The Impact of Traditional Conservation Practices on Species Composition and Diversity Patterns of Sacred Swamps in the Central Western Ghats, India


 Sacred forests are of immense value for their ecosystem functions. Traditional indigenous conservation practices have helped maintaining biological diversity over centuries and have resulted in the preservation of some of the best patches of natural vegetation.
Exclusive taxa find refuge in the micro-climatic conditions of sacred groves and many rare species are found here. Ten sacred swamps and ten non-sacred swamps in the central Western Ghats region, India, with a similar distance from roads, village settlements, or commercial orchards and with nearly the same size, were compared with regard to their species composition, floristic structure, diversity, occurrence of amphibians, odonates and birds.
In the sacred swamps, 122 plant species from 99 genera and 58 families occur against 83 species from 72 genera and 47 families in the non-sacred swamps. Tree stem density was 277 individuals/ha in sacred swamps against 158.4 in non-sacred swamps. Average basal area was 47.57 m 2 /ha in sacred swamps and only 14.60 m 2 /ha in non-sacred swamps. Sacred swamps have higher number of endemic species (28%) when compared to non-sacred swamps. We conclude that the traditional belief system of treating the swamps as sacred has helped to protect these ecologically important forests.


Introduction
Sacred groves play a signi cant role in forest stand survival across the globe (Gadgil and Chandran 1992, Tiwari et al. 1998) and are considered an effective tool in biodiversity conservation (Byers et Gadgil and Vartak 1976). Although some supporting traditions have weakened by modern in uences, sacred groves are frequently more acceptable to local peoples than externally imposed conservation policies (Ntiamoa-Baidu, 1994).
Exclusive taxa nd refuge in the micro-climatic conditions of sacred groves and many rare species are found only there . Numerous studies suggest that the biological spectrum of sacred groves in the tropics closely resembles the typical spectrum of tropical forest biodiversity and that in sacred groves endangered and rare species of ora and fauna are better protected and conserved than elsewhere (Tiwari et al. 1998;Campbell 2004; Shahabuddin and Rao 2010, Shen et al. 2015).
Recurrent human interventions in the forests are known to change habitat tness for many species leading to a decrease in number of species along the disturbance gradient (Pandey and Shukla 1999). While some species may tolerate disturbance, others may not and disappear (Sagar, 2003). Leigh (1965) suggests that stability increases with the complexity of the ecosystem, i.e. with the number of species and their interactions (MacArthur 1955 Murdoch et al. 1972). Especially the structure of the tree stratum has a central role in determining the ecological processes and habitat characteristics in the forest (Kuuluvainen et al. 1996). Structural complexity of forests is, thus, often a good predictor of overall species diversity (Begon et al. 1986) and can be used to assess the conservation or biodiversity value of forest stands (Hansen et al. 1991).
Whereas forest structure informs biodiversity, information on the latter (i.e., species composition, diversity and population structure) is essential to understand forest ecosystem dynamics at various levels (Giriraj 2008), to provide a conceptual framework and measurable indicators to assess the overall ecosystem condition, and to monitor change (Noss 1990).
Such structural richness and tree species diversity are found in the fresh water swamps of the Uttara Kannada district of the Central Western Ghats, India. Fresh water swamps are marshy areas where water ows in perennial streams at constant level throughout the year (Gupta et al. 2006). Within the climax evergreen forests, they occupy poorly drained depressions that often open into a river or rivulet and have their groundwater level very close to the ground surface. Some of these swamps are sacred. Such sacred swamps today only exist close to commercial gardens, roads and settlements (average distance 100 meters, Hegde et al. 2018).
This paper compares species composition and tree population structure in sacred and non-sacred swamps in order to explore whether the traditional belief systems of treating swamps as sacred are effective in protecting ecologically important forests.

