Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 2 of 2
Full-Text Articles in Life Sciences
Gas Exchange And Water Relations Of Two Alpine And Two Arctic Tundra Plant Species, Douglas Allan Johnson
Gas Exchange And Water Relations Of Two Alpine And Two Arctic Tundra Plant Species, Douglas Allan Johnson
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Although water stress is an important selective force in many environments, it is not commonly considered to be of particular importance in tundra areas. Even though large portions of tundra may have an abundance of water, other more exposed areas may become quite dry. This microsite variability with respect to moisture stress was reflected in soil water potential measurements obtained from an alpine tundra area on Niwot Ridge in Colorado. Even though soil water potentials were consistently above -5 bars in a relatively low lying Deschampsia meadow, soil water potentials from an exposed fellfield area were often as low as …
Field Measurements Of Photosynthesis And Leaf Growth Rates Of Three Alpine Plant Species, Douglas A. Johnson
Field Measurements Of Photosynthesis And Leaf Growth Rates Of Three Alpine Plant Species, Douglas A. Johnson
All Graduate Theses and Dissertations, Spring 1920 to Summer 2023
Leaf photosynthetic measurements using a portable 14Co2 field system were carried out and correlative leaf relative growth rates, RGR, were determined at different leaf positions of three alpine plant species throughout the growing season. Initially there was a period of high leaf RGR associated with a period of increasing photosynthetic activity. Following this stage was a long period of no net change in length of the living leaf. During this period, photosynthetic activity generally increased to a maximum level and then decreased steadily. The final ontogenetic stage was a period of negative leaf RGR denoting leaf senescence which …