Abstract
An annotated checklist of 103 macrolichen species is provided based on identification of specimens collected from three different vegetation types within the Bolampatti II forest range, Western Ghats, India. Among them, the dominant order is Lecanorales with 47 species, while the dominant family is Parmeliaceae with 40 species. The foremost genus is Usnea with 15 species.
1. Introduction
Nearly 80,000 species of fungi are available in nature [1]. Of these, approximately 17% are lichenized, forming symbioses with green algae (Chlorophyta, Viridiplantae) or the so called blue-green algae (Cyanobacteria, Bacteria). These relationships produce symbiotic organisms commonly called lichens [2]. Lichens are an outstandingly successful group of symbiotic organisms exploiting a wide range of habitats throughout the world. About 20,000 species of lichens are so far recorded across the globe, among which the Indian subcontinent harbours 2450 (12.25%) species [3]. Tropical forests, because of their complexity and variety of microhabitats, usually harbour a rich diversity of lichens. Even though they are often small and inconspicuous, especially in the lowland forest, they may play a significant role in the forest ecosystem [4]. It has been estimated that 50% of the Indian lichen biota are currently undescribed [5]. In India, the comprehensive regional treatments (both ecological and systematic) on lichens are still not available, and a few cover areas like portions of Western Ghats (Nilgiri and Palni Hills, Himalayas, and North Eastern regions) [6, 7]. Still, many of the pristine Western Ghats ecosystems remain unexplored to list out the extent and type of distribution of lichens [8]. In view to explore such important organisms, the present study has studied the macrolichens from Bolampatti II forest range, Western Ghats. The primary objective of this paper is to enumerate the macrolichens and their distribution within the forest types of the Bolampatti II forest range.
2. Materials and Methods
2.1. Study Area
Bolampatti II forest range, Coimbatore district, Tamil Nadu (part of Western Ghats—76° 33′′ to 76° 46′′ E and 11° 2′′ to 10° 54′′ N), is a part of the Nilgiri Biosphere Reserve, is commonly known as Siruvani Hills (Figure 1), and is one of the biodiversity hotspots of the world. The study site is located west to Coimbatore city and north of the Walayar valley, is shaped like a horse-shoe opening eastwards, and covers an area of 197.66 km2. The Bolampatti valley consists of vegetation types progressively from lower to higher altitudes (east to west) dry deciduous forest (DDF) (4a/C2), moist deciduous forest (MDF), and western tropical evergreen forest (WTEF) (1a/C3) [9, 10]. This valley drains eastwards into the Noyilar and its tributaries. The elevation ranges from 458 m (Noyilar base) to 1,986 m on Periyakunjiramalai at the southwest corner and 1,800 m on Vellingiri peak at the northwest. This hill receives a rainfall of 75–200 cm from the northeast monsoon during September to November, with a dry period of six months. The temperature ranges between 10°C during December and January and 40°C during March to May. The older rock is of Precambrian origin with the formation of mainly Charnockite or Nilgiri gneiss. Soil is mainly of red type in the hills. The foothills generally have sandy loam. The Vellingiri peak is barren and rocky.
2.2. Research Methods
The lichen samples (approximately 3000 specimens) were collected from various vegetation types, namely, dry deciduous forest (DDF), moist deciduous forest (MDF), and western tropical evergreen forest (WTEF) during 2001–2005 by the authors based on ocular survey on all possible lichen occurring substrates, such as tree bark, rocks, leaves, and soil. Lichens on fallen twigs were collected, since they represent the species that occur on canopy. Each sample was given a field number. The specimens were dried and incorporated into a reference collection that is preserved in the Lichen Ecology and Bioprospecting Laboratory, M. S. Swaminathan Research Foundation (MSSRF), Chennai. The specimens were identified based on the internal and external morphological, reproductive, and chemical features following recent literature [11–18], and lichen taxa are classified based on the systematic arrangement provided by Hawksworth et al. [19]. For each of the lichen species collected, their distribution with respect to growth form, substratum preference, and forest types were provided.
3. Results and Discussion
A total number of 103 species of macrolichens under 27 genera in 9 families in 3 fungal orders were recorded within the Siruvani hills (Table 1; Figures 2(a)–2(f)). Fungal order Lecanorales dominate with 47 species followed by Teloschistales (35) and Peltigerales (21). Out of 9 families of lichens, Parmeliaceae (40 species) is the largest family followed by Physciaceae (20), Collemataceae (16), Caliciaceae (14), Ramalinaceae (6), and Lobariaceae (4), and three families were with single species each. The largest genus was Usnea with 15 species followed by Heterodermia and Parmotrema with 13 species each, Leptogium and Pyxine with 11 and 10 species, respectively.
