0143-B1

Changes in Tree Species Diversity in Alkali-Affected Village Ecosystems by Biotechnological Interventions

Seema Bhadauria^[1], B.S. Kushwah and Ekta Bhadauria

Abstract

For the land use-based economic activities of wasteland communities, biodiversity is a driving force for sustainable livelihoods. They attach differential values of biodiversity and often manipulate it in a variety of ways, both in their natural and their multi-species complex agro-ecosystems.

The village agro-ecosystems area is dominated by multiple-use species such as Mangifera indica and Atrocarpus heterophyllus, indicating farmers’ preferences for retaining those trees that are known for their valuable fruits, fodder and leaf manure, etc and standing biomass in agro-ecosystems.

Several alkali-affected land-bearing villages were selected for the use of biotechnological reclamation and planting alkali-resistant fruit-yielding trees. After three years the village ecosystem was entirely changed. The total number of trees in this village was 199, which grew to 681 with a change in biomass from 27.91 to 53.53. Tree types increased from 10 to 21. Biotechnological interventions improved the village ecosystems in terms of productivity, fuel, fodder, fruit and revenue and they improved the soil ecosystem in terms of culturability, a boon.

Introduction

It has been estimated that with the expected increase in the population, an additional 40-million ha for fuel and 10-million ha for fodder, and net sown area of 10-million ha for food are needed by the end of this century. These may be possible provided the usable wastelands are reclaimed, developed and property utilized. Introducing large scale farming and afforestation on dryland is one aspect in developing these lands. Immediate reclamation of culturable wastelands (16.3-million ha.), fallowlands other than current fallow (9.5 million ha.) and utilizable barren or unculturable land (20.1 million ha.) including the gullies and ravines (3.97 million ha.) waterlogged (6 million ha.), alkaline (2.5 million ha.) and soils of shifting cultivating (4.4 million ha.) is urgently needed.

Salt-affected soils differ from normal arable soils in respect of two important properties, namely the amounts of soluble salts and the soil reaction. Excess soluble salts adversely influence soil behavior by changing its physico-chemical properties which is turn have a strong bearing on the activity of plant roots and growth of plants.

Salt-affected soils are known by different local terms. They are called Kallar or Thur in Punjab, Usar or Reh in Uttar Pradesh, Luni in Rajasthan, Khar or Kshar in Gujarat and Maharastra. Chouddu or Uippu in Andhra Pradesh, Choppan in Karnataka. The acreage of salt degraded lands is nearly 10 m ha in the country. These soils occur extensively in different agro-ecological and soil zones of the country, particularly the arid, semi-arid and the dry sub-humid regions.

Excess salts may accumulate in the surface horizons of soils mainly due to the following reasons:

• Secondary salinization associated with waterlogging.

• High salt content of irrigation water.

• Release of immobilized salts already precipitated in soils.

• Atmospheric salt dispositions as in coastal areas.

• Weathering of soil minerals.

• Use of fertilizers.

The relative significance of each source in contributing soluble salts to the root zone depends on the natural drainage conditions, soil properties, irrigation water quality, management practices and distance from the coast line. Soluble salts are either neutral in their reaction (e.g. chlorides and sulfates of sodium, calcium and magnesium) or are the soda salts (carbonate and bicarbonates of sodium) capable of producing alkalinity.

Salt affected soils are grouped according to the nature of plant response to the presence of soluble salts and on the basis of management practices required for their reclamation. Unlike the pedogenic system, it is a simple system of classification requiring information on the nature of soluble salts only. Since salts are either neutral or alkaline in reaction, salty soils are grouped into 2 classes: (i) Saline soils and (ii) Alkali soils.

Cultivating trees in the agricultural systems is one of the major practices in the tropics of South and Southern Asia. It is characterized by an intensive integration of forest trees, agricultural and horticultural crops, and shrubs with a basic objective to ensure sustained availability of multiple products as direct benefits such as food, vegetables, fruits, fodder, fuel, foliage, medicine, and raw materials for agricultural implements. Other indirect benefits are services such as ornamentals, shading, live-fencing and shelter-belt or wind-breaks are also derived¹. Such intermixing of species of agriculture and forestry, often termed as ‘agroforestry’ came into international prominence as a potential source of solutions of many inter-related problems of production and conservation, troubling land-use systems in the tropical and sub-tropical regions. It has also been stated that the tree components along with field crops lead to efficient use of sunlight, moisture and nutrients in agro-ecosystems than in monocropping of either agricultural or forestry crops.

