Search

A controlled experiment was conducted in order to understand how functional and structural traits of species with different leaf habits (Fraxinus ornusandQuercus ilex) shift as a consequence of nitrogen (N) addition (30 kg ha yr−1) and to explore the effect that N has on the water stress response. The experiment was divided in two stages: stage I, N addition under well-watered condition; stage II, N addition under drought. Functionality of the photosynthetic machinery, growth and biomass partitioning were assessed. The N content at leaf level increases inF. ornusonly, which invests resources on photosynthetic machinery, whereasQ. ilextends to store N in non-photosynthetic biomass, increasing relative growth rate and biomass, resulting in different allometric ratio. This effect may play a role in water stress response. Stomatal conductance ofQ. ilextreated with N and subjected to water stress is lower relative to drought treatment. On the contrary,F. ornustakes advantage of N addition that has ameliorative effects on its functionality when drought was imposed. The obtained results, highlighting response mechanisms to multiple stress factors, should help to better understand and assess the performance of forest ecosystems under the foreseen environmental changes. [ABSTRACT FROM PUBLISHER]

The response ofPhragmites australis(Cav.) Trin. Ex. Steudel to zinc (Zn) and lead (Pb) was studied separately in two hydroponic tests, during a three weeks experiment. The effects on ecophysiology and biomass partitioning were evaluated during the metal treatments and at the recovery, and total metal content and accumulation capacity in different plant organs were assessed. Zn and Pb had different effects on the overall measured parameters, highlighting different mechanism of action. In particular, Zn concentration was higher in roots and, being a micronutrient, it was translocated into leaves, producing a reduction of assimilation rate, stomatal conductance (–71.9 and –81.3% respect to the control plant respectively), and a strong down regulation of photosystems functionality both at PSII and PSI level. Otherwise, Pb was accumulated mainly in the more lignified tissue such as rhizomes, with slightly effect on gas exchange. Chlorophyllafluorescence highlighted that Pb inhibits the electron transfer process at the PSI donor side, without recovery after the removal of the metal stress. Despite these physiological limitations,P. australisshowed a high capacity to accumulate both metals, and only slight reduction of biomass, being therefore a suitable species for phytoremediation interventions. [ABSTRACT FROM AUTHOR]

Broadleaved forest is one of the most severely exploited and threatened ecosystems worldwide such that many authors have highlighted the scarcity of undisturbed old-growth broadleaved forests, especially in southern Europe. From an ecological perspective, old-growth forests are considered to be significant for their structural diversity and complex ecological relationships among species. In this paper, we compare ground measurements of leaf area index (LAI) and the remotely sensed normalized difference vegetation index (NDVI) autocorrelation pattern of two old-growth forest stands in the Cilento National Park (southern Italy) with two nearby managed forests stands of the same type. Results show that old-growth forests have higher fine-scale variability in both LAI and NDVI values and longer autocorrelation ranges than the corresponding managed forests. The potential relevance of these findings for the single large or several small (SLOSS) debate is also briefly discussed. [ABSTRACT FROM AUTHOR]