sustainability

The future of environmentally-friendly farming?

Our first paper on the agri-environment has just appeared in this month’s issue of PLoS Biology.  This is an important piece for us as it provides a foundation for empirical work being carried out by several group members.

The paper essentially makes three main points.  The first is that we spend a lot more money subsidizing farming than trying to mitigate its environmental impacts.  We’ve tried to plot this out below.  What you can clearly see is that the purple (mitigation expenditure) is nearly invisible relative to what is spent on subsidizing farming (shown in the orange slices).

Financial support to farmers from taxpayers and consumers associated with agricultural policies as a proportion of the total value of agricultural production (VoP) at the farm gate.

The figure now provides what is essentially a map of the ‘perversity‘ of agricultural subsidies – showing where we spend money to do things that are often bad for the environment and costly to the economy.  A first step in reducing conflict between agriculture and the natural environment would be to do away with the subsidies in orange.

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Fish are a forest product

Our latest paper has just been made freely available in Nature Communications, showing that freshwater fish, an important source of nutrition for humans, are in part produced by forests.  The study focuses on small boreal lakes, which contain upwards of 60% of the world’s freshwater. It suggests that any reductions in forest cover in the boreal ecoregion, such as from industrial activities, will threaten the production of healthy fish populations.

Forest stream at Daisy Lake

Forest stream at Daisy Lake

Small streams that drain forest floors bring microscopic particles of vegetation and soil into water. These get broken down by bacteria, which are then eaten by small invertebrate animals that are main food source for small fish. The research uses a gradient of forest cover in Canada to show that more of this forest organic matter is brought into lakes as the surrounding landscape is vegetated. This produces more bacteria in the near-shore water, which can support more zooplankton, and thus provide more food to small fish. Young fish survive winters and escape predators better if they are larger, so these effects are predicted to carry forward into larger and older animals.

Trapping zooplankton

Trapping zooplankton

The research also uses natural variation in the molecular mass of primary production from land versus water to estimate the proportional of terrestrial resources used by fish. At least 34% of fish biomass was supported by terrestrial vegetation, increasing to 66% with greater forest cover. This suggests that fish increasingly use forest food subsidies as they become available in the small nutrient poor lakes that are characteristic of the boreal ecoregion.

You can read more about the work at the BBC, Planet Earth, weather.com, Al Jazeera America,  or even watch a video at the Weather Network.  It is great to see the work receive this type of reception!  It took over 2 years of my life to produce in collaboration with a number of colleagues mainly at Laurentian University’s Living with Lakes Centre.

Can plants get more carbon for less water?

This week’s group meeting featured a special joint production with Molecular Physiology to welcome Prof Graham Farquhar from the Australian National University.  Graham was in the UK to receive a Rank Prize Fund award for his contributions to food security by helping to guide the breeding of wheat varieties that use water more efficiently.

His talk, “Water user efficiency and water use effectiveness, a stomatal perspective using stable isotopes” was a far-reaching overview of his amazing research career, dating back to his time as a PhD student.  But he started his talk with a very provocative and timely consideration of global changes in rainfall and human population growth.

Rainfall is inherently random.  Sometimes there is too much, sometimes there is too little.  Australia is a country that experiences both these extremes.  For example, there are often heavy floods in the monsoon region while other areas, particularly where agriculture is concentrated in the southern part of the country, is drying up.  The desire to expand cultivated land inevitably means there is more pressure on more marginal rainfall.  An astounding statistic that Graham rolled off was that 1 ha of cultivated land was needed to feed 20 people.  20 people are added to the world’s population about every second!  Clearly, that’s a problem.

Graham’s talk then focused on how plants can use the least amount of water for a fixed amount of carbon.  He began by introducing his classic work on stomatal regulation of transpiration relative to carbon assimilation, which shows the two processes are fundamentally linked.  Changing evaporation will always change assimilation.  He then considered how plants could arrange the temporal expenditure of water to maximize assimilation of CO2.  Carbon isotopes are particularly useful here for discriminating among transpiration efficiencies associated with different genotypes and can help identify future crop varieties that use water more efficiently.  In dry conditions,  greater transpiration efficiency improves crop yield and selects for low C isotope discrimination in leaf dry mater.

As we ran out of time, we were left with questions about how the process of balancing carbon and water demands might be influenced by life history strategy (perennial versus annual) and competition for water in soil.