scholarly journals Influência topoedafoclimática na produção primária bruta no semiárido

2020 ◽  
Vol 13 (6) ◽  
pp. 3119
Author(s):  
Aldenice Correia Lacerda ◽  
Josiclêda Domiciano Galvíncio ◽  
Ygor Cristiano Brito Morais ◽  
Rejane Magalhães de Mendonça Pimentel ◽  
Magna Soelma Beserra de Moura
Keyword(s):  
Primary Production ◽  
Gross Primary Production ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Dry Period ◽  
Zero Capacity ◽  
Capacity Data ◽  
Terra Satellite ◽  
The Relationship ◽  
Semi Arid

 O relevo influencia a precipitação, a produção de biomassa e a produção primária bruta (Gross Primary Production-GPP). Em ecossistemas secos qualquer variação GPP tem importância cientifica uma vez que são ecossistemas bastante vulneráveis devido a alta variabilidade espacial e temporal do clima. Além disso, avaliar a relação entre o relevo e GPP em ecossistemas secos se torna mais fácil por existir um período bem definido com zero de precipitação. O estudo objetivou avaliar a influência do relevo, da altitude, da precipitação e do solo na Gross Primary Production-GPP no Bioma Caatinga. Foram utilizados os produtos MOD17 (GPP), sensor MODIS do satélite Terra e dados de precipitação para os anos de 2015 e 2016, com a aplicação de estatísticas descritivas e multivariadas para identificar correlações e similaridades entre áreas e amostras. Ocorreu grande variação espacial e temporal da GPP em áreas de Caatinga, devido ao relevo, clima e solo. A quantificação da GPP nas áreas de maiores altitudes apresentou médias de 46,87 e 55,84 gC m-2 e menores valores de GPP, de 2,49 e 3,75 gC m-2, em 2015 e 2016, respectivamente. Nas áreas planas, as maiores médias foram 46,03 e 55,84 gC m-2 e as menores 3,75 e 2,49 gC m-², em 2015 e 2016, respectivamente. Ocorreu uma diferença de quase 40% para os menores valores de GPP, quando comparados aos relativos às áreas mais altas e mais baixas. Foi possível avaliar a influência do relevo na GPP devido existir um período seco bem definido e de precipitação zero. Os anos de maiores precipitação têm forte influência nos menores valores de GPP das áreas planas. Assim, no período chuvoso é mais difícil identificar a influência de outros fatores, que não sejam a precipitação, na GPP. Esses resultados são de grande importância para mitigar ou avaliar os efeitos das mudanças climáticas sobre os ecossistemas secos.Palavras-Chave: relevo, sensoriamento remoto, produção primária bruta, sensor MODISEdapho-topo-climatic Influence on gross primary production in semi-arid A B S T R A C TRelief influences formation, biomass production and gross primary production (Gross primary production-GPP). In dry ecosystems any GPP variation is of scientific importance since they are very vulnerable ecosystems due to the high spatial and temporal variability of the climate. In addition, assessing the relationship between relief and GPP in dry ecosystems makes it easier to have a well-defined period with zero special. The study aimed to evaluate the influence of relief, altitude, exclusion and soil in the Primary Gross Production-GPP in the Caatinga Biome. The products MOD17 (GPP), MODIS sensor from the Terra satellite and capacity data for the years 2015 and 2016 were used, with the application of descriptive and multivariate statistics to identify correlations and similarities between areas and accounts. There was a great spatial and temporal variation of the GPP in Caatinga areas, due to the relief, climate and soil. Quantification of GPP in areas of higher altitudes showed averages of 46.87 and 55.84 gC m-2 and lower values of GPP, of 2.49 and 3.75 gC m-2, in 2015 and 2016, respectively. In the flat areas, the highest averages were 46.03 and 55.84 gC m-2 and the lowest 3.75 and 2.49 gC m-2, in 2015 and 2016, respectively. There was a difference of almost 40% for the lowest values of the GPP, when compared to those related to the highest and lowest areas. It was possible to evaluate the influence of the relief on the GPP because there is a well-defined dry period with zero capacity. The years of greater capacity have a strong influence on the lower values of GPP in flat areas. Thus, in the rainy season, it is more difficult to identify the influence of factors other than exclusion on GPP. These results are of great importance to mitigate or assess the effects of climate change on dry ecosystems.Keywords: relief, remote sensing, gross primary production, MODIS sensor

scholarly journals Modelling spatial and temporal dynamics of gross primary production in the Sahel from earth-observation-based photosynthetic capacity and quantum efficiency

