Landscapes Forest and Global Change - ESA - Escola Superior ...

M.B. Horta & E. Keizer 2010. Assessment of human and physical factors influencing distribution of vegetation degradation
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The presence and absence of damaging activities was verified through the marks and signs of
fire, cutting, free grazing, fences, tracks and garbage. In order to investigate the relationship
among the variations in vegetation degradation (scores) and human and physical factors,
regression and correlation analysis were performed using SPSS software. The significant factors
comprised those that presented p values significant at α = 0.05, for a one-tailed test.
3. Result
The results of the categorization of the 28 sample plots of the forest areas into vegetation
degradation conditions are presented in the Table 1. From the total of areas sampled, 28% were
classified as extremely degraded (4), 36% as highly degraded (3), and 36% were found
moderately degraded (2). The forest intermediate stage (FIS) presented 60% of the sample plots
classified as highly degraded and 40% as moderately degraded. The forest advanced stage
(FAS), otherwise, comprehended 40% of sample units classified as highly degraded and 60% as
moderately degraded. The scrub areas (S) were all (100%) classified as extremely degraded.
For the savannah (SA) and rocky shrublands formations (RS), in the totality of 19 sample plots,
10 % were found extremely degraded (4), 6% presented highly degraded (3), 37% were
classified as moderately degraded (2), 37% low degraded (1) and 10% not degraded (0) (Table
2). The savannah had 9% of the sample plots classified as highly degraded, 46% as moderately
degraded, 36% as low degraded and 9% as not degraded. The rocky shrublands comprehended
25% classified as extremely
The results of the correlation analysis, obtained from linear regression, for investigation of the
relationship among vegetation degradation scores and human and physical factors, in the forest
areas, are shown in the Table 3. The physical factor slope presented a significant negative
correlation coefficient (R2 = - 0.223; p = 0.011) to vegetation degradation in the forest areas.
The correlation analysis results for the savannah and rocky shrublands formations (Table 4)
showed that the human factor distance to tourist sites was the one that presented a significant
correlation (R2 = - 0.250; p = 0.029) to vegetation degradation.
Activities of cutting and grazing were found in higher proportion in the FIS (60% and 50%
respectively) and FAS (40% and 70%), while the presence of fire was evidenced only in the FIS
(10%). Signs of fire occurred in higher proportion in the scrub (100%), savannah (100%) and
rocky shrublands (100%). Grazing activities were also testified as important in those areas,
occurring in 88% of the scrub, 90% of the savannah and 75% of the rocky shrublands areas.
Indicators of mining activities, on the other hand, were restricted to the rocky shrublands areas
(25%), due to the presence of the rock substrate, especially quartzite, target of exploitation.
Besides that, garbage signs (cans, plastics, etc) resulted from tourist activities were observed
only in the rocky shrublands (25%). From the 47 sampled areas 87% showed the presence of
tracks, and 81% the absence of fences.
Table 1: Categorization of sample plots of the forest areas according to vegetation degradation indicators
(Ia – Invasive Species Cover; Ib - Understory Cover; Ic – Canopy Cover)
Sample
Vegetation Degradation Vegetation Degradation
Type Ia Ib Ic
Plots
Scores
Classes
1 FIS 2 3 2 -6.816 3
2 FIS 2 2 2 -10.504 2
3 FIS 3 3 2 20.553 3
4 FIS 3 3 2 27.488 3
5 FIS 2 3 3 6.914 3
6 FIS 1 3 2 -21.307 2
7 FIS 3 3 2 29.753 3
Forest Landscapes and Global Change-New Frontiers in Management, Conservation and Restoration. Proceedings of the IUFRO Landscape Ecology
Working Group International Conference, September 21-27, 2010, Bragança, Portugal. J.C. Azevedo, M. Feliciano, J. Castro & M.A. Pinto (eds.)
2010, Instituto Politécnico de Bragança, Bragança, Portugal.