Year: 1999
Type: dissertation
Abstract: Phenology, the study of recurring biological cycles and their connection to climate, is a growing field o f global change research.Vegetation phenology exerts a strong control over carbon cycles, weather, and global radiation partitioning between sensible and latent heat fluxes.Phenological monitors of the timing and length of the growing season can also be used as barometers of vegetation responses to climatic variability.In the following chapters, I present research investigating the monitoring and interpretation of growing season dynamics.Ecological modeling is limited more by data availability than by model theory.In particular, the description o f vegetation functional types (biomes) for distributed modeling has been lacking.In chapter 1 ,1 present a documented description and sensitivity analysis of the 34 parameters used in the ecosystem model, BIOME-BGC, for m ajor temperate biomes.I applied BIOME-BGC in the eastern U.S. deciduous broad leaf forest and found that minor phenological variation created large impacts on simulated net ecosystem exchange of carbon (chapter 2).In addition to simulating the effects of growing season variability, it is also important to develop accurate field monitoring techniques, both as a means of testing modeling activities and as a validation of satellite remote sensing estimates.I conducted an intercomparison of field techniques that could be used to m onitor phenological dynamics in arid ecosystems (chapter 3).I found that methodological barriers to rapid, low cost monitoring were severe, but that a digital camera with both visible and near-infrared channels was a viable option.Satellite remote sensing provides the only means of obtaining consistent estimates of phenological variation at a global scale, yet our understanding of these data has been limited by a lack o f ground observations.To address this problem, I proposed, developed, and wrote a phenology measurement protocol for the Global Leaming and Observations to Benefit the Environment (GLOBE) program.Using satellite estimates of the tim ing of 1999 spring growth and the network of GLOBE observations, I found that satellite predictions of spring growth occur during the initial growth of dom inant upper-canopy species.u
Source: The Mathematics Enthusiast
Author: Michael A. White
Language: English
Subfield: Ecology
Field: Environmental Science
Domain: Physical Sciences
SDGs: Climate action, Life on land
Open Access status: green
OpenAlex ID: W35670648