scholarly journals Spatiotemporal Dynamics of the Carbon Budget and the Response to Grazing in Qinghai Grasslands

2022 ◽  
Vol 12 ◽  
Author(s):  
Xiaotao Huang ◽  
Chunbo Chen ◽  
Buqing Yao ◽  
Zhen Ma ◽  
Huakun Zhou
Keyword(s):  
Spatial Heterogeneity ◽  
Primary Productivity ◽  
Regional Differences ◽  
Carbon Budget ◽  
Carbon Sources ◽  
Net Ecosystem Exchange ◽  
Grassland Management ◽  
Spatiotemporal Dynamics ◽  
Northwestern Part ◽  
Average Value

Estimating the grassland carbon budget is critically important for ensuring that grassland resources are used sustainably. However, the spatiotemporal dynamics of the carbon budget and the response to grazing have not yet been characterized in Qinghai grasslands. Here, we estimated the gross primary productivity (GPP) and net ecosystem exchange (NEE) in Qinghai grasslands using the improved Biome-BGCMuSo model to characterize the spatiotemporal dynamics of the carbon budget and the response to grazing in this region from 1979 to 2018. The GPP of Qinghai grasslands fluctuated during the study period, with an average annual value of 118.78 gC/m2. The NEE of Qinghai grasslands fluctuated from 1979 to 2018, with an average value of −5.16 gC/m2. After 2,000, GPP increased, and NEE decreased in a fluctuating manner. There were clear regional differences in GPP and NEE. GPP was low in most areas of Qinghai, and GPP was high in eastern and southern Qinghai. The southern, southeastern, and northeastern parts of Qinghai were mainly carbon sinks, and the northwestern part of Qinghai and the region between the southeastern and northeastern parts of Qinghai were mainly carbon sources. Grazing generally decreased GPP and increased NEE in Qinghai grasslands from 1979 to 2018. There was spatial heterogeneity in the effect of grazing on GPP and NEE. Under grazing, GPP and NEE were significantly decreased mainly in eastern Qinghai, and GPP and NEE were significantly increased mainly in southern and eastern Qinghai. NEE was most affected by grazing in eastern Qinghai. The results of this study aid our understanding of the mechanism driving variation in the grassland carbon budget and provide new data that could be used to support local grassland management.

Variability of ecosystem carbon source from microbial respiration is controlled by rainfall dynamics

2021 ◽  
Vol 118 (52) ◽  
pp. e2115283118
Author(s):  
Heng Huang ◽  
Salvatore Calabrese ◽  
Ignacio Rodriguez-Iturbe
Keyword(s):  
Primary Productivity ◽  
Microbial Growth ◽  
Net Primary Productivity ◽  
Carbon Sources ◽  
Terrestrial Ecosystems ◽  
Rainfall Regime ◽  
Physical Factors ◽  
Scale Parameters ◽  
Complex Interactions ◽  
Soil Heterotrophic Respiration

Soil heterotrophic respiration (Rh) represents an important component of the terrestrial carbon cycle that affects whether ecosystems function as carbon sources or sinks. Due to the complex interactions between biological and physical factors controlling microbial growth, Rh is uncertain and difficult to predict, limiting our ability to anticipate future climate trajectories. Here we analyze the global FLUXNET 2015 database aided by a probabilistic model of microbial growth to examine the ecosystem-scale dynamics of Rh and identify primary predictors of its variability. We find that the temporal variability in Rh is consistently distributed according to a Gamma distribution, with shape and scale parameters controlled only by rainfall characteristics and vegetation productivity. This distribution originates from the propagation of fast hydrologic fluctuations on the slower biological dynamics of microbial growth and is independent of biome, soil type, and microbial physiology. This finding allows us to readily provide accurate estimates of the mean Rh and its variance, as confirmed by a comparison with an independent global dataset. Our results suggest that future changes in rainfall regime and net primary productivity will significantly alter the dynamics of Rh and the global carbon budget. In regions that are becoming wetter, Rh may increase faster than net primary productivity, thereby reducing the carbon storage capacity of terrestrial ecosystems.

scholarly journals Improving simulated Amazon forest biomass and productivity by including spatial variation in biophysical parameters

