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Table 5.12 Crown Biomass Productivity Some
Well Known Fodder Trees
|Name of Specks||Crown Biomass|
|Acacia nilotica||13-2 7|
While dominant forestry science universalises wood fibre yield as total biomass yield, people's forestry knowledge linked to fodder needs has a different perception of biomass productivity. Diverse economic interests lead to conflicting perceptions of 'biomass', 'yield', 'productivity', etc. Conflicts related to land use generated by Eucalyptus cultivation are thus at the economic as well as epistemological levels. They are multidimensional because land has to satisfy the multidimensional needs of fuel, fodder, food and fibre! With wood fibre and pulp interest being economically dominant, expansion of wood fibre cultivation is undermining the land use potential for food and fodder and generating conflicts within rural communities.
Water Balance of Eucalyptus Cultivation
The single most important conflict generated by the reckless expansion of fucalyptus has been through its impact on water resources. Throughout the country reports are available of the rapid destruction of water resources as a consequence of large scale planting of Eucalyptus. Babuguna recorded the following statement of an elderly forest ranger in the Nainital Tarai of Uttar Pradesh 'We felled mixed natural forests of this area and planted
Eucalyptus... Our handpumps have gone dry as the water-table has gone down. We have committed a sin. Mahashweta Devi described the impact of Eucalyptus on water resources in the tribal areas of Bihar and West Bengal in the following words:
I am concerned with the India I know. My India is of the poor, starving and helpless people. Most of them are landless and the few who have land are happy to be able to make most of the given resources. To cover Purulia, Bankura, Midnapur, Singbhum, Palamau with Eucalyptus will be to rob my India of drinking and irrigation watery'
On 15 August 1983 farmers of Barka and Holahalli villages in the district of Tumkur in the state of Karnataka, marched en masse to the forest nursery and uprooted millions of Eucalyptus seedlings, planting tamarind and mango seeds in their place. According to them, the plantation of Eucalyptus in the catchment of the streams feeding their agricultural lands had led to the drying up of these vital water resources. Describing the state of the mainstream feeding the village Guttalagollahalli, a local farmer complained, 'Earlier we would take our cattle to this stream in the summer. But now, as the stream is dry, we have to fetch water from a well. The hydrological impact of Eucalyptus on water resources has been systematically studied by the hydrological division of the CSIRO in Australia. A long-term experiment established that, during years with precipitation less than 1,000 mm, deficits in soil moisture and groundwater were created by Eucalyptus. A permanent water deficit was avoided by significantly high rainfall of 1,477 mm in one of the five years studied. The results of the long term hydrological study showing that when rainfall is of the order of 1,000 mm or less Eucalyptus plantations create deficits both in the soil moisture and groundwater are summarised in Table 5.13. Quite clearly in the semi-arid regions of India, where rainfall is about 700 mm, the soil moisture and groundwater deficits created by Eucalyptus plantations will act cumulatively, resulting in groundwater depletion, soil aridisation, desertification and water conflicts. Such regions never enjoy rainfall of the order of 1,500 mm which, in the Australian habitat, provide surplus precipitation to make up for the deficit created in years with low rainfall. Eucalyptus, which is ecologically adapted to its native habitat in Australia, threatens to become a serious ecological hazard in the water deficient regions of India. Nowhere in its native habitat is Eucalyptus observed to be a self-sustaining system of vegetation in regions poorly endowed with water. The introduction of Eucalyptus in the dry zones of India does not have the built-in safeguards provided by sites of its natural occurrence. In spite of the internationally recognised, systematic studies on the hydrological impact of Eucalyptus, foresters in India have continued to deny the fact that Eucalyptus disturbs the hydrological balance in low rainfall zones, showing that natural resource conflicts are epistemological in nature. Tewari, President of the Forest Research Institute of India, contributed to the special issue of Indian Forester on Eucalyptus:
Table 5.13 Changes in Soil Moisture and and Groundwater Eucalyptus catchments
Of late in India a lot of controversy has arisen over the water consumption behaviour of Eucalyptus planted in afforestation programmer in social forestry. It has been alleged that Eucalyptus plantations consume large quantities of water to the extent that they deplete local water resources such as streams, wells, etc. This notion does not appear to be correct as no experimental data in support has so far been presented... There is no scientific basis in the popular fallacy that Eucalyptus lowers the groundwater table.
