Guenter Hoch

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The carbon charging of pines across the treeline ecotone of three different climatic zones (Mexico 19°N Pinus hartwegii, Swiss Alps 46°N P. cembra and northern Sweden 68°N P. sylvestris) was analyzed, to test whether a low-temperature-driven carbon shortage can explain high-elevation tree limits, and whether the length of the growing season affects the(More)
Carbohydrate stores may hold the answer to the old question whether treeline trees are carbon limited. However, it is still unknown how sensitively mobile carbon pools reflect the carbon supply status of trees in cold climates. There may be an inherent lower limit to the depletion of these pools, which could restrict their usefulness as indicator values.(More)
Phenological events, such as the initiation and the end of seasonal growth, are thought to be under strong evolutionary control because of their influence on tree fitness. Although numerous studies highlighted genetic differentiation in phenology among populations from contrasting climates, it remains unclear whether local adaptation could restrict(More)
Kinematic recordings of orofacial movements by means of electromagnetic articulography were performed in an akinetic-rigid Parkinsonian patient presenting with intermittent speech freezing in diadochokinesis tasks (rapid repetitions of the syllable /ta/). During freezing periods the patient produced a sustained /a/ instead of the required consonant-vowel(More)
Current threats to biodiversity, such as climate change, are thought to alter the within-species genetic diversity among microhabitats in highly heterogeneous alpine environments. Assessing the spatial organization and dynamics of genetic diversity within species can help to predict the responses of organisms to environmental change. In this study, we(More)
Decreased gas exchange as trees grow tall has been proposed to explain age-related growth declines in trees. We examined changes of mobile carbon stores (starch, sugars and lipids) with tree height in ponderosa pine (Pinus ponderosa) at two sites differing in water availability, and tested the following hypotheses: (1) carbon supply does not become(More)
Fruiting is typically considered to massively burden the seasonal carbon budget of trees. The cost of reproduction has therefore been suggested as a proximate factor explaining observed mast-fruiting patterns. Here, we used a large-scale, continuous 13C labeling of mature, deciduous trees in a temperate Swiss forest to investigate to what extent fruit(More)
Alpine dwarf shrub communities are phenologically linked with snowmelt timing, so early spring exposure may increase risk of freezing damage during early development, and consequently reduce seasonal growth. We examined whether environmental factors (duration of snow cover, elevation) influenced size and the vulnerability of shrubs to spring freezing along(More)