2013 ◽  
Vol 10 (4) ◽  
pp. 2255-2272 ◽  
Author(s):  
A. D. A. Castanho ◽  
M. T. Coe ◽  
M. H. Costa ◽  
Y. Malhi ◽  
D. Galbraith ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Spatial Heterogeneity ◽  
Spatial Variation ◽  
Primary Productivity ◽  
Amazon Basin ◽  
Net Primary Productivity ◽  
Above Ground Biomass ◽  
Biophysical Parameters ◽  
Simulation Accuracy ◽  
Forest Biome

Abstract. Dynamic vegetation models forced with spatially homogeneous biophysical parameters are capable of producing average productivity and biomass values for the Amazon basin forest biome that are close to the observed estimates, but these models are unable to reproduce observed spatial variability. Recent observational studies have shown substantial regional spatial variability of above-ground productivity and biomass across the Amazon basin, which is believed to be primarily driven by a combination of soil physical and chemical properties. In this study, spatial heterogeneity of vegetation properties is added to the Integrated Biosphere Simulator (IBIS) land surface model, and the simulated productivity and biomass of the Amazon basin are compared to observations from undisturbed forest. The maximum RuBiCo carboxylation capacity (Vcmax) and the woody biomass residence time (τw) were found to be the most important properties determining the modeled spatial variation of above-ground woody net primary productivity and biomass, respectively. Spatial heterogeneity of these properties may lead to simulated spatial variability of 1.8 times in the woody net primary productivity (NPPw) and 2.8 times in the woody above-ground biomass (AGBw). The coefficient of correlation between the modeled and observed woody productivity improved from 0.10 with homogeneous parameters to 0.73 with spatially heterogeneous parameters, while the coefficient of correlation between the simulated and observed woody above-ground biomass improved from 0.33 to 0.88. The results from our analyses with the IBIS dynamic vegetation model demonstrated that using single values for key ecological parameters in the tropical forest biome severely limits simulation accuracy. Clearer understanding of the biophysical mechanisms that drive the spatial variability of carbon allocation, τw and Vcmax is necessary to achieve further improvements to simulation accuracy.

scholarly journals WAYS v1: a hydrological model for root zone water storage simulation on a global scale

2019 ◽  
Vol 12 (12) ◽  
pp. 5267-5289 ◽  
Author(s):  
Ganquan Mao ◽  
Junguo Liu
Keyword(s):  
Spatial Heterogeneity ◽  
Soil Water ◽  
Regional Differences ◽  
Hydrological Model ◽  
Root Zone ◽  
Water Storage ◽  
Global Scale ◽  
Distribution Model ◽  
Lumped Model ◽  
Zone Water

Abstract. The soil water stored in the root zone is a critical variable for many applications, as it plays a key role in several hydrological and atmospheric processes. Many studies have been conducted to obtain reliable information on soil water in the root zone layer. However, most of them are mainly focused on the soil moisture within a certain depth rather than the water stored in the entire rooting system. In this work, a hydrological model named the Water And ecosYstem Simulator (WAYS) is developed to simulate the root zone water storage (RZWS) on a global scale. The model is based on a well-validated lumped model and has now been extended to a distribution model. To reflect the natural spatial heterogeneity of the plant rooting system across the world, a key variable that influences RZWS, i.e., root zone storage capacity (RZSC), is integrated into the model. The newly developed model is first evaluated based on runoff and RZWS simulations across 10 major basins. The results show the ability of the model to mimic RZWS dynamics in most of the regions through comparison with proxy data, the normalized difference infrared index (NDII). The model is further evaluated against station observations, including flux tower and gauge data. Despite regional differences, generally good performance is found for both the evaporation and discharge simulations. Compared to existing hydrological models, WAYS's ability to resolve the field-scale spatial heterogeneity of RZSC and simulate RZWS may offer benefits for many applications, e.g., agriculture and land–vegetation–climate interaction investigations. However, the results from this study suggest an additional evaluation of RZWS is required for the regions where the NDII might not be the correct proxy.

scholarly journals Towards an improved organic carbon budget for the western Barents Sea shelf

2014 ◽  
Vol 10 (2) ◽  
pp. 569-587 ◽  
Author(s):  
I. Pathirana ◽  
J. Knies ◽  
M. Felix ◽  
U. Mann
Keyword(s):  
Organic Carbon ◽  
Sea Ice ◽  
Primary Productivity ◽  
Carbon Budget ◽  
Barents Sea ◽  
Carbon Accumulation ◽  
The Arctic ◽  
Sediment Surface ◽  
Organic Facies ◽  
Facies Modelling

