Narrow vessels - a hallmark of frost-adapted evergreen leaves.

The freezing-induced formation of embolisms in xylem conduits presents one of the challenges faced by evergreen leaves in frost-experiencing regions. Given that the probability of permanent embolism formation is related to the conduit diameter, we hypothesized that diameters of the vessels in evergreen leaves should be smaller than in deciduous leaves. We used live botanical garden collections to sample leaves of 21 evergreen and 47 deciduous species originating from various temperate biotopes and representing a broad taxonomic diversity.

Effects of lianas on forest biogeochemistry during their lives and afterlives.

Climate change and other anthropogenic disturbances are increasing liana abundance and biomass in many tropical and subtropical forests. While the effects of living lianas on species diversity, ecosystem carbon, and nutrient dynamics are receiving increasing attention, the role of dead lianas in forest ecosystems has been little studied and is poorly understood. Trees and lianas coexist as the major woody components of forests worldwide, but they have very different ecological strategies, with lianas relying on trees for mechanical support.

Negative phototropism of the shoots helps temperate liana Hedera helix L. to locate host trees under habitat conditions.

Lianas employ a variety of searching mechanisms to find support; however, it is not clear to what extent environmental signals are used to help direct the search. Several adventitious root climbers have been shown to bend away from light and grow toward darker areas or objects, in one case including actual tree trunks. In the literature, this negative phototropism (NP) has also been informally and inconsistently reported from a temperate root climber Hedera helix L.

Anatomical acclimation of mature leaves to increased irradiance in sycamore maple (Acer pseudoplatanus L.).

Trees regenerating in the understory respond to increased availability of light caused by gap formation by undergoing a range of morphological and physiological adjustments. These adjustments include the production of thick, sun-type leaves containing thicker mesophyll and longer palisade cells than in shade-type leaves. We asked whether in the shade-regenerating tree Acer pseudoplatanus, the increase in leaf thickness and expansion of leaf tissues are possible also in leaves that are already fully formed, a response reported so far only for a handful of species.