On the protection of "protected areas"

Abstract

Tropical moist forests contain the majority of terrestrial species. Human actions destroy between 1 and 2 million km(2) of such forests per decade, with concomitant carbon release into the atmosphere. Within these forests, protected areas are the principle defense against forest loss and species extinctions. Four regions-the Amazon, Congo, South American Atlantic Coast, and West Africa-once constituted about half the world's tropical moist forest. We measure forest cover at progressively larger distances inside and outside of protected areas within these four regions, using datasets on protected areas and land-cover. We find important geographical differences. In the Amazon and Congo, protected areas are generally large and retain high levels of forest cover, as do their surroundings. These areas are protected de facto by being inaccessible and will likely remain protected if they continue to be so. Deciding whether they are also protected de jure-that is, whether effective laws also protect them-is statistically difficult, for there are few controls. In contrast, protected areas in the Atlantic Coast forest and West Africa show sharp boundaries in forest cover at their edges. This effective protection of forest cover is partially offset by their very small size: little area is deep inside protected area boundaries. Lands outside protected areas in the Atlantic Coast forest are unusually fragmented. Finally, we ask whether global databases on protected areas are biased toward highly protected areas and ignore "paper parks." Analysis of a Brazilian database does not support this presumption.

Fig. 1.

Percentage of natural vegetation inside and outside protected areas in the four geographic areas of analysis: Amazon forest (A), Atlantic coast forest (B), Congo forest (C), and West African forest (D). IUCN categories are arranged in descending order of protection from I to VI. Categories I–IV are managed for biodiversity protection, whereas Categories V and VI are subject to multiple-use management. All protected areas are taken from the WDPA. Negative distances are inside protected areas; positive distances are outside. See also Fig. S2.

Fig. 2.

Number of square kilometers included in the analysis at each 2-km distance increment in the four regions (see also Fig. S3). See Fig. 1 legend for symbol definitions.

Fig. 3.

Fragmentation measurements for differing percent natural vegetation across the four regions analyzed. (Upper) Two areas (A and B, both 200 km²) experiencing similar deforestation (40–45%) but different levels of fragmentation. The map outline in C highlights the locations of the two plots in the Atlantic coast region of analysis. (Lower) (D) The range of fragmentation possible from 1,000 randomly deforested landscapes. (E) The fragmentation and deforestation values in and around protected areas in the four regions of analysis. Black circles on lines correspond to the distance in (negative values) or out (positive values) from protected area boundaries. Distance values (in kilometers) are located immediately above each circle. All protected area categories were combined for the analysis. The deforestation and fragmentation results of the two areas shown in A and B are highlighted by the letters A and B.

Fig. 4.

Images of four protected areas of differing IUCN categories made by using satellite (LandSat 5) imagery. (A) Brazil: Jau National Park (IUCN II). (B) Brazil: Sooretama Biological Reserve (IUCN Ia). (C) Nigeria: Okomu Forest Reserve (IUCN II). (D) Ghana: Nini-Suhien National Park (IUCN II) and Ankasa River Forest Reserve (Miscellaneous). The white line indicates the boundary of the protected areas (as reported by the WDPA), which are all enclosed, except for the top left, where the park lies to the east of the boundary.

Fig. 5.

Comparison between the WDPA (open circles) and the IBAMA (filled circles) datasets for two regions of Brazil. On the left is the percentage of natural vegetation inside and outside protected areas in the Brazilian Amazon forest (A) and Brazilian Atlantic coast forest (C). On the right is the number of square kilometers included in the analysis at each 2-km distance interval for the Brazilian Amazon forest (B) and Brazilian Atlantic coast forest (D). All protected area categories have been combined. Negative distances are inside protected areas; positive distances are outside.