In recent years, people are meeting their diverse biomass needs from the trees in cultivated lands. Such large-scale dependence may act as threat to reduction in tree diversity and density on the farmlands. In view of the depleting timber, NTFP resources in the wild, a diverse agro-ecosystem may help people to meet varied needs. Here, we examined the ecosystem of a village in the Mainpuri District of Uttar Pradesh affected by alkalinity to understand trees species diversity, species similarity, and estimate the standing biomass of species in different agro-ecosystems and end uses. This was compared by the changed scenario after 3 years by using biotechnological methods for reclamation of soil and transplantation of alkali resistant grafted trees.

The villagers were motivated to adopt multicropping concepts between agricultural and forestry crops under a Department of Biotechnology, Ministry of Science and Technology, Government of India, New Delhi sponsored project by using biotechnological methods of reclamation of alkali soil and transplanting alkali resistant budded trees of economical and ecological importance. The microclimate developed by such practices made the soil fertile and many other plants could survive. It has been stated that the tree components along with field crops lead to efficient use of sunlight, moisture and nutrients in agro-ecosystem than in monocropping of either agricultural or forestry crops. This kind of practice was new to these villagers.

Village Ishwarpur belongs to Mauza Nauner of Mainpuri District of Uttar Prades (Fig. 1) which is about 6 km from Local Bus Station, Dannahar situated in between Ghiror and Mainpuri (Fig. 2) It has 66,752 hectares of alkali land lying unculturable.

The soil is highly alkaline (plate-1) with following soil properties (Table-1). The entire village ecosystem encompasses an area of 525 ha. out of which 220 ha is unculturable alkali wasteland. The detail land use patterns and sampling are shown in Table 2.

Table 1

Physico - Chemical Characteristics of the alkali soil of village, Ishwarpur.

Table 2

Details of the Land - use categories and area sampled in Ishwarpur village ecosystem of Mainpuri District before and after biotechnological intervention.

Materials & Methods

Biodiversity Analysis of Village Ecosystem: A village with above description was selected and complete data on ecosystem study was obtained (Tables 2-6) by quadrat analysis. Land use patterns, life style, agricultural practies and energy planning were noted.

The sample plots were randomly laid in each land-use system such as home-gardens, paddy streams boundary and tank bunds, minor forest and adjacent reserve forest. Details of area sampled are given in Table-2. The total length of paddy and stream boundary was estimated using the village maps. The total length of stream boundary was 1145 m, while paddy boundary was 335 m and wasteland 200 m. The width maintained for these boundaries was 2 m Data regarding species name, GBH, total trees height, etc. were collected in five locations sampled in 1999, where trees greater than 10 cm diameter at breast height were recorded. Information regarding nativity of species (exotic or native) and their physiognomic characters (evergreen or deciduous) was obtained from the literature. Shannon-Weiner’s species diversity index and Sorenson’s similarity index were calculated following Krebs². The index was calculated for all samples pooled over each land-use category. End-use and domestication patterns of several species that are grown in their home-gardens were collected through household interviews.

Stem diameter and tree height account for larger proportion of variability in woody biomass of trees. Basal area and height were used for estimating biomass using equations as suggested by Murali³ et al.

Bioreclamation of alkali soil

Land Development

Land Marketing and levelling: Measuring of plantation site and marking by boundary channels on square grid basis was done. The layout of plantation site was planned as per designed programme.

Out of the four levelling methods viz,. plane method, profile method, plan inspection method and contour adjustment methods, the plane method of levelling was employed

Protection Against Browsing: The plans for afforestation programmes should include measures for protection against stray animals and wild life. Much of the afforestation efforts may be of little avail if saplings are not protected against chewing, grazing and nibbling etc. by stray animals and wild life. The opted control measure against grazing was:

Barbed Wire Fencing: Fencing posts 2.0 - 3.5 m in length preferably of RCC cement are fixed at about 3 - 3.5 m distance and 4 to 6 strands to two ply galvanized barbed wire with 4 barbs spaced at 7-10 cm apart are then fixed to the poles. Fixing of branches of thorny plants like Acacia can further enhance effectiveness of the fence against entry of wild animals.

