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RESULTS AND DISCUSSION
Species diversity, endemism and relic status
The Western Ghats constitute one of the unique biological regions of the world with high level of endemism in flora and fauna. Kathalekan landscape is one of well wooded hills and valleys. A small area of 2.25 km2 studied using 18 transects (covering 3.6 ha) had 132 tree species of 92 genera and 37 families. In the 10 sub-quadrats/transect (each 5 × 5 m) for enumerating shrubs and tree saplings, covering altogether 0.45 ha, 33 families, 59 genera and 66 species were recorded. Although survey of herbs requires repeated visits we could, nevertheless, in a short period observe 169 species belonging to 110 genera and 40 families. We also recorded 31 species of lianas and climbers belonging to 30 genera and 22 families.
Through nine transects in the NSSF, we recorded 1335 trees belonging to 97 species of 37 families; from nine transects in the SSF was recorded 1026 trees belonging to 81 species of 27 families. Fig. 12 depicts species-area relationship. The average tree number per transect was higher (148) in NSSF than SSF (114). Dipterocarpaceae is the leading NSSF family with 328 trees of only two species viz. Hopea ponga and Dipterocarpus indicus, followed by non-swamp species of Myristicaceae (108 trees), mainly Knema attenuata and small numbers of Myristica malabarica,and M. dactyloides. Myrtaceae follows with 108 trees, of various species of Syzygium. S. gardneri, a well established climax species of the region is the most dominant. The edges of swamps and streams in the SSF are also dominated by Dipterocarpaceae (206 trees), followed by swamp exclusives M. magnifica, Gymnacranthera canarica, of Myristicaceae (196 trees) exclusive to the swamp proper. Cornaceae (97 trees) is represented by Mastixia arborea. Exclusive to the SSF are also Semecarpus kathalekanensis and Syzygium travancoricum. Distribution of some notable relic species in the nine grids is given in Table 4. Only small number of trees species, having special adaptations in their root systems and physiology to cope up with the anaerobic conditions of the swamp (Hook and Scholtens 1978; Kozlowski 1982). Table 5 and Table 6 provide details on tree diversity in SSF and NSSF respectively and family-wise tree numbers are given in Fig. 13. Shannon-Weiner diversity index is higher for NSSF than SSF. Chandran and Mesta (2001) had also reported low diversity of Myristica swamp forests.
Fig. 12. Species-area relationship (NSSF and SSF species)
| Table 4. Distribution of some relic tree species in the nine grids of Kathalekan, central Western Ghats, India. |
| Grid # |
Di |
Pa |
My |
Gy |
Mf |
Hb |
Se |
Sy |
| 1 |
+ |
+ |
+ |
+ |
+ |
+ |
|
|
| 2 |
+ |
+ |
+ |
+ |
+ |
|
|
|
| 3 |
+ |
+ |
|
+ |
+ |
|
|
|
| 4 |
+ |
+ |
+ |
+ |
|
|
|
+ |
| 5 |
+ |
|
+ |
+ |
|
|
+ |
+ |
| 6 |
+ |
+ |
+ |
|
|
+ |
+ |
+ |
| 7 |
+ |
+ |
+ |
+ |
+ |
+ |
|
+ |
| 8 |
+ |
|
+ |
+ |
|
+ |
|
+ |
| 9 |
+ |
+ |
+ |
|
|
|
|
+ |
| Di–Dipterocarpus indicus, Pa–Palaquium ellipticum, My–Myristicamagnifica, Gy–Gymnacranthera canarica, Se–Semecarpus kathalekanensis, Sy–Syzygium travancoricum, Mf–Mesua ferrea, Hb–Holigarna beddomei |
| Table 5. Grid-wise details regarding tree diversity and evergreenness in SSF of Kathalekan, Central Western Ghats, India. |
| Grid # |
No. of species |
No. of individuals |
% of evergreen trees |
Shannon-Weiner index |
| 1 |
37 |
119 |
99.16 |
2.92 |
| 2 |
27 |
106 |
99.05 |
2.67 |
| 3 |
32 |
117 |
97.43 |
2.74 |
| 4 |
29 |
116 |
99.13 |
2.52 |
| 5 |
21 |
91 |
98.9 |
2.55 |
| 6 |
30 |
125 |
99.2 |
2.76 |
| 7 |
37 |
105 |
99.04 |
3.08 |
| 8 |
29 |
126 |
100 |
2.69 |
| 9 |
33 |
121 |
99.17 |
3.04 |
| Total |
81 |
1026 |
|
|
| Average |
31 |
114 |
99.00 |
|
| SSF–Stream/swamp forest |
| Table 6. Grid-wise details regarding tree diversity and evergreenness in NSSF of Kathalekan, Central Western Ghats, India. |
| Grid # |
No. of species |
No. of individuals |
% evergreen |
Shannon-Weiner index |
| 1 |
41 |
157 |
99.58 |
3.39 |
| 2 |
39 |
173 |
99.42 |
3.18 |
| 3 |
37 |
104 |
91.35 |
3.42 |
| 4 |
38 |
129 |
98.45 |
3.12 |
| 5 |
39 |
158 |
97.47 |
3.16 |
| 6 |
23 |
165 |
98.79 |
2.39 |
| 7 |
44 |
141 |
95.74 |
3.36 |
| 8 |
34 |
113 |
97.35 |
2.91 |
| 9 |
18 |
186 |
98.92 |
1.77 |
| Total |
97 |
1335 |
|
|
| Average |
35 |
148 |
97.45 |
|
| NSSF–Non-stream/swamp forest |
Fig. 13 Family-wise number of trees in SSF and NSSF. For the first 20 families.