2017 ◽  
Vol 14 (5) ◽  
pp. 1333-1348 ◽  
Author(s):  
Torbern Tagesson ◽  
Jonas Ardö ◽  
Bernard Cappelaere ◽  
Laurent Kergoat ◽  
Abdulhakim Abdi ◽  
...  
Keyword(s):  
Primary Production ◽  
Quantum Efficiency ◽  
Vegetation Index ◽  
Photosynthetic Capacity ◽  
Gross Primary Production ◽  
Earth Observation ◽  
Arid Ecosystems ◽  
Spatially Explicit ◽  
Equivalent Water Thickness ◽  
Semi Arid

Abstract. It has been shown that vegetation growth in semi-arid regions is important to the global terrestrial CO2 sink, which indicates the strong need for improved understanding and spatially explicit estimates of CO2 uptake (gross primary production; GPP) in semi-arid ecosystems. This study has three aims: (1) to evaluate the MOD17A2H GPP (collection 6) product against GPP based on eddy covariance (EC) for six sites across the Sahel; (2) to characterize relationships between spatial and temporal variability in EC-based photosynthetic capacity (Fopt) and quantum efficiency (α) and vegetation indices based on earth observation (EO) (normalized difference vegetation index (NDVI), renormalized difference vegetation index (RDVI), enhanced vegetation index (EVI) and shortwave infrared water stress index (SIWSI)); and (3) to study the applicability of EO upscaled Fopt and α for GPP modelling purposes. MOD17A2H GPP (collection 6) drastically underestimated GPP, most likely because maximum light use efficiency is set too low for semi-arid ecosystems in the MODIS algorithm. Intra-annual dynamics in Fopt were closely related to SIWSI being sensitive to equivalent water thickness, whereas α was closely related to RDVI being affected by chlorophyll abundance. Spatial and inter-annual dynamics in Fopt and α were closely coupled to NDVI and RDVI, respectively. Modelled GPP based on Fopt and α upscaled using EO-based indices reproduced in situ GPP well for all except a cropped site that was strongly impacted by anthropogenic land use. Upscaled GPP for the Sahel 2001–2014 was 736 ± 39 g C m−2 yr−1. This study indicates the strong applicability of EO as a tool for spatially explicit estimates of GPP, Fopt and α; incorporating EO-based Fopt and α in dynamic global vegetation models could improve estimates of vegetation production and simulations of ecosystem processes and hydro-biochemical cycles.

scholarly journals Estimation of Terrestrial Global Gross Primary Production (GPP) with Satellite Data-Driven Models and Eddy Covariance Flux Data

2018 ◽  
Vol 10 (9) ◽  
pp. 1346 ◽  
Author(s):  
Joanna Joiner ◽  
Yasuko Yoshida ◽  
Yao Zhang ◽  
Gregory Duveiller ◽  
Martin Jung ◽  
...  
Keyword(s):  
Primary Production ◽  
Eddy Covariance ◽  
Satellite Data ◽  
Gross Primary Production ◽  
Satellite Observation ◽  
Data Driven ◽  
Spatial And Temporal Variability ◽  
Light Use Efficiency ◽  
High Productivity ◽  
Use Efficiency

We estimate global terrestrial gross primary production (GPP) based on models that use satellite data within a simplified light-use efficiency framework that does not rely upon other meteorological inputs. Satellite-based geometry-adjusted reflectances are from the MODerate-resolution Imaging Spectroradiometer (MODIS) and provide information about vegetation structure and chlorophyll content at both high temporal (daily to monthly) and spatial (∼1 km) resolution. We use satellite-derived solar-induced fluorescence (SIF) to identify regions of high productivity crops and also evaluate the use of downscaled SIF to estimate GPP. We calibrate a set of our satellite-based models with GPP estimates from a subset of distributed eddy covariance flux towers (FLUXNET 2015). The results of the trained models are evaluated using an independent subset of FLUXNET 2015 GPP data. We show that variations in light-use efficiency (LUE) with incident PAR are important and can be easily incorporated into the models. Unlike many LUE-based models, our satellite-based GPP estimates do not use an explicit parameterization of LUE that reduces its value from the potential maximum under limiting conditions such as temperature and water stress. Even without the parameterized downward regulation, our simplified models are shown to perform as well as or better than state-of-the-art satellite data-driven products that incorporate such parameterizations. A significant fraction of both spatial and temporal variability in GPP across plant functional types can be accounted for using our satellite-based models. Our results provide an annual GPP value of ∼140 Pg C year - 1 for 2007 that is within the range of a compilation of observation-based, model, and hybrid results, but is higher than some previous satellite observation-based estimates.

