توصيفگر ها :
دواير ساليانه رشد , گاهشناسي آوندي , چوب بهاره , چوب پاييزه , تراكم آوندي , اندازه آوندي , تجمع آوندي , پوشش آوندي
چكيده انگليسي :
Recently, scientists consider the assessment and prediction of climate change effects on forests, which act as the lungs of the Earth, to be very important. Among the important forests are mangrove forests, which are ecologically, economically, and socially significant. Mangrove forests generally thrive in humid and rainy regions, but Iranian mangroves are present on the southern coasts with a warm and dry climate. Climate change can have more significant effects on these habitats; therefore, further studies are needed on the growth of these trees and their response to climate change. To investigate the effects of climate change on mangrove forests in southern Iran, two tree species, Avicennia marina and Rhizophora mucronata, were selected. In general, 25 Rhizophora mucronata discs were sampled near Bandar Sirik and 40 Avicennia marina discs were sampled in the northern part of Qeshm Island in 2019. In this study, five Avicennia marina (planted) and five natural discs, along with five Rhizophora mucronata planted discs, were selected for dendrochronological studies. The aim of this study was to produce dendrochronology for both species based on vessel parameters and combine them with anatomical studies to identify the boundaries of annual growth rings. Initially, the largest and smallest growth radii were cut from each disc, and slides were prepared for microscopic imaging. After analyzing the images in ROXAS using coding in R software, the trends of changes in vessel parameters, including vessel density, vessel size, and vessel coverage percentage, were quantified. The obtained microscopic images allowed for anatomical investigations. In Avicennia marina species, fragmentary growth and various morphological appearances in cambium bands, consistent with previous studies in different parts of the world, were observed. In Rhizophora mucronata species, the presence of scalariform perforation plates and tyloses was confirmed, consistent with results from other studies on this species in other habitats. In comparing the anatomy of both species, a clear difference in the type of vessel accumulation was observed. In natural Rhizophora mucronata samples, vessel accumulation was clumped together, while in Avicennia marina samples, vessels were arranged in a chain-like or linear manner. Additionally, by using the acquired microscopic images, scanned images of the disc surface and the trend chart of vessel changes along the growth radius were examined to identify the start points of springwood and autumn wood. Furthermore, the width of springwood, autumn wood, and annual growth rings for each year was determined. In another part of this study, it was revealed that if vessel density increases, vessel size decreases, acting as a limiting factor affecting the percentage of vessel coverage. Since there have been few anatomical studies on mangrove tree species on the coasts of the Persian Gulf and the Sea of Oman, this research can serve as a starting point for further studies on these two species regarding anatomy and dendrochronological studies. Additionally, incorporating climatic and environmental parameters into these studies and investigating their effects could provide valuable insights.
