**4.1 Phytodiversity assessment**

### **4.1.1 Random plots**

An analysis of various quantitative inventories of woody species ≥10 cm dbh across the tropics reveals a wide variation in the figures, ranging from 20 species ha-1 in flooded Varzea forest of Rio Xingu, Brazil (Campbell *et al.,* 1992) to 300 species ha-1 in terra firma, Yanamono, Peru (Gentry, 1988). Within peninsular India, in various quantitative inventories of a comparable area for the same tree girth threshold, in tropical forest sites of the southern Western Ghats, species richness ranged from 30 species ha-1 in Nelliampathy (Chandrashekara & Ramakrishnan, 1994), to 57 species ha-1 in Mylodai, Courtallum reserve forest (Parthasarathy & Karthikeyan, 1997a), to 64 to 85 species ha-1 in Kalakad (Parthasarathy *et al.*, 1992) and 90 species on a 3ha scale in Kalakad-Mundanthurai Tiger reserve (Giriraj, 2006). Compared to various moist tropical forest sites in other parts of the world our present study showed comparable species richness and diversity.

The absolute stand density of both the zones across different vegetation communities are ranging from 156 to 486 trees ha-1, with a whole study area average of 365 trees ha-1. Deciduous forests of the zone-1 had higher stand density of 486 trees ha-1 compare to the zone-2 having 386 trees ha-1, the reasons being favorable bioclimatic and edaphic conditions. These stand density are relatively lesser compared to the other sites in the Shervarayan and Kalrayan hills of Eastern Ghats, with the range of 640 to 986 trees ha-1 (Kadavul & Parthasarathy, 1999a) and 367 to 667 trees ha-1 (Kadavul & Parthasarathy, 1999b) respectively. Whereas the tree densities in various tropical evergreen forests of Western Ghats of peninsular India were: 574 to 915 stems ha-1 in medium elevation forest of Kalakad (Parthasarathy, 1999); 852 to 965 stems ha-1 in high elevation forest of Kalakad (Parthasarathy, 2001); 583 stems ha-1 in Kalakad–Mundanthurai area (Ganesh *et al.,* 1996); 482 stems ha-1 in Mylodai, Courtallam reserve forest (Parthasarathy & Karthikeyan, 1997a); a range of 270 to 673 trees ha-1 in the 30 ha of Varagalaiar, Anamalais (Ayyappan & Parthasarathy, 1999), all these in southern Western Ghats and 635 stems ha-1 in Uppangala forest of central Western Ghats (Pascal & Pelissier, 1996). Density of trees (>30 cm gbh) in tropical forests ranges between 245 and 859 (Ashton, 1964; Campbell *et al.,* 1992; Richards, 1996) with intermediate values of 448 to 617 stems ha-1 in Costa Rica (Heaney & Proctor, 1990), 436 stems ha-1 in Reserva Forestal de San Ramon of Costa Rica (Wattenberg & Breckle,

Also beta-diversity (expressed by compositional similarity) differs significantly between sites (Fig. 17). Only the sites 4 and 5 do not significantly differ in their similarity structure. However they have also been quite similar in species composition (as seen in the NMDS plot in Fig. 16) with site 5 being clearly positioned between site 3 and 4. All of the above can partly be grasped also from the species matrix, wherein - even without ordering - it is

A moderate percentage of quadrats (47%) are clustered into the "right" cluster when site membership is (very simplistically) compared to cluster membership. This was obtained by computing a simple Wards clustering with hclust[stats] followed by the application of cutree[stats] which simply cuts the resulting dendogram tree to obtain group (or cluster-) memberships for all tested objects (the quadrats in our case) when the number of groups has

An analysis of various quantitative inventories of woody species ≥10 cm dbh across the tropics reveals a wide variation in the figures, ranging from 20 species ha-1 in flooded Varzea forest of Rio Xingu, Brazil (Campbell *et al.,* 1992) to 300 species ha-1 in terra firma, Yanamono, Peru (Gentry, 1988). Within peninsular India, in various quantitative inventories of a comparable area for the same tree girth threshold, in tropical forest sites of the southern Western Ghats, species richness ranged from 30 species ha-1 in Nelliampathy (Chandrashekara & Ramakrishnan, 1994), to 57 species ha-1 in Mylodai, Courtallum reserve forest (Parthasarathy & Karthikeyan, 1997a), to 64 to 85 species ha-1 in Kalakad (Parthasarathy *et al.*, 1992) and 90 species on a 3ha scale in Kalakad-Mundanthurai Tiger reserve (Giriraj, 2006). Compared to various moist tropical forest sites in other parts of the world our present study showed comparable species richness

