Re: Could tundra vegetation survive on mars if water was discovered?

Hi Patricia,

There is water on Mars, though any water at the surface is frozen due to 
very low surface temperatures (on average -50 degrees Celcius).  Whether 
there was liquid water on Mars in the past or is liquid water in the 
subsurface is still a debate. Some scientists think that it does exist in 
subsurface regions, which would be warm enough for water to exist as a 
liquid.  There are ancient surface features that appear to be the result 
of liquid water activity in the past.  These include flood plains, and 
dendritic valleys that resemble river flow patterns on Earth. 

We don't know if the conditions on Mars are suitable for life to exist.  On 
Earth there are some extremophilic microbes (lovers of extreme environments 
such as hot springs and tundra) that would likely survive if they were on 
Mars.  Whether plants would survive is a different question.  Plants (even 
plants found in cold regions) are more sensitive than extremophilic 
microbes in that they require more stable environmental conditions.   

One major concern is whether nutrients derived from soil minerals are 
available to biological organisms.  What I work on is the phosphate 
geochemistry of Mars, and whether biological organisms could extract the 
phosphate from whatever phosphate minerals exist there.  Since phosphate is 
very important in biological processes (e.g. ATP as the energy currency of 
cells, and phospholipids that comprise the lipid bilayer cell membrane), 
one would think that it is integral to life.  If organisms can't access the 
phosphate from the soil minerals, they can't thrive.  This is the case for 
all nutrients derived from minerals.  At this point, the mineralogy of the 
Martian soil is not known in great detail.  (In the same vein, biological 
organisms require C, N, and O; these elements are available through cycles 
that involve the atmosphere to a large extent.)  

If plants and microbes were brought to Mars (the term for this is 
"terraforming") and survived as well as reproduced, they would 
definitely affect the current environments found on Mars.  One ramification 
of this habitation would be the alteration of the atmosphere (the Martian 
carbon cycle would be changed dramatically if plants were introduced), 
which would change the surface temperature.  This in turn might affect the 
phase in which water exists (liquid or ice) on the surface of Mars.  

Earth is in what we call a habitable zone.  What this means is that 
the conditions found in terrestrial systems are conducive to life.  
Moreover, there is a balance between the nonbiological and biological 
cycles on Earth that promotes the continued existence of life.  Introducing 
life to Mars might alter the Martian environmental conditions in such a way 
that Mars would be so harsh that even the most extremophilic organisms on 
Earth could not survive.  Of course, no one really knows exactly what would 
happen.

Sorry that this is such a long response.  If I didn't answer your question 
sufficiently, please write back.

Sarah Earley
CU Boulder