Regeneration of indigenous Shola species under exotic pine plantations in the Palni Hills, South India

Index of Contents

1. Introduction
1.1 Eco regions and forest biomes of India
1.2 The studied area
1.2.1 Geographical situation
1.2.2 Climatic conditions
1.2.3 Geology and soils
1.2.4 Native vegetation of the Upper Palnis (1700 – 2500m)
1.3 Exotic plantations in the Palni Hills
1.3.1 History of exotic plantations
1.3.2 Use of plantations nowadays
1.4. Problem definition and objectives

2. Methods and Materials
2.1 Strategy of outdoor assessments
2.1.1 Selection criteria for plantations
2.1.2 Number, size and spatial distribution of vegetation plots
2.1.3 Plot design
2.2 Procedure of outdoor assessments
2.2.1 Exploration of plantations
2.2.2 Assessment of general parameters of the plantations
2.2.3 Assessment of location parameters per plot
2.2.4 Assessment of main stand
2.2.5 Assessment of Shola regeneration
2.2.6 Assessment of ground vegetation
2.3 Statistical analysis

3. Results
3.1 Main stands
3.1.1 Composition of species and stock structure
3.1.2 Number of trees, standing supply and base area per ha
3.1.3 Deadwood, damages and human influence
3.1.4 Crown density and crown cover percentage
3.1.5 Regeneration of main stand species
3.2 Ground vegetation
3.2.1Assemblage of species
3.2.2 Dominant species
3.2.3 Competition situation
3.3 Shola regeneration
3.3.1 Composition of species
3.3.2 Population density: number of individuals
3.3.3 Distance to the nearest Shola as potential seed source
3.3.4 Browsing rate and herbivores
3.3.5 Other damages
3.3.6 Vitality: Sprout heights and diameters
3.3.7 Special locations
3.3.8 Altitude, fall of ground and exposition
3.3.9 Spatial dispersion

4. Discussion
4.1. Appraisal of competition
4.2 Appraisal of browsing
4.3 Shola as a potential seed source
4.4 Possible silvicultural measures

5. Summary
(1) What is the current situation of shola regeneration in reference to condition and species assemblage?
(2) How is the competitive situation and what influence does the intraspecific ground vegetation have on the regeneration?
(3) Which other location factors have a verifiable influence on species assemblage and abundance of the regeneration?
(4) What effect do wild herbivores like the Indian Bison have on the regeneration?
(5) Is a successful natural establishment of shola species within the plantation expectable in future?

6. Reference list
6.1 Printed sources
6.2 Internet sources

7. Indices of tables and illustrations
7.1 Index of illustrations
7.2 Index of tables

Appendix: Average crown density grade per plantation (ocular evaluation)

Appendix: Average cover grade and relative frequency of occurrence of ground vegetation species

Appendix: Species assemblage of shola regeneration per plantation

1. Introduction

1.1 Eco regions and forest biomes of India

Caused by the vastness (3.287.590 km²) and by the enormous differences of altitudes within this state – with the Himalaya as a natural border in its north - India offers multifaceted sites which led to the formation of different forest types and forest biomes.

Champion (1936) and Seth (1968) differentiated India into 16 climatic- influenced forest types^[1]:

Forest types according to Champion & Seth:

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For example, alone in the Western Ghats following four eco regions^[2] can be found, each depending from altitude: (1) Northern Western Ghats moist deciduous forests, (2) Northern Western Ghats montane rain forests, (3) Southern Western Ghats moist deciduous forests, (4) Southern Western Ghats montane rain forests (cf. World Wildlife Fund, 2001).

1.2 The studied area

1.2.1 Geographical situation

The Palani Hills or “Palni Hills” are situated in the western part of the state Tamil Nadu, South India (district Dindigul). The Palani Hills, (10˚5’ - 10˚25’ N and 77˚15’ - 77˚50,E) are an eastward spur of the Western Ghats of India with a maximum (east to west) length of 65 km, a maximum width of 40 km (mean width 24 km) and a total area of 2068 km² (cf. Matthew,1999).

The function of the Palni Hills as a critical water shade respectively as a catchment area and origin area of numerous streams is – ecological and economical - important for the whole population of Tamil Nadu, especially for the inhabitants of the planes.

