A FLORISTIC SURVEY OF A UNIQUE LOWLAND RAIN FOREST IN MORAELLA IN THE KNUCKLES VALLEY , SRI LANKA

The luxuriant natural forests of the western lower slope of the Knuckles range have been heavily deforested since the mid-19 th century for conversion to coffee and tea plantations. Consequently, only scant floristic and ecological signatures of the original vegetation are , . Recently, an isolated forest fragment at 500-700 m amsl, not recorded previously, in Moraella Kukul Oya (stream) in the s r of Knuckles range. A vegetation survey recorded a total of 204 flowering plant species in 70 families Eighty-nine (44%) species are endemic to Sri Lanka, while 39 (20%) are nationally threatened. Among the 148 tree, treelet and shrub species identified, 4 ( 0%) have been recorded floral of the Knuckles forest reserve, while 115 (78%) are common to the lowland rain forests of south-western Sri Lanka The existence of (river), suggests that of lowland rain forest formation. These forest fragments likely mark the north-eastern-most limits of distribution of lowland rain forests in Sri Lanka and warrant urgent conservation as biodiversity refugia. They may be the last vestiges of an almost disappearing lowland rain forest type in the Knuckles range.


INTRODUCTION
The Knuckles range ( ), in the Kandy and Matale districts is a northern outlier of the central highlands in Sri Lanka; its peaks are frequently it is locally as 'Dumbara Kanduwetiya'.
' ' -The south-western (SW) and southern sides of the is separated from the main central highlands by the valley of the Mahaweli river (de Rosayro, 1958), also bordering its eastern lowlands.
the left bank of the river is commonly known as the 'Dumbara Mitiyawatha' (meaning 'mist valley';Cooray, 1984).The name Knuckles, was given to it by British surveyors, as its main massif (Fig. 1) resembles a clenched fist (Bambaradeniya and Ekanayake, 2003).The Knuckles forest reserve ( F ) encompasses an area of 180 km 2 within the altitudinal range of 115-1905 m and comprises several hill ranges.The main KR, lying approximately 50 km from Bowatanna reservoir of the Amban Ganga (north-western end; Ganga = river) to Randenigala reservoir of Mahaweli Ganga (south-eastern end), has four major lateral ranges descending towards the north-eastern (NE) (Rambukoluwa range), eastern (Kalupahana range and Dumbanagala range) and SW (Hunnasgiriya range) lowlands (Fig. 2).
Due to its geographic location, graphic varia and altitudinal range, the K exhibits a variety of climatic regimes ranging from wet on the SW and western slopes , to seasonally dry on the eastern and NE slopes .The whole region receives rain mainly from the NE monsoons that prevail from December to February.The wetter western slopes (Rattota, Elkaduwa, Wattegama, Panwila, Hatale, Arattana, Baddegama and Werapitiya) receive rain from both the SW (May-September) and NE monsoons (December-February) and the highland regions are very wet, with mist and strong winds during the monsoons (National Atlas, 1988, Domros, 1974).This area belongs to the WM3b

A B A
Agro-ecological region of Sri Lanka (Fig. 2, Panabokke, 1996).The higher ridge of the act as an orographic barrier.They ensure that relatively little rain from the SW monsoon falls on its eastern and NE slopes (Puwakpitiya, Illukumbura, Pallegama, Narangamuwa, Meemure, Hasalaka, Kalugala and Madugalle), that are influenced by strong desiccating föhn winds, known locally as 'Kachchan' (Legg, 1995;Sri Bharathie, 1993).This high climatic variation in the K has resulted in a diversity of forest types representative of most forest types in the island (Abeywickrama, 1964).ts distinctive floristic composition has already resulted in the demarcation of the as a separate floristic region owing to the high level of infra-generic plant endemism, and the presence of unique Deccan-Gondwanan relicts (Ashton and Gunatilleke, 1987) (2003) reported eight major vegetation types in the KFR.The latter authors refer to only the major vegetation types, while the former gives sub-types within some of the major vegetation types (Table 1).However, neither of the publications reports a Tropical Lowland Rain Forest (TLRF) type , i.e. the typical forest type found in the SW lowlands of Sri Lanka.
The major vegetation type in the foothills below 900 m of the KR located on the drier northern and NE slopes has been classified as Tropical Lowland Wet Semi-Evergreen Forest by de Rosayro (1958).This forest type  (2003), and is confined to the eastern lowlands around Meemure, Pallegama and Illukkumbura.Legg (1995) reported that this forest has lower species diversity than the lowland rain forests and that some plants such as Drypetes sp.found in the semi-evergreen forests are more typical of the drier parts of the island.However, Abeywickrama (1964) reported that many lowland rain forest species are present here, with the exception of species belonging to the family Dipterocarpaceae.O comprehensive studies i carried out by Legg (1995), ed for conservation planning and management, i .This study , but this too, did not any natural forest formations in the wetter western and SW lower slopes (300-900 m) of the KR