Planting Methods

Post-auger hole planting: This methods was designed to facilitate root penetration through kankar layer or hand pans found at some depth in most of the alkali soils. In this method, bore holes of 15-30 cm in diameter are dug to a depth of 120 cm or more such that it pierces beyond the kankar layer. For reducing manual labour cost and speed up the operations, tractor driven augers are now available in the market. Main features of this method are.

• Pierces through hard kanker layer.

• Encourages and trains deeper rooting.

• Does not cause roots to coil or face constriction which adversely affect plant growth.

• Improves the penetration of water through the holes thereby, including better water storage and its availability.

• Ensure deeper reclamation of soil.

• Makes the mixing of fertilizers possible even in deeper layers.

Performance of post-auger hole planting method has been observed to be highly satisfactory in field trails. This method has picked-up well with in foresters. Saplings transplanted in post-auger holes have to be spot irrigated. In order to avoid spot irrigation, the post-auger hole technique has been further refined to reduce irrigation costs. First, auger holes of 15-20 cm in diameter are dug and then connected with each other through an irrigation channel. Thus, the post-auger holes are finally positioned in irrigation furrows. Saplings are then planted in boreholes at a depth of 15-20 cm from original soil surface. The method is a variant of ‘sub surface planting furrow irrigation method’ (SPFIM) elaborated in an ensuing section.

Alternately for high value species like fruit trees, pit of 45 x 45 x 35 cm size are manually prepared and then post-augered (15-20 cm dia.) beyond the kankar layer with a tractor driven auger. The pit-holes are then interconnected with an irrigation channel. Additional benefits accruing from refined post-augur hole method include:

• Ensures easy and uniform application of irrigation.

• Provides for larger volume of reclaimed soil for the development of feeder roots during the initial years of growth.

• Curtails run off and promotes in situ rain water conservation.

Composition of Filling Material

The filling mixture for auger holes is as follows:

(a) Gypsum @ 3.5 kg per hole or on the basis of Gypsum requirement of the soil excavated by auger.

(b) Farmyard manure @ 10 kg per hole along with urea @ 50 gm per hole.

(c) Zinc Sulphate @ 10 to 15 g hole Most alkali soils are deficient in Zinc, it is obligatory to apply it.

(d) BHC 30% @ One Table Spoon per hole to avoid termite attack.

(e) Additional use of rice husk @ 5 kg/hole is beneficial is highly, deteriorated alkali soils and other soils with very poor permeability.

(f) Use of iron sulphate @ 20 g/hole in soil having CaCO₃ content more than 5% is advocated.

(g) 500 g/Auger hole biofertilizer and deoiled neem cake (125 g/Auger hole).

Cultivation of economically important trees in such improved soil solves three problems by providing employment, revenue generation and soil ecomanagement.

Results

The village was surveyed in 1999 and details regarding land use patterns and sampling was obtained. Among 66 households of the village, 16 are landless, 9 own only paddy land, 23 own only home garden and 18 families own both paddy and garden Lands. For those owning paddy lands, the median land holdings in 0.5 ha; the median garden land for garden-land owners is also 0.5 ha. The largest single holding is by one family with 3 ha of paddy and 3 ha of garden land. Among the 60 landholding families, 36 maintain livestock, the minimum being 1, median 5 and maximum 20. There are no goats, sheep or pigs in the catchment; however two farmers have taken up rabbit keeping. The number of livestock is roughly one per ha of the total landholdings, including paddy crop, garden and wasteland.

