نوع مقاله : علمی - پژوهشی
نویسندگان
1 گروه مهندسی آب و خاک-دانشکده کشاورزی-دانشگاه ایلام-ایلام- ایران
2 گروه خاکشناسی، دانشکده کشاورزی، دانشگاه ایلام، ایلام، ایران.
3 علوم جنگل، دانشکده کشاورزی دانشگاه ایلام، ایلام، ایران.
4 گروه مهندسی طبیعت، دانشکده منابع طبیعی و محیط زیست، دانشگاه ملایر، ملایر، ایران.
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Abstract
Introduction and Objective: Litterfall decomposition is one of the most important ecological processes for determining the cycle of nutrient elements and ecosystem function. This process is mainly influenced by three main factors: quality and quantity of plant residues, physical conditions (temperature and humidity) and soil microbes such as bacteria and fungi. It is possible to improve a nutrient cycling and return these elements to the soil via the decomposition of leaves and plant residues. This process improves soil functions, controls soil ecological conditions, and factors affecting the activity of microbial communities and their growth. On the other hand, the accumulation of litterfall and other plant residues on the forest floor is the most important source of organic matter entering in to the soil, and its decomposition is considered one of the most important processes that determine the amount of organic carbon sequestration in the soil. The purpose of this research was to investigate the amount of litterfall decomposition in some broadleaf and coniferous trees in different land uses including garden, agriculture, and forest.
Material and Methods: This research was conducted in Ilam province in 2019, taking into account three land uses, including forest in the protected area of Manshet and Qalarang, garden and agriculture in the north of Ilam city. In order to investigate the process of litter decomposition of three broad-leaved tree species, including Iranian oak (Quercus brantii L.), pistacia (Pistacia atlantica Desf.), hawthorn (Crataegus pontica C.Koch.), and two coniferous species such as black pine (Pinus brutia Ten.) and cerosorbine (Cupressus Sempervirens L.) were selected. Life litter were collected from natural forests and placed in litter bags with dimensions of 20 x 20 cm and 2 mm hole diameter. The total litter bags were 180. After each litter bag collection, litter quality indicators were measured in periods of 60, 120, 180 and 240 days. Litterfall quality indicators included the final limit of litter decomposition, the maximum amount of organic matter lost using weight, and the potential capacity of homogenization. Data analysis was done factorial on the basis of complete random block with three replications through analysis of variance and mean comparison (Duncan's test, probability level of five and one percent) using SAS 9.1 software.
Results: The results showed that the factors of time, species and land use had an effect on the quality indicators of litterfall decomposition. The results showed that the highest amount of organic matter lost belonged to pistacia leaves with 34% after 240 days period and the lowest amount was related to cupressus leaves with 14% in 60 days period. In different land uses, the lowest and the highest amount of organic matter lost was allocated to cupressus with 18% and pistacia with 36.2%, respectively. The decomposition rate of cupressus did not show any significant difference in different uses, but the pistacia and quercus leaves had a higher decomposition rate than other conifers due to their physiological structure and palatability. In agriculture and garden land uses, the final limit of decomposition was obtained in crataegus and pistacia litter more than other litterfalls, but in forest land use, the final limit of decomposition in quercus litter was 65% (due to the original site of quercus trees in Zagros forests) more than other litterfalls became. Also, the highest amount of humicization in three different land uses was related to pistacia and cupressus litter and the lowest rate in forest land use was related to quercus litter with 0.35 parts. In general, according to the obtained results, among different trees, in terms of the final limit of decomposition, the quercus species showed the highest amount, but the litterfall had a higher decomposition rate than other leaves. In addition, it can be concluded that the process of decomposition was somewhat similar in different land uses, because the garden and agriculture used in the past were forests, and with the passage of time they changed their land use, but due to the scientific cultivation and natural conditions they were similar to the forest.
Conclusion: In this study, in forest, agriculture, and garden land uses, the amount of organic matter lost in the dead leaves of oak trees was more than other dead leaves of other tree species. Based on the results of this research, the amount of organic matter lost has also increased over time. In forest land use, oak litterfall was the highest in terms of decomposition rate compared to other tree species. While, the litterfalls of two species of cypress and pistacia compared to other litterfall showed a higher potential capacity of homosization and this caused the reduction of the final limit of decomposition in these litterfalls. It seems that in the forest ecosystem studied in Zagros zone, two species of pistacia and oak have the greatest effect in increasing soil fertility and improving the cycle of nutrients in the soil. So that this effect is significant even after changing the landuse of forest to garden and agriculture. Therefore, for reforestation in the Zagros region, planting pistacia as a species accompany with the oak tree can be prioritized in forestry projects and despite the presence of native species with a favorable decomposition rate up to As much as possible, foresters avoided the entry of conifers in these fields.
Keywords: Persian oak, litter bag, soil, organic matter loss, Ilam.
کلیدواژهها [English]
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