scholarly journals Relationships between primary production and crop yields in semi-arid and arid irrigated agro-ecosystems

2015 ◽  
Vol XL-7/W3 ◽  
pp. 27-30 ◽  
Author(s):  
H. H. Jaafar ◽  
F. A. Ahmad
Keyword(s):  
Primary Production ◽  
Crop Yield ◽  
Vegetation Index ◽  
Crop Yields ◽  
Gross Primary Production ◽  
Remotely Sensed ◽  
Early Assessment ◽  
Food Shortages ◽  
Semi Arid ◽  
Summer Crop

In semi-arid areas within the MENA region, food security problems are the main problematic imposed. Remote sensing can be a promising too early diagnose food shortages and further prevent the population from famine risks. This study is aimed at examining the possibility of forecasting yield before harvest from remotely sensed MODIS-derived Enhanced Vegetation Index (EVI), Net photosynthesis (net PSN), and Gross Primary Production (GPP) in semi-arid and arid irrigated agro-ecosystems within the conflict affected country of Syria. Relationships between summer yield and remotely sensed indices were derived and analyzed. Simple regression spatially-based models were developed to predict summer crop production. The validation of these models was tested during conflict years. A significant correlation (p<0.05) was found between summer crop yield and EVI, GPP and net PSN. Results indicate the efficiency of remotely sensed-based models in predicting summer yield, mostly for cotton yields and vegetables. Cumulative summer EVI-based model can predict summer crop yield during crisis period, with deviation less than 20% where vegetables are the major yield. This approach prompts to an early assessment of food shortages and lead to a real time management and decision making, especially in periods of crisis such as wars and drought.

scholarly journals Spatio-Temporal Variability of Phytoplankton Primary Production in Baltic Lakes Using Sentinel-3 OLCI Data

2020 ◽  
Vol 12 (15) ◽  
pp. 2415
Author(s):  
Tuuli Soomets ◽  
Kristi Uudeberg ◽  
Kersti Kangro ◽  
Dainis Jakovels ◽  
Agris Brauns ◽  
...  
Keyword(s):  
Primary Production ◽  
Temporal Variability ◽  
Carbon Fixation ◽  
Remote Sensing Data ◽  
Spatial And Temporal Variation ◽  
Spatial And Temporal Variability ◽  
Phytoplankton Primary Production ◽  
Spatio Temporal ◽  
Lake Size

Phytoplankton primary production (PP) in lakes play an important role in the global carbon cycle. However, monitoring the PP in lakes with traditional complicated and costly in situ sampling methods are impossible due to the large number of lakes worldwide (estimated to be 117 million lakes). In this study, bio-optical modelling and remote sensing data (Sentinel-3 Ocean and Land Colour Instrument) was combined to investigate the spatial and temporal variation of PP in four Baltic lakes during 2018. The model used has three input parameters: concentration of chlorophyll-a, the diffuse attenuation coefficient, and incident downwelling irradiance. The largest of our studied lakes, Võrtsjärv (270 km2), had the highest total yearly estimated production (61 Gg C y−1) compared to the smaller lakes Lubans (18 Gg C y−1) and Razna (7 Gg C y−1). However, the most productive was the smallest studied, Lake Burtnieks (40.2 km2); although the total yearly production was 13 Gg C y−1, the daily average areal production was 910 mg C m−2 d−1 in 2018. Even if lake size plays a significant role in the total PP of the lake, the abundance of small and medium-sized lakes would sum up to a significant contribution of carbon fixation. Our method is applicable to larger regions to monitor the spatial and temporal variability of lake PP.

scholarly journals Influência entre relação de radiação fotossinteticamente ativa e radiação global na produtividade primária bruta para Santa Rita do Passa Quatro - SP

2018 ◽  
Vol 40 ◽  
pp. 52
Author(s):  
Celina Cândida Ferreira Rodrigues ◽  
Maria Do Rosário Alves Patriota ◽  
Bernardo Barbosa da Silva ◽  
André Bezerra Oliveira
Keyword(s):  
Data Analysis ◽  
Primary Production ◽  
Linear Equation ◽  
Photosynthetically Active Radiation ◽  
Gross Primary Production ◽  
Global Radiation ◽  
Active Radiation ◽  
The Relationship

