scholarly journals A dynamic volume and biomass growth model system for even-aged downy birch stands in south-western Europe

2013 ◽  
Vol 87 (1) ◽  
pp. 165-176 ◽  
Author(s):  
E. Gomez-Garcia ◽  
F. Crecente-Campo ◽  
B. Tobin ◽  
M. Hawkins ◽  
M. Nieuwenhuis ◽  
...  
Keyword(s):  
Growth Model ◽  
Western Europe ◽  
Model System ◽  
Biomass Growth ◽  
Downy Birch

scholarly journals A Dynamic Stand Growth Model System for Loblolly Pine Responding to Mid-Rotation Treatments

Forests ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 556
Author(s):  
Mauricio Zapata-Cuartas ◽  
Bronson P. Bullock ◽  
Cristian R. Montes ◽  
Michael B. Kane
Keyword(s):  
Growth Model ◽  
Loblolly Pine ◽  
Basal Area ◽  
Model System ◽  
Growth And Yield ◽  
Site Quality ◽  
Response To Treatment ◽  
Plantation Management ◽  
Vegetation Control ◽  
Dominant Height

Intensive loblolly pine (Pinus taeda L.) plantation management in the southeastern United States includes mid-rotation silvicultural practices (MRSP) like thinning, fertilization, competitive vegetation control, and their combinations. Consistent and well-designed long-term studies considering interactions of MRSP are required to produce accurate projections and evaluate management decisions. Here we use longitudinal data from the regional Mid-Rotation Treatment study established by the Plantation Management Research Cooperative (PMRC) at the University of Georgia across the southeast U.S. to fit and validate a new dynamic model system rooted in theoretical and biological principles. A Weibull pdf was used as a modifier function coupled with the basal area growth model. The growth model system and error projection functions were estimated simultaneously. The new formulation results in a compatible and consistent growth and yield system and provides temporal responses to treatment. The results indicated that the model projections reproduce the observed behavior of stand characteristics. The model has high predictive accuracy (the cross-validation variance explained was 96.2%, 99.7%, and 98.6%; and the prediction root mean square distance was 0.704 m, 19.1 trees ha−1, and 1.03 m2ha−1 for dominant height (DH), trees per hectare (N), and basal area (BA), respectively), and can be used to project the current stand attributes following combinations of MRSP and with different thinning intensities. Simulations across southern physiographic regions allow us to conclude that the most overall ranking of MRSP after thinning is fertilization + competitive vegetation control (Fert + CVC) > fertilization only (Fert) > competitive vegetation control only (CVC), and Fert + CVC show less than additive effect. Because of the model structure, the response to treatment changes with location, age of application, and dominant height growth as indicators of site quality. Therefore, the proposed model adequately represents regional growth conditions.

scholarly journals The comprehensive model system COSMO-ART – radiative impact of aerosol on the state of the atmosphere on the regional scale

2009 ◽  
Vol 9 (4) ◽  
pp. 14483-14528 ◽  
Author(s):  
B. Vogel ◽  
H. Vogel ◽  
D. Bäumer ◽  
M. Bangert ◽  
K. Lundgren ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Western Europe ◽  
Aerosol Particles ◽  
Regional Scale ◽  
Global Radiation ◽  
Model System ◽  
First Episode ◽  
Clear Correlation ◽  
The Impact

Abstract. A new fully online coupled model system developed for the evaluation of the interaction of aerosol particles with the atmosphere on the regional scale is described. The model system is based on the operational weather forecast model of the Deutscher Wetterdienst. Physical processes like transport, turbulent diffusion, and dry and wet deposition are treated together with photochemistry and aerosol dynamics using the modal approach. Based on detailed calculations we have developed parameterizations to examine the impact of aerosol particles on photolysis and on radiation. Currently the model allows feedback between natural and anthropogenic aerosol particles and the atmospheric variables that are initialized by the modification of the radiative fluxes. The model system is applied to two summer episodes, each lasting five days, with a model domain covering Western Europe and adjacent regions. The first episode is characterised by almost cloud free conditions and the second one by cloudy conditions. The simulated aerosol concentrations are compared to observations made at 700 stations distributed over Western Europe. For each episode two model runs are performed; one where the feedback between the aerosol particles and the atmosphere is taken into account and a second one where the feedback is neglected. Comparing these two sets of model runs, the radiative feedback on temperature and other variables is evaluated. In the cloud free case a clear correlation between the aerosol optical depth and changes in global radiation and temperature is found. In the case of cloudy conditions the pure radiative effects are superposed by changes in the liquid water content of the clouds due to changes in the thermodynamics of the atmosphere. In this case the correlation between the aerosol optical depth and its effects on temperature is low. However, on average a decrease in the 2 m temperature is still found. In both cases a reduction in the daily temperature range, due to the aerosol optical depth, can be seen with an average value of −0.13 K over Germany.

