High and far: biases in the location of protected areas

Abstract

Background: About an eighth of the earth's land surface is in protected areas (hereafter "PAs"), most created during the 20(th) century. Natural landscapes are critical for species persistence and PAs can play a major role in conservation and in climate policy. Such contributions may be harder than expected to implement if new PAs are constrained to the same kinds of locations that PAs currently occupy.

Methodology/principal findings: Quantitatively extending the perception that PAs occupy "rock and ice", we show that across 147 nations PA networks are biased towards places that are unlikely to face land conversion pressures even in the absence of protection. We test each country's PA network for bias in elevation, slope, distances to roads and cities, and suitability for agriculture. Further, within each country's set of PAs, we also ask if the level of protection is biased in these ways. We find that the significant majority of national PA networks are biased to higher elevations, steeper slopes and greater distances to roads and cities. Also, within a country, PAs with higher protection status are more biased than are the PAs with lower protection statuses.

Conclusions/significance: In sum, PAs are biased towards where they can least prevent land conversion (even if they offer perfect protection). These globally comprehensive results extend findings from nation-level analyses. They imply that siting rules such as the Convention on Biological Diversity's 2010 Target [to protect 10% of all ecoregions] might raise PA impacts if applied at the country level. In light of the potential for global carbon-based payments for avoided deforestation or REDD, these results suggest that attention to threat could improve outcomes from the creation and management of PAs.

Figure 1. Numbers of countries and the percent of their ecoregions with greater than 10% protection.

A, B, C, D, E, F, G each plots the cumulative number of countries at 20 year increments. PAs with no date of creation in the database occur first in 1900, and remain in each preceding temporal increment. H) Number of ecoregions versus the percent of a country's ecoregions protected. No trend is found for countries with many ecoregions to differ greatly from those with few.

Figure 2. A full description of the IUCN I/VI protected area network for the United States.

Variables include elevation, slope, distance to roads, distance to urban areas, species richness, and agricultural suitability. The x-axis corresponds to the variable being measured. The y-axis is the difference between the proportion of the country at each interval and the proportion of the network at the same interval. Values greater than zero (dashed horizontal line) indicate a disproportionate level of protection, while values less than zero indicate a disproportionate absence of protection. Visualizing network distributions in this way allows one to see discrepancies in protection across wide ranges of variables at a high resolution.