Study Area
The Western Ghats Mountain ranges, running parallel along the west coast of India, constitute one of the

Methods
Ten sacred swamps (total area 5.60 ha) and ten non sacred swamps (total area 5.71 ha) of similar size were studied. The sacred swamps had an average distance to the nearest road, settlement or commercial orchard of 109 m (standard deviation 19.5), the non-sacred swamps an average distance of 332 m (standard deviation 66.7) ( Table 1).
Vegetation was assessed between December 2013 and April 2014 in transects of 5 m wide and variable length (100-1000 m) along the stream, covering a total area of 1.70 ha (sacred swamps) and 1.71 ha (non-sacred swamps). Since the swamps have a linear shape, almost the entire depression part of the swamps was surveyed. The species composition in the catchment area of the swamp forests was assessed in a transect of 50 m x 5 m perpendicular to the edge on either side of each swamp. All plant species were identi ed using regional and standard oras (Cooke 1903, Talbot 1909, Gamble and Fischer 1935 and keys (Pascal and Ramesh 1987). Tree girth was measured at breast height using a measuring tape. Tree diameters were categorized in 11 diameter classes of 30 cm, with the smallest class having 1-30 cm and the largest ≥ 301 cm diameter at breast height (DBH).  Biomass productivity (stem density and basal area), frequency and importance value index (IVI) of tree species were calculated according to Bonham (2013).
Frequency is the number of times a plant species is present in a given number of quadrats of a particular size or at a given number of sample points. Frequency is usually expressed as a percentage.
Density is an expression of numerical strength of a species in a community. It is calculated as: The basal area of a stand is the total stem area at breast height of all trees in a plot divided by the total area of that plot (Cain 1959;Chaturvedi and Khanna, 1994): The Family Importance Value (FIV) for growing stock (volume of all trees ≥ cm DBH) was calculated as follows; The value of the Simpson index varies between 0 and 1. As D increases, diversity decreases (Simpson 1949).
To record the regenerating species, two plots (quadrates) of 5 x 5 m were laid out; one at the 50 th and another at the 100 th meter of each transect of varying length along the river. Trees (seedlings) with less than 30 cm DBH were considered as the regenerating potential of the species. The natural regenerates were grouped into following regeneration classes for further analysis (

Results
In the sacred swamps 122 species from 99 genera and 58 families were found against 83 species from 72 genera and 47 families in the non-sacred swamps (Fig. 1, Fig. 2, Table 2). Lauraceae, Apocynaceae, Anacardiaceae, Moraceae, Myristicaceae and Rubiaceae were the most species-rich families in the sacred swamps, whereas in the non-sacred swamps Euphorbiaceae, Anacardiaceae, Arecaceae, Apocynaceae, Celastraceae, Dipterocarpaceae, Lauraceae and Myristicaceae.  Myristicaceae have the highest Family Importance Value both in the sacred (99.14 %) and in the nonsacred swamps (61.2). Other important families are the Anacardiaceae (26.16%) and the Celastraceae (20.54%) in the sacred, and the Arecaceae (45.6%) in the non-sacred swamps (Figs. 3 and 4).
Most trees with a GBH > 30 cm fall in the 30-60 cm category both in the sacred (68.4 %) and in the sacred swamp swamps (51.8 %, Fig. 5). 28% of the plant species are endemic to the Western Ghats in the sacred against 23% in the non-sacred swamps (annex 1). Number of species and individuals from amphibian, birds, butter ies and odonata are found to be higher in the sacred swamps compared to the non-sacred swamps ( Table 4).
The Simpson index for all fauna was 0.40 in the sacred and 0.36 in the non-sacred swamps, whereas the Shannon index was − 1.1 and − 1.2, respectively.
Three critically endangered amphibian species from the IUCN Red List, Nyctibatrachus dattatreyaensis, Pseudophilautus amboli and Micrixalus kottigeharensis, were found to occur in both sacred and nonsacred swamps, however, non-sacred swamps were represented by only 6 individuals where as it was 22 individuals in sacred swamps. (Table 5).

