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Search Results: 1 - 10 of 8731 matches for " Aboveground Production "
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Influence of early dry season fires on primary production in western Serengeti grasslands, Tanzania  [PDF]
Shombe Ntaraluka Hassan
Open Journal of Ecology (OJE) , 2011, DOI: 10.4236/oje.2011.12003
Abstract: Short-term, i.e. 4-9 weeks aboveground net primary production (ANPP) temporal patterns during the first post-fire year in western Seren-geti National Park, and potential differences in the factors limiting ANPP between burnt and non burnt grasslands were examined and es-tablished. Fire stimulated growth at early post-fire stages, even during the dry season, July-October and led to larger increments in green phytomass compared to the non burnt grassland at the onset of short rains, Octo-ber-December. Further, ANPP in burnt plots correlated well with the ratio leaf/total standing phytomass suggesting that the accumulation of standing dead material can be a limiting factor to ANPP in burnt grass-lands. However, ANPP in burnt plots was unrelated to rainfall contrary to earlier arguments, but reached peak earlier and declined early in the rain season, perhaps due to the interactive effects of fire and grazing in the area. In non burnt plots, the temporal change in ANPP was more related to rainfall availability, at least until mid-growing season. Also, the phytomass structure differed between burnt and non burnt grasslands, and together with litter did not recover to non burnt levels within the first post-fire year. The study has demonstrated that the desire of the fire man-agement program in Serengeti National Park, which is to supply green forage to both migra-tory and resident populations during dry season is being fulfilled.
Estimation of Tree Biomass, Carbon Stocks, and Error Propagation in Mecrusse Woodlands  [PDF]
Tarquinio Mateus Magalh?es, Thomas Seifert
Open Journal of Forestry (OJF) , 2015, DOI: 10.4236/ojf.2015.54041
Abstract: We performed a biomass inventory using two-phase sampling to estimate biomass and carbon stocks for mecrusse woodlands and to quantify errors in the estimates. The first sampling phase involved measurement of auxiliary variables of living Androstachys johnsonii trees; in the second phase, we performed destructive biomass measurements on a randomly selected subset of trees from the first phase. The second-phase data were used to fit regression models to estimate below and aboveground biomass. These models were then applied to the first-phase data to estimate biomass stock. The estimated forest biomass and carbon stocks were 167.05 and 82.73 Mg·ha-1, respectively. The percent error resulting from plot selection and allometric equations for whole tree biomass stock was 4.55% and 1.53%, respectively, yielding a total error of 4.80%. Among individual variables in the first sampling phase, diameter at breast height (DBH) measurement was the largest source of error, and tree-height estimates contributed substantially to the error. Almost none of the error was attributable to plot variability. For the second sampling phase, DBH measurements were the largest source of error, followed by height measurements and stem-wood density estimates. Of the total error (as total variance) of the sampling process, 90% was attributed to plot selection and 10% to the allometric biomass model. The total error of our measurements was very low, which indicated that the two-phase sampling approach and sample size were effective for capturing and predicting biomass of this forest type.
Cálculo de la receptividad ganadera a escala de potrero en pastizales de la Pampa Deprimida
Vecchio,María Cristina; Golluscio,Rodolfo A; Cordero,Miriam I;
Ecolog?-a austral , 2008,
Abstract: we estimated the carrying capacity (cc) of a farm by combining satellite images, aimed at measuring the area of each plant community, with biomass measurements to estimate aboveground net primary production (anpp) and the proportion of anpp that can be consumed by animals (harvest index; hi). we estimated cc of each paddock as the mean cc of the different plant communities, weighed by the area occupied by each community within the paddock. carrying capacity of each community was obtained as the ratio between the product of anpp x hi and the individual annual intake. we estimated the anpp of the most conspicuous plant communities (b and i) within an area that had been fenced to exclude domestic herbivores two years before the beginning of this study. we estimated hi as the ratio between consumption and anpp, estimating animal intake from the biomass loss between entry and exit of animals from grazed paddocks. community b showed a higher anpp and hi than community i (4584 vs. 2969 kg dm.ha-1.yr-1 and 75% vs. 61%, respectively). the carrying capacity of each paddock ranged between 0.6 and 0.8 animal units.ha-1.yr-1, was associated to the proportion of the area occupied by community b, and was higher than the cc estimated from empirical models. our results suggest that both quality and reliability of cc estimates depend on quality and reliability of available anpp and hi data.
Eficiência de convers?o da radia??o fotossinteticamente ativa incidente em biomassa aérea da vegeta??o campestre natural no bioma Campos Sulinos do Brasil
Fonseca, Eliana Lima da;Silveira, Vicente Celestino Pires;Salomoni, Eduardo;
Ciência Rural , 2006, DOI: 10.1590/S0103-84782006000200047
Abstract: the conversion efficiency of the photosinthetically active radiation in the above ground biomass in the natural pasture of the 'campos sulinos' bioma was calculated in this work; the period considered was the main pasture growth season. the area of study was located at embrapa pecuária sul, in bagé (rs) and the pasture was under continuous grazing. the results indicated variations in the values of this efficiency according to the phenological stage of the grazed pasture, which demonstrates that it is not possible to use the same estimate value for biomass accumulation during periods smaller than a year.
Responses of temporal dynamics of aboveground net primary productivity of Leymus chinensis community to precipitation fluctuation in Inner Mongolia
内蒙古羊草草原植物群落地上初级生产力时间动态对降水变化的响应

