Table 1. Explanatory variables and associated hypotheses for analyses of forest change in Puerto Rico.
| |
| |
|
Explanatory Variables |
Data Source |
Hypothesized
Relationship |
Rationale |
| |
|
Socioeconomic |
|
|
|
Population density
(1980, 1990) |
U.S. Census |
+ Defor
- Refor |
Higher population density will be associated with greater land use
intensity. |
Population density change
(1980-1990, 1990-2000) |
U.S. Census |
+ Defor
- Refor |
Urban-rural migration may drive deforestation for suburban development
(MacDonald and Rudel 2005). |
Normalized per capita income
(1980†, 1990) |
U.S. Census |
+ Defor
- Refor |
Rising local incomes may be associated with higher local land use intensity
and suburbanization (Margo 1992). |
Normalized income change
(1980-1990†, 1990-2000) |
U.S. Census |
+ Defor
- Refor |
Short-term increases in local income may reflect suburban development
(Parés-Ramos et al. 2008). |
|
Percent of area in reserve/protected area |
GAP (Gould et al. 2007) |
- Defor
+ Refor |
Protected areas can deter forest cover change (Helmer 2004). |
|
|
|
|
|
|
Biophysical |
|
|
|
|
Life zones |
USGS (2009) |
w/ ↑Moisture,
- Defor
+ Refor |
Precipitation is likely to affect vegetation dynamics and favor regrowth
(Daly et al. 2003) or alternatively, reforestation may be slower in drier
areas because of fires (Brandeis et al. 2007). |
|
Median slope |
USGS (2009) |
- Defor
+ Refor |
Slope affects development and agricultural cost (Turner et al. 2009,
Crk et al. 2009). |
|
Median soil agricultural capacity (1 is most fertile, 10 is least
fertile) |
USGS NRCS (2007) |
+ Defor
- Refor |
Marginal lands are often the first areas to reforest because they are more
likely to be abandoned than areas with high quality soil (Mather and Needle
1998). |
Total forest cover
(1977, 1991) |
IITF/USDA Forest Service |
+ Refor |
By facilitating seed dispersal to abandoned sites, the extent and spatial
distribution of forest cover can influence the rate of forest recovery
(Thomlinson et al. 1996, Helmer et al. 2008, Crk. et al.
2009). |
|
| |
† Per capita income data for 1980 only available at the municipality scale.
IITF = International Institute of Tropical Forestry
|