Tree crop Interaction and Ecological Benefits of Teak based Agroforestry system
Author: Mukesh kumar, N.S. Thakur and Ram Gopal
Navsari Agricultural University, Navsari, Gujarat


Introduction:

There are different agroforestry systems and practices prevailing throughout the world. These systems and practices have evolved due need of the rural people and some are market driven. The components of agroforestry systems are also influenced due to these factors. Similarly farmers preference regarding woody component either fruit or timber species is also affected by the nature and importance of the respective component. Teak is one of the oldest timber component agroforestry systems throughout the world. Teak is considered as king of timber species and suitable ideotype for agroforestry system because of having deciduous nature, sparse canopy and deep root system. Burma (now Myanmar) began planting teak using the taungya system in 1856. Natural cover of teak in the world is about 29.035 million ha and the planted teak in 38 tropical countries covers 4.346 million ha (Kollert and Cherubini, 2011). It is well established fact that vegetal components growing together on same piece of land have to share the available resources for their growth and development. Thus resulting in interaction what is called tree-crop interactions (TCI).

Biological diversity and Ecological balance

  • Agroforestry systems are unique in terms of the complex biodiversity of both the agricultural produce and the adjoining biotic components.
  • Agroforestry systems have potential for reduced dependence on chemical fertilizers and pesticides which leads to maintain biodiversity.
  • It attracts various fauna such as birds, butterfly etc which is attributed to pollination, seed dispersal of several plant species.
  • Manipulation of tree/crop component in an agroforestry system encourages built-up of the natural enemies of the pest, simultaneously creating ecological conditions that will suppress population build-up of the pest (Paul & Lalnunsangi, 2011)
Brief review of Tree-crop interactions

Negative interaction:

Agroforestry system namely Agri-silviculture (wheat + teak, Rice + teak), Silvi-medicinal (teak + aloe + coleus + stevia + kalmegh + lemongrass + citronella + palmarosa + patchouli), Agri-silvi-pastoral (groundnut + teak + grass + subabul), Agri-silviculture (teak + soybean + greengram + frenchbean + blackgram), Agri-silvi-horti-pastoral (teak + papaya + sorghum + groundnut + chilli + ragi + grass + subabul), Agri-silvi-pastoral (teak + subabul+ groundnut), Agri-horti-silviculture (paddy + maize + sunhemp + teak + Eucalyptus tereticornis + Acacia molucana + Casuarina equisetifolia + Dalbergia sisoo + sapota) and Agri-silvi-pastoral system (sorghum + groundnut + subabul + grass + teak) exhibited negative impact on under storey crops, whereas teak had beneficial effect with respect to its growth in studies carried out by Sharma et al. (2011), Nagarajaiah et al. (2012), Venkatarao et al. (2007), Mutanal and Nadagoudar (2004), Patilet al. (2010), Patil et al. (2011), Mutanal et al. (2002), and Mutanal et al. (2009) , respectively.

Positive interaction:

Agroforestry system Agri-silvi-pastoral with tree crop combinations Sorghum + teak + grass + subabul + groundnut) developed by Mutanal & Nadagoudar (2004) showed positive tree-crop interactions.

Table No.1: Tree-Crop Interaction Observed Under Teak Based Agroforestry System

Agroforestry system Effect of teak on understorey Effect on Teak Sources/Authors
Agri-silviculture -ve +ve Amita et al. (2011)
Silvi-medicinal -ve +ve Nagarajaiah et al. (2012)
Agri-silvi-pastoral +ve +ve Mutanal & nadagoudar (2004)
Agri-silvi-pastoral -ve +ve Venkatarao et al.(2007)
Agri-silvi-pastoral -ve +ve Mutanal & prabhakar (2009)
Agri-horti-silvi-pastoral -ve +ve Patil et al. (2010)
Agri-silviculture -ve +ve Patil et al. (2011)
Agri-silvi-pastoral -ve +ve Mutanal et al. (2002)
Ecological benefits:

Soil fertility, light transmission ratio, soil moisture status studied under Agri-silvi-pastoral system (sorghum + teak + grass + subabul + groundnut) by Mutanal & Nadagoudar (2004).

Carbon stock and Carbon dioxide removal by teak under Agri-silvi-horti-pastoral system (Sapota + Grass + Teak + Field crop) was estimated to the tune of 0.0383 kg/tree, 0.140 kg/tree, respectively (Patil et al., 2010).

In another study, Carbon stock and CO2 removal by teak (8 years old) under Agri-silviculture (teak + wheat) was estimated to the tune of 25.700 tons/ha and 94.319 tons/ha, respectively and soil fertility was increased under (Teak + wheat) system by Sharma et al. (2011).

Natural enemy of pest population (Biodiversity) was recorded higher in fringe area under Agri-silviculture system by Paul & Lalnunsangi (2011).

Recommended teak based Agroforestry systems and associated species in tropical, humid and subhumid zone

Regions/Zone Agroforestry system Woody components Fruit trees Crops
Tropical Farm boundary Jack fruit Teak Sesbania grandiflora Lawsonia inermis coconut Paddy Tapioca Turmeric
Humid Agri-silviculture Teak Ceiba pentendra Casuarina spp. - Paddy Cowpea Groundnut


Conclusions:

The available studies on tree-crop interactions in teak based agroforestry systems revealed that in most of systems, under storey crops had low productivity exhibiting the negative impact. However, in all the studies it was teak productivity was increased. Although systems showed negative impact on understory crops nevertheless the loss in productivity may be accounted compensated by ecological benefits. Agroforestry systems with appropriate spatial arrangement and right orientation if practiced complementarily effect harnessed.


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About Author / Additional Info:
Student of Navsari Agricultural University.