Kamaljit K. Sangha

Litter production, decomposition and nutrient release in cleared and uncleared pasture systems of Central Queensland, Australia

The temporal impact of clearing trees on litter production, litter decomposition and on C, N and P release through decomposition of litter was examined in the pasture systems of a semi-arid zone of central Queensland. Paired sites for cleared pastures (developed from clearing woodlands) and uncleared (intact woodland) pastures were selected to represent three dominant tree communities of the region i.e. Eucalyptus populnea, E. melanophloia and Acacia harpophylla, with three different time-since-clearing (5, 11–13 and 33 y) treatments. Yearly litter production was greater at uncleared sites (1732–1948 kg ha−1 y−1 for eucalypt and 2596 kg ha−1 y−1 for acacia communities) compared with cleared sites (1038–1282 kg ha−1 y−1 for eucalypt and 1100 kg ha−1 y−1 for acacia communities averaged over three time-since-clearing treatments). Rates of litter decomposition and of release of C, N and P from decomposing litter were higher at cleared than uncleared sites for all three tree communities. The cleared and uncleared sites did not differ significantly in total amount of C and N released per year since the concentrations of C and N were greater in litter from uncleared sites but the rate of release was less than that at cleared sites. Slow but continuous release of nutrients in eucalypt and acacia woodlands may be an adaptation of these communities to maintain the nutrient cycle and to avoid leaching of nutrients in the nutrient-poor soils of the region.

Impact of tree clearing on soil pH and nutrient availability in grazing systems of central Queensland, Australia

In Queensland, land is cleared at high rates to develop pastures for enhanced production and the associated monetary gains. However, pasture production declines over time in cleared pastures until a new equilibrium is reached. The present study focussed on elucidating the reasons for decline in pasture production and finding the key soil properties that are affected due to clearing. Paired sites for cleared and uncleared pastures were selected to represent 3 dominant tree communities of the semi-arid tropics in central Queensland, i.e. Eucalyptus populnea, E. melanophloia, and Acacia harpophylla. The cleared pastures were chosen to represent 3 different durations of time since clearing (5, 11–13, and 33 years) to evaluate the temporal impact of clearing on soil properties. Various soil parameters were studied: macronutrients—available N (NH4+and NO3–), total N, and available P; micronutrients—Cu, Fe, Zn, and Mn; exchangeable cations—Ca, Mg, Na, and K (also macronutrients); pHw; and electrical conductivity. Of these, pHw showed a significant response to time of clearing for all 3 tree communities. Soil pHw increased significantly at cleared sites relative to uncleared (native woodland) pastures, and the increase was highly correlated with concentrations of exchangeable Ca, Mg, and Na. The change in soil pHw and exchangeable cations was more evident at >0.30 m soil depth. The increase in soil pHw in cleared pastures decreased the availability of soil nutrients for plant growth and, hence, pasture productivity. The interactions of different soil properties down the profile as a result of changes caused by clearing are important when interpreting the effects of clearing on soil properties.

Comparative ecological-economic analysis of growth performance of exotic Eucalyptus tereticornis and indigenous Dalbergia sissoo in mono-culture plantations.

This paper describes the comparative growth performance of and monetary returns for Eucalyptus tereticornis and Dalbergia sissoo plantations in northern India. The growth is analysed in terms of annual and relative growth rates of bole, crown and marketable heights and volumes, and diameter at breast height. The measurements were taken at 6–8 and 19–21 years of age. The economic gains are considered for five components, i.e. timber, fuel-wood, fodder, oil and ash. The old plantations of D. sissoo are found to be more sustainable in terms of growth performance and net monetary return. The total monetary gains estimated are Rs. 13.4 million per hectare in the case of D. sissoo, but only Rs. 7.4 million per hectare for E. tereticornis, even after including the value of all rotational crops possible within the 21-year life span. This integrated analysis challenges the long claimed forest policy that fast growing trees perform better than indigenous trees.

