title: Analysis of biophysical and anthropogenic variables and their relation to the regional spatial variation of aboveground biomass illustrated for North and East Kalimantan, Borneo.
abstract: BACKGROUND
  Land use and land cover change occurring in tropical forest landscapes contributes substantially to carbon emissions. Better insights into the spatial variation of aboveground biomass is therefore needed. By means of multiple statistical tests, including geographically weighted regression, we analysed the effects of eight variables on the regional spatial variation of aboveground biomass. North and East Kalimantan were selected as the case study region; the third largest carbon emitting Indonesian provinces.
  
  
  RESULTS
  Strong positive relationships were found between aboveground biomass and the tested variables; altitude, slope, land allocation zoning, soil type, and distance to the nearest fire, road, river and city. Furthermore, the results suggest that the regional spatial variation of aboveground biomass can be largely attributed to altitude, distance to nearest fire and land allocation zoning.
  
  
  CONCLUSIONS
  Our study showed that in this landscape, aboveground biomass could not be explained by one single variable; the variables were interrelated, with altitude as the dominant variable. Spatial analyses should therefore integrate a variety of biophysical and anthropogenic variables to provide a better understanding of spatial variation in aboveground biomass. Efforts to minimise carbon emissions should incorporate the identified factors, by 1) the maintenance of lands with high AGB or carbon stocks, namely in the identified zones at the higher altitudes; and 2) regeneration or sustainable utilisation of lands with low AGB or carbon stocks, dependent on the regeneration capacity of the vegetation. Low aboveground biomass densities can be found in the lowlands in burned areas, and in non-forest zones and production forests.
authors.affiliation: Copernicus Institute of Sustainable Development, Group Energy and Resources, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands.
authors.forename: Carina
authors.initials: C
authors.lastname: Van der Laan
authors.affiliation: Copernicus Institute of Sustainable Development, Group Energy and Resources, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands.
authors.forename: Pita A
authors.initials: PA
authors.lastname: Verweij
authors.affiliation: SarVision BV, Agro Business Park 10, 6708 PW Wageningen, The Netherlands.
authors.forename: Marcela J
authors.initials: MJ
authors.lastname: Quiñones
authors.affiliation: Copernicus Institute of Sustainable Development, Group Energy and Resources, Utrecht University, Heidelberglaan 2, 3584 CS Utrecht, The Netherlands.
authors.forename: André Pc
authors.initials: AP
authors.lastname: Faaij
keywords: Aboveground biomass; Biophysical and anthropogenic variables; Disturbance; East Kalimantan; Geographically weighted regression; Multiple regression; North Kalimantan; Spatial analysis; Tropical forest landscapes