Whilst making people aware of the consequences of climate change and land fragmentation is important, choosing how to deliver that message is equally important (Image Credit: Backbone Campaign, CC BY 2.0, Image Cropped)
Tag Archives: climate
Are polar bear habitat resource selection functions developed from 1985-1995 data still useful? (2019) Durner et. al, Ecology and Evolution, https://doi.org/10.1002/ece3.5401
Ecologists often attempt to predict where species are using the spread of the resources that the species depends upon. This is done because often it’s simply easier to monitor the resources than the species. Resource selection functions (RSFs) are a tool which use the likelihood of a resource being used to predict a species distribution. However, if the landscape the resource is found in changes drastically, a resource selection function may start to be less useful.
In the early 2000s, using data collected in the 80s and 90s, US scientists developed RSFs for polar bears, a species which has regrettably become the poster child for the survival of the Arctic ecosystem. Even back then, the bears’ preferred habitat was receding. Now, with human-driven climate change severely reducing sea ice and markedly altering the bears’ habitat, this week’s authors wanted to know how well those RSFs work nowadays.
When we think of global warming, we tend to be a bit selfish and think of how it affects us in our daily lives, but the warming temperatures on our planet have the potential to affect the base of all of our food webs, plants (Image Credit: Matt Lavin, CC BY-SA 2.0).
Phenology in a warming world: differences between native and non-native plant species (2019) Zettlemoyer et al., Ecology Letters, https://dx.doi.org/10.1111/ele.13290
The timing of life-history events (such as births, growing seasons, or reproductive period) is called “phenology”, and this aspect of an organism’s life is particularly sensitive to climate change. So much so that changes in the phenology of certain processes are often used as an indicator of climate change and how it affects a given organism.
We’ve talked about the effects of rising temperatures in animals here on Ecology for the Masses, but there is a lot of evidence in the scientific literature for climate change causing a multitude of different changes in the phenology of various plants. Not only does the direction of the change differ (some organisms experience delays in certain events, others have earlier starts), but the size, or magnitude, of the change also differs. The authors of today’s study wanted to examine these changes in the context of an invasive plant species and how it may be able to outcompete a native plant.
Contrasting consequences of climate change for migratory geese: Predation, density dependence and carryover effects offset benefits of high-arctic warming (2019) Layton-Matthews et al., Global Change Biology, DOI: 10.1111/gcb.14773
Most of us know that climate change will bring warmer, shorter winters to most parts of the world. For many species in areas like the Arctic, it would be easy to interpret this as a good thing – plants grow earlier, so animals get more food, right? Naturally it’s never that simple. Many herbivorous species have evolved in sync with climate cycles so that their reproduction peaks when food becomes available. If season start dates change, these species may not be able to change their own cycles in time. Additionally, what happens if populations of their predators suddenly boom?
Today’s authors wanted to know what role a warming climate played in the population fluctuations of migratory barnacle geese (Branta leucopsis).
What They Did
The population of barnacle geese studied have their breeding grounds on Svalbard, an island north of mainland Norway that lies deep in the Arctic circle. The geese migrate here from the south (Scotland) every year, hatching around the start of July. Data on bird clutch size and success hatching data was used to determine reproductive success of the geese, whilst mark-recapture data was used to determine their survival chances at different life stages. Data was collected over the last three decades, with over three thousand nests and five thousand individuals monitored in this time.
Survival data was compared to climate data like date of spring onset, average temperature and variation in rainfall, which attempted to capture the likely amount of food the herbivorous geese had access to. Estimates of Arctic fox (Vulpus lagopus) predation at their breeding grounds in Svalbard were also used to see how predator populations affected the geese.
What They Found
Whilst egg production for the geese increased, it was offset by increasing mortality among young geese. This was likely driven by an increase in Arctic fox numbers. Any benefits that increased populations may have had also may have been countered by density-dependent effects during winter in Scotland – when populations increase resources dry up and reproduction rates suffer.
Did You Know: Mark-Capture Data
The survival of every individual in a population is almost always impossible to determine. Ecologists have adapted, and mark-recapture models have become one of the more popular ways to determine the chance of an individual having survived over a time period. It simply involves marking a series of captured individuals of a population, and seeing how many of them were recaptured after a given time. It may sound like a stab in the dark, but modern statistics has made it possible to obtain quite accurate survival data using this technique.
Whilst the researchers did have climate data for the wintering and spring stopover grounds for the geese, the data which came from Svalbard was much more detailed. whilst the results here are quite in-depth, it still remains that there’s a large chunk of very relevant data missing. Getting similar data from spring and winter grounds would naturally make the results more informative, but it would also take an enormous amount of time and resources.
More resources doesn’t just mean more geese. Areas like Svalbard have fairly simple food webs, with relatively few predator and prey species. But the interactions between these species can still be complex. More reindeer carcasses (another result of climate change, read more about it here) mean more foxes, which means more predation on geese. Less ice also means more polar bears getting stranded on Svalbard, many of which have started preying on goose eggs.
Results like these give much needed insight into how food webs will morph as temperatures increase. If we can develop models for simple ecosystems that are being affected more strongly than others now, it means we can create complex models when climate change starts hitting other regions harder.
Last week, my colleague Stefan Vriend had published an article explaining the concept of the Anthropocene – the proposed name for the epoch that started when humans had a noticable impact on the earth’s geology. Two days beforehand, an article appeared in the Atlantic proclaiming that the Anthropocene was a joke. The basic tenet of the article was that because our impact on the planet has taken place over such a short period of time, the fact that we’ve seen fit to name a new geological epoch (the Anthropocene) after the short timespan that we’ve been wreaking havoc on the planet is incredibly self-centred and arrogant.
Image Credit: Chiltepinster, CC BY-SA 3.0, Image Cropped