The absolute stand density of both the zones across different vegetation communities are ranging from 156 to 486 trees ha-1, with a whole study area average of 365 trees ha-1. Deciduous forests of the zone-1 had higher stand density of 486 trees ha-1 compare to the zone-2 having 386 trees ha-1, the reasons being favorable bioclimatic and edaphic conditions. These stand density are relatively lesser compared to the other sites in the Shervarayan and Kalrayan hills of Eastern Ghats, with the range of 640 to 986 trees ha-1 (Kadavul & Parthasarathy, 1999a) and 367 to 667 trees ha-1 (Kadavul & Parthasarathy, 1999b) respectively. Whereas the tree densities in various tropical evergreen forests of Western Ghats of peninsular India were: 574 to 915 stems ha-1 in medium elevation forest of Kalakad (Parthasarathy, 1999); 852 to 965 stems ha-1 in high elevation forest of Kalakad (Parthasarathy, 2001); 583 stems ha-1 in Kalakad–Mundanthurai area (Ganesh *et al.,* 1996); 482 stems ha-1 in Mylodai, Courtallam reserve forest (Parthasarathy & Karthikeyan, 1997a); a range of 270 to 673 trees ha-1 in the 30 ha of Varagalaiar, Anamalais (Ayyappan & Parthasarathy, 1999), all these in southern Western Ghats and 635 stems ha-1 in Uppangala forest of central Western Ghats (Pascal & Pelissier, 1996). Density of trees (>30 cm gbh) in tropical forests ranges between 245 and 859 (Ashton, 1964; Campbell *et al.,* 1992; Richards, 1996) with intermediate values of 448 to 617 stems ha-1 in Costa Rica (Heaney & Proctor, 1990), 436 stems ha-1 in Reserva Forestal de San Ramon of Costa Rica (Wattenberg & Breckle,

obvious that only few species occur on more than one or on even more sites.

been specified.

**4. Discussion** 

and diversity.

**4.1.1 Random plots** 

**4.1 Phytodiversity assessment** 

1995), 420 to 777 stems ha-1 in Brazil (Campbell *et al.,* 1992) and 639 to 713 stems ha-1 in Central Amazonia (Ferreira & Prance, 1998).

The basal area for both the zones is ranging from 2.89 and 40.95 m2ha-1 for ≥30 cm girth threshold. Thorn forest of the zone-1 had least basal area and high basal area was observed in the semi-evergreen forest of northern Eastern Ghats (40.95 m2ha-1). The mean basal area value of the present study is also lesser than the values for the comparable girth threshold of ≥30cm gbh of several other tropical forests: 28.1 and 30.8 m2ha-1 respectively of dry evergreen forest sites of Kuzhanthaikuppam and Thirumanikkuzhi (Parthasarathy & Karthikeyan, 1997b) Puthupet (Parthasarathy & Sethi, 1997) on the Coromandel coast of south India; 24.2 m2ha-1 of Malaysia (Poore, 1968), 27.6 to 32.0 m2ha-1 and 25.5 to 27.0 m2ha-1 of Brazilian Amazon (Campbell *et al.,* 1986, 1992); 27.8 and 41.67 m2ha-1 of Costa Rica (Lieberman & Lieberman, 1987; Watternberg & Breckle, 1995); 32.8 to 40.2 m2ha-1 of Central Amazonian upland forest (Ferreira & Prance, 1998); 42.6 m2ha-1 of Courtallam reserve forest in the Indian Western Ghats (Parthasarathy & Karthikeyan, 1997a); 39.7 m2ha-1 of Uppangala forests, central Western Ghats, India (Pascal & Pelissier, 1996); and 25.91 to 47.75 m2ha-1 in the 30 ha of Varagalaiar, Anamalais, southern Western Ghats (Ayyappan & Parthasarathy, 1999). But a value of present study is lesser than: 53.3 to 94.6 m2ha-1 and 55.3 to 78.3 m2ha-1 of Kalakad, southern Western Ghats, India (Parthasarathy 1999; Parthasarathy, 2001) and the values of a couple of other tropical forests: 47 (for alluvium) to 49.5 m2ha-1 (for slope forest) of New Caledonia (Jaffre & Veillon, 1990), and 62 m2ha-1 of Monteverde, Costa Rica (Nadkarni *et al.,* 1995).

