Diversity and distribution of Pteridophytes from Satara District , Maharashtra ( India )

sach2010d@gmail.com Abstract The diversity and distribution along different ecological gradients of eighty six species of pteridophytes from the Satara district were studied. Amongst these species most common species were viz., Adiantum philippense, Aleuritopteris bicolor, Azolla pinnata subdp. asiatica, Marsilea minuta, Pityrogramma calomelanos, Pteridum revolutum, Pteris vittata, Selaginella ciliris and Tectaria coadunata.


Introduction
Pteridophytes are an ancient group of species, characterized as a significant plant group in biography as they are with a large number of relict and endemic taxa.They provide us a lot of information about the evolution of plants, their components and on evolutionary aspects of biogeography (Tryon and Tryon, 1982).Generally, the pteridophytes are distributed along a latitudinal gradient, with the highest diversity in the tropics (mainly in mountainous areas) (Kornas, 1993).The most common environmental variables related to floristic composition from local to regional scales are soil characteristics (nutrients content and texture), topography, (Vormisto and Svenning, 2004), moisture availability and the length of the dry period (Engelbrecht et al., 2005;Zuquimet al., 2009).
However, there is no such report on the diversity and distributional studies of Pteridophytes from Satara district (Maharashtra).This emphasizes to study the diversity and distribution of the pteridophytes along with a different altitudinal zones.
The maximum diversity was observed at the high altitude zone, high rainfall zone, high atmospheric humidity and low temperature zone.

Material and Methods
The study of spatial distribution of pteridophytes along the environmental gradients viz., altitude, temperature, rainfall and atmospheric humidity were carried out from Satara district (Map 1).The altitude range was measured by using GPS (Garmin GPSmap 60CSx).However, the categorization of pteridophytes based on rainfall, temperature and humidity is constructed on the basis of data available in the meteorological center (Table 1).

Results and Discussion
Each species of fern has its own preferences of micro habitat depending on the temperature, humidity, soil type, moisture, pH, light intensity, etc., and in many cases are very specific indicators of the conditions they need.It is well observed and noted that most species of ferns succeed under high humidity and shade conditions unless they are species that prefer more xeric conditions and are more heliophilous (Dudani et al., 2014).The change in diversity and distribution along the ecological gradients and potential mechanism were studied.
During the present investigation diversity and distribution of 86 species of pteridophytes along the various ecological gradients viz., elevation gradient, rainfall zones, temperature and atmospheric humidity in Satara district were studied and grouped under respective categories.

Diversity and distribution of pteridophytes along altitudinal ranges
The altitudinal gradient is a complex one and varied in climate, edaphic and biotic factors.With increasing elevation, there is a decrease in temperature and an increase in precipitation, relative humidity and increases soil moisture.The maximum height of Satara district is 1500 m.Based on the altitude range pteridophytes were categorized into three zones viz., Foothill zone (below 600 m), Middle hill zone (above 600 and below 1000 m) and high elevation zone (above 1000 m).

Moderate rainfall Pteridophytes:
The zone where rainfall is above 1000 mm but below 3000 mm per annum.The pteridophytes growing in this zone are as follows: Actiniopteris radiata (Sw.)Link., Adiantum capillus-veneris L., A. caudatum L., A. incisum

Discussion
The maximum pteridophytes were observed above 1000m (high altitude, 77 species) whereas only 34 species were observed at low altitude (600 m).The most common pteridophyte species viz., Adiantum philippense L., Aleuritopteris ancepsBlanf.Biologists have recognized the variations in species richness along the elevation gradients.Lellinger (1985) reported the greatest number of pteridophytes in mountain forests of Panama at 1500 m., a similar result was found by Parris et al., (1992).Hemp (2002) studied the ecology of pteridophytes on the southern slopes of Mt.Kilimanjaro.He found the highest numbers of species were observed between 1200-1800 m a.s.l., similar results were observed during the present investigation on distribution of pteridophytes along altitudinal gradients.
influence the species richness along the elevation gradients (Whittakar et al., 1967) (2003) studied the fern species richness along the central Himalayan elevational gradient, Nepal.According to them fern richness has a unimodel response along the energy gradients and a linear response to moisture gradients.They also stated that the importance of moisture on fern distribution as the peak coincide spatially with climatic factors that enhance the moisture level.All the above observations on the distribution of pteridophytes along different climatic factors of Satara district were agreed with investigations of earlier authors in different geographical regions of the globe.

Conclusion
Species diversity and distribution at different altitudinal zones were diverse based on their withstanding capacity to those conditions.Similarly, pteridophytic flora may be controlled by the environmental factors such as temperature, rainfall and humidity whereas the deep ravines, continuously flowing streams, water channels, thick evergreen forests regulate the canopy of this attractive vegetation.