Emerging opportunities for developing a diversified land sector economy in Australia’s northern savannas

We explore sustainable land sector opportunities for Australia’s 1.2 million km2 northern savanna rangelands where extensive beef cattle pastoralism is the predominant contemporary land use. Our focal region is characterised by mean annual rainfall exceeding 600 mm, ecologically bountiful wet season water availability followed by 6–8 months of surface water deficit, mostly nutrient-poor soils, internationally significant biodiversity and carbon stock values, very extensive dry season fires in pastorally unproductive settings, a sparse rural population (0.14 persons km–2) comprising a high proportion of Indigenous people, and associated limited infrastructure. Despite relatively high beef cattle prices in recent seasons and property values escalating at a spectacular ~6% p.a. over the past two decades, long-term economics data show that, for most northern regions, typical pastoral enterprises are unprofitable and carry significant debt. Pastoral activities can also incur very significant environmental impacts on soil and scarce dry season water resources, and greenhouse gas emissions, which currently are not accounted for in economic sustainability assessments. Over the same period, the conservation sector (including National Parks, Indigenous Protected Areas) has been expanding rapidly and now occupies 25% of the region. Since 2012, market-based savanna burning projects aimed at reducing greenhouse gas emissions occur over a further 25%. Returns from nature-based tourism focussed particularly on maintaining intact freshwater systems and associated recreational fishing opportunities dwarf returns from pastoralism. The growth of these latter industries illustrates the potential for further development of profitable ‘ecosystem services’ markets as part of a more environmentally and socially sustainable diversified regional land sector economy. We outline some of the imminent challenges involved with, and opportunities for developing, this new industry sector.

MODERN AGRICULTURAL PRACTICES AND ANALYSIS OF SOCIO-ECONOMIC AND ECOLOGICAL IMPACTS OF DEVELOPMENT IN AGRICULTURE SECTOR, PUNJAB, INDIA - A Review

Agriculture is a backbone of economy in the Indian state of Punjab where Green revolution was introduced early in 1960s and has contributed largely to make India self-sufficient in food production. Although, Green Revolution has enhanced food production and consequently the economic returns in agriculture sector, but it has many backlash effects. This study analyses the modern agriculture systems that were introduced with Green Revolution largely at the expense of over-and misuse of land and water resources and loss of biodiversity. It evaluates the impact of changes in agricultural systems on the breakdown of socio-cultural fabric. Rural people, particularly agricultural communities, are facing many serious problems including farmers suicides, health problems such as cancer, loss of work culture among the youngsters, excessive use of alcohol and drugs and loss of cultural identity for people. Punjab, which used to be one of the progressive states in India, is suffering from the loss of natural, social and health capital. This study applies an integrated approach to assess the various costs and benefits of the current agricultural system in terms of well-being of people and of associated ecological and economic perspectives. It further suggests some innovative solutions for the current problems. A holistic approach applied in this study to assess Green Revolution from socio-cultural, economic and ecological perspectives provides an in depth view of the problems that people are facing in so called economically developed state of Punjab in India.

Impacts of Land Cover Change on Conservation, a Linkage of Spatial Analysis and Anthropogenic Activities in Tanzania

We used spatial analysis to assess the Land Use Land Cover (LULC) changes, and studied the impacts of LC changes on conservation of buffer zone of the Selous Game Reserve (SGR) and their implication on community’s livelihood in Vikumbulu Ward of Kisarawe District, Tanzania. Socio-economic data from Kisarawe District and TNBS were linked to spatial data to offer an integrated perspetive of LULC change in the Ward. Three cloud free image dates of 1998, 2011 and 2015 were analysed using System for Automated Geoscientific Analyses (SAGA) GIS for three categories of land cover, i.e. forest, wooded grassland and bare land/settlements/cultivation. Vikumbulu demographic and socio-economic data were linked to spatial data applying distance as a function of LULC change. Spatial analysis has shown a decreasing trend of forest and woodland cover in Vikumbulu Ward between 1998 and 2015. The sharp decline indicates increasing social economic activities such as shifting agriculture and charcoal burning as an outcome of population growth and poverty. Rapid conversion of forest cover to wooded grassland occurred between 1998 and 2015 in Vikumbulu Ward. However, loss of forest cover was associated with a decreasing trend in wooded land in the ward between 2011 and 2015. As there was only 0.15% area under crop cultivation in Vikumbulu until 2015, it is highly likely that LC change is caused by charcoal burning and shifting cultivation. This study suggests developing integrated strategies that target LULC change, conservation and people’s livelihoods to effectively improve the current situation in rural areas of Tanzania.