Multiple regression analysis using ANCOVA (analysis of covariance) was performed to detect possible associations between land cover change, and socio-economic and biophysical variables at the level of individual villages which can considered as homogeneous units in terms of ethnicity, livelihood and biophysical setting. ANCOVA is a widely applied technique as it allows evaluating BMS-777607 solubility dmso the combined effect of a range of both categorical and numerical predictors
(Maneesha and Bajpai, 2013). ANCOVA was performed for each one of the four land cover change types (deforestation, reforestation, land abandonment, and expansion of arable land) as the dependent variable. A multicollinearity test was carried out to detect correlation between explanatory
variables. Multicollinearity diagnostics were performed by calculating the Variation Inflation Factors (VIF) and the Tolerance (TOL). In this study, variables with VIF greater than 2 and TOL less than 0.6 are excluded from the analyses as proposed by Allison (1999). The final models included ethnicity and effect of preservation as categorical variables; engagement in tourism, cardamom cultivation, poverty rate, population click here growth, slope, distance to rivers, distance to main road and distance to Sa Pa town as numerical variables (Table 3). ANCOVA model parameters were estimated using XLSTAT software, and the explanatory power of the ANCOVA models was assessed by the Goodness of fit statistics, R2. Fig. 2 shows the land cover maps for the years 1993, 2006 and 2014. The overall accuracy of the land cover classification was assessed at 80.0%, 86.4% and 84.6% (quantity disagreement of 5.0%, 2.8%, 4.4% and allocation disagreement of 15.0%, 10.8%, 11.0%) for the land cover maps of 1993, 2006 and 2014, respectively. crotamiton The land cover pattern in Sa Pa district is strongly determined by the topography. Valleys are generally cultivated. Steep slopes and mountain peaks are predominantly covered by forests or shrubs. Patches of forest are concentrated
on the Hoang Lien mountain range in the southern part of Sa Pa district, and are also found on remote steep slopes. Shrubs are widely distributed, and can be found in valleys, mountain peaks or on steep slopes. Between 1993 and 2014, the overall area covered by forest and arable land increased slightly (with respectively +3% and +2%) while shrubs decreased with −5% (Fig. 2D). However, land cover changes are not linear in SaPa district, and there exist substantial temporal differences. During the first period (1993–2006), the study area experienced a general trend of deforestation for expansion of arable land. Between 1993 and 2006 the area covered by forest decreased by −1% while arable land increased by +4%, respectively. The deforestation tendency seems to be reversed after 2006 in Sa Pa district.