Dinâmica de reflorestamentos visando a restauração da paisagem... 
hl tlie years of 92, 94 and 95, 1 plot was laimched in an area witii no 
addition of siirface soil, and in the years of93 and 96, 2 sucli plots. 
The paraineters calcidated were: (i) diversity and abundance, (ii) 
current yearly mortality, (iii) diameter growtli and corresponding 
current yearly increase, (iv) annual current increase of basal area. 
There was a decrease in nuniber of species being monitored in 
reforestations undertaken in 92, 94 and 96, respectively of 2, 2 and 
17 species. The niimber of individuais being monitored remained 
unchanged only in the plantings ofSl, 84 and 86 - it decreased in the 
reinaining ones. Mortality in plantings in areas with surface soil, for 
all ages under analysis, was always lower than I07c, as opposed to 
what was observed in plantings with no surface soil - except for the 
yearof 1994, when the rate was 2.1%. Increase in growth of diameter 
in the I980s ranged from +0.27 (in 1982) to +7.05% (in 1984). But in 
the 1990s it ranged from +11.04% to + 166.327o (in 1996), in 
reforestations with surface soil; where no surface soil was added, 
limits ranged from +15. 527c (1994) to + 192.3 17o (1996). Current 
increase in basal area was positive in practically all years of the 
study (with or without addition of surface soil) excepting 1982. 
KEY WORDS; Heterogeneous reforestation, Permanent plot, Forest 
dynamics, Forest restoration, Degraded area, Bauxite mining, Amazon. 
INTRODUÇÃO 
Na região dc Porto Trombetas, munieípio de Oriximiná (PA), a 
Mineração Rio do Norte (MRN), promove a lavra a céu aberto da 
bauxita desde a década de 70. O minério encontra-se no subsolo de 
uma área coberta pela floresta tropical densa, da sub-região dos baixos 
platôs da Amazônia, domínio da floresta densa das baixas altitudes 
cuja fisionomia apresenta dois estratos distintos: um emergente e outro 
uniforme. Trata-se de uma floresta que se destaca no bioma amazônico 
por apresentar alta diversidade arbórea e valores altíssimos de biomassa 
(Salomão & Santos 1997, Salomão eí al. 1999) e, também, elevado 
volume de madeira de grande valor comercial (Projeto Radambrasil 
1976). 
Para a extração da bauxita é necessário remover toda essa 
vegetação, pois a mesma encontra-se entre 4-6 m de piolundidade. De 
159 
cm 
SciELO 
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