Gerhard Zotz

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Whether rising atmospheric carbon dioxide (CO2) concentrations will cause forests to grow faster and store more carbon is an open question. Using free air CO2 release in combination with a canopy crane, we found an immediate and sustained enhancement of carbon flux through 35-meter-tall temperate forest trees when exposed to elevated CO2. However, there was(More)
Grape (Vitis vinifera cv Silvaner) vine plants were cultivated under shaded conditions in the absence of ultraviolet (UV) radiation in a greenhouse, and subsequently placed outdoors under three different light regimes for 7 d. Different light regimes were produced by filters transmitting natural radiation, or screening out the UV-B (280-315 nm), or(More)
In 2003, Central Europe experienced the warmest summer on record combined with unusually low precipitation. We studied plant water relations and phenology in a 100-year- old mixed deciduous forest on a slope (no ground water table) near Basel using the Swiss Canopy Crane (SCC). The drought lasted from early June to mid September. We studied five deciduous(More)
The current knowledge of the physiological ecology of vascular epiphytes is reviewed here with an emphasis on the most recent literature. It is argued that by far the most relevant abiotic constraint for growth and vegetative function of vascular epiphytes is water shortage, while other factors such as nutrient availability or irradiation, are generally of(More)
Although there is unambiguous evidence for vascular epiphytic plants to be limited by insufficient water and nutrient supply under natural conditions, it is an open debate whether they are primarily phosphorus (P) or nitrogen (N) limited. Plant (15) N fractionation and foliar N : P stoichiometry of a tank epiphyte (Vriesea sanguinolenta), and its response(More)
BACKGROUND AND AIMS This study examined the physiological basis of the cost of reproduction in the epiphytic bromeliad Werauhia sanguinolenta, growing in situ in a tropical lowland forest in Panama. METHODS Entire mature plants were sampled repeatedly over the course of 2 years, which represents the common interval between reproductive events. Due to the(More)
Virtually all plants show a certain degree of variation among individual metamers during ontogeny. In some cases, however, there are abrupt and substantial changes in form and function (e.g. in leaf form, leaf size, phyllotaxy, internode length, anthocyanin pigmentation, rooting ability, or wood structure). These plants were called “heteroblastic” by Karl(More)
The epiphytic orchid, Dimerandra emarginata, occurs in habitats characterized by high light intensities and very variable water supply. Long-term observations of the water status indicate that this species experienced at least moderate water stress over most of the year. Well-watered, it showed high rates of net CO2 uptake (A, 7 μmol m−2 s−1), high(More)
Insufficient nitrogen (N) and phosphorus (P) frequently limit primary production. Although most nutrient studies on vascular epiphytes have focused on N uptake, circumstantial evidence suggests that P rather than N is the most limiting element for growth in this plant group. We directly tested this by subjecting a total of 162 small individuals of three(More)