WANG Yuhui,ZHOU Guangsheng,
王玉辉
,周广胜

生态学报 , 2004,
Abstract: This paper describes the relationship between aboveground net primary productivity (ANPP) and precipitation in Leymus chinensis community based on the observations made in Inner Mongolia grassland from 1981 to 1994. Our results showed significant differences in annual and seasonal precipitation patterns. Most of the annual precipitation was distributed between June and August with the highest in July. A quadratic relationship was discovered between the ANPP and the accumulative precipitation from the October in previous year to the August of current year; however, no significant correlation between the ANPP and annual or monthly precipitation was detected. The identification of the period of accumulative precipitation appeared to be important in developing a NPP model for the Leymus chinensis community.
Effects of Climate Change on Vegetation in Desert Steppe Inner Mongolia  [PDF]
Shan Dan, Hejing Li, Liuyan Ping, Xing’en De
Natural Resources (NR) , 2013, DOI: 10.4236/nr.2013.44038
Abstract:

As the largest ecosystem in China, Grassland not only provides abundant natural resources for the regional economic development, but also safeguards the environment of north China as it acts as an ecological protective screen. However, because of the arid and semi-arid regions, most grassland are limited by climate seriously, changes in precipitation and temperature can affect the community composition and primary productivity within and through grassland ecosystems. Based on the long period climate data and observational data of vegetation in DAMAOQI grassland Inner Mongolia, the study analyzed the climate change and its effect on community properties by using the linear trend method, etc. The results showed that climate change presented increasing temperature and fluctuant precipitation in the last decades. More precipitation could increase species diversity, and precipitation was better than the temperature for diversity exponents. According to these results, the strategy of soil and water conservation ecological rehabilitation would be provided to respond to the climate change. Increase the vegetation coverage and alleviate soil erosion relying on the self-restoration capability of natural ecosystems under ecological theories, erect a development system on the balance among the water, the forage and the animal. Transform those traditional extensive methods and enhance family farms vigorously by local conditions, the most important of which is water resource. The strategy of ecological rehabilitation advocates in the soil and water conservation and the ecological construction can be adjusted to the aim that establishes a conservation-minded society and a friendly environment society.

