| Protected areas(PAs)represent one of the most important conservation strategies for reducing biodiversity loss.The number of PAs has risen remarkably over the last few decades.Yet,biodiversity is still being lost at alarming rates,even within many of those PAs.Furthermore,studies have demonstrated that not all PAs are effective in eliminating human pressure on biodiversity.Hence,understanding the factors that determine the levels of human pressure within PAs remains a key objective.In this thesis,I examined the factors that influence the levels of human settlements within PAs at the global level.Using the random forests technique,an ensemble machine learning method,and a vast number of PAs(ranging from 81,100 to 137,523),I assessed the importance of nine factors in determining the levels of human settlements within PAs including their management objective as reflected by their IUCN Category.The International Union for Conservation of Nature(IUCN)classifies PAs into six categories that range from strict nature reserves to areas in which multiple human uses are allowed.The common but untested assumption is that the human settlements’ levels within PAs are determined largely by their management objective,with less strict PAs having higher levels of settlements.My results,though,show that the differences between the categories were,for the most part,minor.The largest determinant of human settlements within PAs was accessibility,measured as the time required to reach the PA from the nearest urban center.These results were consistent across all of the subregions of the world examined.Other less important factors included the extent of cropland within PAs and their mean elevation and slope.My findings suggest that PAs located nearer urban centers are more likely to have higher levels of human settlements,irrespective of their other characteristics(such as management objective and year of establishment).Therefore,managing those PAs successfully will be necessary for achieving the post-2020 biodiversity targets,which are expected to be adopted at the upcoming 15 th Conference of the Parties(COP-15),in Kunming,China. |
