogen content of grasses was largely unaffected by elevated CO2, and among the fynbos species, only L. laureolum and Leucadendron xanthoconus showed changes in foliar nitrogen content under elevated CO2, but these were of different magnitude. The overall decrease in nitrogen and phosphorus and consequent increase in C:N and C:P ratio in both ecosystems, along with the increase in polyphenolics and tannins in L. laureolum in the fynbos ecosystem, may negatively affect forage quality and decomposition rates. It is concluded that fast growing grasses do not experience sink limitation and invest extra carbon into growth rather than polyphenolics and tannins and show small species-specific chemical changes at elevated atmospheric CO2 concentrations. Responses of fynbos species are varied and were species-specific. 相似文献
4.
灌木生物量模型是预测灌木生物量最有效的方法。选择腾格里沙漠南缘荒漠生态系统中常见的4种灌木（驼绒藜(Ceratoides latens)、盐爪爪(Kalidium foliatum)、珍珠猪毛菜(Salsola passerina)、红砂(Reaumuria soongarica)）为研究对象,以株高（H）和冠幅（C）的复合因子灌木体积（V）为自变量,通过回归分析,分别构建了4种灌木和混合物种的叶、新生枝、老龄枝、地上部分、地下部分和整株生物量的预测模型。通过决定系数（R2）、估计值的标准误（SEE）和回归检验显著水平（p＜0.05）筛选出了最优的生物量估测模型。结果显示:4种灌木的生物量模型主要以幂函数W=aVb为最优模型,少数以三次函数W=a+bV+cV2+dV3为最优模型。灌木生物量与V之间呈极显著的相关关系（p＜0.001）,决定系数较高,分别为:叶片（0.775＜R2＜0.866）,新生枝（0.694＜R2＜0.840）,老龄枝（0.819＜R2＜0.916）,地上部（0.832＜R2＜0.917）,地下部分（0.74＜R2＜0.808）,全株（0.811＜R2＜0.912）,说明预测模型可以应用于此4种灌木的生物量估算。不同物种之间及不同器官之间的生物量模型存在差异,在实际使用中,要根据物种来选择相应的模型。生物量模型的建立有助于全面估算荒漠生态系统的生物量,并进一步评估生态系统不同碳库的碳存储量与碳循环。为有效提高荒漠草地碳储量、合理实施生态系统管理和人为干预提供科学依据。 相似文献
5.
Spatial patterns and environmental factors influencing leaf carbon content in the forests and shrublands of China 总被引：1，自引：0，他引：1
Hang Zhao Li Xu Qiufeng Wang Jing Tian Xuli Tang Zhiyao Tang Zongqiang Xie Nianpeng He Guirui Yu 《地理学报(英文版)》2018,28(6):791-801
Leaf carbon content (LCC) is widely used as an important parameter in estimating ecosystem carbon (C) storage, as well as for investigating the adaptation strategies of vegetation to their environment at a large scale. In this study, we used a dataset collected from forests (5119 plots) and shrublands (2564 plots) in China, 2011–2015. The plots were sampled following a consistent protocol, and we used the data to explore the spatial patterns of LCC at three scales: plot scale, eco-region scale (n = 24), and eco-region scale (n = 8). The average LCC of forests and shrublands combined was 45.3%, with the LCC of forests (45.5%) being slightly higher than that of shrublands (44.9%). Forest LCC ranged from 40.2% to 51.2% throughout the 24 eco-regions, while that of shrublands ranged from 35% to 50.1%. Forest LCC decreased with increasing latitude and longitude, whereas shrubland LCC decreased with increasing latitude, but increased with increasing longitude. The LCC increased, to some extent, with increasing temperature and precipitation. These results demonstrate the spatial patterns of LCC in the forests and shrublands at different scales based on field-measured data, providing a reference (or standard) for estimating carbon storage in vegetation at a regional scale. 相似文献
6.
为探究科尔沁沙地3种优势固沙灌木生物量的分配特征，以黄柳（Salix gordejevii）、差不嘎蒿（Artemisia halodendron）和小叶锦鸡儿（Caragana microphylla）为对象，采用全挖法在个体水平上研究了固沙灌木生物量构件及其占比、R/S
7.
Olivier R. van Lier Richard A. Fournier Robert L. Bradley Nelson Thiffault 《International Journal of Applied Earth Observation and Geoinformation》2009,11(5):334-343
Invasive ericaceous shrubs (e.g. Kalmia angustifolia, Rhododendron groenlandicum, Vaccinium spp.) may reduce the regeneration and early growth of black spruce (Picea mariana) seedlings, the most economically important boreal tree species in Quebec. Our study focused, therefore, on developing a method for mapping ericaceous shrubs from satellite images. The method integrates very high resolution satellite imagery (IKONOS) to guide classifiers applied to medium resolution satellite imagery (Landsat-TM). An object-oriented image classification approach was applied using Definiens eCognition software. An independent ground survey revealed 80% accuracy at the very high spatial resolution. We found that the partial use (70%) of classified polygons derived from the IKONOS images were an effective way to guide classification algorithms applied to the Landsat-TM imagery. The results of this latter classification (78.4% overall accuracy) were assessed by the remaining portion (30%) of unused very high resolution classified polygons. We further validated our method (65.5% overall accuracy) by assessing the correspondence of an ericaceous cover classification scheme done with a Landsat-TM image and results of our ground survey using an independent set of 275 sample plots. Discrimination of ericaceous shrub cover from other land cover types was achieved with precision at both spatial resolutions with producer accuracies of 87.7% and 79.4% from IKONOS and Landsat, respectively. The method is weaker for areas with sparse cover of ericaceous shrubs or dense tree cover. Our method is adapted, therefore, for mapping the spatial distribution of ericaceous shrubs and is compatible with existing forest stand maps. 相似文献
8.
