Volume 18, Issue 4 (1-2025)
مرتع 2025, 18(4): 582-598 |
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Khosravi Mashizi A, Sharafatmandrad M, Jahantab E. Investigating the Effect of Removal and Addition of Litter on the Facilitating Role of Shrub and Grass Species in Semi-Arid Rangelands of Kerman Province Using Structural Equation Model. مرتع 2025; 18 (4) :582-598
URL: http://rangelandsrm.ir/article-1-1295-en.html
URL: http://rangelandsrm.ir/article-1-1295-en.html
Department of Nature Engineering, Faculty of Natural Resources, University of Jiroft, Jirof
Abstract: (592 Views)
Background and objectives: In arid and semi-arid regions, plant species create microclimates under their shade, facilitating the establishment of other species. Litter production in ecosystems fluctuates due to management and environmental reasons. Understanding how understory plant growth and soil nutrient cycling respond to litter amounts can provide insights into the feedback between rangeland ecosystems, climate, and management changes.
Methodology: Before the growing season, 60 plots were established under the canopy of 20 adult plants of each species (Astergalus gossypinus Fisch., Hyparrhenia hirta (L.) Stapf, and Artemisa aucheri Boiss.) for litter treatments. For each species, in 5 plots, all litter was removed (0% litter) and placed on the litter of 5 other plots (200% litter). In 5 plots, half of the litter was removed, and 5 plots were maintained as control plots (100% litter). At the end of the growing season, the number of individual species under A. gossypinus, H. hirta, and A. aucheri was recorded, and their production was estimated by cutting and weighing. Soil samples (1 kg) were taken from a depth of 0 to 30 cm in each plot to determine organic carbon (using Walkey and Black methods) and soil moisture (using the weight method).
Results: The three species showed significant differences in understory plant production at the 95% confidence level. For A. gossypinus, the highest production of understory species was observed in the 200% litter treatment, while A. aucheri showed no significant difference across treatments at the 95% confidence level. In H. hirta, the highest production of understory species was observed in the 0% litter treatment. For all three species, carbon and soil moisture significantly decreased with litter removal and increased with litter addition (p < 0.05). The structural equation model indicated that nitrogen-fixing species had the greatest direct effect on the sub-shrub species (p < 0.01). Litter had a significant indirect effect on the species under A. gossypinus through soil moisture and carbon (p < 0.05).
Conclusion: Shrub species played a more effective role than grass species in facilitating understory plant growth. There was no consistent relationship between litter removal/addition and understory production. Species responses to litter removal/addition varied significantly. Litter quality had a greater impact on the facilitating role of species than litter quantity. In general, species with a higher facilitating role were more sensitive to litter removal/addition, a factor that should be considered in pasture management plans.
Methodology: Before the growing season, 60 plots were established under the canopy of 20 adult plants of each species (Astergalus gossypinus Fisch., Hyparrhenia hirta (L.) Stapf, and Artemisa aucheri Boiss.) for litter treatments. For each species, in 5 plots, all litter was removed (0% litter) and placed on the litter of 5 other plots (200% litter). In 5 plots, half of the litter was removed, and 5 plots were maintained as control plots (100% litter). At the end of the growing season, the number of individual species under A. gossypinus, H. hirta, and A. aucheri was recorded, and their production was estimated by cutting and weighing. Soil samples (1 kg) were taken from a depth of 0 to 30 cm in each plot to determine organic carbon (using Walkey and Black methods) and soil moisture (using the weight method).
Results: The three species showed significant differences in understory plant production at the 95% confidence level. For A. gossypinus, the highest production of understory species was observed in the 200% litter treatment, while A. aucheri showed no significant difference across treatments at the 95% confidence level. In H. hirta, the highest production of understory species was observed in the 0% litter treatment. For all three species, carbon and soil moisture significantly decreased with litter removal and increased with litter addition (p < 0.05). The structural equation model indicated that nitrogen-fixing species had the greatest direct effect on the sub-shrub species (p < 0.01). Litter had a significant indirect effect on the species under A. gossypinus through soil moisture and carbon (p < 0.05).
Conclusion: Shrub species played a more effective role than grass species in facilitating understory plant growth. There was no consistent relationship between litter removal/addition and understory production. Species responses to litter removal/addition varied significantly. Litter quality had a greater impact on the facilitating role of species than litter quantity. In general, species with a higher facilitating role were more sensitive to litter removal/addition, a factor that should be considered in pasture management plans.
Type of Study: Research |
Subject:
Special
Received: 2024/10/29 | Accepted: 2024/12/15 | Published: 2025/01/29
Received: 2024/10/29 | Accepted: 2024/12/15 | Published: 2025/01/29
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