Grid-wise details regarding tree endemism are given in Table 7. Number of endemics and percentage of endemism are higher in SSF, highlighting its importance. Endemics that require wetter conditions tend to congregate in the streams and swamp habitats of the relic forest. Of the tree species Semecarpus kathalekanensis that merits inclusion in the IUCN Red List as Critically Endangered, as it is newly discovered and with less than 50 breeding individuals (Vasudeva et al. 2001)and others already Red Listed, such as Syzygium travancoricum and (Critically Endangered), Hopea ponga and Myristica magnifica (Endangered) and Gymnacranthera canarica (Vulnerable) are swamp specific. Chandran and Mesta (2001) had also observed higher tree endemism in the Myristica swamps than in adjoining forests. Details of dominant tree species of NSSF and SSF, according to IVI, are given in the Table 8 and Table 9. Kathalekan is a high evergreen forest reflecting favourable moisture conditions. There is a negligible mix of deciduous trees in the grid 3 of NSSF. Those trees, which lack regeneration under the dense canopy of evergreens, indicate past disturbances.
| Table 7. Grid-wise details of tree endemism in the SSF and NSSF of Kathalekan, Central Western Ghats, India. |
| Forest types |
No. of
transects |
No. of
families |
No. of sp. |
Endemic sp |
% endemic
sp |
Total trees |
% tree
endemism |
| SSF |
9 |
27 |
81 |
36 |
44.5% |
1026 |
71.3% |
| NSSF |
9 |
34 |
97 |
33 |
35% |
1335 |
51.08% |
| SSF–Stream/swamp forest, NSSF–Non-stream/swamp forest |
| Table 8. Leading 10 (in bold) Importance Value Index tree species (grid-wise) in the SSF of Kathalekan, central Western Ghats, India. |
| Trees |
Grid-wise Importance Value Index (IVI) |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
| Gymnacranthera canarica |
45.26 |
17.15 |
64.39 |
99.29 |
47.62 |
-- |
-- |
26.55 |
-- |
| Mastixia arborea |
35.74 |
52.04 |
16.73 |
26.38 |
26.65 |
6.65 |
8.91 |
37.19 |
9.89 |
| Myristica magnifica |
35.33 |
28.11 |
-- |
29.29 |
15.26 |
-- |
-- |
40.84 |
11.82 |
| Syzygium cumini |
15.26 |
-- |
2.74 |
-- |
-- |
-- |
-- |
-- |
-- |
| Dimocarpus longan |
13.63 |
11.46 |
9.64 |
13.60 |
11.36 |
15.17 |
31.38 |
5.37 |
16.77 |
| Pterospermum diversifolium |
13.31 |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
| Syzygium hemisphericum |
8.42 |
20.63 |
11.46 |
4.22 |
-- |
5.27 |
-- |
6.65 |
5.01 |
| Dipterocarpus indicus |
8.11 |
19.57 |
11.19 |
11.16 |
17.09 |
-- |
41.83 |
3.07 |
21.82 |
| Mesua ferrea |
8.08 |
-- |
-- |
-- |
-- |
-- |
4.36 |
-- |
-- |
| Hopea ponga |
7.90 |
27.82 |
41.83 |
11.06 |
29.31 |
62.74 |
-- |
22.89 |
35.75 |
| Syzygium gardneri |
6.01 |
18.94 |
2.74 |
10.96 |
5.28 |
4.44 |
28.90 |
-- |
13.15 |
| Olea diocia |
6.80 |
10.07 |
5.68 |
3.59 |
3.91 |
13.12 |
2.70 |
15.64 |
22.64 |
| Lophopetalum wightianum |