OBJECTIVES
The present investigation was particularly focused on establishing what the natural forest type would have been on the western lower slopes and valleys of the KR prior to the introduction of coffee and tea plantations since the mid-19 th century by the British planters (Legg, 1995).occurred ere the 'c ' ' ' etc. ------ The objectives of this investigation were twofold: (i) to carry out a floristic inventory of the remnant forest patches on the lower western foothills of the KR and list the species therein; (ii) to determine to what extent the flora of this forest resemble that of the lowland wet evergreen forests or rain forests of SW Sri Lanka and the lowland semi-evergreen and lower montane forests described previously from the KR.

Identification of remnant forest patches
The existence of remnant natural forest patches was determined through a study of the relevant 1:50,000 topographic maps of the western slopes of the KR, followed by field reconnaissance surveys for verification.

Study area
Reconnaissance surveys of the western and SW slopes of the KR revealed the presence of two forest remnants, about 2 km apart.Both forests are situated within the 'Patha' (lower) and 'Meda' (mid-) Dumbara Administrative Divisions in the western and SW valley of the KR.These fragments are located outside the present boundary of the KFR within the Panwila Forest Beat and administered by the Kandy District Secretariat.The smaller of the two, located at 7° 23' 06.30"-7° 24' 04.60" N, 80° 44' 29.96" -80° 45' 03.45" E, is 48 ha in extent and between 500-650 m amsl, and on the Hulu Ganga, in close proximity to Kosgama village.The larger is about 95 ha in extent, at 7° 21 ' 37.68" -7° 22' 46.02" N, 80° 43' 20.64" -80° 44' 12.20" E, also between 500-700 m amsl on the banks of the Kukul Oya (Oya=stream), one of the tributaries of Hulu Ganga.This latter area is known as Moraella (or Morahela) and located SW of a south-east of Hatale tea plantation.The larger forest fragment, hereafter referred to as the Moraella forest, was selected as our study area.This lies on the SW limits of the Knuckles floristic region of Sri Lanka (Ashton and Gunatilleke, 1987).The fragment selected was also mapped using Arc GIS 9.2 (ESRI, USA) software (Fig. 3).

Climate of study area
The study site lies within an area of mean annual rainfall >2500 mm (Fig. 4; National Atlas 1988).The mean monthly rainfall for the Moraella forest area was determined from the data maintained at the Madulkele Tea Factory (from 1997-2006) located approximately 2 km away.

Floristic survey
A floristic inventory of the Moraella forest was made based on several reconnaissance surveys carried out during 2006-2010.Representative samples of its plant species that could not be identified in the field were collected, preserved and herbarium specimens prepared for identification at the National Herbarium, Peradeniya.As far as possible, taxa in all angiosperm life form groups [trees, treelets, shrubs, herbs, epiphytes (only Orchidaceae and Loranthaceae) and climbers] were inventoried, and a list was prepared.Among the plant species identified, the endemic species were determined using 'A Checklist of the Flowering Plants of Sri Lanka' (Senaratne, 2001), and the national and/or global conservation status of species was determined using the IUCN Red List, 2007.
The checklist of flora compiled for the Moraella forest was then compared with published floral lists of tree, treelet and shrub species for the tropical lowland rain forests (TLRF) Sinharaja, Kottawa, Hinidumkanda, Kanneliya and Gilimale forests (all in the southwestern lowlands) and also for lowland forests in the KR (Gunatilleke et al., 2004a;Gunatilleke and Gunatilleke, 1991;Bambaradeniya and Ekanayaka, 2003;de Rosayro, 1958;Anon., 1997b).