In both the zones, family-wise five predominant families explain the dominance of the forests which includes Combretaceae, Mimosaceae, Euphorbiaceae, Caesalpiniaceae and Rubiaceae. It contributes 39% of the family dominance which characterize the tree community pattern and in close range with other tropical forests regions (Gordon *et al.*, 2004; Linares-Palomino & Ponce-Alvarez, 2005) while the other Indian Eastern Ghats site, where the family Oleaceae (26.6%) dominated (Kadavul & Parthasarathy, 1999a) and in dry evergreen forests in south India, where the Melastomataceae and Rubiaceae with 56% dominated (Parthasarathy & Karthikeyan, 1997b).

The trend of decreasing diversity and density with increasing girth class is in conformity with the studies of Chittibabu & Parthasarathy (2000); Jeffre & Veillon (1990); Kadavul & Parthasarathy (1999a, b); Newbery *et al.,* (1992) and Paijmans (1970). Both the zones had typical reverse J-shaped structure for girth frequency (Fig. 4o). Northern region of the Andhra Pradesh explains mature stands in all the girth-class with good regeneration were in close conformity with other tropical forests around the world (Chittibabu & Parthasarathy, 2000; Kadavul & Parthasarathy, 1999a, b; Manokaran & Kochummen, 1987; Nadkarni *et al.*, 1995; Sukumar *et al.,* 1992).

### **4.1.2 Continuous plots for the six sites**

A total of 197 species, 139 genera and 57 families (Table 3) were stated from six transects covering thee-ha of the tropical forests in Northern and Southern Andhra Pradesh, Eastern Ghats. Species richness (43-72 species ha-1) and species diversity 2.9-3.6 H') are comparable with the other sites in the Eastern Ghats. The mean value of 60 species ha-1 recorded in the present study is higher than that of 43 species ha-1 in Shervarayan hills (Kadavul & Parthasarathy, 1999a), 57 species ha-1 in Mylodai forest of Courtallum (Parthasarathy & Karthikeyan, 1997b). In Mudumalai tropical forest, Western Ghats, the 12 most common

Spatial Patterns of Phytodiversity - Assessing Vegetation Using (Dis) Similarity Measures 177

pressure on the forests and these region having low altitudinal and precipitation formation

Generally it is assumed that fragmentation and disturbance have a considerable influence on species richness (Connell, 1978; Huston, 1979). However, in the data set from the Eastern Ghats, this is only partly the case. Disturbance does not seem to drive species richness in the investigated area (Fig. 5 and 6). On the other hand this result might hint at a problem with

The separation of the plots in zone 1 from the plots of zone-2 is relatively clear (along the NMDS axes 2 in Fig. 8). Such obvious grouping is rarely found in ecological data sets. This means that the two zones are relatively distinct in their vegetation composition. However, astonishingly there is no further grouping within the zones regarding to the categorical parameters fragmentation, disturbance, and richness (also Fig. 8). When the zones are considered separately (Fig. 10) it becomes even more obvious that these parameters (at least in their representation of the actual research) do not drive the differentiation in species composition. Thus, not only richness but also species composition is not driven by

Often richness drives compositional similarity of plots because plots with largely different species number very naturally tend to have only very few species in common. However, even that is not the case in the present data (Fig. 10). This holds also when the classification is much finer than displayed in Fig. 10. One reason for that might lay in the overall high beta-diversity in the region: The intercept of the distance decay relationship is comparably low (see e.g. Condit et al., 2002 for comparison data from the Neotropics) which indicates a low similarity (and therewith high beta-diversity) even at short distances between plots. Species richness, fragmentation and disturbance all have only very minor influence on species composition. Furthermore they are not linearly related to one another. Therefore a joint index cannot be build. If something like a surrogating indicator is the aim, the environmental parameters recorded have to be much more numerous. Furthermore, they

Similar findings are to be stated regarding the rate of the decrease of similarity with distance. Compared to data from the Neotropics (e.g. Condit *et al.*, 2002, 0.0019-0.00055/km) the distance decay rate in zone-1 (0.00022/km) fits nicely in. Astonishingly the rate is much lower in zone-2 (0.000088/km) and as already discussed in the previous paragraph, the intercept is also very low. This means that it doesn't matter how far two plots are from each other. There is always the chance that two plots can be very different regarding their tree

But even at this low decay rate a phenomenon occurs which seems to be ubiquitous to all distance decay data: There is comparably faster decrease on short distances. This has also been reported by (Jurasinski, 2007) who attributed it to the predominance of dispersal over niche assembly in the short range around vegetation samples. In the investigated data it can be found on all evaluated subsets of the data. This supports the idea of a ubiquitous pattern

**4.2 Spatial patterns of phytodiversity using Dis (Similarity measure)** 

resulted to low-level of population structure.

the disturbance classification.