-- |
9.32 |
9.92 |
13.56 |
14.29 |
-- |
-- |
7.48 |
2.45 |
| Calophyllum apetalum |
-- |
-- |
39.27 |
-- |
-- |
7.92 |
-- |
-- |
-- |
| Garcinia gummi-gutta |
-- |
-- |
10.96 |
-- |
7.29 |
19.22 |
6.81 |
-- |
5.16 |
| Calophyllum tomentosum |
-- |
-- |
7.16 |
-- |
26.70 |
6.31 |
-- |
3.01 |
14.37 |
| Syzygium travancoricum |
-- |
-- |
-- |
10.65 |
-- |
25.84 |
-- |
54.83 |
25.86 |
| Hydnocarpus laurifolia |
-- |
-- |
-- |
7.17 |
-- |
12.02 |
5.73 |
8.63 |
-- |
| Semecarpus kathalekanensis |
-- |
-- |
-- |
4.13 |
42.45 |
-- |
-- |
-- |
-- |
| Caryota urens |
-- |
7.09 |
4.21 |
-- |
17.79 |
2.99 |
4.51 |
9.11 |
2.86 |
| Elaeocarpus tuberculatus |
-- |
3.16 |
-- |
-- |
10.02 |
13.62 |
-- |
6.84 |
-- |
| Mangifera indica |
3.17 |
3.19 |
6.66 |
3.09 |
3.88 |
15.15 |
-- |
5.31 |
-- |
| Diospyros candolleana |
5.73 |
3.22 |
2.74 |
-- |
-- |
13.68 |
2.94 |
6.67 |
8.22 |
| Aglaia elaeagnoidea |
5.87 |
3.26 |
2.76 |
-- |
-- |
12.62 |
15.05 |
2.79 |
10.99 |
| Ficus nervosa |
2.85 |
-- |
-- |
-- |
-- |
-- |
14.93 |
-- |
8.85 |
| Holigarna beddomei |
5.01 |
-- |
-- |
-- |
-- |
9.10 |
12.28 |
4.54 |
-- |
| Meiogyne pannosa |
-- |
-- |
-- |
-- |
-- |
-- |
12.14 |
-- |
2.46 |
| Litsea spp. |
6.0 |
7.95 |
-- |
3.15 |
-- |
-- |
11.70 |
-- |
-- |
| Diospyros crumenata |
-- |
-- |
6.10 |
-- |
-- |
5.45 |
9.95 |
-- |
-- |
| Palaquium ellipticum |
3.94 |
-- |
-- |
-- |
-- |
-- |
8.47 |
-- |
3.96 |
| SSF–Stream/swamp forest |
| Table 9. Leading 10 (in bold) Importance Value Index tree species (grid-wise) in the NSSF of Kathalekan, central Western Ghats, India. |
| Trees |
Grid-wise Importance Value Index (IVI) |
| 1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
| Litsea floribunda |
23.20 |
-- |
6.84 |
-- |
7.28 |
-- |
-- |
-- |
-- |
| Dimocarpus longan |
20.23 |
15.28 |
12.81 |
21.98 |
13.37 |
-- |
2.01 |
9.91 |
9.69 |
| Syzygium hemisphericum |
17.85 |
-- |
-- |
-- |
4.51 |
-- |
-- |
8.27 |
-- |
| Knema attenuata |
17.55 |
23.73 |
15.36 |
8.16 |
30.55 |
5.30 |
8.26 |
7.63 |
12.47 |
| Holigarna grahamii |
16.20 |
17.76 |
17.32 |
11.62 |
6.57 |
8.73 |
19.91 |
12.68 |
32.63 |
| Syzygium gardneri |
14.31 |
32.07 |
33.07 |
11.96 |
26.04 |
-- |
14.53 |
-- |
-- |
| Dipterocarpus indicus |
13.93 |
12.46 |
26.04 |
40.82 |
28.70 |
42.51 |
31.10 |
6.84 |
4.72 |
| Aglaia elaeagnoidea |
12.48 |
9.81 |
12.33 |
13.73 |
15.58 |
6.39 |
11.21 |
13.28 |
12.54 |
| Garcinia talbotii |
11.44 |
14.42 |
11.07 |
14.48 |
2.43 |
-- |
7.82 |
-- |
-- |
| Sysygium spp. |
11.07 |
-- |
-- |
8.15 |
10.18 |
8.83 |
3.29 |
6.28 |
9.02 |
| Hopea ponga |
5.73 |
23.91 |
5.54 |
22.34 |
14.14 |
35.64 |
9.84 |
45.14 |
115.43 |
| Palaquium ellipticum |
-- |
14.15 |
11.20 |
12.84 |
12.13 |
-- |
6.01 |
-- |
-- |
| Persea macrantha |
5.51 |
11.26 |
2.99 |
2.77 |
4.73 |
4.78 |
-- |
-- |
4.29 |
| Mesua ferrea |
-- |
10.54 |
4.57 |
-- |
