Uncertainty in above ground forest biomass (AGB) estimates at broad-scale depends primarily on three sources of error that interact and propagate: measurement error, model error, and sampling error. Using Monte Carlo simulations, we compare the total propagated error for two sets of regional-level component equations for lodgepole pine AGB, and...
The Amazon rainforest is a critical hotspot for bio-diversity, and plays an essential role in global carbon, water and energy fluxes and the earth's climate. Our ability to project the role of vegetation carbon feedbacks on future climate critically depends upon our understanding of this tropical ecosystem, its tolerance to...
Resolving the debate surrounding the nature and controls of seasonal variation in the structure and metabolism of Amazonian rainforests is critical to understanding their response to climate change. In situ studies have observed higher photosynthetic and evapotranspiration rates, increased litterfall and leaf flushing during the Sunlight-rich dry season. Satellite data...
We show that the vegetation canopy of the Amazon rainforest is
highly sensitive to changes in precipitation patterns and that
reduction in rainfall since 2000 has diminished vegetation greenness
across large parts of Amazonia. Large-scale directional
declines in vegetation greenness may indicate decreases in carbon
uptake and substantial changes in...
Vegetation carbon uptake and respiration constitute the largest carbon cycle of the planet with an annual turnover
in the order of 120 GT. Currently, neither ecosystem carbon uptake (through photosynthesis) nor ecosystem
carbon release (through respiration) can be measured directly during the daytime. Instead, flux-tower measurements
rely on nighttime respiration...
A process-based forest growth model, 3-PG (Physiological Principles Predicting
Growth), parameterized with values of soil properties constrained by satellite-derived
estimates of maximum leaf area index (LAI[subscript max]), was run for Douglas-fir (Pseudotsuga
menziesii) to contrast the extent to which site growth potential might vary across western
North America between a...
High spatiotemporal resolution satellite imagery is useful for natural resource management and monitoring for land-use and land-cover change and ecosystem dynamics. However, acquisitions from a single satellite can be limited, due to trade-offs in either spatial or temporal resolution. The spatial and temporal adaptive reflectance fusion model (STARFM) and the...
Surface energy balance is a major determinant of land surface temperature and the Earth's climate. To date, there is no approach that can produce effective, physically consistent, global and multi-decadal energy–water flux data over land. Net radiation (R[subscript n]) can be quantified regionally using satellite retrievals of surface reflectance and...
Understanding canopy radiation regimes is critical to successfully modeling vegetation growth and function.
For instance, the vertical distribution of photosynthetically active radiation (PAR) affects vegetation growth,
informative upon carbon and energy cycling. Availing upon advances in information capture and computing
power, geometrically explicit modeling of forest structure becomes increasingly possible....
The Mongolian Steppe is one of the largest remaining grassland ecosystems. Recent studies have reported widespread
decline of vegetation across the steppe and about 70% of this ecosystem is now considered degraded. Among
the scientific community there has been an active debate about whether the observed degradation is related to...