For several years now efforts have been made to “reserve forest land” (these forests are already among the protected areas of Tamil Nadu) to “Wildlife Sanctuary and National Park” as their upgrade will increase their IUCN status from level VI - Protected Area with Sustainable Use of Natural Resources to IV - Habitat/Species Management Area or II - National Park and improve the habitat and wildlife conservation of this area.

Ian Lockwood published 2003 in the Indian magazine “Frontline“: “In the early 1990s, the Tamil Nadu Forest Department submitted a proposal to the State government to protect much of the Palni Hills by declaring the area a wildlife sanctuary or a national park. The proposal was the result of a remarkable collaborative effort by the State Forest Department, the Palni Hills Conservation Council (PHCC) and several concerned individuals. Ten years later, the area still awaits the notification in this regard. In the meantime, mounting pressure on the habitat from encroachment and increased tourist inflow has taken its toll on the hills.”

Until today (2011) these efforts failed.

1.2.2 Climatic conditions

The Upper Palnis (and thus Kodaikanal) have a quasi-temperate climate, despite low altitude, with moderate temperatures of low annual range, and moderate and well- distributed rainfall. Maximum temperatures vary little from month to month; minimum temperatures vary a little more owing to slightly greater depression of winter months. Among the hill stations of India, Kodaikanal is said to record the lowest maximum temperature in summer and the highest minimum in winter. In summer (April - September) there are average temperatures between 11,3°C and 20,9°C, in winter (October - February) between 8,2˚C and 10,8˚C (cf. wmo). Ground frost may occur during the winter time, but rarely. According to VTC the last frost occurrence in the Upper Palnis was in November, 2007. (cf. Balcar & Stuart, 2010).

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Illustration 1: Average monthly rainfall for Kodaikanal

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Illustration 2: Average monthly rainfall for Kodaikanal

The bulk of the annual rainfall is received during the north- east monsoon (October – December), with a lesser amount during the south- west monsoon (June – September). But unlike on the western side of the Western Ghats, there is a sharp dry season (January – May) that has qualified Kodaikanal to become the preferred hill station. The maximum wind velocity is during May – August, when cyclones may occur (cf. Matthew, 1999).

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Table 1: Climatic conditions of Kodaikanal according to WMO (World Meteorological Organisation) for 1961 -1990

According to sagareiya (1979) there are four seasons:

1.) Dry season (Dec. – March): rainfall scarce, sun warm; frosts occur
2.) Warm season (April – June): showers occasional; sun hot: the ‘season’ time.
3.) Southwest monsoon (June- Sep.): moderate rainfall
4.) Northeast monsoon ( Oct. – Nov.): maximum rainfall

1.2.3 Geology and soils

The Ghats are part and parcel of that great mass of solid rock which is the Deccan. That means their cores are very old, consisting mostly of metamorphic schist’s, Charnockites and gneisses dating back to the Archaean. They are geologically identical to the Central Mountains of Sri Lanka (cf. T.N. Forest Department, 2007). Yet Radhakrishna (1993) dates the formation of the Western Ghats back to Quaternary and Neogene.

Weathering of these rocks has resulted in the formation of a particular family of soils. These have not been surveyed in detail, but they have been included by Chatterji (1957) under the broad class of red soils common in south India. He describes this soil as “a sandy loam, low in bases, high in sesquioxides, with signs of leaching”. Characteristics of these soils in profile are as follows: The top soils vary in thickness from a few mm on badly eroded sites to 90 cm. The presence of iron and aluminium oxides in abundance gives a dominantly red or red- yellow, generally porous layer, up to more than 1m in thickness above the parent rock soil. The clay content of some other sub soils is very low according to field observations. In the lower part of depressions, organic soils, characterized by great depths of peaty material, are found. These soils are generally very poor drained (cf. T.N. Forest Department, 2007). The soils of coniferous forests and of oak forests at higher altitudes under moist temperate climate are acidic in reaction and have high organic matter and nitrogen contents.

Laterite: This is a compact to vesicular rock composed essentially of a mixture hydrated oxides of aluminum and iron and a small amount of manganese oxide, titanium, etc. It is developed in the regions of heavy rainfalls with a typically intermittent moist climate. Lateratic soils are poor in nutrients P, K, and Ca, and deficient in N. The pH ranges from 4.5 to 5.5 and the base exchange capacity is low.