-- |
-- |
4.79 |
-- |
-- |
| Artocarpus hirsutus |
-- |
-- |
16.84 |
-- |
-- |
-- |
-- |
-- |
-- |
| Drypetes elata |
-- |
-- |
9.06 |
2.63 |
-- |
-- |
-- |
-- |
-- |
| Diospyros candolleana |
6.34 |
2.65 |
-- |
14.23 |
5.50 |
6.83 |
2.00 |
2.82 |
7.68 |
| Canarium strictum |
-- |
-- |
-- |
12.40 |
-- |
-- |
-- |
-- |
-- |
| Olea dioica |
10.71 |
-- |
5.06 |
3.01 |
20.54 |
57.63 |
11.19 |
36.15 |
39.59 |
| Calophyllum tomentosum |
-- |
6.31 |
3.80 |
5.56 |
9.40 |
36.85 |
-- |
-- |
-- |
| Syzygium cumini |
-- |
-- |
-- |
-- |
-- |
20.69 |
-- |
5.33 |
-- |
| Ixora brachiata |
-- |
-- |
7.02 |
-- |
-- |
15.14 |
-- |
-- |
17.82 |
| Symplocos racemosa |
-- |
-- |
7.32 |
5.54 |
-- |
12.53 |
-- |
6.52 |
-- |
| Holigarna ferruguinea |
5.49 |
-- |
-- |
-- |
6.64 |
10.03 |
-- |
-- |
-- |
| Aglaia anamallayana |
2.05 |
5.78 |
9.02 |
-- |
-- |
-- |
18.81 |
-- |
-- |
| Litsea spp. |
5.22 |
5.35 |
-- |
4.41 |
2.01 |
-- |
16.23 |
8.28 |
-- |
| Garcinia gummi-gutta |
2.61 |
2.63 |
6.75 |
2.41 |
-- |
-- |
11.63 |
-- |
-- |
| Polyalthia fragrans |
-- |
-- |
-- |
2.92 |
-- |
-- |
9.85 |
-- |
-- |
| Syzygium travancoricum* |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
33.51 |
-- |
| Myristica magnifica* |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
15.18 |
-- |
| Hydnocarpus laurifolia |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
10.14 |
8.44 |
| Lagerstroemia microcarpa |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
-- |
8.41 |
NSSF–Non-stream/swamp forest
* Swamp specific tree species occur only where the transect happens to pass through a swamp |
Neither high number of endemic tree species in a forest nor high percentage of tree endemism necessarily confers relic status to a forest. For instance Tulsani has about 83% tree endemism (Table 3), mainly due to domination of Knema attenuata,of Myristicaceae, that grows well in the fire protected secondary forests of Western Ghats. Moreover the hills of Tulsani were under shifting cultivation until a century ago (Pearson and Aitchison 1908).
Some grassy/savannized hill tops, having a shifting cultivation past, occur in grids 2, 3, 5, 6 and 9. One such between grids 2 and 5 is known as “seven-year kumri” (kumri refers to slash and burn cultivation). This hill has isolated clumps of stunted, fire tolerant trees and shrubs, such as Careya arborea, Glochidion johnstonei, Catunaregam spinosa, Tamilnadia uliginosa, Bombax malabaricum, Scutia myrtina, Terminalia paniculata,etc. Such savannized hill tops indicate that in the past people had lived amidst a mosaic of primeval forests, including swamps, shifting cultivation areas and fallow forests. The prohibition of shifting cultivation in the late 19th century has caused slow advance of forests closing in on these clearances.
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