This conflicting understanding of the ecology of Eucalyptus is rooted in the epistemological limitations of the existing forestry science. Reductionist forestry science, instead of enlightening the people in appropriate afforestation progrsmmes, and in turn enriching it self If of their wisdom, continues to protect narrow interest groups. The role of Eucalyptus cultivation in altering hydrological stability can be explained on the basis of the mechanism of root spread of the species under various moisture conditions.
The shallow and laterally spread root system characteristic of Eucalyptus in low rainfall zones has two significant ecological impacts. The vast network of roots just below the soil surface extracts every bit of moisture made available to the soil by precipitation. It, therefore, inhibits other plant growth by competing for scarce moisture. This partly explains why Eucalyptus plantations in dry zones do not show any undergrowth. In dry regions of Karnataka farmers cultivating food crops dig trenches to reduce this impact from neighbouring Eucalyptus plantations. The second and more serious impact of this effective mechanism of Eucalyptus to take up moisture that infiltrates to the soil is the blocking of the percolation processes which would recharge groundwater. The depletion of groundwater takes place when its recharge is interrupted due to evapotranspiration losses under conditions of low rainfall. In complete denial of the established hydrological principles which state that high evapotranspiration rates can deplete groundwater resources by blocking recharge processes, senior forest officials in India have found in the shallow and laterally spread root system of Eucalyptus a most ingenious idea to confuse the people and policy-makers on this issue. At a specially organised press conference, Shyamsundar, the Chief Conservator of Forests of Karnataka, claimed that: 'One of the main criticisms against Eucalyptus that it lowers down the ground water table was baseless as the roots of Eucalyptus rarely went lower than 3 4 metres. Hence it could not tap subterranean water.
From the water balance it is evident that the higher the evapotranspiration the less will be the water available for percolation and recharging of underground water sources. It is also obvious that when the underground recharge is totally dependent on percolation and when the water rquirement of a species is high and is of the order of the total precipitation, there will be no water available for recharging groundwater. Given the available scientific estimates of water requirements of a species and given the rainfall data, the water balance equation is the single and most direct means for assessing the impact of a particular species on water resources. Just as much as Newton's equations of motion provide the predictive tools for the movement of bodies along a trajectory, the water balance equation provides the predictive tool for assessing the impact of land use on water resources.
In the low rainfall zone of peninsular India, the large-scale introduction of a species like Eucalyptus hybrid which has water requirements in the range of 70() 1,200 mm will predictably inhibit recharge of underground water resources. Empirical reports of the drying up of water resources confirm what the scientific principles predict. The response of the 'scientific' foresters to these reports is a one line and unjustified statement that 'unless the water table is higher than 3 metres in any given region, Eucalyptus hybrid cannot tap the water table'. To say that tapping of underground water resources by the tap root is the only process of depleting groundwater by the trees is to say the least, against all accepted principles of plant sciences. Soil moisture provides the primary source of water for plant life. In arid regions, where rainfall is the only source for replenishing soil moisture and recharging groundwater, the introduction of plants with a high water requirement will obviously destroy the hydrological balance of vulnerable ecozones. The Deccan plateau is one such vulnerable ecozone. Being in the rainshadow of the Western Ghats it receives scanty rainfall. Geologically characterised by shallow top soil layers overlying the hard rocks of the Deccan, the groundwater resources in this ecozone are localised pockets of water percolating through fissures and cracks in the hard rocks. The planting of Eucalyptus in these regions is a sure way of blocking the process of percolation by using up the available moisture for the growth of Eucalyptus plantations at the soil surface itself. Ironically, this zone which is the most vulnerable, has been described as a 'preferred zone' for the growth of Eucalyptus in social forestry. Conflicts over water arising from Eucalyptus cultivation have been most significant in such regions and have generated movements against the large scale spread of the species.
