Normally when you think of shifting altitudes of plants in
response to climate change, you would probably expect plants to move
uphill for cooler elevations in response to their physiological needs.
You’re correct to an
extent. There have been many examples of shifts in tree lines and plants to
higher elevations during the 20th century. A few from the many observations include: higher altitude shifts in vegetation at the Swedish Scandes Mountains, as well as the 1-4 meters shift in elevation per decade of Alpine plants in the European Alps, and an average
of 65 meters shift upwards of plants in Southern California’s Santa Rosa Mountains within 30 years……. and the list goes on!
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| Surprise! The Answer is........ Both! |
However, here’s the plot twist: one recent study I came across suggest that in contrasts to what most people would expect … plants also move downhill in response!
Water Availability Is Key
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A study in Science compared records of altitudinal
distribution of 64 plant species in Northern Californian mountain ranges taken
in 1930, and the same information taken in 2011. Unexpected results showed that
instead of moving uphill due to rise in regional temperature, the elevation of plant
species decreased by approximately 80 meters. It was suggested that the downhill
movement was likely driven by species’ niche tracking of changes in regional climatic
water balance – the balance between lost of water to evaporation and water
gained from rainfall - instead of temperature. This is due to the increases in precipitation and snowfall in
California since 1930s that has resulted in a decreased climatic water deficit and an
increase in water availability at lower elevations than ever before, resulting
in the pattern of downward shifts in species that prefer
wetter, lower areas.
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| Plants on the Mountain Ranges of Northern California |
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| Northern Californian Mountain Ranges where plants are shifting downhill! |
I guess this certainly
reminds us that temperature is not the only factor defining species’
distribution. It clearly shows that understanding and estimating future
temperature trends is not enough, we also need to pay attention to how other
factors like precipitation may alter and how this, in turn, will affect regional water
balance and the types and abundance of species present. Understanding
how they respond is crucial, as plants play an important role for many
ecological communities around the world by providing services, such as habitat
and food.
Hope you liked this short post! See you all next week! :)
Hi Eva! What a curious post! Although I don't know very much about ecology I do think that there are lots of factors that control organisms e.g. sunshine and availability of food/ nutrients for plants - what could be the climate change effects on these and will they affect high latitudes plants?
ReplyDeleteHi Mona! Thanks for your comment!
DeleteYes, there are indeed a lot of factors that control the distribution of organisms. Distribution caused by climate change are often linked to species-specific physiological thresholds and their tolerances of environment conditions, such as: temperature, soil pH, water availability, salinity, minerals/nutrients….and many more. Nonetheless, other factors, such as species interaction & competition, territory and food availability, dispersal ability can also affect species distribution!
As you mentioned – sunshine will definitely affect the distribution of plants species according to their photosynthetic needs – for example the evergreen trees need large amount of sunlight. As well as, the availability of nutrients for plants. It is suggested that due to climate change, some places are increasingly becoming more arid. Where these places are situated at, nitrogen levels will likely decrease, but phosphorus will increase (http://phys.org/news/2013-10-production-decline-climate-affects-soil.html check out this article!). This will not only reduce productivity of plants (especially those at the dryland), but it will also cause major shift in species through different mechanisms – such as dispersal.
Going back to your inquiry on plants situated at higher latitude/altitude and how changes in nutrient & sunshine levels as a result of climate change:
These higher-latitude plants will be in particular more sensitive and vulnerable to climate change. Soil nutrient availability at higher latitude areas is naturally very low due to the low temperature conditions. Although higher temperatures (as a result of climate change) at these regions may potentially lead to higher soil nutrient mineralization rates. However, it is known that soil warming within realistic limits will likely have no effect on the increase availability of phosphorus.
In terms of increase temperature/sunshine at these higher latitude areas as a result of climate change – it will definetly play a main role in affecting the future distribution of plant species, as well as the whole structure of the Arctic biome (if you’re interested, you can check out my discussion on this topic on the transformation of Arctic biome from my previous post here: http://combatnow-impactsareclear.blogspot.co.uk/2015/11/troubling-transformation-in-arctic-but_6.html).
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