Forest Fragmentation and Its Potential Implications in the Brazilian Amazon between 2001 and 2010

In recent decades, human development pressures have results in conversions of vast tracts of Amazonian tropical rain forests to agriculture and other human land uses. In addition to the loss of large forest cover, remaining forests are also fragmented into smaller habitats. Fragmented forests suffer several biological and ecological changes due to edge effects that can exacerbate regional forest degradation. The Brazilian Amazon has had greatly contrasting land cover dynamics in the past decade with the highest historical rates of deforestation (2001-2005) followed by the lowest rates of forest loss in decades, since 2006. Currently, the basin-wide status and implications of forest fragmentation on remnant forests is not well known. We performed a regional forest fragmentation analysis for seven states of the Brazilian Amazon between 2001 and 2010 using a recent deforestation data. During this period, the number of forest fragments (>2 ha) doubled, nearly 125,000 fragments were formed by human activities with more than 50% being smaller than 10 ha. Over the decade, forest edges increased by an average of 36,335 km/year. However, the rate was much greater from 2001-2005 (50,046 km/year) then 2006-2010 (25,365 km/year) when deforestation rates dropped drastically. In 2010, 55% of basin-wide forest edges were < 10 years old due to the creation of large number of small fragments where intensive biological and ecological degradation is ongoing. Over the past decade protected areas have been expanded dramatically over the Brazilian Amazon and, as of 2010, 51% of remaining forests across the basin are within protected areas and only 1.5% of protected areas has been deforested. Conversely, intensive forest cover conversion has been occurred in unprotected forests. While 17% of Amazonian forests are within 1 km of forest edges in 2010, the proportion increases to 34% in unprotected areas varying between 14% and 95% among the studied states. Our results indicate that the Brazilian Amazon now largely consists of two contrasting forest conditions: protected areas with vast undisturbed forests and unprotected forests that are highly fragmented and disturbed landscapes.

Historical trends of degradation,loss,and recovery in the tropical forest reserves of Ghana

The Upper Guinean Forest region of West Africa,a globally significant biodiversity hotspot,is among the driest and most human-impacted tropical ecosystems.We used Landsat to study forest degradation,loss,and recovery in the forest reserves of Ghana from 2003 to 2019.Annual canopy cover maps were generated using random forests and results were temporally segmented using the LandTrendr algorithm.Canopy cover was predicted with a predicted-observed r2 of 0.76,mean absolute error of 12.8%,and mean error of 1.3%.Forest degradation,loss,and recovery were identified as transitions between closed(>60%cover),open(15–60%cover)and low tree cover(<15%cover)classes.Change was relatively slow from 2003 to 2015,but there was more disturbance than recovery resulting in a gradual decline in closed canopy forests.In 2016,widespread fires associated with El Niño drought caused forest loss and degradation across more than 12%of the moist semi-deciduous and upland evergreen forest types.The workflow was implemented in Google Earth Engine,allowing stakeholders to visualize the results and download summaries.Information about historical disturbances will help to prioritize locations for future studies and target forest protection and restoration activities aimed at increasing resilience.