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Is the growth of Rhododendron influenced by duration of snow cover or growing season length?

Morales Barquero, Lucía (2009) Is the growth of Rhododendron influenced by duration of snow cover or growing season length?

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Abstract:The dwarfing of trees along the elevation gradient in mountainous terrain has been attributed to adverse climatic conditions, but the effect of these conditions on tree growth rates have rarely been investigated. The aim of this research is to study the spatial variability of the height and of the internodal length of two Rhododendron species and to investigate its relation with the duration of snow cover and the length of the growing season. Tree height and internodal distance were measured for two Rhododendron species (Rhododendron campanulatum and R. campylocarpum) along altitudinal gradients near the treeline in Sagarmatha National Park, Nepal. Linear regression revealed significant declines of both tree height and internodal distance with increasing elevation. The internodal distance did not significantly differ between N, E, S and W exposed branches of individual plants, but exposition had a significant effect on variation on internodal distance between plants. A very regular decline of internodal distance of individual branches was found. MODIS time series were used to investigate whether snow cover duration (MOD10A1 daily data 2000 to 2007) and the length of the growing season (16- day NDVI composite of MOD13Q1, 2000 to 2008) could explain this decrease of internodal distance. Internodal distance did not relate to the number of days with more than 10% or more than 50% of snow cover. Savitzky-Golay, double logistic regression and asymmetric Gaussian functions however did not reveal significant relation between internodal distance and length of the growing season. These results suggest that factors other than duration of snow cover and the length of the growing period influence the growth rates of these two Rhododendron species. Keywords: Khumbu Himal; treeline; Rhododendron sp.; internodal distance; fractional snow cover; growing season length, MODIS.
Item Type:Essay (Master)
Faculty:ITC: Faculty of Geo-information Science and Earth Observation
Programme:Geoinformation Science and Earth Observation MSc (75014)
Link to this item:https://purl.utwente.nl/essays/93039
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