**4.2.1 Compositional similarity** 

disturbance or fragmentation.

should preferably be on continuous scales.

**4.2.2 Distance decay** 

species composition.

species made up to 90.6% while 7 species were represented by only one individual (Sukumar *et al.*, 1992).

Species number per ha found in the present study is smaller in comparison with Malaysian lowland rain forests having 164 and 176 species (Malaysia, Wyatt-Smith, 1966), 150 species (Indonesia, Whitmore, 1990), 223 and 214 species ha-1 (Malaysia, Proctor *et al.,* 1983). The wide range of species number 43-72 found in the present study plots can be attributed to the change in elevation, and bioclimatic variations. As compared to the tropics, neo-tropics show a much more complicated situation. In 1 ha plots of tropical rain forests, 91 species (Guiana, Davis & Richards, 1933), 87 species (Brazil, Black *et al.,* 1950) and 83 species (Venezuela, Jordan *et al.,* 1989) with DBH >10cm were reported. These values are lower than in the forest investigated in Xishuangbanna, SW China with 119 species (Cao & Zhang, 1997) and in present study (153 species). Such species diversity pattern may diminish as a function of altitude (Lieberman *et al.,* 1996).

The mean stand density of 409 stems ha-1 and range of 307 to 525 stems ha-1 in the tropical forests of northern Andhra Pradesh is well within the range of 276 - 905 stems ha-1 reported for trees ≥10cm gbh in the tropics (Ghate *et al.*, 1998; Sundarapandian & Swamy, 1997; Sukumar *et al.*, 1997 & Murali *et al.*, 1996). This range of stand density in the present study is comparable with the other Eastern Ghats sites (Shervarayan hills - Kadavul & Parthasarathy, 1999a; Kalrayan hills - Kadavul & Parthasarathy, 1999b; Coromandel coast - Parthasarathy & Sethi, 1997). Low density was observed in other tropical sites across the world, which includes Costa Rica - 448 to 617 ha-1 (Heaney & Proctor, 1990); Brazil - 420 to 777 ha-1 (Campbell *et al.,* 1992); Malaysia - 250-500 ha-1 (Primack & Hall, 1992).

The species-accumulation curve (Fig. 5) for the six different sites varied because of the changes in topography and rainfall. *Site* 1 and 4 were initially steep, and later we observed a tendency towards flattening and similar such pattern was observed for the *Site* 5 & 6. *Site* 2 & 3 didn't reach an asymptote due to high species richness and as well landscape heterogeneity. Similar patterns were noticed in different areas of Eastern and Western Ghats (Kadavul & Parthasarathy, 1999 a, b; Parthasarathy, 1999; Parthasarathy, 2001).

The most obvious variation in tree species and the proportion of dominant species in the six sites can directly be attributed to altitudinal and rainfall distribution. Particularly species richness increase at moderate elevation and beyond the altitude range, there is tendency towards decline (Giriraj *et al.,* 2003); similar pattern was observed in site1. Families with rare occurrences represented by single and double species were 36 for both the study sites.

Current study identified 57 families and the most predominant species rich families are Rubiaceae (18), Euphorbiaceae (16), Fabaceae (11) and Caesalpiniaceae (9) and similar such predominance were recorded from Shervarayan hills (Kadavul & Parathasarthy, 1999a). Steege *et al.*, (2000) and Martin & Aber (1997) reported Leguminosae as the most abundant family in neo-tropical forests. Top ten families explain the species characteristics and found to be 66% (1620 individuals out of 2,457 individuals) dominant for the study site.

Girth class frequency showed L-shaped population structure (Fig. 4) of trees except for *site* 3 and 5. This pattern is in conformity with many other forest stands in Eastern & Western Ghats such as Shervarayan hills (Kadavul & Parathasarthy, 1999a); Kalrayan hills (Kadavul & Parthasarathy, 1999b); Kakachi (Ganesh *et al.,* 1996); Uppangala (Pascal & Pelissier 1996); Mylodai-Courtallum RF (Parthasarathy & Karthikeyan, 1997b). *Site* 3 & 5 didn't have a clear population structure might due to anthropogenic pressure in the form of shifting cultivation for their livelihood. In general the Northern Eastern Ghats (EG) of Andhra Pradesh (AP) exhibit large-scale deforestation as observed in Chapter-3 and southern EG of AP do have pressure on the forests and these region having low altitudinal and precipitation formation resulted to low-level of population structure.
