Valuing the Ecosystem Services Provided by the Natural Capital of Soils - A Systems Modelling Approach

Since April 2007, Estelle has been undertaking PhD research jointly through NZCEE and AgResearch (Agriculture & Environment Group). The aim of Estelle Dominati’s research is to determine the “value” of the ecosystem services provided by soils and use this as a basis for valuing the soils natural capital. This research will focus on developing an understanding of the linkages between soils attributes and functions and soils ecosystem services.

Different classifications of ecosystem services exist in the literature (Daily, 1997; de Groot, 2002; Constanza, 1997). However, classifications of soil services are scarce (Daily, 1997; Sandhu, 2008; Vesely, 2006) and quite often the differences between soil processes (“functions of”) and soil services (“functions for”) are confused.

The challenge of this research is to assemble in a more structured way the suite of ecosystem services provided by soils through the linking of soil attributes and the major bio-chemical cycles of soils with the soils ecosystems services.

We have a good understanding of soil forming processes (Molloy, 1993) and of the soil factors influencing the water, nitrogen, carbon and phosphorus cycles (McLaren, 1990; Stevenson, 1999). Using this knowledge, we will link soil forming processes to soil attributes described by pedologists, and in association with soil processes link these to, and aggregate to soil services.

We aim to build a model that will link the factors of soil formation (time, climate, parent material, topography, organisms and land uses), soil attributes (texture, pH, carbon content…), soil processes (mineralisation, denitrification…) and soil agro-ecoservices (once identified).

Once the soil services have been identified and quantified, we will value these services and, through the links between soil attributes and functions, attempt to link soil properties values to the economic value of the services provided. Several valuation methods will be utilised to explore the sensitivity of the valuation to the method employed.

The research focus is at the farm level, and more specifically on valuing the services provided by soils on dairy farms. Two locations have been selected to represent soils with distinct differences: the Manawatu, with the Tokomaru silt loam, a Pallic soil; and the Waikato, with the yellow-brown loam, an Andisol. The choice of landscapes in these two regions is not random: These two soil types exhibit mark differences in their origins, parent materials, texture and structure, P chemistry, N dynamics, and resilience that influence the way they are farmed. We are expecting to detect major differences in the value of the services provided by these two soils and by default in their natural capital. 

At this stage in the development of the thesis, little consideration has been given to considering the subject beyond the farm scale. This may become necessary if we are to value all the services or lack of, because the influence of the farm extends beyond the property boundary (e.g. Emissions).

Contact Estelle Dominati for more details.