RESULTS AND DISCUSSION
The mean annual rainfall in the vicinity of the Moraella forest is >2500 mm, which is comparable to that of the TLRF areas in SW Sri Lanka (Fig. 4).However, Sinharaja and Gilimale forest areas receive 4000-5000 mm and even >6000 mm in very wet years (Domros, 1974;National Atlas, 1988).In the general area of Madulkele close to the Moraella forest, a mean monthly rainfall around 100 mm (Fig. 5) has been recorded even during the least wet months, as also recorded in rain forests like Sinharaja.
The vegetation surveys conducted in the Moraella forest study site recorded a total of 204 angiosperm species, belonging to 70 families (Appendix 1).Among these were 124 tree-, 9 treelet-, 15 shrub-, 36 of herbaceous specie , graminoid The site is rich in orchids, represented by 14 epiphytic 5 terrestrial species.There were 19 species of climbers as well.Among the plant species identified in Moraella forest, 89 (44%) are endemic to Sri Lanka (Table 2).Based on the IUCN Red List categories, among the species identified, 39 (20%) are assessed as nationally threatened; 18 of them are globally threatened.Seven species (4%) are nationally near threatened (Table 2, Appendix 1).
, the majority of the species, viz., 115 (78%) of the tree, treelet and shrub species in the present study, have also been from the TLRF of SW Sri Lanka (Anon., 1997b;Gunatilleke et al., 2004a &b andGunatilleke andGunatilleke, 1991) (Appendix 1).The Dipterocarpaceae is abundant in the vegetation of the Moraella forest, and is represented by Dipterocarpus zeylanicus Thw., Shorea dyeri Thw.ex Trimen and Vateria copallifera (Retz.)Alston (Fig. 6).These species have not been recorded in the KFR in previous , ; Additionally, the three species referred to above co-exist with other plant species characteristic of TLRF of SW Sri Lanka.For these reasons, Moraella forest can be considered as a TLRF or a dipterocarp forest (Greller et al., 1993).abundance parian 0 of k and a Isolated individuals of these dipterocarp species have been observed in Nichola Oya (near Horagolla and Halgolla) and the general area of Rattota (pers.obs.).Interestingly another riverine forest with a population of an endemic dipterocarp, Stemonoporus acuminatus has been reported in Mahawela on the banks of Maha Oya within the Victoria-Randenigala-Rantembe Sanctuary at the south-eastern end of the KR (Anon., 1997a)  Considering these climatic and floristic data, it could be inferred that Moraella forest and its surrounding region most likely mark the northeastern limit of the distribution of TLRF, characterise .One may question whether a change in climate of SW Sri Lanka from an ever wet to a less wet seasonal climate would affect the survival of the Doona species in its TLRF.
e Moraella possibly, riverine and SW now restricted to a small area.T e this At present, illegal logging of timber trees (Fig. 7), encroachments for tea and spice cultivation and for settlements are among its main threats.Other potential threats include invasive alien plant species.Clidemia hirta (L.) D. Don, Pinus caribaea Morelet, Acacia sp. and Alstonia macrophylla Wall have invaded the disturbed parts of the forest in Moraella (Fig. 7).These invasive plant species could aggressively interact with the seedling growth of the native species, by shading them out, and/or competing for limited resources such as water during less wet periods, nutrients and space.
(Celastraceae), Chionanthes albidiflora Thw.(Oleaceae) and Glochidion acutifolium Alston (Euphorbiaceae), and five endangered species (Appendix 1) were also recorded by us.The unidentified Dipterocarpus species (suspected to be D. insignis) and Shorea dyeri, when found, were only recorded in very small populations in other lowland rain forests in SW Sri Lanka previously sampled by us (Gunatilleke and Gunatilleke 1991); but in Moraella forest they are abundant in the canopy and they have a relatively high population in this habitat.Thus, Moraella forest, though a small isolated fragment surrounded by tea plantations still serves as a refugium for these species and for the 89 endemic species as well (Table 2), highlighting the importance of its conservation.Though the forest fragment close to Kosgama village was not extensively surveyed, its structure and canopy species are similar to Moraella forest.Together they represent a , KR The present study also provides an insight into what native plant species could be selected for reforestation and restoration programs in the neighbouring pine plantations and grasslands in the KR (Fig. 8), ., The failure to recognize a lowland forest type in the KR during previous forest surveys may be because most of the lowland forest formations below 900 m elevation, particularly on the western and SW foot hills of the KR i.e. the Mi , had already been converted to cash crop plantations and no large parcels of forests had been detected in aerial photographs worthy of investigation by previous investigators (de Rosayro, 1958).Since the Moraella and other such forest fragments lie outside the contiguous forests in the KFR, they were probably not included in Legg's 1995 survey.Other recent floristic surveys conducted oo, had focused on lower and upper montane rain forests in the K (Jayasuriya et al., 1993;Werner, 200 ) possibly for the same reason.
As this forest is outside the protected area of the F inclu forest fragments of th within the within its would enrich the ecosystem diversity of this globally significant protected area.Remnant forest fragments, like the Moraella forest, can be considered as biodiversity refugia, which have facilitated the survival of native biota, over centuries or millennia, under changing environmental conditions.These refugia may offer many taxa the best chances for survival under anthropogenic climate change (Keppel et al., 2011).Identification of such refugia is also important for conservation as they could serve as catalysts for recolonization of the surrounding non-forest matrix.Recent national level assessments too, have emphasized the need to identify biodiversity refugia in the island, located outside the existing protected area network, establish them as corridors and buffer zones and link them to the protected forests to enhance their conservation (Jayasuriya et al., 2006;de Silva. 2007).
As done earlier (Wikramanayake and Gunatilleke, 2002), a plea is made again to establish tree corridors of natural forest species between the vestigial isolated forest fragments already ed reserve, through a well coordinated restoration programme.The areas that could be restored to bring about this connectivity are outlined in Fig. 8. Restoration would enhance the sustained management of these very small forest fragments, ensuring conservation of the rich genetic diversity in Moraella lowland rain forest in the KR.In: Erdelen, W., Preu, C., Ishwaran, N. and Madduma Bandara, C.M. (eds.),Proceedings of the International Symposium on Ecology and Landscape APPENDIX 1: Plant species recorded in Moraella forest (column 2) and their distribution in forest types within the Knuckles Forest Reserve (KFR) and other lowland rainforests of SW Sri Lanka (KO: Kottawa, HI: Hinidumkanda, KA: Kanneliya, S: Sinharaja, G: Gilimale).The endemic (E), native (N) and introduced (I) status of species, as well as their IUCN threatened status: globally threatened-vulnerable (GVU), critically endangered (GCR) and endangered (GEN) and nationally threatened-vulnerable (NVU), endangered (NEN), critically endangered (NCR), near threatened (NNT) and not threatened (NOT) species.