In desert shrubland ecosystems water and nutrients are concentrated beneath shrub canopies in ‘resource islands’. Rain falling on to these islands reaches the ground as either stemflow or throughfall and then either infiltrates into the soil or runs off as overland flow. This study investigates the partitioning of rainwater between stemflow and throughfall in the first instance and between infiltration and runoff in the second. Two series of 40 rainfall simulation experiments were performed on 16 creosotebush shrubs in the Jornada Basin, New Mexico. The first series of experiments was designed to measure the surface runoff and was performed with each shrub in its growth position. The second series was designed to measure stemflow reaching the shrub base and was conducted with the shrub suspended above the ground. The experimental data show that once equilibrium is achieved, 16% of the rainfall intercepted by the canopy or 6·7% of the rain falling inside the shrub area (i.e. the area inside the shrub's circumscribing ellipse) is funnelled to the shrub base as stemflow. This redistribution of the rainfall by stemflow is a function of the ratio of canopy area (i.e. the area covered by the shrub canopy) to collar area (i.e. a circular area centred on the shrub base), with stemflow rate being positively correlated and throughfall rate being negatively correlated with this ratio. The surface runoff rate expressed as a proportion of the rate at which rainwater arrives at a point (i.e. stemflow rate plus throughfall rate) is the runoff coefficient. A multiple regression reveals that 75% of the variance in the runoff coefficient can be explained by three independent variables: the rainfall rate, the ratio of the canopy area to the collar area, and the presence or absence of subcanopy vegetation. Although the last variable is a dummy variable, it accounts for 66·4% of the variance in the runoff coefficient. This suggests that the density and extent of the subcanopy vegetation is the single most important control of the partitioning of rainwater between runoff and infiltration beneath creosotebush. Although these findings pertain to creosotebush, similar findings might be expected for other desert shrubs that generate significant stemflow and have subcanopy vegetation. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
9.
Using China's ground observations, e.g., forest inventory, grassland resource, agricultural statistics, climate, and satellite data, we estimate terrestrial vegetation carbon sinks for China's major biomes between 1981 and 2000. The main results are in the following: (1) Forest area and forest biomass car- bon (C) stock increased from 116.5×106 ha and 4.3 Pg C (1 Pg C = 1015 g C) in the early 1980s to 142.8×106 ha and 5.9 Pg C in the early 2000s, respectively. Forest biomass carbon density increased form 36.9 Mg C/ha (1 Mg C = 106 g C) to 41.0 Mg C/ha, with an annual carbon sequestration rate of 0.075 Pg C/a. Grassland, shrub, and crop biomass sequestrate carbon at annual rates of 0.007 Pg C/a, 0.014― 0.024 Pg C/a, and 0.0125―0.0143 Pg C/a, respectively. (2) The total terrestrial vegetation C sink in China is in a range of 0.096―0.106 Pg C/a between 1981 and 2000, accounting for 14.6%―16.1% of carbon dioxide (CO2) emitted by China's industry in the same period. In addition, soil carbon sink is estimated at 0.04―0.07 Pg C/a. Accordingly, carbon sequestration by China's terrestrial ecosystems (vegetation and soil) offsets 20.8%―26.8% of its industrial CO2 emission for the study period. (3) Considerable uncertainties exist in the present study, especially in the estimation of soil carbon sinks, and need further intensive investigation in the future. 相似文献
10.
低覆盖度沙蒿群丛的水平配置结构与防风固沙效果研究 总被引：25，自引：9，他引：16
针对覆盖度小于28%的沙蒿群丛,通过野外测试和风洞模拟实验,研究了行带式、等株行距和随机不均匀等3种水平配置格局的防风固沙效果及其流场特征。结果表明：①行带式配置格局具有非常显著的阻碍和降低风速的作用,流场结构稳定规则;等株行距次之;随机不均匀配置格局内局部有风速抬升现象流场结构复杂多变。②行带式配置格局带间形成“凹月”形稳定沙面并能出现结皮,流沙被完全固定,而随机不均匀分布的沙蒿群丛内有明显的风蚀现象。③行带式配置格局在带的背风侧和迎风侧分别形成4.0 m和0.5 m的一个风速显著降低区,成为提高防风固沙效果的核心。 相似文献