Threats impact levels to 98 tropical African protected areas at a continental and regional scale.

<p>Clockwise from top: Africa (a), Central Africa (b), East Africa (c) and West Africa (d).</p

Influence of tourism activities and PA size on threat level in 83 PAs.

<p>In bold are highlighted significant values (p <i><0.05</i>). See abbreviations in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114154#pone-0114154-t002" target="_blank">Tab 2</a>. AIC, Akaike's Information Criterion; AICw, Akaike Information Criterion weight; Rank, model rank from the smallest to the largest AIC value; k, number of variables including the intercept.</p><p>Influence of tourism activities and PA size on threat level in 83 PAs.</p

Proportion of protected areas with conservation activities between 1990 and 1999 across different African regions.

<p>The number of protected areas with available information on presence and absence of any conservation activity (research, tourism and law enforcement guards) over the considered period were in total 105.</p

Influence of law enforcement activities and PA size on threat levels in 90 PAs.

<p>In bold are highlighted significant values (p <i><0.05</i>). See abbreviations in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114154#pone-0114154-t002" target="_blank">Tab 2</a>. AIC, Akaike's Information Criterion; AICw, Akaike Information Criterion weight; Rank, model rank from the smallest to the largest AIC value; k, number of variables including the intercept.</p><p>Influence of law enforcement activities and PA size on threat levels in 90 PAs.</p

Regional distribution of the protected areas (PAs) in tropical Africa considered in the analyses.

<p>The regions are coloured in different grey scale colours. Light grey represents West Africa, including 54 protected areas; medium grey represents Central Africa, including 31 protected areas; dark grey represents East Africa, including 14 protected areas. On the left-side bottom corner a MODIS NDVI image of Africa, with a red quadrant highlighting the tropical area considered in the study.</p

Influence of research activities and PA size on threat level in 92 PAs.

<p>In bold are highlighted significant values (p <i><0.05</i>). See abbreviations in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0114154#pone-0114154-t002" target="_blank">Tab 2</a>. AIC, Akaike's Information Criterion; AICw, Akaike Information Criterion weight; Rank, model rank from the smallest to the largest AIC value; k, number of variables including the intercept.</p><p>Influence of research activities and PA size on threat level in 92 PAs.</p

Symmetric matrix with Spearman's correlation between all threat impact levels recorded in 98 protected areas.

<p>In bold are highlighted significant correlations (<i>p</i><0.0001) following post hoc test Bonferroni correction (<i>p</i> = 0.05/78). Abbreviations: coh, commercial hunting; suh, subsistence hunting; agr, agriculture; fuw, fuel wood; inf, infrastructure; has, human settlement around; his, human settlement inside; war, war; dis, disease; fir, fire; min, mining; log, logging.</p><p>Symmetric matrix with Spearman's correlation between all threat impact levels recorded in 98 protected areas.</p

Estimated change in elephant dung density (/km²) distribution during 2002–2011 across the Central African forests.

<p>Results are shown as a percentage of the total area of potential elephant habitat overall (A & B) and by country (C & D) for the predictive model with variables: (A & C) survey year, Human Influence Index, corruption and the presence/absence of guards, and (B & D) survey year, proximity to road, human population density, corruption and the presence/absence of guards. The dung density (per km²) intervals are unequal and correspond to the following elephant population categories: extremely low density (0–100), very low (100–250), low (250–500), medium (500–1,000), high (1,000–3,000) and very high (3,000–7,500). With the loss of very high elephant populations in 2011, there is a significant shift into the lower density intervals over the nine years.</p

Elephant dung density and range reduction across the Central African forests.

<p>Predictions are shown for (A) 2002 and (B) 2011 for the model with variables: survey year∧, Human Influence Index***, corruption*** and the presence/absence of guards***, and (C) 2002 and (D) 2011 for the model with variables: survey year∧, proximity to road∧, human population density***, corruption*** and the presence/absence of guards*** (P-values are: ‘***’ <0.001 and ‘∧’ <0.1). Increasingly darker shades of green correspond to higher densities, grey represents extremely low elephant density range (the first interval: 0–100 elephant dung piles/km²) and white is non-habitat (80 survey sites outlined in red). Cutpoints are: 0; 100; 250; 500; 1,000; 1,500; 3,000; 5,000; and 7,500 dung piles/km². Countries 1–5 are: Cameroon; Central African Republic; Republic of Congo; DRC; Gabon.</p

Encounter rate of elephant dung per kilometre.

<p>Results are shown for the 80 survey sites in Central Africa included in this study. Grey shading represents forest cover.</p