ECOLOGICAL STUDIES

7.1 LINEAR Tree Increment Plots (LTI Plots)
Concerted effort all over the country for laying Tree increment plots took shape subsequent to the adoption of the resolution in the third Silvicultural Conference held at Deharadun in the year 1929. It recommended establishment of plots on a long-term basis. During the 1930s' Forest Research Institute, Deharadun laid a large number of plots in different parts of the country in evergreen forests. Another effort was made in 1950s' when Mr. Quereshi the then Silviculturist, Pune, set up 16 Linear Tree Increment plots around Dandeli in Uttara Kannada district. Now there are altogether 15 LTI plots in moist deciduous forests, 7 in evergreen forests and 5 preservation plots in Karnataka. Once in 5 years growth data is being recorded. The main object is to study the diameter incremental of different species under natural conditions. Besides, status of natural regeneration is also being studied in these plots. The details of LTI plots in the state are given in Table 33.
Dr. S.N.Rai, with the assistance of UNESCO reviewed the 'Long Term Research Sites of Tropical Forests of India ' in the year 1996, and the study was published as a book by UNESCO Delhi titled “Long Term Research Sites in Tropical Forest of India”.
Linear Tree Increment and Preservation plots in Karnataka
Sl.No / LTI Plot No. / Locality / Range / Year of formation / Breadth & length in chain / Extent in
ha
Moist Deciduous Forests
1 / 1 / Raulwada / Barchi / 1950 / 1 x 80 / 3.20
2 / 2 / Usoda / Barchi / 1950 / 1 x 80 / 3.20
3 / 3 / Shingatgeri / Barchi / 1950 / 1 x 80 / 3.20
4 / 4 / Karka / Dandeli / 1950 / 1 x 80 / 3.20
5 / 6 / Bailpur / Virnoli / 1950 / 1 x 80 / 3.20
6 / 7 / Veerampalli / Virnoli / 1950 / 1 x 80 / 3.20
7 / 8 / Aurla / Gund / 1950 / 1 x 80 / 3.20
8 / 9 / Shiroli / Virnoli / 1950 / 1 x 80 / 3.20
9 / 10 / Phansoli / Virnoli / 1950 / 1 x 80 / 3.20
10 / 11 / Jambagali / Kulagi / 1950 / 1 x 70 / 2.80
11 / 12 / Kulagi / Kulagi / 1950 / 1 x 80 / 3.20
12 / 13 / Bhagawati / Bhagawati / 1950 / 1 x 80 / 3.20
13 / 14 / Adkehosur / Sambrani / 1950 / 1 x 80 / 3.20
14 / 15 / Bhagawati / Bhagawati / 1950 / 1 x 80 / 3.20
15 / 16 / Mainal / Sambrani / 1950 / 1 x 80 / 3.20
Wet Evergreen Forests
16 / Agumbe / Agumbe / 1940 / 1 x 87 / 3.48
17 / Devimane * / Janmane / 1939 / 1 x 67 / 2.68
18 / Katlekan * / Siddapur / 1939 / 1 x 27 / 1.08
19 / Malemane * / Siddapur / 1939 / 1 x 68 / 2.72
20 / Kodkani / Gersoppa / 1939 / 1 x 60 / 2.40
21 / Bannadpare / Makut / 1939 / 1 x 84 / 3.36
22 / Chippehole / Makut / 1937 / 1 x 60 / 2.40
23 / Talageri / Yellapur / 1937 / 1 x 60 / 2.40
* These plots are also preservation plots.
Note: LTI plot no. 5 was lost due to submersion.
7.2 HYDROLOGICAL STUDIES IN EUCALYPTUS PLANTATIONS
The large scale planting of exotic species like Eucalyptus and Australian Acacias have caused concern to local people in the state. The plantations were thought to have adverse environmental impact particularly in relation to nutrient depletion and high water use from ground table.
To investigate and quantify these environmental impacts, certain field studies were designed to measure the water use and nutrient uptake vis-à-vis growth rates of Eucalyptus in Karnataka in the year 1987. The study was taken up in collaboration with Mysore Paper Mills (MPM), Institute of Hydrology , UK , Oxford Forestry Institute (OFI) and University of Agricural Sciences (UAS), Bangalore . The British Overseas Development Administration (ODA) funded the studies.
1. / At Puradal, the water use of young Eucalyptus plantation was no greater than that of the indigenous dry deciduous forest trees.
2. / At both Puradal and Devabal, the annual water use of Eucalyptus and indigenous forest trees was equal to the annual rainfall (within the experimental measurement uncertainty of about 10 per cent)
3. / The water use of the forest was about twice that of agricultural crops.
4. / At the Hoskote site there were indications that the water use, over the three (dry) years of measurement was greater than the rainfall. At none of the places there was any indication of roots taking water directly from the water table. The Hoskote findings showed that the water use was considerably greater than the rainfall. High priority was given to confirm these results and also to determine the source of this “Extra” water. One hypothesis invoked was soil water “Mining”. If from the day of planting, roots penetrate successively into deeper layers of the soil every year, at the rate of about one meter per year, the water “Mined” from the successively deeper soil layer would be sufficient to account for most of this “Extra” water. An alternative hypothesis is that the trees are drawing water stored in this soil from years with higher than average rainfall. The first hypothesis implies a non-sustainable system in the long term. The second hypothesis would, of course, imply a sustainable system. Further study over a long term may resolve this issue.
7.3 HYDROLOGICAL STUDIES IN ACACIA AURICULIFORMIS PLANTATIONS
A study in collaboration with National Institute of Hydrology, Belgaum was taken-up to study hydrological changes induced by various forest interventions in Uttar Kannada district especially in Acacia auriculiformisplantations. The study was undertaken between the years 1995 and 1999 with financial help from UNESCO. The following are the salient findings of the study:
a). / Infiltration rate is high in coastal areas where Acacia auriculiformisplantations were raised on lateritic soils or on laterite sheet. The rate was found to be 270 - 440mm per hour at Hattikeri. The least infiltration was noticed in grasslands (7mm per hour) at Yettinabail.
b). / Rate of infiltration in clayey soils was low (3-6mm per hour) compared to other type of soils. When afforestation works were taken up, infiltration rate was about 40-180mm per hour in red soils at Urthota. Whereas infiltration rate in the agricultural land was 190-390mm per hour in alluvial soil at Haldipur.
c). / The hydraulic properties of soils showed considerable seasonal variations. It was observed that infiltration rate in dry season is more as compared to wet season.
d). / It was observed that the hydraulic property of undisturbed evergreen forests was 30-240mm per hour followed by a site on which gap regeneration was taken up. The least infiltration rate was observed in grasslands.
e). / Type of the plantation and their age had influence on the hydraulic conductivity of the soil. In case of 10-year-old Acacia plantation, hydraulic conductivity was 58mm per hour followed by 10-year-old Casuarinaequisetifoliaplantation where it was 22.5mm per hour. It was surprising to note that the infiltration rate was very low in 67-year-old Teak plantation.
f). / Type of soil influences the hydraulic conductivity considerably. Coastal sandy soil has a hydraulic conductivity of 132mm per hour, where as clay soil has the least which is 2mm per hour.
g). / Management activities on forest soils affect its physical properties, which in turn influence soil hydraulic properties.
h). / Interception of precipitation by plants and accumulation of litter lead to variation in infiltration.
i). / Soil moisture status shows a considerable increase on reforested degraded land.
j). / Organic matter and other chemical parameters influence the soil characteristics very much. Undisturbed soils with high organic matter content induce higher rate of infiltration.
k). / Mineralogy of soils also plays a role in soil hydraulic properties.