Tree Biomass Estimation in Central African Forests Using Allometric Models  [PDF]
Romeo Ekoungoulou, Donatien Nzala, Xiaodong Liu, Shukui Niu
Open Journal of Ecology (OJE) , 2018, DOI: 10.4236/oje.2018.83014
Abstract: Quantifying the tropical forests’ carbon stocks is presently an important component in the implementation of the emerging carbon credit market mechanisms. This calls for appropriate allometric equations predicting biomass which currently are scarce. In this study, we aimed to estimate above- and below-ground biomass and carbon stocks of trees, and to identify the variation in diameter-height allometry of Ipendja mixed terra firme lowland tropical forest’s trees. The study area is located at Ipendja forest management unit (UFA), close to Dongou district (Likouala Department), in Northern Republic of Congo. This study combined forest inventory data of 1340 trees recorded from eight studied plots distributed in two sites, respectively Mokelimwaekili (i.e., Old-growth forest) and Sombo (i.e., Selective logging forest). Trees measurements were done with rectangular plots, each 25 × 200 m (i.e., 0.5 ha, 5000 m2). In eight studied plots (4 plots per site), only trees with DBH 10 cm were measured and identified. 1340 trees founded were belonged 145 species and 36 botanical families (n = 733 and
Comparison and Prediction of the above Ground Carbon Storage in Croplands on the Inhabited Slopes on Mount Kilimanjaro (Tanzania) and the Taita Hills (Kenya)  [PDF]
Odeny Dickens, Karanja Faith, Mwachala Geoffrey, Pellikka Petri, Marchant Rob
Journal of Geographic Information System (JGIS) , 2018, DOI: 10.4236/jgis.2018.104022
Abstract: Mount Kilimanjaro and the Taita Hills are adjacent montane areas that experience similar climate and agricultural activity, but which differ in their geologic history, nature of elevation gradients and cultures. We assessed differences in cropland above ground carbon (AGC) between the two sites and against environmental variables. One hectare sampling plots were randomly distributed along elevational gradients stratified by cropland type; AGC was derived from all trees with diameter ≥ 10 cm at breast height in each plot. Predictor variables were physical and edaphic variables and human population. A generalized linear model was used for predicting AGC with AIC used for ranking models. AGC was spatially upscaled in 2 km buffer and visually compared. Kilimanjaro has higher AGC in cropped and agroforestry areas than the Taita Hills, but only significant difference in AGC variation in agroforestry areas (F = 9.36, p = 0.03). AGC in cropped land and agroforestry in Kilimanjaro has significant difference on mean (t = 4.62, p = 0.001) and variation (F = 17.41, p = 0.007). In the Taita Hills, significant difference is observed only on the mean AGC (t = 4.86, p = 0.001). Common tree species that contribute the most to AGC in Kilimanjaro are Albizia gummifera and Persea americana, and in the Taita Hills Grevillea robusta and Mangifera indica. Significant and univariate predictors of AGC in Mount Kilimanjaro are pH (R2 = 0.80, p = 0.00) and EVI (R2 = 0.68, p = 0.00). On Mount Kilimanjaro, the top multivariate model contained SOC, CEC, pH and BLD (R2 = 0.90, p = 0.00), whereas in the Taita Hills, the top multivariate model contained elevation, slope and population (R2 = 0.89, p = 0.00). Despite of the difference in land management history of Mount Kilimanjaro and the Taita Hills, mean of AGC in croplands does not differ significantly. Difference occurs on variation of AGC, type of trees contributing AGC, and environmental variables that explain AGC distribution. The research results provide reference for management of carbon sequestration on inhabited montane areas.
Impacts of grazing and climate change on the aboveground net primary productivity of mountainous grassland ecosystems along altitudinal gradients over the Northern Tianshan Mountains, China
天山北坡不同海拔梯度山地草原生态系统地上净初级生产力对气候变化及放牧的响应

ZHOU Decheng,LUO Geping,HAN Qifei,YIN Changying,LI Longhui,HU Yukun,
周德成
,罗格平,韩其飞,尹昌应,李龙辉,胡玉昆