Nutrient Deficit by Eucalyptus Cultivation
Economic and epistemological conflicts over land are not generated merely by how land is used, but how this use affects the productivity and fertility of land. Biological productivity is primarily a function of adequate water for plant life and adequate nutrients for plant growth. Eucalyptus plantations conflict with sustainable land use by undermining the water cycle and mining soil fertility. The assessment of the impact of Eucalyptus plantations on fertility and biological productivity of soil must be based on the integrated impact of the species on various segments of the nutrient cycle. This includes the nutrient uptake for growth, the nutrient return through leaf litter, the biodecomposibility of the leaf litter, and the impact on soil flora and fauna. The biological productivity of the soil under a particular type of tree cover is also dependent on the associate plants that the particular species allows. A species introduced as an exotic in an ecosystem will either enhance or deplete soil productivity depending on whether the complex processes which contribute to biological productivity of land are strengthened or eroded by its ecological impact. Unqualified assumptions that any tree planted in any ecozone will contribute to biological productivity have so far been guiding afforestation schemes under social forestry programmes meant for ecological rehabilitation and soil conservation. The introduction of Eucalyptus in arid zone farm lands illustrates of how tree planting undertaken without an assessment of the environmental impact can itself become the source of destruction of biological productivity of the soil instead of contributing to it. There are two dominant processes through which Eucalyptus undermines the biological productivity of arid regions. The first process is based on the physiology of Eucalyptus as a fast growing exotic which creates serious nutrient deficits. The second process is based on the allelopathic and toxic effects on plant life and soil organisms.
The nutrient requirements of Etucalyptus for rapid growth are excessively high. For this reason it grows well only on fertile soils like clear felled natural forests or good agricultural lands.Quantitative information on the nutrient requirements of Eucalyptus is available. It is known, for example, that Eucalyptus hybrid requires 217 kg of Nitrogen, 100 kg Of Phosphorus and 1,594 kg of Calcium per hectare per year. The high nutrient requirement of Eucalyptus for good growth is also evident from Table 5.14 which shows that on sites of poor quality and poor nutrient status growth rates fall to 0.9 CuM per hectare compared to 12 CuM per hectare in fertile soils. Eucalyptus is being planted on fertile agricultural soils for harvesting at short rotations. This creates nutrient deficits because compared to its high uptake of nutrients, Eucalyptus
Ecology and the politics of survival returns a very small quantity of nutrients to the soil through leaf litter. Its annual return in leaf litter is only 35 kg of Nitrogen, 14 kg of Phosphorus and 335 kg of Calcium per hectare per year The wide gap between the nutrient uptake and nutrient return implies that Eucalyptus plantations create a massive deficit in soil nutrients. At this rate, at the end of the second rotation, after twenty years the total nutrient deficit of the land will be 3,540 kg of Nitrogen, 1,720 kg of Phosphorus and 25,200 kg of Calcium (Table 5.14).
Table 5.14 Nutrient Deficit o Eucalyptus Hybrid Plantation
|Annual nutrient deficit||182||86||1260|
|Deficit after second rotation (twenty years)||3640||1720||15200|
While most trees indigenous to a habitat form a self-sustaining system,of living resources, Eucalyptus plantations harvested at short rotations are non-sustainable. The nutrient deficit created by short rotation harvesting of Eucalyptus hybrid does not imply that Eucalyptus would create deficits under all conditions and would be a non-sustaining form of vegetation in all ecosystems. In its native habitat in Australia, Eucalyptus manages to sustain itself because it is not fast growing in sites of natural occurrence. Commenting on this difference of growth and nutrient uptake between Eucalyptus as an exotic and as a naturally occurring tree in Australia, Pryor states:
The outstanding single feature of the genus is its capacity for rapid growth as an exotic if soil and climate conditions are generally suitable. Many Australian soils are exceedingly deficient in phosphorus and other essential mineral nutrients. Sites which are like this are characteristically occupied by the peculiarly Australian vegetation of which Eucalyptus are a part. On the most extremely nutrient deficit sites Eucalyptus may be excluded almost entirely... In many areas where they are planted outside Australia the basic fertility levels are higher than in the natural Australian habitat. It is for this reason that in many cases the growth is greater when they are seen as an exotic, rather than under natural conditions.
Allelopathic Properties of Eucalyptus
Allelopathy refers to the deleterious effect of one plant on another through the production of chemical retardants that escape into the environment. The allelochemical and toxic effects of Eucalyptus have been scientifically recorded and studied both in India and abroad. Del Moral and Muller were the first to scientifically study allelopathy in Eucalyptus plantations and to analyse this factor as responsible for the absence of herbaceous annuals. Al-Mousawi and Al-Maib studied the pronounced paucity of herbaceous plants in Eucalyptus plantations in Iraq. Commenting on the reduction of seed germination due to Eucalyptus, Swami Rao and Reddy reported:
Investigations revealed that the reduction was not due to soil moisture, nutrient elements and shading. On the other hand, leaf extracts, decaying leaves and soil collected under Eucalyptus canopies inhibited seed germination and seedling growth of associated species. In subsequent research three volatile inhibitors and five water soluble inhibitors were found to be produced by Eucalyptus leaves which inhibited germination of seeds.
