Related Experiment Video
Updated: May 3, 2026

09:04
Leaf Area Index Estimation Using Three Distinct Methods in Pure Deciduous Stands
Published on: August 29, 2019
13.3K
Amazon forests maintain consistent canopy structure and greenness during the dry season
Douglas C Morton1, Jyoteshwar Nagol2, Claudia C Carabajal3
1NASA Goddard Space Flight Center, Greenbelt, Maryland 20771, USA.
Nature
|February 7, 2014
Summary
Seasonal green-up in Amazon forests is an optical illusion caused by sun-sensor geometry, not increased plant growth. Correcting for this artifact reveals stable forest structure, challenging light-limited productivity theories.
Area of Science:
- Ecology and Remote Sensing
- Tropical Forest Dynamics
- Biosphere-Atmosphere Interactions
Background:
- Tropical forest net primary production is regulated by sunlight and rainfall seasonality.
- Previous research suggested light limitation, supported by satellite-observed dry-season greening in the Amazon.
- This phenomenon implies enhanced forest growth during drought periods.
Purpose of the Study:
- To investigate the mechanisms behind the seasonal green-up observed in Amazonian tropical forests.
- To evaluate the role of leaf area and leaf reflectance changes in this phenomenon.
- To determine if optical remote sensing data accurately reflects actual forest productivity changes.
Main Methods:
- Utilized a sophisticated radiative transfer model to simulate forest canopy reflectance.
- Employed independent satellite observations from lidar and optical sensors for validation.
- Analyzed bidirectional reflectance effects related to sun-sensor geometry.
Main Results:
- The apparent seasonal green-up was identified as an artifact of changing near-infrared reflectance due to sun-sensor geometry variations.
- Correction for bidirectional reflectance effects removed seasonal changes in surface reflectance.
- Lidar observations and model simulations showed stable canopy properties throughout the seasons.
Conclusions:
- The stability of Amazon forest structure and reflectance challenges the paradigm of light-limited productivity and drought-enhanced growth.
- Optical remote sensing data requires correction for sun-sensor geometry artifacts to accurately assess vegetation responses.
- Accurate correction is crucial for understanding global vegetation's response to climate variability.
Related Concept Videos
Adaptations that Reduce Water Loss
24.2K
Though evaporation from plant leaves drives transpiration, it also results in loss of water. Because water is critical for photosynthetic reactions and other cellular processes, evolutionary pressures on plants in different environments have driven the acquisition of adaptations that reduce water loss.
24.2K
Seasoning of Wood
811
Seasoning of wood is a crucial process aimed at reducing and stabilizing the moisture content within the wood to prevent future shrinkage, structural damage, or aesthetic issues once the wood is used in construction. Wood naturally swells when it absorbs moisture and contracts as it dries.
Achieving equilibrium moisture content is the goal of seasoning; this is the point where the wood's moisture content stabilizes to align with the moisture levels of the surrounding environment. Proper...
Achieving equilibrium moisture content is the goal of seasoning; this is the point where the wood's moisture content stabilizes to align with the moisture levels of the surrounding environment. Proper...
811
What is Climate?
17.5K
Climate refers to the prevailing weather conditions in a specific area over an extended period. As the saying goes, “Climate is what you expect. Weather is what you get.” Climate is influenced by geographic factors, such as latitude, terrain, and proximity to bodies of water.
17.5K
Meristems and Plant Growth
36.3K
Plants grow throughout their lives; this is called indeterminate growth, and it distinguishes plants from most animals. Although certain parts of plants stop growing (e.g., leaves and flowers), others grow continuously—like roots and stems.
36.3K
Light Acquisition
8.0K
In order to produce glucose, plants need to capture sufficient light energy. Many modern plants have evolved leaves specialized for light acquisition. Leaves can be only millimeters in width or tens of meters wide, depending on the environment. Due to competition for sunlight, evolution has driven the evolution of increasingly larger leaves and taller plants, to avoid shading by their neighbors with contaminant elaboration of root architecture and mechanisms to transport water and nutrients.
8.0K
Responses to Drought and Flooding
10.2K
Water plays a significant role in the life cycle of plants. However, insufficient or excess of water can be detrimental and pose a serious threat to plants.
10.2K

