جستجوی مقالات مرتبط با کلیدواژه « pinus taeda » در نشریات گروه « جنگلداری »

This research was carried out to study the effects of loblolly pine (Pinus taeda) and Populus sp. plantation on some forest soil properties in Lahidjan region. The experimental design was as completely Randomized Block with three treatments (Land covers) and five replicates. For each land cover, five 500 m2 sample plots were established and five trees were randomly selected within the plots. Soil samples were taken from depth 0-20 cm around each tree. Some soil properties such as pH, organic carbon, texture, microbial respiration were analyzed. The results showed that bulk density of soils differed significantly among Pinus taeda and other trees. Poplar plantation increased significantly pH, Ca+Mg, available P and K in contrast to other tree species. Microbial respiration increased significantly under soils of native forests. It is concluded that poplar plantation could increase the soil fertility index.

Biological property is a best indicator for soil quality identification due to its relationships with soil nutrient cycle, respiration, microbial biomass and enzymes activity. The aim of the research was to study the influence of two even-aged and adjacent stands of loblolly pine (Alnus glutinosa L. (Gaertn.) and alder (Pinus taeda L.) on activity of dehydrogenase and urease enzymes, microbial biomass and some of the soil chemical and physical properties at west of Guilan province. Soil sampling was made up to 20 cm depth of soil surface (0-10 and 10-20cm). Dehydrogenase and urease enzymes activities and microbial biomass were measured, using the substrate reaction method and application of spectrophotometer device. The tested soil properties consisted of: texture, bulk density, mean particle density, moisture content, pH, organic carbon, total nitrogen, phosphorus and potassium. The results showed that there were significant differences between the two stands in respect to amounts of dehydrogenase and urease enzymes, microbial biomass, carbon, nitrogen and potassium. The amount of urease and dehydrogenase enzymes, microbial biomass, organic carbon and nitrogen in alder stand was more than in the loblooly Pine stand. There were significant correlations between the enzymes density and microbial biomass, organic carbon, nitrogen, pH, potassium, soil texture and soil porosity. Overall, it might be concluded that the alder stand provided better condition for organic matter and microbial production and microbial biomass development and activity.

In order to study the tree growth and natural regeneration of loblolly pine in a 33-year-old plantation in Pylambra region (Guilan province), 1.5 ha of well stocked stand was selected. This study was done as randomized complete block design with three treatments as: T1, low density (15m2 basal area ha-1), T2, medium density (20m2 basal area ha-1) and T3, high density (25m2 basal area ha-1) with four replicates. Soil surface scarification was carried out at the first year. Diameter at breast height, total height of trees in each plot (1000m2), number and height of pine regenerations in subplot with an area about 10 m2 were measured. Results show that the height of Loblolly pine seedlings ranging from 10 to 150 cm were recorded in different treatments but in terms of the height growth, medium density treatment with 182 stem per ha showed better results and the difference with other treatments was statistically significant.