Discussion
Consistently more species (122 species with 58 plant families) were found to occur in the sacred compared to the non-sacred swamps (87 species and 47 families). Higher species numbers have also been recorded in sacred compared to non-sacred non-swamp sites in the south-eastern coastal belt of India near Pondicherry (Ramanujan and Kadamaban 2001).
Although the number of plant species in the swamps is low compared to well-watered (but not waterlogged) land, the occurring species are often site or habitat speci c and endemic and contribute signi cantly to the regional biodiversity of the Western Ghats and 156 stems per hectare, respectively. The rather small biomass productivity (stem density and basal area) in our samples could be due to the constant water level throughout the year. Conner (1976) and Brinson et al. (1981) found that seasonally ooded open systems are generally more productive than stagnant closed ones. Productivity was approximately double in wetlands subject to periodic ooding, compared to stagnant or slowly owing systems (Mitsch 1991). Further, area of both sacred and nonsacred swamps was small compared to other studies, which are in the terrestrial ecosystems.
In the study sites, tree cutting intensity was high in the non -sacred swamps, which is evident from the presence of cut stumps and cutting of knee roots of Gymnacranthera canarica. We did not nd evidence of cutting in the sacred swamps. The cultivated species Musa paradisiaca and Areca catechu were found only in non-sacred swamps, indicating attempts to convert them into commercial orchards.
Sacred swamps had 28% of endemic species while non-sacred swamps had 23%. Vasanthraj and Chandrashekhar (2006) reported that 37% of the species from Charmady reserve forest are endemics of the Western Ghats, whereas the average endemism for evergreen forests of the Western Ghats is around 41% (Ghate et al. 1998).
Only The interaction between forest disturbance, regeneration and succession determines the size and age distribution of trees (Kuuluvainen et al. 1996). Biological quality ('health') of forests is often indicated by their size class distribution and regeneration ability, with a large proportion of seedlings and saplings re ecting a growing population (Murali et al. 1996). With regard to diameter classes, the sacred swamps show a clear 'reverse J' shape distribution curve, in contrast to the non-sacred swamps, which show a much lower prevalence of the lowest (Fig. 6) and the complete absence of trees in the highest girth classes (Fig. 5).
Amphibian assemblages are good indicators of environmental health (Hager 1998, Gibbs 1998) as amphibians are sensitive to environmental change (Blaustein 1994, Pearman 1997, Daniels 1999). In our study, sacred swamps have a higher number of amphibian species and a higher number of threatened species when compared to non-sacred swamps. Diversity and richness of bird, butter y and odonata species were, however, only marginally higher in the sacred swamps. Higher species richness and composition in non-sacred swamp is an effect of mild disturbance that favours the early invaders and the deciduous species essentially increases the species richness. However, the studies of Murali and Setty (2001) have observed high species richness as well as forest stand in the plots with mild disturbance than the less disturbed plots. Methachen (2002) reported that the disturbed evergreen forests of Uttara Kannada district were oristically more rich compared to undisturbed evergreen forest in terms of species richness as well as diversity indices complying to the 'mild disturbance' theory.

Conclusions
Our study shows that the species composition and diversity patterns -tree population, stem density, and the basal area of tree species -are higher in sacred swamps compared to non-sacred swamps. Regeneration of swampy species is much better in sacred swamps. Both natural and human activities have an effect on species diversity, population structure, and natural regeneration of a forest ecosystem. Vegetation characteristics make it clear that sacred swamps act as safe zones for the in-situ conservation of many endemic and red listed species of the Western Ghats. This condition is made possible, only because the local community restricts anthropogenic activities. This social fencing, i.e. the most viable form of protection in the eld, is based on traditional values of local communities, evolved over long time. Such community behaviour requires a socio-cultural ecosystem to nourish it and local forest dwelling communities must be given credit for ensuring survival of these biodiverse habitats. We conclude that the traditional practices of protecting the swamp forests play an important role in biodiversity conservation.
Declarations Figure 1 Number of genera and species per family in the studied 1.70 ha of sacred swamps.   Family Importance Value for the tree species in the studied non-sacred swamps Size class distribution of trees in girth classes >30cm DBH in the studied sacred and non-sacred swamps Supplementary Files