Forest Degradation Assessment Based on Trend Analysis of MODIS-Leaf Area Index: A Case Study in Mexico

Abstract

Assessing forest degradation has been a challenging task due to the generally slow-changing nature of the process, which demands long periods of observation and high frequency of records. This research contributes to efforts aimed at detecting forest degradation by analyzing the trend component of the time series of Leaf Area Index (LAI) collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) over Central Mexico from 2002 to 2017. The analysis of the trend component is proposed to overcome the challenge of identifying very subtle and gradual changes that can be undetected if only the raw time series is examined. Additionally, the use of LAI as an alternative to other widely used indexes (e.g., Normalize Difference Vegetation Index and Enhanced Vegetation Index) facilitates consideration of the structural changes evident from degradation though not necessarily observable with spectral indices. Overall, results indicate that 52% of the study area has experienced positive trends of vegetation change (i.e., increasing LAI), 37% has remained unchanged, and 11% exhibits some level of forest degradation. Particularly, the algorithm estimated that 0.6% (385 km 2 ) is highly degraded, 5.3% (3406 km 2 ) moderately degraded, and 5.1% (3245 km 2 ) slightly degraded. Most of the moderate and highly degraded areas are distributed over the east side of the study area and evergreen broadleaf appears to be the most affected forest type. Model validation resulted an accuracy of 63%. Some actions to improve this accuracy are suggested, but also a different approach to validate this type of study is suggested as an area of opportunity for future research.

MDPrePost-Net: A Spatial-Spectral-Temporal Fully Convolutional Network for Mapping of Mangrove Degradation Affected by Hurricane Irma 2017 Using Sentinel-2 Data

“…A principal factor behind biodiversity loss is ecosystem degradation [14]. Degradation can be defined as decreases in ecosystem composition, the provision of ecosystem services, productivity, and in vegetation canopy cover, which can all fundamentally alter an ecosystem [15][16][17][18]. Hurricanes are also among natural events that have substantially contributed to mangrove degradation [13,19].…”

Climate Change Impacts on the Water Resources and Vegetation Dynamics of a Forested Sardinian Basin through a Distributed Ecohydrological Model

“…For evaluating trends in the data series, we used the Mann−Kendall (1938) method [116], which allows us to estimate the τ index of the trend, and the Theil−-Sen method (1950,1968) [117,118] for estimating the β trend line slope. The Mann−Kendall and Theil−Sen methods are widely used in ecohydrological studies of climate change [10,119,120].…”

Validation of leaf area index measurement system based on wireless sensor network

“…Song et al used remotely sensed leaf area index (LAI) data to monitor spatial–temporal changes of winter wheat phenology in response to climate warming across the North China Plain, and they found high spatial heterogeneity of winter wheat phenology in pixel scale across the whole area, which could not be detected in previous site-based studies 5 . Reygadas et al analyzed long time series of leaf area index data collected by the Moderate Resolution Imaging Spectroradiometer (MODIS) to determine the trend of forest degradation in Mexico 7 .…”