Farmers in the dry regions of Karnataka affected by Eucalyptus plantations in the neighbouring fields have complained that Eucalyptus makes the soil toxic for seed germination and plant growth and thereby reduces the yield potential of crops in the vicinity. In some areas the impact has been so severe that small farmers surrounded by Eucalyptus plantations have had to dig trenches to protect their food crops. A scientific study was carried out at the University of Agriculture Sciences in Bangalore to determine whether there was any basis of the fear that Eucalyptus inhibited the germination of food crops in its vicinity through allelopathy.
The studies indicate that the toxic substances to the soil through the leaf litter remain for a long time in low rainfall areas and will have inhibitory effect on seed germination of crop plants. The inhibitory effect will be minimised once the toxins are leached out by the rains. It may be said that no crop can be grown successfully near Eucalyptus trees in low rainfall areas, where there is every chance of toxic substances remaining in the soil for a long timed
Not only is Eucalyptus toxic to the germination of other plants, it is also toxic to soil organisms responsible for building soil fertility and improving soil structure. Earthworms are significant among the soil fauna for improving the fertility of the soil through deposition of their faecal material and for increasing the permeability of the soil to air and water. Their activity may increase soil porosity by as much as 27 per cent.
In 1881 Charles Darwin, published his last work, the result of a lifetime's study of earthworms, in which he wrote: 'It may be doubted whether there are many other animals which have played so important a part in the history of the world, as have these lowly organised creatures.'
Soil organisms, like earthworms, are the primary producers of soil fertility. The m:trients in the leaf litter remain locked until decomposed by the soil fauna. The real assessment of the nutrient return to the soil is not obtained merely from estimates of leaf litter, but from the dynamics of its decomposition Soil organisms play a critical role in completing the nutrient cycle in which nutrients move from soil to plants to litter to decomposer to soil. The scanty leaf litter of Eucalyptus is not effectively transformed into decomposed organic matter because Eucalyptus is toxic to soil organisms constituting decomposer food chains. The eathworms- lanipito mauriti-which are responsible for the decomposition of leaf litter are found in most dry land agricultural areas of Kamataka. They are, however, absent in Eucalyptus plantations. Kale and Krishnamurthy have attributed this to the presence of chemical repellents in the leaves. Bano and Krishnamurthy observed the Milliped Jonespellis Spendidus rejecting Eucalyptus leaf litter." Through this invisible pollution of the soil environment, Eucalyptus plantations destroy the living resources which are critical elements of the food chain that maintains the nutrient cycle.
Farmers with an ecological sense of the soil have, in their own intuitive way, characterized the complex of processes by which Eucalyptus destroys soil fertility by naming it the 'Visha Vriksha'. Instead of seriously considering scientific research findings and the farmers' experience, 'scientific foresters' try to brush aside these ecological observations, and defend their special interest and reductionist expertise. For example, Shyamsundar, Chief Conservator of Forests of Karnataka, tried to wish away this recognised and established toxic impact of Eucalyptus on soil fauna when he said: 'It is claimed that exudation of toxic chemicals in Eucalyptus root system destroys micro-organisms. This is a fantastic claim unknown to the scientific community of the world.
In its native habitat, nutrient recycling is achieved by the natural occurrence of fires characteristic of the sclerophyll forests which are dominated by Eucalyptus. Fires release the nutrients locked in the leaf litter thus returning them to the soil, by-passing the decomposes food chain. Further, the specific type of s'oil fauna which slowly decomposes Eucalyptus leaves in Australia does not exist in those areas where it is an exotic.
These strategies for maintaining the nutrient cycle are not associated with Eucalyptus plantations in India. In semi-arid zones Eucalyptus excludes other plant associates through its high water nutrient demands and its allelopathic effects. The large nutrient deficits created by Eucalyptus as an exotic, therefore, cannot be compensated by the nutrient returns from other species. The scanty leaf litter of Eucalyptus is itself not easily biodegradable because Eucalyptus pollutes the soil for decomposing organisms. Thus, there is no quick release of the nutrients locked in the leaf litter. As a result, continuous cultivation of Eucalyptus will leave the soil drained of nutrients.
