scholarly journals The effect of using the plant functional type paradigm on a data-constrained global phenology model

2015 ◽  
Vol 12 (20) ◽  
pp. 16847-16884 ◽  
Author(s):  
S. Caldararu ◽  
D. W. Purves ◽  
M. J. Smith
Keyword(s):  
Spatial Variation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Temporal Dynamics ◽  
Leaf Age ◽  
Plant Functional Type ◽  
Earth System ◽  
Functional Type ◽  
Area Index ◽  
Cell Parameters

Abstract. Leaf seasonality impacts a variety of important biological, chemical and physical Earth system processes, which makes it essential to represent leaf phenology in ecosystem and climate models. However, we are still lacking a general, robust parametrisation of phenology at global scales. In this study, we use a simple process-based model, which describes phenology as a strategy for carbon optimality, to test the effects of the common assumption in global modelling studies that plant species within the same plant functional type have the same parameter values, implying they are assumed to have the same species traits. In a previous study this model was shown to predict spatial and temporal dynamics of leaf area index (LAI) well across the entire global land surface provided local grid cell parameters were used, and is able to explain 96 % of the spatial variation in average LAI and 87 % of the variation in amplitude. In contrast, we find here that a PFT level parametrisation is unable to capture the spatial variability in seasonal cycles, explaining on average only 28 % of the spatial variation in mean leaf area index and 12 % of the variation in seasonal amplitude. However we also show that allowing only two parameters, light compensation point and leaf age, to be spatially variable dramatically improves the model predictions, increasing the model's capability of explaining spatial variations in leaf seasonality to 70 and 57 % of the variation in LAI average and amplitude respectively. This highlights the importance of identifying the spatial scale of variation of plant traits and the necessity to critically analyse the use of the plant functional type assumption in Earth system models.

scholarly journals The effect of using the plant functional type paradigm on a data-constrained global phenology model

2016 ◽  
Vol 13 (4) ◽  
pp. 925-941
Author(s):  
Silvia Caldararu ◽  
Drew W. Purves ◽  
Matthew J. Smith
Keyword(s):  
Spatial Variation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Temporal Dynamics ◽  
Leaf Age ◽  
Plant Functional Type ◽  
Earth System ◽  
Functional Type ◽  
Area Index ◽  
Cell Parameters

Abstract. Leaf seasonality impacts a variety of important biological, chemical, and physical Earth system processes, which makes it essential to represent leaf phenology in ecosystem and climate models. However, we are still lacking a general, robust parametrisation of phenology at global scales. In this study, we use a simple process-based model, which describes phenology as a strategy for carbon optimality, to test the effects of the common simplification in global modelling studies that plant species within the same plant functional type (PFT) have the same parameter values, implying they are assumed to have the same species traits. In a previous study this model was shown to predict spatial and temporal dynamics of leaf area index (LAI) well across the entire global land surface provided local grid cell parameters were used, and is able to explain 96 % of the spatial variation in average LAI and 87 % of the variation in amplitude. In contrast, we find here that a PFT level parametrisation is unable to capture the spatial variability in seasonal cycles, explaining on average only 28 % of the spatial variation in mean leaf area index and 12 % of the variation in seasonal amplitude. However, we also show that allowing only two parameters, light compensation point and leaf age, to be spatially variable dramatically improves the model predictions, increasing the model's capability of explaining spatial variations in leaf seasonality to 70 and 57 % of the variation in LAI average and amplitude, respectively. This highlights the importance of identifying the spatial scale of variation of plant traits and the necessity to critically analyse the use of the plant functional type assumption in Earth system models.

scholarly journals Topographic controls on the leaf area index and plant functional type of a tundra ecosystem

2008 ◽  
Vol 96 (6) ◽  
pp. 1238-1251 ◽  
Author(s):  
Luke Spadavecchia ◽  
Mathew Williams ◽  
Robert Bell ◽  
Paul C. Stoy ◽  
Brian Huntley ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Plant Functional Type ◽  
Functional Type ◽  
Area Index ◽  
Topographic Controls ◽  
Tundra Ecosystem

scholarly journals Spatial variation and seasonal dynamics of leaf-area index in the arctic tundra-implications for linking ground observations and satellite images