(a)
(b)
(c)
(d)
(e)
(f)
Fourteen (14) genera were with single species each. Among the forest types studied, MDF contain 55 lichens followed by WTEF with 51 and DDF with 48 species, in which, 21 lichen species were specific to DDF while 24 to MDF and 21 to WTEF. Thirty-seven (14) lichen species were common to all the forest types. Seven (7) species were shared between DDF and MDF, while 6 species between DDF and WTEF, and 24 species between MDF and WTEF.
Among the species recorded, 92.2% of lichens were colonized on bark (corticolous), followed by 6% on rock (saxicolous), 0.8% on soil (terricolous), and a single lichen species both on bark and rock substratum. Bark colonizing lichens were maximum in both MDF & WTEF (47% each) followed by DDF (43%). Rock colonizing lichens were maximum in MDF (4) followed by DDF (3) and WTEF (1). Single soil colonizing lichen Cladonia sp. was found in MDF. Lichen Parmotrema praesorediosum was found colonizing both on bark as well as on rock in DDF type.
The photobiont distribution showed 80% of lichens with Trebouxia and 20% of lichens with Nostoc sp. Trebouxia containing lichens were maximum in WTEF and MDF with 34% each, followed by DDF (32%). Nostoc-containing lichens were maximum in MDF (44%) followed by WTEF and DDF (28% each).
Lichens with Trebouxia as photobiont dominate tropical regions with an alternating wet and dry period and include macrolichens in Parmeliaceae and macrolichens and crusts in Bacidiaceae (syn. Ramalinaceae), Physciaceae, and Pertusariaceae [20]. The Trebouxia containing macrolichens in DDF are also equally present in WTEF and MDF, prevailing in our study sites. It includes lichen families such as Parmeliaceae, Physciaceae, and Caliciaceae. Wolseley and Hawksworth [20] reported that the Trebouxia dominated families may occur with increasing dryness and/or disturbance as caused by fire in Thailand.
The Nostoc-containing lichens were found dominant in MDF, while there was equal distribution of Trebouxia containing lichens in all the forest types studied. Lichen taxa with cyanobacteria are more common in the moister forests; species of Collema and Parmeliella were found in DDF as well as SEF, and Leptogium cyanescens was found in all forest types [21]. The lichen species such as Collema actinoptychum, Collema flaccidum, and Collema furfuraceum are confined only to DDF, while Collema subflaccidum is found both in DDF and WTEF. The lichens Leptogium cyanescens and Leptogium denticulatum are found in all forest types as in the case of lichens of northern Thailand forests [21].
Lichen communities of the seasonal evergreen forest (SEF) and tropical mixed deciduous forest (TMDF) are moisture-dependent and shade-adapted, whereas lichen communities of the DDF are adapted to xerophytic conditions and photophilous [21]. This pattern of distribution can be attributed to the sensitivity of the lichen photobiont to drought or high temperatures, which determines the survival of a lichen thallus [21], and the Trebouxia containing lichens are known to survive better in the open and dry [22, 23] condition prevailing in the DDF. The seasonal evergreen and tropical mixed deciduous forests of Thailand [24] were reported to contain more numbers of shade-tolerant Trentepohlia containing lichens compared to dry deciduous forests of Thailand. More number of shade-tolerant and moisture-dependent Nostoc-containing lichens were observed in MDF type in Bolampatti II forest range also. Lichen families with cyanobacteria and/or chlorococcoid algae include Lobariaceae and Collemataceae, and are more frequent in humid forests. The adaptations to tropical shaded moist conditions are the presence of cyanobacteria and Trentepohlia as photobionts [25].
Bergamini et al. [26] state that macrolichens may be good indicators of lichen species richness because of the highly significant relationships. The species turnover within the study sites was very similar for all lichens and macrolichens. The similar trend was also observed in our study sites. In northern Thailand, the lichen species characteristic of disturbance such as Pyxine consocians and Dirinaria consimilis is also observed in DDF of Bolampatti II forest range. The rate of colonization and growth of these species is an indication of the rate of change [24].
4. Conclusion
The present study revealing the occurrence of 103 macrolichens from 197.66 km2 forest area indicates the lichen species richness of the study area and their availability for further ecological monitoring. It is desirable to develop location-specific and lichen-centric conservation strategies using this baseline data to protect the valuable and yet poorly studied ecologically-important group called lichens.
Acknowledgments
The authors thank Professor M. S. Swaminathan and the Executive Director, MSSRF, for their encouragement and support, Dr. D. K. Upreti for his critical comments on identification and reconfirmation, Principal Chief Conservator of Forests, Tamil Nadu, and District Forest Officer, Coimbatore, for necessary field permit, field guides Mr. P. Chokkalingam, Mr. P. Radhan, Mr. Senthil and Mr. Selvam for their help, Council of Scientific and Industrial Research, New Delhi, and Government of India for the financial support.