Red soils: They are deficient in organic matter and poor in plant nutrients. Their color is due to the presence of ferric oxide. They have a low base status and a poor exchange capacity.

(cf. P.K. Khosla and R.N. Sehgal (1988).

Illustration 2: Red Lateratic Soil”, Kodai- Road (about 2100m)

1.2.4 Native vegetation of the Upper Palnis (1700 – 2500m)

The undulating plateau consists of Grasslands interspersed with Sholas: These are patches – between less than 1 ha to some hundred ha spatial dispersion - of dense isolated woods composed of evergreen trees occurring along the folds on the undulating plateau, often associated with a stream in the middle. Trees are characteristically stunted, seldom above 15m, profusely branched and supporting a large number of epiphytes like mosses and ferns, in addition to numerous creepers and stragglers along the periphery like Clematis, Persicaria, Rosa and Rubus. Among the more dominant genera of trees are Syzigium (3), Ilex (3), Turpinia, Meliosma (2), Elaeocarpus (3), Eurya, Gordonia, Litsea (2), Michelia, Phoebe (2), Rhododendron and Daphniphyllum. Sholas are probably one of the most valuable treasures of the hills, as prime watershed and as shelter for wildlife, in addition to being the terminal refuge for endangered species of flora and fauna.

The rolling downs of the undulating plateau were formerly covered with grasslands, dominated by genera like Eragrostris, Arundinella, Bothriochlora, Digitaria, Themeda, Tripogon, Chrysopogon, Cymbopogon, Apudla and Eulalia.(…) (cf. Matthew, 1999)

The Palani Hills are one of the most important “hot spots” of biodiversity in the world.

1.3 Exotic plantations in the Palni Hills

1.3.1 History of exotic plantations

Hill communities have harvested firewood from sholas and grazed their animals in the grasslands for centuries. The first indiscriminate felling of shola came with the establishment of British settlements in Ooty, Coconoor and Wellington in the early 1800’s. Sholas around these areas became the source of firewood for a very fast growing population. Recognizing the need to protect sholas, a ‘timber conservancy”- system was established in 1841. By this time, however, many sholas in the vicinity of the settlements had already disappeared and the conservancy measures were not adequately enforced. Around the same time while sholas were vanishing, a plantation culture was on the rise and Australian exotics were introduced between 1840 and 1856. These included four Acacia species, all commonly referred to as “wattle”, conifers and Eucalyptus globulus or “blue gum”. These plantations were supposed to meet the fuel wood and timber needs of the area (cf. T. N. Forest Department, 2007).

Pines (Pinus) were amongst conifers the most extensively tried ones. Between 1905 and 1915, over 370 hectares were planted (mostly with Pinus radiata (80%)), largely by the Forest Department, originally as a source of timber and fuel wood for the growing population.

Three major disasters sealed the fate of the pine plantations: the first, in February 1920, was a fire that burnt for three days over 217 hectares - destroying over 95.000 trees - secondly the cyclone of 6 May, 1930, blew down over 30.000 trees, and finally, a fire of 1940 wiped out trees of another 14 hectares. (cf. T.N. Forest Department, 2007).

At present exotic pine trees characterise the landscape around Kodaikanal, together with Eucalyptus and Wattle, and have altered the face of the indigenous vegetation.

The FAO (1993) said that currently forest plantations cover 40 to 50 mills of ha in the tropical and subtropical parts of the earth, mainly exotic species like Eucalyptus sp. and Pinus sp. Current data say that in 2005 India alone had over 3000 ha of land covered by (mostly exotic) plantations.

According to Evans (1992) following species were used for tropical plantations worldwide:

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Following the global relevance, these three genera also dominate the forest plantations in the Western Ghats (cf. matthew, 1999).

1.3.2 Use of plantations nowadays

According to the „Forest Survey of India “(State of Forest Report 2009), about 22% of Tamil Nadu are covered with 28,306 skm² covered of forest yet the „National Forest Policy” of 1988 allots a forest percentage of 33.33%. Thus efforts are still beeing made to expend to expend the area under forest by massive afforestation. In the course of the “Tamil Nadu Afforestation Project“ from 1997, degraded forests should get restored by law and elderly plantations with an expansion of over 95,000 ha should get conserved and not be used any more (cf. pachamal, Minister of Forests, 2010).

