Impacts of progressive deforestation

Introduction

Here we use Costing Nature (v. 2.46) and its land use change model to look for thresholds in biodiversity and ecosystem service loss on progressive deforestation in an area comprising lowland and montane environments in Peru, Ecuador, Colombia and Brazil.  The deforestation scenario uses recent rates to project forward a progressive forest loss and replacement with cropland.  The scenario applied was:



This leads to the following timeline of forest cover change from baseline,50,150 and 200 years:

Tree cover change

 baseline
 50
 150
 200


Results

 Years* Tree cover
%		 Carbon stock
(t/km2)		 Water pollution (%)
Potential bundled services index
(0-1)
 Realised bundled services index
(0-1)		Species richness (amphibians, reptiles, mammals, birds)
0 (baseline) 67 13722 8.3 0.682 0.306 710
 50 62 13554 13.6 0.648 0.310 706
 100 60 13464 16.3 0.633 0.313 701
 150 57 13366 19 0.62 0.316 696
 200 54 13234 22.6 0.60 0.321 690
*(all tabulated values are mean for the study area)

All variables decrease in a mildly non-linear way according with the geographical variation of the variable in question compared with the areas converted.  Tree cover declines by  13%, carbon stock by 3.6%, water pollution increases by 14% (with initial increases the most significant).  The potential bundled ecosystem services index declines as one might expect but the realised ecosystem, services index actually increases slightly on conversion.  This is explained by the fact that conversion brings more agriculture and associated infrastructure meaning that realised hazard mitigation services from the remaining forests increase.  Species richness declines more or less linearly reflecting the smooth distribution of species ranges in this area in comparison with the pattern of deforestation and the fact that v 2.46 does not account for the effect of edges on species loss (or carbon loss).