(A) Rate of mature forest loss at each time interval, estimated from single-date image classification
Figure 3. (A) Rate of mature forest loss at each time interval, estimated from single-date image classification. The mean rates of forest loss declined from 2.20% yr−1 pre-ban (1986–1996) to −1.38% yr−1 post-ban (1996–2011). Means and non-overlapping 95% confidence intervals for the pre-ban and post-ban periods are shown, in addition to the rate of forest loss over shorter time periods. (B) Total forest (mature forest, native reforestation, and exotic tree plantations) loss rate, with non-overlapping 95% confidence intervals. The rate of total forest loss was derived from three image dates and change detection analysis independent from mature forest area estimates (see supplementary materials available at stacks.iop.org/ERL/8/034017/mmedia).
Forest protection policies potentially reduce deforestation and re-direct agricultural expansion to already-cleared areas. Using satellite imagery, we assessed whether deforestation for conversion to pasture and cropland decreased in the lowlands of northern Costa Rica following the 1996 ban on forest clearing, despite a tripling of area under pineapple cultivation in the last decade. We observed that following the ban, mature forest loss decreased from 2.2% to 1.2% per year, and the proportion of pineapple and other export-oriented cropland derived from mature forest declined from 16.4% to 1.9%. The post-ban expansion of pineapples and other crops largely replaced pasture, exotic and native tree plantations, and secondary forests. Overall, there was a small net gain in forest cover due to a shifting mosaic of regrowth and clearing in pastures, but cropland expansion decreased reforestation rates. We conclude that forest protection efforts in northern Costa Rica have likely slowed mature forest loss and succeeded in re-directing expansion of cropland to areas outside mature forest. Our results suggest that deforestation bans may protect mature forests better than older forest regrowth and may restrict clearing for large-scale crops more effectively than clearing for pasture.