There is also a prohibition by law to harvest Pine, Acacia or Eucalyptus growing beyond plantations. (cf. lockwood, 2003).

1.4. Problem definition and objectives

For biologists the term “exotic” normally includes, that a non- native or alien plant or animal threats and adulterates the indigenous flora and fauna. Biological invasions by exotic species are one of the greatest threats to the ecological and economic well-being of the planet. Alien species can act as vectors for new diseases, alter ecosystem processes, change biodiversity, disrupt cultural landscapes, reduce the value of land and water for human activities and cause other socio-economic consequences for man (cf. DAISIE^[3], 2009).

While the two primary Five Year Plans (1951 – 56 and. 1957- 61) centred around rehabilitation and consolidation of forests, the third plan set a new aim, lifting forests from purely conservative an biological management, to increase their production by creating man-made forests of quick- growing and valuable species in place of the existing ones. (…) In order to encourage State governments to undertake large scale plantations of quick growing exotic species, mainly to meet the requirements of the paper and pulp industry, 100% assistance from the Centre was given and thus over 87,000 ha were planted (cf. Sagareiya, 1979).

Today, the conservation of indigenous forests is at the very fore and the view of exotic plantations under experts is more differently evaluated. According to matthew (1991) the plantations are one of the main reasons for the decrease of indigenous species. Nowadays numerous NGO´s (“Non- Governmental Organizations“) try to stop the disappearance of sholas and the ongoing spread of exotic plants in different projects; and, for example, the Forest Department of Tamil Nadu plants indigenous tree species and run some nurseries.

Harvesting of plantations to bring back shola and in the name of restoration is no solution but helps Rubus (native) and other sun- loving weeds to take over quickly (cf. Balcar and Stuart, 2010).

The VCT members have already realized years ago that “… in the previously encroached margins subsequently planted with Pine (Pinus patula) Shola seedlings are beginning to establish themselves along with those planted under the current Pambar Shola Restoration and Regeneration Research Project (PSRRRP) …” (cf. Balcar and Stuart, 2003). This means that the currently not used plantations could serve as a protective shield for shola species. The aim of this study is to prove these observations scientifically, to provide a complete vegetation assessment of shola regeneration under exotic pine plantations for the first time and a description of abundance^[4], dominance^[5] and condition of regeneration. A comparative analysis of different location parameters shell also help to describe the most important location factors.

The aim of this study was to answer the following questions:

- What is the current situation of shola regeneration in reference to condition and species assemblage?
- How is the competitive situation and what influence does the intraspecific ground vegetation have on the regeneration?
- Which other location factors have a verifiable influence on species assemblage and abundance of the regeneration?
- What effect do wild herbivores like the Indian Bison have on the regeneration?
- Is a successful natural establishment of shola species within the plantation expectable in future?

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Illustration 3: Typical Pine plantation (8) with Shola regeneration and Ageratina adenophora

A more in-depth knowledge about these points could help to develop concepts in future to actively advance the positive effects of plantations by adequate measures. This could afford to use the plantations for the ecological regeneration of the Palni Hills and, by the way, to reduce useless and expensive planting measures.

2. Methods and Materials

2.1 Strategy of outdoor assessments

Basic concept of this study was to determine exactly the current condition of shola regeneration, ground vegetation and main stand in different pine plantations so that afterwards conclusions could be drawn from this concerning short- term developments of the plantations and the course of action concerning restoration to be taken. The idea was to determine differences between shola regeneration within the plantations and to identify their reasons employing analytical comparisons of different plantations. Those considerations determined the choice of plantations previously.

2.1.1 Selection criteria for plantations

In this study the investigations were concentrated on pine; the same study ( or at least similar) would be applicable on Acacia and Eucalyptus.

The chosen Pine plantations were situated within the same level of altitude and thus not under 1700m (to stay within the same vegetation zone) and within a practicable distance to Kodaikanal.

Plantations without any ground vegetation and shola regeneration (tourist spots) were excluded from the research for several reasons. All together 9 plantations around Kodaikanal were analysed, with a little, medium or high regeneration rate in each case appearance to allow further comparisons.