Abstract. There is generally a lack of knowledge on how marine organic carbon accumulation is linked to vertical export and primary productivity patterns in the Arctic Ocean. Despite the fact that annual primary production in the Arctic has increased as a consequence of shrinking sea ice, its effect on flux, preservation, and accumulation of organic carbon is still not well understood. In this study, a multi-proxy geochemical and organic-sedimentological approach is coupled with organic facies modelling, focusing on regional calculations of carbon cycling and carbon burial on the western Barents Shelf between northern Scandinavia and Svalbard. OF-Mod 3-D, an organic facies modelling software tool, is used to reconstruct and quantify the marine and terrestrial organic carbon fractions and to make inferences about marine primary productivity changes across the marginal ice zone (MIZ). By calibrating the model against an extensive set of sediment surface samples, we improve the Holocene organic carbon budget for ice-free and seasonally ice-covered areas in the western Barents Sea. The results show that higher organic carbon accumulation rates in the MIZ are best explained by enhanced surface water productivity compared to ice-free regions, implying that shrinking sea ice may reveal a significant effect on the overall organic carbon storage capacity of the western Barents Sea shelf.

scholarly journals Combining livestock production information in a process-based vegetation model to reconstruct the history of grassland management

2016 ◽  
Vol 13 (12) ◽  
pp. 3757-3776 ◽  
Author(s):  
Jinfeng Chang ◽  
Philippe Ciais ◽  
Mario Herrero ◽  
Petr Havlik ◽  
Matteo Campioli ◽  
...  
Keyword(s):  
Primary Productivity ◽  
Net Primary Productivity ◽  
Biomass Productivity ◽  
Grassland Management ◽  
Global Scale ◽  
Surface Energy Budget ◽  
Greenhouse Gas Balance ◽  
Large Spatial Scale ◽  
Management Intensity ◽  
Grass Biomass

Abstract. Grassland management type (grazed or mown) and intensity (intensive or extensive) play a crucial role in the greenhouse gas balance and surface energy budget of this biome, both at field scale and at large spatial scale. However, global gridded historical information on grassland management intensity is not available. Combining modelled grass-biomass productivity with statistics of the grass-biomass demand by livestock, we reconstruct gridded maps of grassland management intensity from 1901 to 2012. These maps include the minimum area of managed vs. maximum area of unmanaged grasslands and the fraction of mown vs. grazed area at a resolution of 0.5° by 0.5°. The grass-biomass demand is derived from a livestock dataset for 2000, extended to cover the period 1901–2012. The grass-biomass supply (i.e. forage grass from mown grassland and biomass grazed) is simulated by the process-based model ORCHIDEE-GM driven by historical climate change, rising CO2 concentration, and changes in nitrogen fertilization. The global area of managed grassland obtained in this study increases from 6.1  ×  106 km2 in 1901 to 12.3  ×  106 km2 in 2000, although the expansion pathway varies between different regions. ORCHIDEE-GM also simulated augmentation in global mean productivity and herbage-use efficiency over managed grassland during the 20th century, indicating a general intensification of grassland management at global scale but with regional differences. The gridded grassland management intensity maps are model dependent because they depend on modelled productivity. Thus specific attention was given to the evaluation of modelled productivity against a series of observations from site-level net primary productivity (NPP) measurements to two global satellite products of gross primary productivity (GPP) (MODIS-GPP and SIF data). Generally, ORCHIDEE-GM captures the spatial pattern, seasonal cycle, and interannual variability of grassland productivity at global scale well and thus is appropriate for global applications presented here.

