An Eye in the Sky Sees That Our Forests Can Die

Earth’s forests are extremely important for biodiversity, the global economy, and weather patterns worldwide. Trees provide habitat for other plants, animals, microbes, and so on, and large forests can influence weather by releasing large volumes of water vapour into the atmosphere.  On top of this, global forests uptake large quantities of CO2 from the atmosphere, helping to offset the release of CO2 from fossil fuel emissions.  One issue however, is that humanity has been engaged in global deforestation for quite some time now.  In a recent issue of Science, Hansen et al. (Hansen et al. 2013. Science 342:850) examined global forest loss across the planet from 2000 to 2012 using satellite mapping of the globe.

Overall, tropical forests were the hardest hit: over 700 million square kilometres of forest were lost over the 12 years.  The worst levels of deforestation were seen in Brazil, where forest lost exceeded 40,000 km2 per year.  Forest fires in the boreal forests (think northern Canada, Europe, Asia) drove a decline in forest cover, and this could get worse in the coming decades as forest fires are expected to increase.  There is good news however, Brazil has implemented forestry management practices that have reduced levels of deforestation by over 50% down to ~20,000 km2 per year.

As a species, we are finally capable of visualizing exactly how much influence we have on our environment.  We can see that Earth has lost ~2.3 million km2 of forest cover over the past 12 years (~1/4 of the area of the United States).  Now there is direct evidence of the consequences of our actions on a global scale.  Now, more than ever, we need to act, we need to fix the damage we have wrought.

Stay safe and stay informed,

Joe

Removing the Doubt About Drought

Drought stress is arguably one of the most important stresses in terms of its effects on plant growth and in our case, food supply.  Drought stress occurs when a plant does not have enough water for an extended period of time.  Plants such as trees and crops have a vascular system – analogous to the human vascular system, plants draw in water and nutrients through a series of tubes (called xylem and phloem).  A plant needs a continuous source of water to keep water and nutrients flowing though the plant.  Without enough water, an air bubble forms (called an embolism), causing the upper parts of a plant to dry out and eventually die under drought stress.

So why does this matter?  Well agriculture is very water intensive and drought can be very bad for food production.  However during a drought scenario, when a farmer may have limited water reserves, being able to tell when a plant is drought-stressed could mean the difference between saving year’s crop yield with targeted irrigation and losing it.  Using sunflowers, Marchand et al. (Marchand et al. 2013. Plant, Cell and Environment 36:2175-2189) set out to find a biomarker for drought stress – a signal that could be used to detect when a plant starts to become drought stressed.  The authors looked at the expression levels of many genes and compared them to different measures of drought stress currently used (e.g. the amount of water in soil).

The authors found that they could analyze three genes to reliably determine if a sunflower was drought stressed, however due to the length of time from sampling the plant to getting the results, their technique does not allow pre-emptive watering to reduce drought stress.  This is a down-side, but let’s look at the implications.

Having a biomarker for drought stress would allow farmers to breed better plants by selecting for plants that better resist drought stress.  On top of this, technological advancement might allow the technique to be used in pre-emptive watering, provided the genetic analysis could be sped up.  This research highlights one of the many ways that plant scientists are working to make a more sustainable and secure food supply: by using science to select the best crops and determine the best time(s) and way(s) to use our limited resources.

Stay safe and stay informed,
Joe