2.1.2 Number, size and spatial distribution of vegetation plots

The demand to research at least 5% of the whole spatial distribution per plantation by vegetation assessments determined number and size of the assessment plots. According to this 22 plots per ha were under examination, each with 25sqm (5m x 5m) for the assessment of shola regeneration and ground vegetation and respectively 49sqm (7m x 7m) for the assessment of main stand (= 5,5%). With the help of a raster the plots were schematicaly distributed over the whole plantiona area and measured by measure tape. As shown in table 2, all in all 165 plots were under examination with a total area of around 0.4 ha. The total area was measured with the help of GPS (Explorist 100 from Magellan).

Table 2: Number, size and spatial distribution of vegetation plots

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Illustration 4: schematic plot design

2.2 Procedure of outdoor assessments

2.2.1 Exploration of plantations

The experience of Tanya Balcar and Robert Stuart from VTC were a great help to find qualified plantations. Every plantation got a number at random, as most of them didn´t have an official name. Spatial distribution of plantations was measured with GPS („Global Positioning System“). They didn´t get a long- term mark, but with GPS they are traceable every time. The GPS- coordinates – latitude and longitude – are shown in the following table:

Table 3: GPS- coordinates of the surveyed pine plantations

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2.2.2 Assessment of general parameters of the plantations

Because the Forest Department couldn´t give the exact age of the plantations and there aren´t any records, Tanya Balcar and Robert Stuart were again a great help and often the only source regarding to the age or year of establishment. In some cases it was possible to count annual growth rings of lying trees to estimate the age of the area.

In case of plantation 3, (“Trichy Research Area“) it was not possible to categorize the exact pine species of main stand. In “The Flora of the Palni Hills, South India “(matthew, 1999) this species is simply listed as „ Pinus sp.“. The main stand of the other plantations was mainly built by Pinus patula (plantation 2; 4.1; 4.2; 5; 6; 7) and only in one case (plantation 10) by Pinus roxburghii, a species with its origin in the Himalaya.

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Illustration 5: Pinus sp. (plantation 3)

To know if the plantations are situated within the desired level of altitude (min. 1850m and max. 2400m) the altitude was measured by GPS, and also the distance to the supposed nearest shola. Finding the presumptive nearest shola was often difficult because of steep or confusing terrain and therefore measurement errors are possible. Table 4 and 5 show the most important average data for each plantation:

Table 4: Average DBH, age and height of plantations

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Table 5: Average Exposition, altitude and inclination of plantations

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2.2.3 Assessment of location parameters per plot

Inclination/ fall of ground and exposition were surveyed for every plot with a precision compass and clinometer (Suunto Tandem), altitude and coordinate with GPS- each measurement in the plot centre.

Crown density and canopy were surveyed also in the plot centre to avoid side- effects and described as follows:

Crown density (cf. hussendörfer, 2008) :

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To get another and more objective information about light conditions, the crown density was measured at 16 points per plot (7m x 7m) with a “Kronenspiegel” (“crown mirror” Kutschenreiter Wien). To describe the grade of crown density the following grading was used:

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Table 6: Crown density index and corresponded crown density

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To survey special local characteristics following categories were used:

- Close to water/ river side
- Rocky ground
- Topography: gaps, depression, top
- Forest edge / clearing
- No special characteristics

To survey kind and structure of humus a simple soil profile (40cm depth) was done for every plot.

Other surveyed parameters were droppings, crosses and traps to verify the influence of big wild herbivores.

For the valuation of species diversity and intraspecific competition situation the coverage of vegetation was surveyed, layer by layer. To evaluate the total cover per layer following life-forms were differed:

- Grass
- Fern
- Herb/ Subshrub (Climber: Liana / Struggler) (Climber: Vine)
- Shrub/ Tree (perennial woody plants)

[...]

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^[1] Forest types: Technically a forest type is a category of forest, defined generally with reference to its geographical location, climatic and edaphic features, composition and condition (P.K. Khosla and R.N. Sehgal, 1988).

^[2] Eco region:"a relatively large area of land or water that contains a geographically distinct assemblage of natural communities" (cf. WWF)

^[3] DAISIE: (D elivering A lien I nvasive S pecies I nventory for E urope ); more than 11,000 alien species have been documented by DAISIE, a unique three year research project with more than 100 European scientists, funded by the European Union that provides new knowledge on biological invasions in Europe

^[4] Abundance: the total number of organisms in a biological community; abundance of individuals or abundance of species per unit of area

^[5] Dominance: high percentage of individuals of one species in a biological community