Bwa-yo - Société Audubon Haiti

Piyon 149
Table 17.2 Equations used to estimate biomass components (dry weight) of G. sepium in Haiti.
COMPONENT REGRESSION EQUATIONI R 2 d RANGE SITE
(em)
Total aboveground biomass
Usable wood weight
Usable wood weight
0.085Ld;
0.079Ld;
0.021hLd;
(cross-site regression)
0.98
0.98
0.96
1.8 - 8.1
1.8 - 8.1
1.8 - 15.3
Nan Marron
Nan Marron
10 world-wide sites
wi 1 in Haiti
I d =Stem diameter measured at 0.3 m above ground level, in em. h =Total tree height, in m. n = Number of stems at
0.3 m above ground
ease problems have been associated with this species in Haitian nurseries.
Biomass Studies: Equations to estimate the yield oftotal and wood biomass of G. sepium
are provided in Table 17.2. The study was conducted in 1990 at Nan Marron in
northwest Haiti. These equations allow one to estimate the amount of total and wood
weights, in dry kilograms, based on stem measurements. Stewart et al. (1992) published
a cross-site equation to estimate wood yield forthe species based in part on data collected
from the Nan Marron site.
Growth Performance: G. sepium was established in several species trials during the
1980s. The species has exhibited very mixed results, failing or showing poor growth on
most ofthe sites (Table 17.3). Height growth is inferior to most ofthe tree species con::'
sidered for timber, hardly achieving annual height increments of 1 m yr-l (Fig. 17.6).
Reasons for this performance are not easily understood, except that the species does not
appear as drought hardy as one would expect from reading the literature. Furthermore,
factors such as stock quality and genetic source ofthe seed seem to have been underestimated
as they influence the productivity of G. sepium greatly. Significant differences
between the survival and early growth ofseedling stock compared with rooted cuttings
were observed at Lapila (Fig. 17.4). Whereas, rooted cuttings exhibited an average 85%
survival rate and 2.5 m height growth in 18 months, seedlings averaged 40% survival
and grew to only 1.5 m. Since much of the seed is imported from Central American
Table 17.3 Site and growth parameters of G. sepium trials in Haiti.
SITE ELEVATION ANNUAL AGE SURVIVAL HEIGHT d 2 DRY WOOD
(m) RAINFALL (yr) (%) M.A.I. l M.A.I. YIELD
(nun) (m) (em) (kg tree· l )
Lapila 350 1145 1.6 85 1.6
Paillant 600 1300 2.0 22 0.2
Cabaret 80 900 2.0 38 0.4 0.7 0.2
Jean Rabel 107 1045 2.9 23 0.6 1.1 0.8
Marmont 280 1450 3.0 72 1.4 1.5 3 1.7
Cabaret 80 900 3.3 52 0.5
MareGrand Bois 20 1200 3.3 12 0.4 0.9 '0.2
Fond-des-Blancs 250 1335 4.0 49 0.6 0.8 0.4
Papaye 250 1450 4.4 40 1.0 1.0 1.8
Nan Marron 450 600 4.8 96 0.7 1.0 1.5
I M.A.I. =Mean annual increment. 2 d =Stem diameter measured at 0.3 m above ground level, in em. 3Stem diameter at
1.3 ill above ground level, in em.