Prevailing Environmental Conditions have Capacity to affect Distribution of Plants within Pacific Northwest Region – Lab Report

The Pacific Northwest is characterized by temperate climatic conditions with alpine climate dominating the areas of the high mountains and arid and semi-arid climates present in the areas east of the mountains particularly those affected by the rain shadow effect. The Pacific Northwest supports diverse numbers of flora from savannah grasslands to maritime forest to rainforests (Peterson et al, 2014). This report asks to determine whether prevailing environmental conditions have the capacity to affect the distribution of plants within the Pacific Northwest region by proving the hypothesis that climatic conditions have influenced the distribution of plants in the Pacific Northwest and their change will continue to influence this distribution in the years to come.


This research utilized to identify plant species by comparing the characteristics of the species that were encountered during the research period with the pictures contained within the website’s photo gallery. The identified plants were then grouped on the basis of environmental habitat in order to assist in proving the hypothesis presented by this paper.


Sub- Alpine and Alpine meadowsMountain HemlockTouga mertensianaHigh elevation Alpine climate above the tree line. 
Pacific silver firAbies amabilis 
Alaska yellow cedarChamaecyparis nootkatensis 
Englemann sprucePicea engelmannii 
Lodgepole pinePinus contorta 
Maritime coniferous forestRed AdlerAlnus rubraOcean, coastal habitat
Big leaf mapleAcer macrophyllum
Oregon white oakQuercus garryana
Western HemlockTsuga heterophylla
Douglas firPseudotsuga menziesii
Dry Corniferous forestPonderosa pinePinus ponderosaArid and semi-arid areas
True firsAbies grandis
Western larchLarix occidentalis
Western white pinePinus monticola
Western juniperJuniperus occidentalis


Alpine plant life often thrives in highly elevated areas and are characterized by short growing seasons in deep persistent winter and cool summers. Low air and soil temperatures facilitate the short nutrient cycling phase of these plants. Due to the changing climatic conditions within the Pacific Northwest region, these optimal growth conditions might not be present and Alpine vegetation is projected to decrease significantly by the turn of the century. Temperatures are expected to increase by two to four degrees Celcius by the end of the century. There will be wetter winters, drier and hotter summers due to the action of greenhouse gases on the environment. Alpine and sub-Alpine vegetation might respond to these changes within the environment by seeking refuge in the Northern Cascade Mountains of high elevation or decrease in numbers significantly.

Mild wet winters favour evergreen conifers by facilitating their assimilation of carbon requirements during the cooler months when they have no leaves. Old winters lower the rate of photosynthesis allow the proliferation of growth and productivity by the reduction of reserves of carbon (Gholz, 1982). High vapour pressure deficits during summer and low precipitation limit the level of productivity in maritime conifers by inducing partial or complete stomata closure. The environmental effects of global warming may reduce increase wet conditions during winter and increase dry conditions during summer and lead to the decline in maritime coniferous plant species.

Dry coniferous plant species are adapted to the stress of drought and can survive dry summers by reducing growth rate until high precipitation periods. Summers where low availability of water in the social significantly impedes the process of photosynthesis leading to low plant growth. The growth of these plants is therefore limited to the early months of summer and spring when conditions such as the high prevalence of water in the soil and mild temperatures provide the necessary conditions for growth. The climatic conditions necessary for the increased productivity of dry coniferous plants are expected to be reduced by the earlier levels of snowmelt and decreasing snowpack in the mountains. Moreover, the warm conditions in winter will reduce the fraction of precipitation falling in the form of snow and the warmer summers and springs promote earlier onset of drought and increase its duration and intensity. These environmental factors will increase the level of drought stress imposed on dry coniferous plants and might impede productivity in species especially those that grow only to low elevations (Kusnierczyk & Ettl, 2002)


Plant biology relies on the effects of environmental conditions to facilitate growth and development. In the absence of a favorable environmental condition, plants must develop responses to these changes by natural selection of traits that would better survive in the new environment through long distance mechanisms of pollen dispersal. Vegetation may also respond to the changes in climate by migrating from environments with unfavourable conditions to those with optimal conditions of growth. Despite the capacity of the Pacific Northwest to support may vegetative species due to the favourable temperate climatic conditions, the effects of carbon dioxide pollution on these favourable conditions and on plant processes such as photosynthesis, respiration, root and shoot proliferation, as well as overall growth and reproduction, is worrisome. Moreover, the level of greenhouse gas emission has made the earth an unpredictable environment in terms of weather and the effects of these conditions have been a decline in vegetative life and death of some rare plant species. There is a need to develop strategies to manage the process of environmental change and reduce the rate at which it is happening in order to ensure vegetative life does not continue declining as it is (Joyce et al, 2009).

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