Results
Table 2. Results showing the proportion of threatened species populations under each climate scenario for drought condition. The Hargreaves moisture deficit (CMD) is used to define drought conditions. The CMD values for past (1961-1990) are used as a threshold value for each species under each climate scenario.
The proportion of each species threatened under drought conditions (Table 2) represents the number of individuals within a specific climate scenario that fell outside the threshold limit from the past dataset divided by the total number of individuals present from the past data set. The threshold limit was determined by excluding the top 5% of values for Hargreaves climatic moisture deficit (CMD) under the past (1961-1990) climate scenario. For every climate scenario the range of values for a climate variable shift. It is obvious that for RCP 8.5 there is a greater proportion of threatened species than the RCP 4.5. Similarly, the 2080 timeframe also shows a greater proportion of species threatened than the 2050 timeframe. The most threatened species within this dataset is the Colorado pine, Incense cedar, and Western larch.
Figure 6. Maps of study region showing the distribution of threatened species under drought conditions with Hargreaves moisture deficit for each climate scenario and timeframe as base map layer
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Lets ZOOM IN
Figure 7. From left to right is RCP 4.5 2050, RCP 8.5 2050, RCP 4.5 2080 & RCP 8.5 2080. Zoomed in frame shows Pacific North west including Oregon, Washington, Vancouver island, Haida Gwaii, and Southern British Columbia and Alberta.
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The distribution of species threatened as a result of drought conditions was mapped (Figure 6). These maps show a concentration of threatened species near the southern portion of the study region. The northern distribution of species shows little change throughout RCP 8.5 2050, RCP 4.5 2080, and RCP 4.5 2050. This means the populations of northern tree species might be more protected from drought and that these northern areas are less susceptible to drought events under the future climate scenarios. This also points to the sensitivity of the southern areas as the moisture deficit is already high, as shown by the base layer coloration (Figure 6). A drought event could have lasting and serious ecological consequences to these areas. These patterns of moisture deficit that we see mapped could also initiate species migration northward (McKenney et. al, 2007). However, the extent to which this migration could take place is uncertain.
From the zoomed in perspective, the increase in species threatened increases as timeframe and RCP scenarios also increase (Figure 7). Furthermore, there is an increase in species threatened in the same regions that are already experiencing moisture deficit. There are few noticeable increases in threatened species in areas that have no moisture deficit. These areas should be used to help guide conservation efforts to protect these zones of climate refugia.
If these models are correct, the generation of this data and visual aids like maps will help bolster an effort to prioritize conservation efforts and research initiatives.
From the zoomed in perspective, the increase in species threatened increases as timeframe and RCP scenarios also increase (Figure 7). Furthermore, there is an increase in species threatened in the same regions that are already experiencing moisture deficit. There are few noticeable increases in threatened species in areas that have no moisture deficit. These areas should be used to help guide conservation efforts to protect these zones of climate refugia.
If these models are correct, the generation of this data and visual aids like maps will help bolster an effort to prioritize conservation efforts and research initiatives.