scholarly journals The acclimative biogeochemical model of the southern North Sea

2017 ◽  
Vol 14 (19) ◽  
pp. 4499-4531 ◽  
Author(s):  
Onur Kerimoglu ◽  
Richard Hofmeister ◽  
Joeran Maerz ◽  
Rolf Riethmüller ◽  
Kai W. Wirtz
Keyword(s):  
Growth Model ◽  
North Sea ◽  
Model System ◽  
Coastal Areas ◽  
Biogeochemical Model ◽  
Observation Data ◽  
Autotrophic Growth ◽  
Southern North Sea ◽  
Curvilinear Grid ◽  
Physiological Flexibility

Abstract. Ecosystem models often rely on heuristic descriptions of autotrophic growth that fail to reproduce various stationary and dynamic states of phytoplankton cellular composition observed in laboratory experiments. Here, we present the integration of an advanced phytoplankton growth model within a coupled three-dimensional physical–biogeochemical model and the application of the model system to the southern North Sea (SNS) defined on a relatively high resolution (∼ 1.5–4.5 km) curvilinear grid. The autotrophic growth model, recently introduced by Wirtz and Kerimoglu (2016), is based on a set of novel concepts for the allocation of internal resources and operation of cellular metabolism. The coupled model system consists of the General Estuarine Transport Model (GETM) as the hydrodynamical driver, a lower-trophic-level model and a simple sediment diagenesis model. We force the model system with realistic atmospheric and riverine fluxes, background turbidity caused by suspended particulate matter (SPM) and open ocean boundary conditions. For a simulation for the period 2000–2010, we show that the model system satisfactorily reproduces the physical and biogeochemical states of the system within the German Bight characterized by steep salinity; nutrient and chlorophyll (Chl) gradients, as inferred from comparisons against observation data from long-term monitoring stations; sparse in situ measurements; continuous transects; and satellites. The model also displays skill in capturing the formation of thin chlorophyll layers at the pycnocline, which is frequently observed within the stratified regions during summer. A sensitivity analysis reveals that the vertical distributions of phytoplankton concentrations estimated by the model can be qualitatively sensitive to the description of the light climate and dependence of sinking rates on the internal nutrient reserves. A non-acclimative (fixed-physiology) version of the model predicted entirely different vertical profiles, suggesting that accounting for physiological flexibility might be relevant for a consistent representation of the vertical distribution of phytoplankton biomass. Our results point to significant variability in the cellular chlorophyll-to-carbon ratio (Chl : C) across seasons and the coastal to offshore transition. Up to 3-fold-higher Chl : C at the coastal areas in comparison to those at the offshore areas contribute to the steepness of the chlorophyll gradient. The model also predicts much higher phytoplankton concentrations at the coastal areas in comparison to its non-acclimative equivalent. Hence, findings of this study provide evidence for the relevance of physiological flexibility, here reflected by spatial and seasonal variations in Chl : C, for a realistic description of biogeochemical fluxes, particularly in the environments displaying strong resource gradients.

scholarly journals Generalized logistic growth modeling of the COVID-19 outbreak: comparing the dynamics in the 29 provinces in China and in the rest of the world

2020 ◽  
Vol 101 (3) ◽  
pp. 1561-1581 ◽  
Author(s):  
Ke Wu ◽  
Didier Darcet ◽  
Qian Wang ◽  
Didier Sornette
Keyword(s):  
Growth Model ◽  
Western Europe ◽  
Control Measures ◽  
Logistic Growth ◽  
Global Pandemic ◽  
The World ◽  
Containment Measures ◽  
Logistic Growth Model ◽  
The Impact ◽  
Scenario Projections

Abstract Started in Wuhan, China, the COVID-19 has been spreading all over the world. We calibrate the logistic growth model, the generalized logistic growth model, the generalized Richards model and the generalized growth model to the reported number of infected cases for the whole of China, 29 provinces in China, and 33 countries and regions that have been or are undergoing major outbreaks. We dissect the development of the epidemics in China and the impact of the drastic control measures both at the aggregate level and within each province. We quantitatively document four phases of the outbreak in China with a detailed analysis on the heterogeneous situations across provinces. The extreme containment measures implemented by China were very effective with some instructive variations across provinces. Borrowing from the experience of China, we made scenario projections on the development of the outbreak in other countries. We identified that outbreaks in 14 countries (mostly in western Europe) have ended, while resurgences of cases have been identified in several among them. The modeling results clearly show longer after-peak trajectories in western countries, in contrast to most provinces in China where the after-peak trajectory is characterized by a much faster decay. We identified three groups of countries in different level of outbreak progress, and provide informative implications for the current global pandemic.

