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Hochschule Weihenstephan-Triesdorf

The role of Acacia auriculiformis

Restoration of Tropical Dry Evergreen Forest

at the Coromandel Coast, South India:

BACHELOR THESIS

Author:

Supervisor:

Theresa Riedl

Submission date:

Jägerstraße 12

Freising, July 2012

85737 Ismaning

Prof. Dr. Jörg Ewald

Faculty of Forestry and Forestry

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2The information about the historical background in this chapter is based on an interview

with Jean Pouyet about the history of Auroville over the last four decades and on personal

communication with Patrick from Revelation about the treatments of the study sites.

Fig.4: Ravine at the Auroville plateau

3.5 History of study sites2

At the beginning of Auroville in the late 1960’s, the usual land use form was dry land

farming with two sowings a year. Land with no deep rooted vegetation which had been

plowed and therefore is of loose structure, is not able to absorb the heavy rains that are

occurring in that region a couple of times a year. As soon as the top soil was saturated,

the runoff started and was responsible for the transport of soil particles and the degradation

of the plateau, what impaired the conditions till the land was nerved by ravines (Fig.4) and

not suitable for agriculture anymore.

In the 1980’s, slowly the land got converted from dry land farming to Cashew plantations.

Cashew tree trees that are not as shallow rooted as the annual plants that were used in

dry land farming were attenuating the impact of the water, which meliorated the conditions

above the ground that otherwise would have been bare for months and trampled by a huge

amount of cattle that were herded by local people.

The afforestation efforts started in the early 1970’s when the early inhabitants of Auroville

tried to use small plantations of evergreen trees as windbreaks.

These attempts led to an enlargement of the planted areas, supported by the knowledge

of fast growing and drought resistant exotics that the Aurovillians had gained at that time.

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A majority of the survey plots are located in the Auroville community Revelation, where the

first attempts took place approximately in 1975/1976. Like in many other

But only since the 1980’s, the management of the forest was done consciously. Farming has

been clearly separated from the forest area. The sanctuary was extended and surrounded

by living fences to prevent cutting and grazing. Beside of that, many species have been

planted due to the aim to reintroduce native tree species that were not regenerating by

themselves at that time, like Diospyros ebenum or Mimusops elengi

communities, the first efforts were to plant fruit trees and to do agriculture. Beside of that, the

first big trees like Pterocarpus santalinus, Tectona grandis and Albizzia lebbeck

(Fig.5). Pictures of Revelation before and after the restoration are attached in

Appendix 1.

Fig.5: Tree nursery in Revelation

But the most important was the establishment of a sanctuary near the ravine, where the soil

was mostly eroded and therefore useless for agriculture.

were planted.

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These two areas are adjacent and represent one treatment each (Fig.6): The Old Sanctuary

(OS) and the New Sanctuary (NS). The important difference is the length of time, in which the

treatment was implemented. The Old Sanctuary was founded 37 years ago, the New Sanctuary

was established 17 years ago. Another important difference between the two treatments is the

fact, that the Old Sanctuary simply has been protected, while the New Sanctuary was entirely

planted with Acacia auriculiformis in the beginning (for a short overview see Table 2). Beside

that, especially over the last couple of years, saplings of native tree species were introduced to

accelerate the colonization of the area by trees where no adult individuals were left that could

act as seed resource. More saplings were planted in the New Sanctuary (detailed information

about the planted species is attached in Appendix 5).

4.1

Fig.6: Aerial image of the two study sites in Auroville

Selection of study sites 1

(Google Earth, August 2011, modified)

For the study, three different treatments in two study sites on the Auroville plateau were chosen.

To investigate the effect of A. auriculiformis on the regeneration and to enable studying the effect

of other parameters like soil properties, an unreal time series was established to the state prior

to afforestation. Together with Mr. Jean Pouyet, who was one of the people starting tree planting

in Auroville, an area outlying Auroville near the old airport of Pondicherry was chosen. These

areas are still under anthropogenic pressure like

Two of these three areas are located in the Auroville community Revelation and are already

under restoration.

4. Methodology

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Treatment

Initial State /

since

Protected

Tab.2: Overview of treatments and their characteristics

New Sanctuary 1994

Fig.7: Distribution of the numbered plots in the Old Sanctuary and the New Sanctuary

livestock grazing, fuel wood collection and fire and therefore in a similar condition as the other

two treatments were in prior to protection and planting. It is the third treatment and is called

“Initial State” (IS).

Old Sanctuary 1974

The plots were distributed according to a grid. The number of plots was calculated in respect to

the area size with a plot density of one plot per acre and a buffer zone of minimum 10m to the

forest edge.

Disturbance

4.3 Number and distribution of plots

Anthropogenic

To have a reliable foundation for the plot distribution, a revision of the existing maps of revelation

had to be made. The plots that were assessed in the Initial State were not installed permanently,

so it was not necessary to establish maps for this treatment.

No planting

Planting of A. auriculiformis

No planting

4.2 Maps

No

Planting of nurse trees in the

beginning

No

Yes

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A description of the position of the plots is attached in the appendix.

Fig.8: Plot demarcation

The plot itself was divided into three layers, in which the assessment was done:

• the circular plot •

the square plot •

and five regeneration plots

4.4 Plot demarcation and design

These three layers were done to get different data of the tree layer the shrub layer and the

herb layer (see chapter 3.5).

(200m2)

In order to the monitor the successional changes over a long time, a permanent plot system

was installed. Based on that, the material for the plot demarcation was required to be very

weather-resistant and the plots were therefore anchored with plastic pipes (Fig.8). To protect

the pipes of termites and dirt, the top was covered with plastic caps.

(25m2)

One plot was marked on five points, whereupon four pipes were placed at the edges of a

square and the fifth pipe marked the middle of the square (Fig.9).

The result was nine plots in each treatment in Revelation and ten plots in the Initial State area,

whereat it was not possible to install plots in the whole area due to ravines or areas within the

treatment that were not representative. In Revelation, the distance between two plots was

40m.

(1m2 each)

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