Proceedings of the Workshop - Georg-August-Universität Göttingen

The difference in the same pool over a particular period of time is obtained per hectare,
in which case it is estimated by:
where
,
Annual change of carbon storage in ton/year.
Carbon storage in the pool during the period i
3. Results & Discussion
3.1. Evaluation of cartographic precision in the detection of land-use change
The reliability of the maps elaborated for detecting modifications in land-use was
estimated by calculating the Kappa index. This index calculates the error associated to
the assignation of different categories of land-use in the photo-interpreted polygons not
visited in the field. A Kappa index of 0.88 was determined with an overall acceptability
of 0.96, which provides an adequate level of reliability in the allocation of the different
types of land-use.
3.2. Land-use changes
The analysis for each study period shows that the category of land-use corresponding
to urban and industrial areas is the one with the largest surface of change (20%) from
1993 to 2007. This urban growth is shown in studies such as the Araucanía region
development strategy; in which, an intense migration from the countryside to the city is
suggested, reaching a total of 67.7% (INE 2002) and focused primarily in the city of
Temuco.
The Forest land-use is still changing in the surface area, increasing by 13%
between 1993 and 2007 (Table 1).
The land-uses that reduce their share are mainly agricultural land and
unrecognized areas by 12.5 and 10.7% respectively. Agricultural land-use category
decreased mainly due to surface transfer to the plantations sub-use category. Other
land-uses that decreased are shrublands/grasslands and wetlands with 9% and 4%
during the period 1993-2007.
Table 1. Surface area per category of land-use to each studied year (ha, %)
Land use
1993 2007 Change
Surface (ha) (%) Surface (ha) (%) Surface (ha) (%)
1Cities ad Towns 11409.1 0.4 13696.9 0.4 2287.8 20.1
2 Agricultural lands 932431.8 29.1 815602.2 25.4 -116829.6 -12.5
3 Pasture and Shrubland 675153.9 21.2 611686.5 19.2 -63467.4 -9.4
4 Forest 1369494.3 43.0 1548934.4 48.7 179440.1 13.1
5 Wetlands 27717.4 0.9 26507.3 0.8 -1210.1 -4.4
6 Areas without vegetation 78740.9 2.5 78047.2 2.5 -693.7 -0.9
7 Snow and Glaciers 31032.4 1.0 30896.6 1.0 -135.8 -0.4
8 Lakes- lagoons-Rivers 55405.3 1.7 56018.2 1.8 612.9 1.1
9 Unrecognized Areas 39.1 0.0 34.9 0.0 -4.2 -10.7
Total 3181424.2 100.0 3181424.2 100.0 0.0 0.0
‐ 22 -