Can spatial heterogeneity explain the perceived imbalance in Lake Superior's carbon budget? A model study

2012 ◽  
Vol 117 (G3) ◽  
pp. n/a-n/a ◽  
Author(s):  
Val Bennington ◽  
Galen A. McKinley ◽  
Noel R. Urban ◽  
Cory P. McDonald
Keyword(s):  
Spatial Heterogeneity ◽  
Carbon Budget ◽  
Model Study

scholarly journals PENGARUH KEDALAMAN TERHADAP NILAI PRODUKTIVITAS PRIMER DI WADUK JATIBARANG SEMARANG

2016 ◽  
Vol 5 (3) ◽  
pp. 150-156
Author(s):  
Wiwi Siti Rohmah ◽  
Suryanti Suryanti ◽  
Max Rudolf Muskananfola
Keyword(s):  
Chlorophyll A ◽  
Primary Productivity ◽  
Chemical Parameters ◽  
Average Value ◽  
Depth Difference ◽  
Sampling Locations ◽  
Regression Test ◽  
Productivity Measurements ◽  
Descriptive Method ◽  
Simple Regression

ABSTRAK Waduk Jatibarang merupakan salah satu waduk yang tergolong baru di Kota Semarang. Untuk mencegah terjadinya penurunan kualitas perairan pada waduk dimasa mendatang, penting dilakukan pengukuran tingkat kesuburan perairan waduk secara berkala. Salah satu cara untuk mengetahui tingkat kesuburan perairan waduk yaitu dengan melakukan pengukuran produktivitas primer perairan dan kandungan klorofil-a serta parameter fisika-kimia perairan. Penelitian ini dilakukan pada bulan Februari-Maret 2016 di Waduk Jatibarang Semarang. Tujuan dari Penelitian ini adalah untuk mengetahui nilai produktivitas primer perairan berdasarkan perbedaan kedalaman serta untuk mengetahui pengaruh kedalaman terhadap nilai produktivitas primer perairan di Waduk Jatibarang, Semarang. Metode yang digunakan dalam penelitian ini adalah Deskriptif lokasi sampling, yaitu Stasiun I; Inlet, Stasiun II perairan tengah waduk dan Stasiun III Outlet dalam tiga kali pengulangan dengan rentang waktu satu minggu. Hasil pengukuran produktivitas primer pada ketiga stasiun per kedalaman adalah; kedalaman 0 m berkisar 54,750-90,000 mgC/m3/hari, kedalaman 5 m berkisar 91,500-102,750 mgC/m3/hari, kedalaman 10 m berkisar 39,750-64,500 mgC/m3/hari dan kedalaman 15 m berkisar 20,250-45,5000 mgC/m3/hari. Berdasarkan nilai tersebut maka perairan waduk Jatibarang tergolong sebagai perairan Mesotrofik-Eutrofik. Rata-rata nilai kandungan klorofil-a minggu ke-1 0,6913 mg/m3, minggu ke-2 0,6665mg/m3, dan minggu ke-3 0,4409 mg/m3. Hasil uji regresi sederhana menunjukan terdapat pengaruh variabel kedalaman dan kandungan klorofil-a terhadap produktivitas primer sebesar 51,3%. Kata Kunci : Produktivitas Primer; Klorofil-a; Waduk Jatibarang Semarang  ABSTRACT Jatibarang Reservoir is one of the new reservoirs in Semarang. To prevent the degradation of reservoirs water quality in the future, it is important to measure the dam water fertilization periodically. Like one of the ways to determine the level of fertility of the dam water is by measuring the primary productivity of the water and chlorophyll-a and physic-chemical parameters of the waters. This study was conducted from February to March 2016 in Semarang Jatibarang Reservoir. The aim of this study is to determine the primary productivity of waters based on depth difference and the depth effects on primary productivity of the waters of the Jatibarang reservoir, Semarang. The method used in this study is descriptive method. Sampling locations are station I; Inlet, Station II: middle of reservoir and stations III: Outlet with three repetitions for the period of one week. The results of primary productivity measurements at each stations per depth is; at the depth of 0 m the results ranges from 54.750 to 90.000 mgC/m3/day, at the depth of 5 m from 91.500 to 102.750 mgC/m3/day, at the depth of 10 m from 39.750 to 64.500 mgC/m3/day and at the depth of 15 m from 20.250 to 45.5000 mgC/m3/day. Based on these results, it is concluded that the water of Jatibarang Reservoir is classified as Mesotrofik-eutrophic waters. The average value of chlorophyll-a in the first week is 0.6913 mg/m3, in the 2nd week is 0.6665 mg/m3, and the 3rd week is 0.4409 mg/m3. The results of simple regression test reveals that there is a significant effect of water depth and chlorophyll-a on primary productivity is  51.3%. Keywords: Primary Productivity, Chlorophyll-a, Jatibarang Reservoir Semarang

scholarly journals ESTIMASI PRODUKTIVITAS PRIMER PERAIRAN BERDASARKAN KONSENTRASI KLOROFIL-A YANG DIEKSTRAK DARI CITRA SATELIT LANDSAT-8 DI PERAIRAN KEPULAUAN KARIMUN JAWA