scholarly journals A novel acclimative biogeochemical model and its implementation to the southern North Sea

2017 ◽  
Author(s):  
Onur Kerimoglu ◽  
Richard Hofmeister ◽  
Joeran Maerz ◽  
Kai Wenzel Wirtz
Keyword(s):  
Growth Model ◽  
North Sea ◽  
Transport Model ◽  
Coupled Model ◽  
Remote Sensing Data ◽  
Model System ◽  
Biogeochemical Model ◽  
Internal Resources ◽  
Southern North Sea ◽  
Curvilinear Grid

Abstract. Ecosystem models often rely on heuristic descriptions of autotroph growth that fail to reproduce various stationary and dynamic states of phytoplankton cellular composition observed in laboratory experiments. Here, we present the integration of an advanced phytoplankton growth model within a coupled 3-dimensional physical-biogeochemical model, and the implementation of the model system to the Southern North Sea (SNS) defined on a relatively high resolution (~ 1.5–4.5 km) curvilinear grid. The autotrophic growth model, recently introduced by Wirtz and Kerimoglu (2016), is built up on a set of novel concepts for the allocation of internal resources and operation of cellular metabolism. The coupled model system consists of the general estuarine transport model (GETM) as the hydrodynamical driver, a lower trophic level model and a simple sediment diagenesis model. We force the model system with realistic atmospheric and riverine fluxes, background turbidity caused by suspended particulate matter and open ocean boundary conditions. For a simulation for the period 2000–2010, we show that the model system satisfactorily reproduces the physical and biogeochemical states of the system, as inferred from comparisons against data from long-term monitoring stations, sparse measurements, continuous transects, and remote sensing data. In particular, the model shows high skill both in coastal and off shore waters, and captures the steep gradients in nutrient and chlorophyll concentrations observed prevalently across the coastal transition zone. We show that the cellular chlorophyll to carbon ratio show significant seasonal and lateral variability, the latter amplifying the steepness of the transitional chlorophyll gradient, thus, pointing to the relevance of resolving the physiological acclimation processes for an accurate description of biogeochemical fluxes.

scholarly journals The comprehensive model system COSMO-ART – Radiative impact of aerosol on the state of the atmosphere on the regional scale

2009 ◽  
Vol 9 (22) ◽  
pp. 8661-8680 ◽  
Author(s):  
B. Vogel ◽  
H. Vogel ◽  
D. Bäumer ◽  
M. Bangert ◽  
K. Lundgren ◽  
...  
Keyword(s):  
Aerosol Optical Depth ◽  
Optical Depth ◽  
Western Europe ◽  
Aerosol Particles ◽  
Regional Scale ◽  
Global Radiation ◽  
Model System ◽  
First Episode ◽  
Clear Correlation ◽  
The Impact

Abstract. A new fully online coupled model system developed for the evaluation of the interaction of aerosol particles with the atmosphere on the regional scale is described. The model system is based on the operational weather forecast model of the Deutscher Wetterdienst. Physical processes like transport, turbulent diffusion, and dry and wet deposition are treated together with photochemistry and aerosol dynamics using the modal approach. Based on detailed calculations we have developed parameterisations to examine the impact of aerosol particles on photolysis and on radiation. Currently the model allows feedback between natural and anthropogenic aerosol particles and the atmospheric variables that are initialized by the modification of the radiative fluxes. The model system is applied to two summer episodes, each lasting five days, with a model domain covering Western Europe and adjacent regions. The first episode is characterised by almost cloud free conditions and the second one by cloudy conditions. The simulated aerosol concentrations are compared to observations made at 700 stations distributed over Western Europe. For each episode two model runs are performed; one where the feedback between the aerosol particles and the atmosphere is taken into account and a second one where the feedback is neglected. Comparing these two sets of model runs, the radiative feedback on temperature and other variables is evaluated. In the cloud free case a clear correlation between the aerosol optical depth and changes in global radiation and temperature is found. In the case of cloudy conditions the pure radiative effects are superposed by changes in the liquid water content of the clouds due to changes in the thermodynamics of the atmosphere. In this case the correlation between the aerosol optical depth and its effects on temperature is low. However, on average a decrease in the 2 m temperature is still found. For the area of Germany we found on average for both cases a reduction in the global radiation of about 6 W m2, a decrease of the 2 m temperature of 0.1 K, and a reduction in the daily temperature range of −0.13 K.

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