2017 ◽  
Vol 12 (9) ◽  
pp. 095002 ◽  
Author(s):  
Sari Juutinen ◽  
Tarmo Virtanen ◽  
Vladimir Kondratyev ◽  
Tuomas Laurila ◽  
Maiju Linkosalmi ◽  
...  
Keyword(s):  
Spatial Variation ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Seasonal Dynamics ◽  
Satellite Images ◽  
Arctic Tundra ◽  
The Arctic ◽  
Area Index

scholarly journals Inferring Amazon leaf demography from satellite observations of leaf area index

2011 ◽  
Vol 8 (5) ◽  
pp. 10389-10421 ◽  
Author(s):  
S. Caldararu ◽  
P. I. Palmer ◽  
D. W. Purves
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Land Surface ◽  
Amazon Basin ◽  
Leaf Age ◽  
Leaf Phenology ◽  
Spatial And Temporal Variability ◽  
Demographic Model ◽  
Area Index ◽  
Starting Point

Abstract. Seasonal and year-to-year variations in leaf cover imprint significant spatial and temporal variability on biogeochemical cycles, and affect land-surface properties related to climate. We develop a demographic model of leaf phenology based on the hypothesis that trees seek an optimal Leaf Area Index (LAI) as a function of available light and soil water, and fitted it to spaceborne observations of LAI over the Amazon Basin, 2001–2005. We find the model reproduces the spatial and temporal LAI distribution whilst also predicting geographic variation in leaf age from the basin center (2.1 ± 0.2 yr), through to the lowest values over the deciduous Eastern Amazon (6 ± 2 months). The model explains the observed increase in LAI during the dry season as a net addition of leaves in response to increased solar radiation. We anticipate our work to be a starting point from which to develop better descriptions of leaf phenology to incorporate into more sophisticated earth system models.

scholarly journals The carbon cycle in the Australian Community Climate and Earth System Simulator (ACCESS-ESM1) – Part 1: Model description and pre-industrial simulation

2017 ◽  
Vol 10 (7) ◽  
pp. 2567-2590 ◽  
Author(s):  
Rachel M. Law ◽  
Tilo Ziehn ◽  
Richard J. Matear ◽  
Andrew Lenton ◽  
Matthew A. Chamberlain ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Leaf Area Index ◽  
Leaf Area ◽  
Model Description ◽  
Interannual Variations ◽  
Earth System ◽  
Area Index ◽  
Australian Community ◽  
Ocean Carbon ◽  
Community Climate

Abstract. Earth system models (ESMs) that incorporate carbon–climate feedbacks represent the present state of the art in climate modelling. Here, we describe the Australian Community Climate and Earth System Simulator (ACCESS)-ESM1, which comprises atmosphere (UM7.3), land (CABLE), ocean (MOM4p1), and sea-ice (CICE4.1) components with OASIS-MCT coupling, to which ocean and land carbon modules have been added. The land carbon model (as part of CABLE) can optionally include both nitrogen and phosphorous limitation on the land carbon uptake. The ocean carbon model (WOMBAT, added to MOM) simulates the evolution of phosphate, oxygen, dissolved inorganic carbon, alkalinity and iron with one class of phytoplankton and zooplankton. We perform multi-centennial pre-industrial simulations with a fixed atmospheric CO2 concentration and different land carbon model configurations (prescribed or prognostic leaf area index). We evaluate the equilibration of the carbon cycle and present the spatial and temporal variability in key carbon exchanges. Simulating leaf area index results in a slight warming of the atmosphere relative to the prescribed leaf area index case. Seasonal and interannual variations in land carbon exchange are sensitive to whether leaf area index is simulated, with interannual variations driven by variability in precipitation and temperature. We find that the response of the ocean carbon cycle shows reasonable agreement with observations. While our model overestimates surface phosphate values, the global primary productivity agrees well with observations. Our analysis highlights some deficiencies inherent in the carbon models and where the carbon simulation is negatively impacted by known biases in the underlying physical model and consequent limits on the applicability of this model version. We conclude the study with a brief discussion of key developments required to further improve the realism of our model simulation.

Generating vegetation leaf area index earth system data record from multiple sensors. Part 1: Theory

2008 ◽  
Vol 112 (12) ◽  
pp. 4333-4343 ◽  
Author(s):  
S GANGULY ◽  
M SCHULL ◽  
A SAMANTA ◽  
N SHABANOV ◽  
C MILESI ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Earth System ◽  
Area Index ◽  
Multiple Sensors ◽  
Data Record ◽  
System Data
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