PRUNING HEIGHT AND ITS EFFECT ON QUANTITATIVE AND QUALITATIVE SEED PRODUCTION IN OLD SAXUAL (Haloxylon aphyllum) FORESTS OF YAZD, IRAN

The high quality and quantity seed production in old saxual shrubs are essential for regeneration and sustainable development of saxual forests in desert areas. The objective of this study was to determine the effects of different pruning height on saxual seed production. The study was carried out in an obviously wilted saxual forest located in Ashkezar desert in Yazd in 1994. The experiment was carried out in a split-plot design with 3 replications, with saxual density (250 and 125 shrubs/ha) as the main plots, and pruning height (10, 35, 70 cm, and a no-cut check) as the sub-plots. Pruning was done on autumn 1994. The forest was protected completely and the quality and quantity of seed production of marked shrubs were investigated on autumn 1999 and 2000. The 2-year results showed that saxual density did not have any significant effect on quality and quantity of saxual seed production (P<0.05). Pruning height had significant effect on percent seed longevity and net saxual seed production (P<0.05). Although no significant difference was observed in viable net seed production under different pruning height, the amount of viable net seed production at 35cm pruning height was 9.7 kg/ha, which seems adequate for saxual regeneration

Relationship between cover and yield of some range species in steppic region of

Sustainable range management needs the accurate estimation yield and determining of grazing capacity in rangelands. It is easy to obtain yield estimation with indirect methods. For this purpose, the relation between cover and forage yield of range species were studied in steppic rangelands of Yazd. Measurements of cover and forage yield were carried out with plot area and clipping and weighting methods, respectively. Every year, one hundred and twenty quadrate plots were systematically assessed from 2000 until 2004 in mid-May. In addition to mentioned measurement, four sampling was done until early November in 2004. Data were analyzed in regression and correlation programs (SPSS 10.0). Results showed that there was significant relation (p<0.01) between cover and forage yield of studied species during 4 years (2001-2004), but 3 species out of 7 studied species had significant relation in 2000-drought year (p<0.05). Obtained relations and also fitted models were varied in different years and stages. Therefore, the yield estimation is possible by using cover, but in dry years. These characteristics are applied for annual yield estimation of steppic range species by double sampling model with cover

Effects of range condition on the temporal diet selection by goats in steppe rangelands of Iran

One of the key factors in managing a rangeland is to determine the relative preference of its major plant species by thegrazing livestock. Preference value of each plant species is affected by plant type, companion plants, availability byanimals, phenological stage, climate condition, and the livestock species. We investigated the grazing behaviour of anative goat (Garizi) in the steppe rangelands of Iran, from May to November 2004. The study was conducted within oroutside of an enclosure, representing a Good Condition (GC) or a Poor Condition (PC) rangeland, respectively. Flocks ofsix goats were selected randomly and their grazing behaviour was monitored by chronometers. Grazing preference wasconsidered as the time goats had spent for grazing each plant species. The grazing season was divided into 4 grazingperiods, 45 days each. Data recording in the GC and PC sites was repeated 3 times during each grazing period. Theexperiment was designed as the completely randomized blocks. In the GC site, grazing pressure on the perennial grassStipa barbata and the perennial chenopod Salsola rigida was low at the beginning of the grazing period, but it wasincreased towards the end of the grazing season. In the PC site, the main grazing pressure was on noxious plants such asScariola orientalis, Launaea acanthoides, and Cousinia deserti. For both GC and PC sites, the time of grazing hadsignificant influences on relative abundances of annual plants and plant litter, which subsequently changed diet selectionby the Garizi goat. One of the key factors in managing a rangeland is to determine the relative preference of its major plant species by thegrazing livestock. Preference value of each plant species is affected by plant type, companion plants, availability byanimals, phenological stage, climate condition, and the livestock species. We investigated the grazing behaviour of anative goat (Garizi) in the steppe rangelands of Iran, from May to November 2004. The study was conducted within oroutside of an enclosure, representing a Good Condition (GC) or a Poor Condition (PC) rangeland, respectively. Flocks ofsix goats were selected randomly and their grazing behaviour was monitored by chronometers. Grazing preference wasconsidered as the time goats had spent for grazing each plant species. The grazing season was divided into 4 grazingperiods, 45 days each. Data recording in the GC and PC sites was repeated 3 times during each grazing period. Theexperiment was designed as the completely randomized blocks. In the GC site, grazing pressure on the perennial grassStipa barbata and the perennial chenopod Salsola rigida was low at the beginning of the grazing period, but it wasincreased towards the end of the grazing season. In the PC site, the main grazing pressure was on noxious plants such asScariola orientalis, Launaea acanthoides, and Cousinia deserti. For both GC and PC sites, the time of grazing hadsignificant influences on relative abundances of annual plants and plant litter, which subsequently changed diet selectionby the Garizi goat