Combining Terra-i and Co$ting Nature to examine ecosystem service impacts of deforestation in Colombia
By Mark Mulligan, King’s College London
The latest update of Terra-i has been used with the Co$ting Nature ecosystem services assessment tool to understand the impacts of recent forest loss in Colombia on biodiversity and ecosystem services.
Co$ting Nature is a web based tool for natural capital accounting and analysing the ecosystem services provided by natural environments (i.e. nature’s benefits), identifying the beneficiaries of these services and assessing the impacts of human interventions. This policy support system (PSS) is a testbed for the development and implementation of conservation strategies focused on sustaining and improving ecosystem services. It also focused on enabling the intended and unintended consequences of development actions on ecosystem service provision to be tested in silico before they are tested in vivo . The PSS incorporates detailed spatial datasets at 1-square km and 1 hectare resolution for the entire world, spatial models for biophysical and socioeconomic processes along with scenarios for climate and land use. The PSS calculates a baseline for current ecosystem service provision and allows a series of interventions (policy options) or scenarios of change to be used to understand their impact on ecosystem service delivery. We do not focus on valuing nature (how much someone is willing to pay for it) but rather costing it (understanding the resource e.g. land area and opportunity cost of nature being protected to produce the ecosystem services that we need and value).
Though we provide input data for application of this model anywhere globally (from remote sensing and other global sources) users can also use this model with their own datasets. Application with the provided datasets takes only half an hour and requires no Geographical Information Systems (GIS) capacity. Bringing in your own datasets will take much longer depending on the availability, level of processing, format and consistency of those datasets and also requires GIS capacity.
Typical applications include ecosystem service assessment, conservation prioritization, analysis of co-benefits e.g. for REDD+ and analysis of pressures and threats on carbon and biodiversity in general or for specific planned agricultural, industrial or extractive interventions.
Deforestation in Colombia 2004-2015
Figure 1 shows that rates of deforestation for Colombia (% land per year) differ between the various deforestation datasets with GFC showing a mean of 0.18%/yr, FORMA showing 0.12 %/yr and Terra-i showing 0.069 %/yr. Terra-i indicates deforestation on 0.82% of land in the period 2004-March 2015 distributed as shown in Figure 2. Deforestation is concentrated in the Colombian Amazon, parts of northern Colombia and the Magdalena Valley and the Pacific Coast. Deforestation in the cloud forest zones is likely underestimated because of observation limitations caused by cloud frequency in these areas.
We use these data in Co$ting Nature to produce an historic land use change scenario and better understand the impact of this change on Colombia’s ecosystem services. The scenario applied is as shown below in figure 3. The scenario reduces tree cover by 80% in all pixels that Terra-i observed deforestation and replaces the previous land use with the most suitable according to the GAEZ agricultural suitability maps.
Impacts on Ecosystem Services
The resulting scenario leads to changes in biodiversity and ecosystem services. Areas in which ecosystem services decrease as a result of this deforestation are shown in figure 4. Carbon services decrease greatest (green and blue colours) in dense montane and lowland forests. The greatest impact on water services is where deforestation occurs close to (upstream of) large population centres eg Cali. Hazard mitigation services decrease greatest wherever there is infrastructure downhill and downstream of deforestation e.g. throughout the Andean foothills .
Counter-intuitively deforestation leads to increases as well as the expected decreases (as reported here). Where ecosystem services increase this is because deforestation adds infrastructure (agricultural land) and people that utilise services that were not utilised before. A service is not a service until it is used. Figure 5 shows that the bundle of services (water, carbon, hazard mitigation) decreases where deforestation occurs in or upstream of areas with existing human infrastructure (llanos, Andes) but increases in other areas where there was relatively little previous infrastructure eg Amazon, Pacific lowlands.
Costing Nature estimates that the 11 years of deforestation shown by Terra-i has put some 280M tonnes of carbon stock under threat, which is around 3.7 times the CO2 emissions of nearly 76 million tonnes of CO2 per year reported for Colombia in 2011. Annual deforestation puts under threat the equivalent of 34% of Colombia’s annual CO2 emissions.
Impacts on Biodiversity
Deforestation is also expected to impact on biodiversity. Expected decreases in the Co$ting Nature biodiversity index are greatest in the Amazon (green and blue colours) where the (combined richness and endemism) index is generally greatest.
Costing Nature estimates that this deforestation in the last 11 years has put some 9% of Colombia’s known species richness under threat and a further 11% of the country’s known endemics under threat.
Both deforestation data and ecosystem services data are subject to uncertainty but simple analyses like the one shown here can indicate the pressure points on ecosystem services that deforestation creates, even in a short period like 11 years.