We investigated carbon (C) uptake and respiratory losses of an adult Pinus cembra tree at the alpine timberline throughout an entire year by means of an automated, multiplexing gas exchange system. These chamber measurements were then combined with biomass data for scaling up the C budget to the tree level. Integrated over an entire year, the cumulative C gain of the tree under study was 23.5 kg of C in 2002. The daily C balance was negative for 5 months and the estimated total wintertime respiratory losses were 9% of the amount of C fixed during the growing season. The total annual C loss of the tree consumed 55% of the annual net C gain and the remaining surplus was stored in new tissues (36%) and used for fine root growth (9%). Thus, the overall C budget of P. cembra at the upper timberline is balanced fairly well, although the C sink strength in fine roots is strongly limited owing to low root zone temperatures when compared to conifers at lower elevation sites.
Trees at high elevations are exposed to a combination of high irradiance, extreme climate and increasingly higher ozone concentrations. As a defense, trees are equipped with an antioxidative system protecting them from reactive oxygen species (ROS) induced directly (by e. g. ozone) or via interaction of stress with primary plant metabolism. Although the effect of high elevation stress on growth and the antioxidative metabolism of spruce (Picea abies [L.] Karst.) has been studied widely, very little information exists for European larch trees (Larix decidua Mill.). Therefore, we investigated the content of the antioxidants glutathione, ascorbate and tocopherol, and of photoprotective pigments of larch needles growing at valley (1000 m a.s.l.) and timberline (2000 m) stands of the northern (Austrian) and southern (Italian) Limestone Alps. The glutathione content of larch needles increased with elevation in the northern and southern Alps. Larch needles contained higher contents of oxidized glutathione at all high elevation sites. In addition, the glutathione content in larch needles of the southern Alps was higher than that in the north, suggesting a higher antioxidant defence capacity. In the Austrian Alps, the ascorbate content increased with elevation. Xanthophylls in larch needles grown at the timberline were in a more de-epoxidized state than those from lower elevation. Our study points out that the protective systems of larch needles along elevational gradients are largely comparable to evergreen conifers. Foliar biochemical attributes of larch can be used as a system to monitor the stress status of trees.
KEY WORDS: 3D surveying and mapping, snow drift, snow avalanches, digital surface models, multitemporal
ABSTRACT:This contribution presents an automated terrestrial laser scanning (ATLS) setup, which was used during the winter 2016/17 to monitor the snow depth distribution on a NW-facing slope at a high-alpine study site. We collected data at high temporal [(sub-)daily] and spatial resolution (decimetre-range) over 0.8 km² with a Riegl LPM-321, set in a weather-proof glass fibre enclosure. Two potential ATLS-applications are investigated here: monitoring medium-sized snow avalanche events, and tracking snow depth change caused by snow drift. The results show the ATLS data's high explanatory power and versatility for different snow research questions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.