Vulnerability to xylem embolism by freeze-thaw cycles and water stress was quantified in ring-porous (Quercus gambelii Nutt.), diffuse-porous (Populus tremuloides Michx., Betula occidentalis Hook.), and conifer species (Abies lasiocarpa Nutt., Juniperus scopulorum Sarg.). Embolism was measured by its reduction of xylem hydraulic conductivity; it was induced by xylem tension (water-stress respon...

Tree seedling flooding tolerance for 22 species was assessed under controlled field condi­ tions. Initial heights under control (freely draining soil, n = 20 per species) and flooded (stand­ ing water, depth = 10 cm, n = 20 per species) conditions were measured in March 1990. Sur­ vival, height and diameter growth were determined after 120 days. Recovery from flooding effects was assessed in th...

Acer pseudoplatanus L., Acer platanoides L. and Betula pendula Roth. have been studied under the urban pollution in Sofia during 3 years period. The aim of the study was, by statistical multifactorial analysis, to assess the value changes in morphological parameters of species under air pollution and potential for species usage as bioindicators in observed regions. The statistical analysis incl...

We reconstructed Holocene water-level and vegetation dynamics based on pollen and plant macrofossils from a coastal lake in Upper Michigan. Our primary objective was to test the hypothesis that major fluctuations in Great Lakes water levels resulted in part from climatic changes. We also used our data to provide temporal constraints to the mid-Holocene dry period in Upper Michigan. From 9600 to...

Estimations of phylogenies from morphological and molecular data often show contrasting results. We compared morphological and molecular phylogenies in an ancient family of woody dicots, the Betulaceae (birch family). The phylogeny of the family was estimated from parsimony analysis of morphological characters in the genera Alnus, Betula, Carpinus, Corylus, Ostrya, and Ostryopsis and from parsi...

Pollen is one of the most common causes of allergy worldwide, making the study of their molecular composition crucial for the advancement of allergy research. Despite substantial efforts in this field, it is not yet clear why some plant pollens strongly provoke allergies while others do not. However, proteases and protease inhibitors from allergen sources are known to play an important role in ...