生态学报 , 2012,
Abstract: Grazing and climate change are the two key factors influencing the aboveground net primary productivity (ANPP) in the grassland ecosystems. However, the impacts of grazing on ANPP are still in considerable disagreement, and little is known about its combined effects with climate change in the arid mountainous grassland ecosystems. In this study, we simulated the ANPP dynamics of mountainous grassland ecosystems along altitudinal gradients (i.e. LAG: lower-mountain arid grassland, FMG: forest meadow grassland, and AMG: alpine meadow grassland) over the Northern Tianshan Mountains under the impacts of climate change only (Clm) and by the combined effects with grazing (ClmGra) during 1959-2009 using a modified Biome-BGC model, and modeled the responses of the ANPP to grazing intensities (GIs) by setting 27 different levels of GIs (ranging from 0 to 8 sheep/hm2) as well. Model results indicated that the ANPP increased generally with the warm-humid climate change only in all the three grassland ecosystems, whereas the impacts of grazing on ANPP varied with grassland type. Grazing decreased ANPP in FMG and AMG by 30.0% and 33.2% respectively, in contrast, it resulted in a 1.3% increase of ANPP in LAG because the lower GIs before 1980 generally promoted the ANPP over LAG. Moreover, the responses of ANPP to the increasing GIs varied with grassland type, and the ANPP in LAG decreased significantly after a moderate increase and this changing trend is especially significant during drought years. Nevertheless, the ANPP always decreased non-linearly with increasing GIs in both FMG and AMG. These results suggested that the climate change in the past 50 years may benefit the productivity of the mountainous grassland ecosystem in the arid region of central Asia, but the increasing GIs decreased the productivity substantially. The ANPP of FMG and AMG decreased non-linearly with elevating GIs, but the ANPP may increase under the impact of lower GIs in LAG, especially in drought years. Nevertheless, there are uncertainties in our simulations and the responses of the productivity to increasing GIs together with the underlying mechanisms in arid mountainous grassland ecosystems, more field experiments are needed to validate these preliminary results.
黄土丘陵区白羊草与达乌里胡枝子混播草地生产力与土壤水分利用研究
Study on Biomass Production and Soil Water Use of Bothriochloa isaemum and Lespedeza davurica Mixture Grassland in Loess Hilly-gully Region

,,高志娟,舒佳礼,吴爱姣,徐炳成
- , 2016, DOI: 10.7606/j.issn.1004-1389.2016.02.003
Abstract: 为合理利用黄土丘陵区优良乡土草种,并寻求利用其进行人工草地建设的最佳混播比例组合,选取白羊草(Bothriochloa isaemum)和达乌里胡枝子(Lespedeza davurica)为研究材料,采用生态替代法,按照二者行比设置7种混播比例组合(即0∶10,2∶8,4∶6,5∶5,6∶4,8∶2和10∶0),比较研究混播比例对草地植株株高、地上生物量和水分利用效率等的影响。结果表明:混播草地中白羊草与达乌里胡枝子的株高均明显高于各自单播草地;混播草地的地上生物量和水分利用效率均显著高于二者各自单播草地;草地地上生物量和水分利用效率以白羊草和达乌里胡枝子混播比例为6∶4的显著最高,单播达乌里胡枝子草地(即0∶10比例组合)显著最低。表明,白羊草与达乌里胡枝子存在混播互补效应,其中比例组合为6∶4的草地在生物量和水分利用效率方面具有比较优势。
The purpose of the study is to rationally use and seek ideal mixture ratio of native species in loess hilly-gully region so as to establish artificial grassland.One field experiment was conducted by using a replacement series design in which Bothriochloa ischaemum and Lespedeza davurica were sowed as row ratios of 0∶10, 2∶8, 4∶6, 5∶5, 6∶4,8∶2 and 10∶0 in the same plot.The plant height, aboveground biomass production, water use efficiency of grassland under each mixture ratio were investigated and compared.The results indicated that plant heights of the two species in mixtures were significantly higher than those in their respective monoculture.The aboveground biomass production and water use efficiency of the two-species mixture grassland were higher than their respective monoculture.The aboveground biomass production and water use efficiency were significantly higher at B.ischaemum∶ L.davurica ratio 6∶4, and the minimum was in L.davurica in monoculture (i.e.0∶10 ratio).All these suggest that the existed complementary effect between B.ischaemum and L.davurica in mixture grassland, and the B.ischaemum∶ L.davurica ratio of 6∶4 had comparative advantage in aboveground biomass production and water use efficiency.
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