Figure 5.6 Over Conflicts over species (a) The Role d Indigenous Species
Figure 5.6 Over Conflicts over species (b) The Role d Eucalyptus in Agroffasystem
Land for Food or Land for Wood?
Conflicts over land use for food production and land use for commercial wood production have emerged from social forestry programmer at three levels.
First, the transfer of land from food crops to Eucalyptus plantations has generated a conflict between the two uses with lands previously under the staple food, ragi, now producing wood. According to a sample survey of the Karnataka government, nearly 13 per cent of agricultural land in one district was already under Eucalyptus in 1985, and this figure has increased since then, because under social forestry, the cultivation of Eucalyptus has been expanding systematically. Most of this expansion is at the cost of the area under ragi. The area and production of ragi is shown in Table 5.15 which clearly indicates that there has been a dramatic reduction in food crop.production as a result of the expansion of wood production.
Table 5.15 Area and Production of Ragi in Kolar District during 1977-78 to 1981-82
|1981 82||46000 (estimate)||NA|
Source Bureau of Economics and Statistic. Karnataka.
The rural poor of Kolar have been doubly hit by this loss of traditional crops to Eucalyptus. First, the decrease in food production leads to higher food prices. Second, it reduces empoyment and, hence, leads to lower incomes; thus increasing even further the gap between basic requirements and the ability of the rural poor to satisfy them. That impact cannot be assessed merely in financial terms. More significant is the deterioration in physical health and nutritional status as a result of shifting from the traditional staple diet of millets and pulses.
To assess the loss in nutrition
due to a shift to Eucalyptus cultivation, a study was carried out
in Malur taluk of Kolar district and Koratagere taluk of Tumkur
district, Karnataka. Three villages in each taluk were stratified
according to the distance from the taluk headquarters the centre
of market activities. Villages that lie within 10 km distance
from the taluk headquarters, those that lie between 10-20 km, and
those which are more than 20 km.
|Taluk||10 km||10-20 km||20 km|
In each village 10 per cent of the households were selected from each of the following categories landless, those holding below 1 hectare, those holding between 1-2 hectares, those holding between 2-4 hectares, and those with more than 4 hectares. The pattern of classification is similar to that of the government which is based on coarse grain cultivation. According to this classification, those holding below 1 hectare are called marginal farmers, those holding between 1-2 hectares are small farmers, between 2-4 hectares are medium farmers and above 4 hectares are large farmers.
Data was collected to determine the extent of landholding, crops grown, the quantum of grains sold versus retained for consumption, facilities for irrigation, their daily food consumption, availability of milk, etc.
The distribution of households according to land-ownership in the two regions is described in Table 5.16.
The output from land being dependent not only on the landholding, but also on the irrigation facility available, the total wet land in each area was also taken into account. The distribution of land gives an indication of the utilization of dry land for the cultivation of ragi (Eleusine Coracana) and groundnut in Koratagere as against the use of land for cultivation of ragi and Eucalyptus in Malurtaink (Table 5.17). Further break up of land utilisation according to ownership (Table 5.18) describes the extent of land used for food crops and Eucalyptus in the two regions respectivly. Nearly 42 per cent of the land owned by the households interviewed was under Eucalyptus cultivation, regardless of the area held by the individual farmers.
Tables 5.16 Distribution of Sample Farmers according to Land-ownership
|< 1 hectare||7||17.0||5||14.7|
Table 5.17 Distribution of Land in the Two Regions
Table 5.18 Proportion of Land Used for Cultivation
This is further substantiated by the distribution of land, crop wise including line crops
and paddy (Table 5.19). There is ample evidence of mixed cropping with avare (Dolichos Lab Lab), tuvar (Cajanus Cajan) and alasande (Vigna Catjung) grown as line crops. The average yield per acre in the two regions. despite wide variations also reiterate the fact that Koratagere has a higher output per acre in comparison with Malur. The same observation expressed in terms of nutritive value of food (Table 5.20) highlights the fact that per acre output of energy in terms of calories, protein, calcium, iron and Vitamin A is much higher in Koratagete taluk than in Malur taluk.
Table 5.19 Distribution of Land (Crop-Wise)
|Average Yield/Acre (kg)|
|Mean (S D)||Mean (S D)|
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