Species of Paulownia are fast-growing trees that are planted in many countries in green spaces and agroforestry systems. We studied the influence of irrigation on the diameter growth of 2-year-old Paulownia tomentosa ...Species of Paulownia are fast-growing trees that are planted in many countries in green spaces and agroforestry systems. We studied the influence of irrigation on the diameter growth of 2-year-old Paulownia tomentosa saplings planted in 3 m 9 3 m grids at Nazlou Campus of Urmia University, Iran. Completely randomized experimental design was used with four irrigation amount, viz.10, 15, 20 and 25 L, and three irrigation intervals, viz. 3-and 6-days, in 8 replications. During the growth season, we measured collar diameters of all saplings at the end of each month. Diameter growth declined with reduced irrigation amount and increased irrigation interval. The lowest average diameter growth（9 mm） was recorded for 10 L water at 6-day intervals and maximum average diameter growth（28.7 mm） was recorded for 25 L volume at 3-day intervals. The latter treatment resulted in significantly greater diameter growth than any other treatment（except20 L at 3-day intervals）. More than 80 % of diameter growth was achieved in the first 3 months. Therefore, it is essential to irrigate with 25 L of water at 3-day intervals during the first three growth months to achieve maximum diameter growth for 2-year-old P. tomentosa saplings.展开更多
Forest edges have been well studied in temperate and tropical forests,but less so in open canopy forests.We investigated edge influence on plant species diversity and soil properties in sparse oak forest fragments.Dat...Forest edges have been well studied in temperate and tropical forests,but less so in open canopy forests.We investigated edge influence on plant species diversity and soil properties in sparse oak forest fragments.Data were collected along three transects from the edge to the interior of three small(under 10 ha)and three large(over 10 ha)oak forest fragments in Kermanshah Province,Iran.We measured herbaceous plants(<0.5 m in height)and soil attributes at 0(forest edge),25,50,100 and 150 m.We quantified species diversity using the Shannon index,used rarefaction to compare species richness between two different sizes of fragments and applied non-metric multidimensional scaling ordination to investigate the variation in species composition.We estimated the distance of edge influence using randomization tests.Generalized linear mixed models with post-hoc Tukey’s HSD tests were used to assess the effects of distance from edge and fragment size on diversity and soil properties.We found greater species richness,diversity and evenness at the edge of both small and large fragments and lower nitrogen and organic carbon at the edge compared to the interior of large fragments,with most changes within 50 m of the edge.Species composition,organic carbon and total nitrogen were significantly different between small and large fragments.Our findings of significant edge influence on herbaceous plants and soil properties in these sparse forests provide a significant contribution to the literature on edges,especially in relation to herbaceous plants.展开更多
文摘Species of Paulownia are fast-growing trees that are planted in many countries in green spaces and agroforestry systems. We studied the influence of irrigation on the diameter growth of 2-year-old Paulownia tomentosa saplings planted in 3 m 9 3 m grids at Nazlou Campus of Urmia University, Iran. Completely randomized experimental design was used with four irrigation amount, viz.10, 15, 20 and 25 L, and three irrigation intervals, viz. 3-and 6-days, in 8 replications. During the growth season, we measured collar diameters of all saplings at the end of each month. Diameter growth declined with reduced irrigation amount and increased irrigation interval. The lowest average diameter growth（9 mm） was recorded for 10 L water at 6-day intervals and maximum average diameter growth（28.7 mm） was recorded for 25 L volume at 3-day intervals. The latter treatment resulted in significantly greater diameter growth than any other treatment（except20 L at 3-day intervals）. More than 80 % of diameter growth was achieved in the first 3 months. Therefore, it is essential to irrigate with 25 L of water at 3-day intervals during the first three growth months to achieve maximum diameter growth for 2-year-old P. tomentosa saplings.
基金financially supported by the vice chancellor for research and technology of Urmia University and received no external funding.
文摘Forest edges have been well studied in temperate and tropical forests,but less so in open canopy forests.We investigated edge influence on plant species diversity and soil properties in sparse oak forest fragments.Data were collected along three transects from the edge to the interior of three small(under 10 ha)and three large(over 10 ha)oak forest fragments in Kermanshah Province,Iran.We measured herbaceous plants(<0.5 m in height)and soil attributes at 0(forest edge),25,50,100 and 150 m.We quantified species diversity using the Shannon index,used rarefaction to compare species richness between two different sizes of fragments and applied non-metric multidimensional scaling ordination to investigate the variation in species composition.We estimated the distance of edge influence using randomization tests.Generalized linear mixed models with post-hoc Tukey’s HSD tests were used to assess the effects of distance from edge and fragment size on diversity and soil properties.We found greater species richness,diversity and evenness at the edge of both small and large fragments and lower nitrogen and organic carbon at the edge compared to the interior of large fragments,with most changes within 50 m of the edge.Species composition,organic carbon and total nitrogen were significantly different between small and large fragments.Our findings of significant edge influence on herbaceous plants and soil properties in these sparse forests provide a significant contribution to the literature on edges,especially in relation to herbaceous plants.
