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Showing 2 results for Species Response Curve
Fateme Heidari, Ghasem Ali Dianati Tilaki, Seyed Jalil Alavi,
Volume 5, Issue 11 (3-2018)
Abstract
The plant species response to environmental gradients indicates that the impact of environmental factors on plants. This study was done in the rangeland of Galandrood watershed in Mazandaran province. The objective of this study was investigation on the response of Bromus tomentellus Boiss. and Achillea. millefolium L. species to some environmental gradients using the generalized additive model (GAM). Towards this attempt 153 quadrates of 1m2 along altitude gradient were taken. The sampling method was randomized-systematic. In the area sampled, presence of Br.tomentellus and A. millefolium species, altitude, slope and aspect were recorded. Soil samples were taken from 0-20 cm in each quadrate. In each sample, pH, N, EC, organic carbon, the percentage of sand, silt and clay were measured. In order to study the shape of response curve in relation to the mentioned variables, GAM model was used with binomial distribution function. The data were analyzed by R ver.3.0.2 computer programe. The results showed that the response curve of Br. tomentellus to the altitude gradient has monotonically increasing and then flat trend but for A.millefolium was monotonically decreasing trend. The highest presence of Br. tomentellus was recorded in 2417 m along altitude gradient but for A.millefolium has been recorded 2125 m. sand content in the soil is a parameter that had significant positive impact on Br. tomentellus species distribution but this variable significant negative impact on A.millefolium species distribution.
Sedigheh Zarekia, Hamidreza Mirdavoodi2, Ali Mirhoseini, Alibeman Mirjalili, Mohammad Taghi Zare,
Volume 9, Issue 18 (10-2021)
Abstract
Non-living environmental factors have a major impact on the distribution and yield of plant species. To this end, the relationship between soil and topographic variables on the response of Salsola kerneri (Wol.) Botsch plant species in Yazd province is evaluated. Generalized Additive Models (GAM) were used to investigate the specieschr('39') response to environmental factors. The results showed that S. kerneri grows in areas with cold arid climate with an average rainfall of about 100 to 120 mm and an average temperature of about 14 to 16 ° C. According to the studied habitats, S. kerneri is distributed at an altitude of 1750 to 2350 meters a.s.l. This species grows in clay-sandy loam soils with salinity between 0.7 to 4.5 and acidity of 8.2 and nitrogen content of 0.04. The average canopy cover of this species in Sadrabad and Khoranagh habitats is 1.8 and 1.3 percent, respectively. Response pattern of S. kerneri along the saturation moisture and litter percentage of soil surface, followed the monotonic increase model, and with the increase of these values, its frequency and percentage of vegetation increased. Conversely, the response of this species along the slope of the amount of electrical conductivity (EC) follows the monotonic decrease model, and with the increase of this factor, the presence and percentage of vegetation has decreased. response pattern S. kerneri followed the Unimodal model along the slope of sand, clay, limestone and altitude, and its optimal growth rate for these factors was 59, 23, 12 and 2200 meters above sea level, respectively. The results of S. kerneri phenology studies showed that the growth of this plant begins in the second half of March. Flowering usually begins in early July and seeds are formed in the third decade of September. Seed shedding begins in mid-November and continues until the first week of December, when the seed stage arrives. The best time to collect seeds is late October. Examining the ecological needs of S. kerneri in relation to topographic and soil factors, provided valuable information about this species that can be considered in vegetation management and rangeland improvement operations in similar areas.
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