Environment and Forestry

The aim of this study was to determine greenhouse gas (GHG) emissions and indicators for energy use and to evaluate energy sensitivity of seed and grain corn production in Pars Abad Moghan, Iran. The data was collected by a face-to-face interview method from 144 corn farms during 2011 year. Most of energy consumption in seed and grain corns was related to diesel fuel and chemical fertilizers. The net energy, energy productivity, energy intensity and GHG emission were -4688.77 MJ ha-1, 0.06 Kg MJ-1, 16.4 MJ Kg-1 and 1810.11 kg CO2eq ha-1 for seed corn and 58330.63, 0.18, 5.53 and 1490.13 kg CO2eq ha-1 for grain corn, respectively. The percentage share of renewable, nonrenewable, direct and indirect energies were 3, 97, 46 and 54 for seed corn, and 2, 98, 50 and 50 for grain corn, respectively. The highest value of GHG emission belonged to diesel fuel with share of 64.22% and 66.66 % of total emission for seed and grain corn, respectively. An econometric model was also developed to estimate the impact of energy inputs on yield by using Cobb-Douglas production function. For this purpose, seed and grain corn yields were assumed to be functions of energy inputs.

There is a depletion of Vitellaria paradoxa populations mainly due to agricultural encroachment, seasonal fires and over exploitation notwithstanding its numerous benefits. This has affected natural regeneration and altered population structure of the species. The objectives of the study were 1) to determine the density of regeneration, saplings and mature V. paradoxa under different land use types 2) to determine stand structure of V. paradoxa under various land use types and 3) to compare the population structure of saplings and mature trees. Fifteen plots each of 20*20m were established using systematic random sampling in different land use types: Cultivated fields, fallow land and virgin land for the measurement of tree heights, diameters and number of individuals. Fallow land recorded higher regeneration and saplings density compared to the other land uses. Mature V. paradoxa was dominant in cultivated land. Fallow land had more stable population with better regeneration compared to cultivated land and virgin land. Height of regeneration in cultivated land was significantly different (p?0.05) compared to the other land use types. There was no significant difference between saplings stand structure. Mature Vitellaria paradoxa stand structure in cultivated fields was significantly different (p?0.05) compared to the other land use types. This study confirms that different land use types influence the population structure of Vitellaria paradoxa and there is anthropic selection.