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Estimating Gross Primary production and hydrological processes in páramo grasslands
Published in Veronica Graciela Minaya Maldonado, Ecohydrology of the Andes Paramo Region, 2017
Veronica Graciela Minaya Maldonado
Many process-based vegetation models currently available but, some may not properly represent the carbon, nitrogen, water fluxes and mass for the vegetation and soil components. Yet, these components are exceptionally important in the high-altitude tropical grasslands. Looking briefly at a few models we see their limitations in this regard. For example, WOFOST (WOrld FOod STudies) has limitations related to the simulation of cold and heat stresses, damage from excess water, hail, strong winds and other extreme conditions (Boogaard et al., 1998). LANDIS-II (Forest Landscape Simulation Model) is intended for broad-scale simulations and detailed representation of nutrient cycling and other ecophysiological processes are not yet included (Aber, 1997; Ollinger et al., 2002). DGVMs (Dynamic Global Vegetation Models) (e.g. HYBRID, IBIS, LPJ-DGVM) were developed to cope with the global problems and are able to show multiple interactions of biosphere-hydrosphere vulnerability to climate and land use change over large domains (Gerten et al., 2004; Sitch et al., 2003). For this model, limitations including generalizing plants to a few functional types, inability to route water among simulated units, clear representation of carbon and nitrogen cycles as well as soil processes still exist (Quillet et al., 2010).
The future of global land change monitoring
Published in International Journal of Digital Earth, 2023
The third and an increasingly popular approach is to apply econometric techniques on time-series of satellite data to quantify human factors that are not directly observable from remote sensing. Recent examples include Li et al. (2022), who applied fixed-effect models to quantify the cropland area change caused by the Syrian Civil War, and Olsen et al. (2021), who applied a quasi-experimental method to define the relationship between cropland abandonment and armed conflicts in South Sudan. Lastly, Dynamic Global Vegetation Models (DGVMs), by simulating vegetation distribution under past, current and future climate conditions, provide a valuable way to quantify terrestrial ecosystem responses to broad-scale environmental changes (Prentice et al. 2007; Sitch et al. 2008). The impacts of individual processes such as CO2 fertilization and N deposition on vegetation cover can be simulated in a spatially explicit manner by DGVMs (Zhu et al. 2016). With substantial human perturbations to the Earth system in the Anthropocene, human-induced environmental change, natural variations and human land use are increasingly intertwined (Gauthier et al. 2015; Lewis, Edwards, and Galbraith 2015; Popkin 2021). Disentangling the impact of the diverse and interactive drivers of land change continues to be a challenging and active direction in land change research.