Family
Species

Figure 1 .
Figure 1.Part of Moraella forest (A) on the SW foothills of the Knuckles Range (B) in the background.

Figure 3 .
Figure 3. Locations of the lower Dumbara rain forest (Moraella and Kosgama forest fragments) in the Knuckles Range, in relation to Hulu Ganga and one of its tributaries, the Kukul Oya (Coordinates based on Sri Lanka Datum 1999, National Atlas, 1988).

Figure
Figure 4. Map of Sri Lanka (in part) showing the rainfall ranges of Moraella and Kosgama forests in the Kunckles Range and in Sinharaja, Kottawa, Hinidumkanda, Kanneliya and Gilimale forests in the South West (Source: National Atlas of Sri Lanka, 1988).

Figure 5 .
Figure 5. Mean monthly rainfall from 1997 to 2006 compiled from data recorded at Madulkele tea factory, (850 m amsl), which is situated ~2 km north of the Moraella forest.

Figure 7 .Figure 8 .
Figure 7.An illegally logged timber tree of Dipterocarpus zeylanicus (upper) and invasive species of Pinus caribaea (A) and Alstonia macrophylla (B) patches in the neighbourhood of the wet lowland rain forest (C) (lower) in Moraella, in the Knuckles Range.
. De Rosayro (1958) recognized three major vegetation formations, viz., Lowland Tropical Wet Semi-evergreen Forest, Sub-montane Tropical Wet Semi-evergreen Forest and Montane Tropical Wet Evergreen Forest, based on aerial photointerpretation correlated with extensive field enumerations.He further classified them into 16 sub-divisions of vegetation types within the KR.More recently, Bambaradeniya and Ekanayake

Table 2 . (A) Proportions of flowering plant species in different distributional range categories in Moraella forest and (B) IUCN Red List categories (IUCN Red List, 2007), where percentages were calculated based on the total number of identified species (n=197 species).
Anon. (1997b).Designing an optimum protected areas system for Sri Lanka's natural forests.Published by the IUCN/WCMC/FAO for the Forest Department of Sri Lanka.