The village ecosystem was defined as the boundary marked by the revenue department of the state government. The boundary is mainly drawn on the basis of the land owned, cultivation, non-crop lands, settlements, streams, water bodies, roads, hills, wastelands, and community or village/minor forest lands. In the present study all the land use systems and types are treated as an ecosystem. This village ecosystem consists of 18 ha of minor forest with dominant species such as Cajanus cajan, Saccharum and Vetiveria. The estimated annual harvest of biomass from minor forest is at the rate of 2.4 t/ha, which is more than eight times of level of production. Out of the total biomass harvested annually, 30% is used as fuel, 17% is used as small timber and the remaining 12% is used as manure.

Regarding tree resources in home gardens, there were 475 individuals belongings to 67 tree species in 30 home gardens over a sampling area of 1.28 ha. The dominant species were Magnifera indica, Artocarpus heterophyllus and Acacia nilotica and Prosopis. The estimated tree density was 62 per hectare, and species diversity was 1.20 (Table 3).

Table 3

Characteristics of vegetation in different land uses in alkali affected village ecosystem of Mainpuri District before and after biotechnological intervention.

Regarding tree resources in paddy boundary, there were 40 individuals belonging to 15 species in the sampled area of 0.11 ha. The dominant tree species were and Cassia saimea, with an estimated density of 373 trees per hectare diversity of 2.35.

Considering tree resources in village ecosystem were 55 individuals belonging to 77 species in a sampled area of 1.7 ha of agro-ecosystem. Further, additional 44 species were encountered on non-agricultural lands in the village ecosystem, which include Saccharum munja, minor forest.

Out of the species present in the agro-ecosystem, the predominant ten species account for 0.4% of the total tree population. Among the to ten species, five are local and five are exotic. Among the 80 species encountered in the agro-ecosystem, local fruit-yielding species like M.indica topped the list (Table 4). The estimated standing biomass was 0.16 tons per capita and 20.50 tons ha^-1 of agro-ecosystem. Local multipurpose tree species such as Acacia, Prosopis, Azadirachta dominated the standing biomass (Table 3).

Table 4

Standing biomass and tree population in village agro-ecosystem of alkali affected wasteland before biotechnological intervention.

Farmers have a good knowledge of growth rates and useful products to many tree species, and were able to learn about exotic species also. All farmers identified species that serve as shade, wind-break, live fence, and their importance to maintain soil fertility. Thus people are aware of the inter-related benefits of a balanced mix of species for the home-garden. People of this region are less dependent on fuel wood plants and home-garden trees for such purpose. Most of the households in the studied village are using fuel-efficient stoves or biogas for cooking, except marginal farmers. Probably this could be the reason for people opting fruit-yielding tree species for self-consumpiton than going for timber or firewood species.

Our study has revealed that the species found in the agro-ecosystems are similar to those found in adjacent forest, indicating the willingness of the farmers to mimic the natural forest in their agro-ecosystems after biotechnological interventions (Table 5). The scenario of the village ecosystem changed. The soil could be reclaimed to pH-8.5 within 3 years and number of tree species reached to 681 and types of trees were 21. Out of these trees, 10 plants were income generating and estimated biomass was totally 53.53t and maximum percentage was of Emblica followed by Popular. Thus it is appropriate to consider local community as an integral part of ecosystem function for effectively managing agro-ecosystems in the tropics, with a concern of biodiversity. Although this study analyses on tree diversity and end uses of tree species in different locations and village ecosystem, many questions concerning agro-ecosystem have to be answered to understand the suitability of species in different land uses of the village ecosystem. Some of these aspects to be studied include influence of forest trees on horticultural crops, lopping methods, contribution of these trees for nutrient cycling and determination of tree crop/field crop combination.

Table 5

Standing biomass and tree population in agro-ecosystem of alkali affected after biotechnological intervention in Mainpuri District.

Table 6

Distribution of tree population according to end uses in Ishwarpur village agro-ecosystem of Mainpuri District.

References

1) Michon, G., Bompard, J., Hecketseiler, P. and Ducatillion, C., Agrofor. Syste., 1983,. 1, 117-129

2) Krebs, J., Ecology: The Experimental analysis of Distribution and Abundance, Harper and Row Publishers, New York.

3) Murali, K. S., Bhat, D M. and Ravindra nath, N. H., CES Technical Report Number 81, Centre for Ecological Science, Indian Institute of Science, Bangalore, 2000