This work aims to establish a relationship between the photosynthetically active radiation (PAR) and the global radiation (Rg) for Santa Rita do Passa Quatro (SP), during the period from February 2005 to February 2006 and evaluate its impact on gross primary production (GPP). Data of Rg (Wm-2) and PAR (μmols s-1m-2) were obtained from the mirometeorological tower located in Gleba Cerrado Giant Foot. Data analysis allowed the establishment of a linear equation to express the relationship between PAR (MJ m-2) and Rg (MJ m-2) as: PAR = 0.3787 Rg or PAR = 1.742 Rg, for PAR (μmols s-1m-2) and Rg (MJ m-2). This relationship is indicated for the GPP determination when there is no PAR measurements.

scholarly journals Nitrogen fluxes in Western streams

2017 ◽  
Vol 40 ◽  
pp. 61-68
Author(s):  
Hilary L. Madinger ◽  
Robert O. Hall Jr.
Keyword(s):  
Nitrogen Fixation ◽  
Primary Production ◽  
Aquatic Ecosystems ◽  
Additional Data ◽  
Gross Primary Production ◽  
Dissolved Gas ◽  
Dissolved Nitrogen ◽  
Relationship Types ◽  
Stream Nitrate ◽  
The Relationship

Nitrogen pollution to streams is altering the nitrogen cycling in unknown ways, causing challenges for predicting nitrogen fixation fluxes within aquatic ecosystems. Increasing nitrate pollution decreases the amount of nitrogen fixation occurring in streams. However, the relationship between stream nitrate concentration and the rate of nitrogen fixation is unknown. We predict that lower nitrate streams will have the highest rates of nitrogen fixation. Additionally, there will be much more energy produced in streams with nitrogen fixation compared to the amount required to fix the nitrogen. We estimated whole-stream gross primary production and nitrogen fixation fluxes using the diel change in dissolved nitrogen and oxygen gases compared to the expected dissolved gas saturation. Our whole-stream method is preferable to chamber estimates to understand the relationship between energy requirements for nitrogen fixation and gross primary production, but additional data is needed to distinguish between relationship types and make our measurements generalizable.   Featured photo by Intermountain Forest Service, USDA Region 4 Photography on Flickr. https://flic.kr/p/jbTRUj

scholarly journals The Links between Canopy Solar-Induced Chlorophyll Fluorescence and Gross Primary Production Responses to Meteorological Factors in the Growing Season in Deciduous Broadleaf Forest

2021 ◽  
Vol 13 (12) ◽  
pp. 2363
Author(s):  
Xiangfen Cheng ◽  
Yu Zhou ◽  
Meijun Hu ◽  
Feng Wang ◽  
Hui Huang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Chlorophyll Fluorescence ◽  
Primary Production ◽  
Forest Canopy ◽  
Meteorological Factors ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Growing Season ◽  
Near Surface ◽  
The Relationship

Solar-induced chlorophyll fluorescence (SIF) is a hopeful indicator, which along with remote sensing, is used to measure the photosynthetic efficiency and gross primary production (GPP) of vegetation in regional terrestrial ecosystems. Studies have found a significant linear correlation between SIF and GPP in a variety of ecosystems. However, this relationship has mainly been established using SIF and GPP data derived from satellite remote sensing and continuous ground-based observations, respectively, which are difficult to accurately match. To overcome this, some studies have begun to use tower-based automatic observation instruments to study the changes of near-surface SIF and GPP. This study conducts continuous simultaneous observation of SIF, carbon flux, and meteorological factors on the forest canopy of a cork oak plantation during the growing season to explore how meteorological factors impact on canopy SIF and its relationship with GPP. This research found that the canopy SIF has obvious diurnal and day-to-day variations during the growing season but overall is relatively stable. Furthermore, SIF is greatly affected by incident radiation in different weather conditions and can change daily. Meteorological factors have a major role in the relationship between SIF and GPP; overall, the relationship shows a significant linear regression on the 30 min scale, but weakens when aggregating to the diurnal scale. Photosynthetically active radiation (PAR) drives SIF on a daily basis and changes the relationship between SIF and GPP on a seasonal timescale. As PAR increases, the daily slopes of the linear regressions between SIF and GPP decrease. On the 30 min timescale, both SIF and GPP increase with PAR until it reaches 1250 μmol·m−2·s−1; subsequently, SIF continues to increase while GPP decreases and they show opposite trends. Soil moisture and vapor pressure deficit influence SIF and GPP, respectively. Our findings demonstrate that meteorological factors affect the relationship between SIF and GPP, thereby enhancing the understanding of the mechanistic link between chlorophyll fluorescence and photosynthesis.

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