2017 ◽  
Vol 14 (1) ◽  
Author(s):  
Mulkan Nuzapril ◽  
Setyo Budi Susilo ◽  
James Parlindungan Panjaitan
Keyword(s):  
Chlorophyll A ◽  
Attenuation Coefficient ◽  
Primary Productivity ◽  
Chlorophyll Concentration ◽  
Euphotic Zone ◽  
Landsat 8 ◽  
Secchi Disk ◽  
Estimation Model ◽  
Chlorophyll A Concentration ◽  
Average Value

Sea primary productivity is an important factor in monitoring the quality of sea waters due to his role in the carbon cycle and the food chain for heterotrophic organisms. Estimation of sea primary productivity may be suspected through the values of chlorophyll-a concentration, but surface chlorophyll-a concentration was only able to explain 30% of the primary productivity of the sea. This research aims to build primary productivity estimation model based on chlorophyll-a concentration value of a surface layer of depth until depth compensation. Primary productivity model of relationships with chlorophyll concentration were extracted from Landsat-8 imagery then it could be used to calculated of sea primary productivity. The determination of the depth classification were done by measuring the attenuation coefficient values using the luxmeter underwater datalogger 2000 and secchi disk. The attenuation coefficient values by the luxmeter underwater, ranges between of 0.13-0.21 m-1 and secchi disk ranged, of 0.12 – 0.21 m-1. The penetration of light that through into the water column where  primary productivity is still in progress or where the depth of compensation ranged from 28.75 – 30.67 m. The simple linier regression model between average value of chlorophyll- concentration in all euphotic zone with sea primary productivity has high correlation, it greater than of surface chlorophyll-a concentration (R2 = 0.65). Model validation of sea primary productivity has high accuracy with the RMSD value of 0.09 and satellite-derived sea primary productivity were not significantly different. The satellite derived of chlorophyll-a could be calculated into sea primary productivity.Abstrak Produktivitas primer perairan merupakan faktor penting dalam pemantauan kualitas perairan laut karena berperan dalam siklus karbon dan rantai makanan bagi organisme heterotrof. Estimasi produktivitas primer perairan dapat diduga melalui nilai konsentrasi klorofil-a, namun konsentrasi klorofil-a permukaan laut hanya mampu menjelaskan 30% produktivitas primer laut. Penelitian ini bertujuan untuk membangun model estimasi produktivitas primer berdasarkan nilai konsentrasi klorofil-a dari lapisan kedalaman permukaan sampai kedalaman kompensasi. Model hubungan produktivitas primer dengan konsentrasi klorofil-a yang diekstrak dari citra satelit Landsat-8 kemudian dapat digunakan untuk mengestimasi produktivitas primer satelit. Penentuan klasifikasi kedalaman dilakukan dengan mengukur nilai koefisien atenuasi menggunakan luxmeter underwater datalogger 2000  dan secchi disk. Nilai koefisien atenuasi dengan menggunakan luxmeter underwater berkisar antara 0,13 -0,21m-1 dan secchi disk berkisar antara 0,12 – 0,21 m-1. Penetrasi cahaya yang masuk ke kolom perairan dimana produksi primer masih berlangsung atau kedalaman kompensasi berkisar antara 28,75 – 30,67 m. Model regresi linier sederhana antara konsentrasi klorofil-a rata-rata seluruh zona eufotik dengan produktivitas primer perairan memiliki korelasi yang lebih tinggi dibandingkan konsentrasi klorofil-a permukaan dengan R2= 0,65. Validasi model produktivitas primer memiliki keakuratan yang tinggi dengan RMSD sebesar 0,09 dan produktivitas primer satelit secara signifikan tidak berbeda nyata dengan produktivitas primer data insitu. Sehingga  nilai konsentrasi klorofil-a satelit dapat ditransformasi menjadi produktivitas primer satelit.

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