increased number of tree species. Finally, in the old Casuarina stand and the
tropical dry forest we found that 90 % of the species that we recorded were trees.
Interestingly, we found a larger number of trees species in the old Casuarina
stands than in the tropical dry forest.
Species composition was also different in the study plots. In the young stand,
herbs (Urochloa maxima, Commelina erecta, Palafoxia lindenii), shrubs and small
trees (Citharexylum ellipticum, Solanum diphyllum, Trixis inula, Lycianthes lenta,
Malvaviscus arboreus, Bursera simaruba), and woody climbers (Gonolobus
barbatus and Passilfora spp.) were found. Mature stands have a similar number of
herbaceous and woody species as the young stand, but species richness and
Study plots
Study plots
C a s a u r in a o n f o r e d u n e
Y o u n g p lo t s
M a t u r e p lo t s
O ld
p lo t s
T r o p ic a l f o r e s t
Species richness
0
5
10
15
20
25
C a s a u r in a o n f o r e d u n e
Y o u n g p lo t s
M a t u r e p lo t s
O ld
p lo t s
T r o p ic a l f o r e s t
Shannon Diversity Index
0.0
0.5
1.0
1.5
2.0
2.5
3.0
(a)
(b)
Fig. 14.3 a Species richness
and b diversity values
(Shannon diversity index) for
the five stands. Highest
diversity and species number
were found in the tropical dry
forest and in the older
Casuarina plots
14 The Impacts on Natural Vegetation
223