Ellen Cieraad's Research

Quantative plant ecology & physiology

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Mountain ecosystems are vulnerable to effects of climate change

Some of the biggest effects of climate warming are being observed in the polar regions; but the climate in mountainous regions are also rapidly changing. For example, the rate at which climate change is happening in the European Alps, is more than double that of the average across the Northern Hemisphere.


Treeline at Craigieburn, New Zealand

Plants are moving pole-ward and uphill trying to keep up with the climate they thrive in. Clear examples of this are treelines that are advancing uphill (but that doesn’t happen everywhere). We know that plants adapted to cold climates are being driven out of their natural ranges – and in the mountainous areas they might run out of space! However, beyond observing changes in the distributions of species, we still have a very poor understanding of the processes that accompany the climatic changes occurring in mountainous areas.

Sweden-based Dr. Jordan Mayor and David Wardle (SLU in Uppsala), organised and set up a study with an international research team, including myself, to investigate whether, at a global scale, we see universal shifts in ecosystem properties across elevational gradients. Our paper was published in Nature this week.

Mayor J, et al. Elevation alters ecosystem properties across temperate treelines globally – Nature, 25 Jan 2017 nature.com/articles/doi:10.1038/nature21027


Treelines in the different study regions (Photos J Mayor – Mayor et al. 2017 Extended data Fig 1)

The long-term and broad-scale changes that are instigated by climate change are hard to study using experiments. So instead, we used elevation as a surrogate for climate warming. This is possible because, as a consequence of warming, in 80 years from now, any particular elevation is expected to experience the temperature that is currently found 300 meters lower. Studying the properties of vegetation and soil along elevational transects near the treelines in seven regions (including the European Alps, Hokkaido Japan, Rocky Mountains USA-Canada, Patagonia, New Zealand, and Australia) allowed us to predict the effects of warming across temperate mountain regions world wide.


Treelines in the different study regions (Photos J Mayor – Mayor et al 2017 Extended data Fig 1)


We found remarkably consistent patterns across these extremely varied mountain regions. Decreasing elevation (increasing temperature) consistently increased the availability of soil nitrogen for plant growth – so we can expect that warming will consistently improve plant nitrogen nutrition. However, plant phosphorus availability was not controlled by elevation (and thus temperature) in the same way. This resulted in a pattern where the balance of nitrogen-to-phosphorus in plant leaves was very similar across the seven regions at higher elevations, but diverged greatly across the regions at lower elevation. This means the nitrogen-to-phosphorus ratio is constrained by low temperatures but at higher temperatures, regional factors and differences between regions become more important.

We also found that with increasing temperature, the patterns in plant nutrition were paralleled by changes in the amount and quality of organic matter in the soil and the microbial community. Our study allowed us to untangle the effects of vegetation type (forest below treeline, and alpine above it) on these patterns, and we found that the changes were at least partly independent of any effect of the vegetation. This means that effects of warming on ecosystem properties will occur irrespective of whether treeline shifts up-slope.

Our results not only suggest that warming could affect the way that plants grow, but also that these changes are linked to effects of warming on soils, especially the cycling of key nutrients that sustain the growth of plants. It provides evidence that expected temperature changes over the next 80 years have the potential to greatly disrupt the functional properties of mountain ecosystems and result in increased disequilibrium in the above- and below-ground ecosystem components, and the links between them.

The changes in mountain ecosystem processes identified in this study may have important implications for which plants grow in mountain ecosystems (affecting biodiversity), and the potential upward shift of treelines. Such shifts are expected have an effect on the local climate itself, and may indeed speed up the warming process, as forests reflect less and retain more heat than lower, less green vegetation.

We used elevational gradients to predict what will happen in mountainous ecosystems as the climate warms – this is a powerful approach to understanding the processes that are occurring at an increasing pace in these areas. However such changes are also likely to occur in lower lying areas. Much remains unknown about how human-driven climate change will affect the Earth in the long-term and over larger spatial scales.


This article in the news: 

Vermont university  How climate change threatens mountaintops (and clean water)
Also reported in EurekAlert – global source Science News Environmental News Network 

Manchester university Study reveals that climate change could dramatically alter fragile mountain habitats. Related content also reported by Phys.org , Reddit.com , New Zealand Ministry of Foreign Affairs , EurekAlert

AlphaGalileo Rise in temperature impacts mountain ecosystem

Leidsch Dagblad (in Dutch) Klimaatverandering verandert boomgrens newspaper clip

De kennis van nu (in Dutch) Wie over 80 jaar nog wil skiën heeft een probleem

Leiden university (in Dutch) Temperatuurstijging tast ecosysteem bergen aan

My news desk (in Swedish) Varmare klimat kan få stor inverkan på bergsekosystem jorden runt

Umea university (in Swedish) Ett varmare klimat kan påverka alpina ekosystem över hela världen

Science at APA (in German) Klimawandel bringt weltweit massive Änderungen für Bergpflanzen

Nature Asia (in Japanese)


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Double whammy caused by climate change

Invasive species can have detrimental effects on ecosystem services, including food security and indigenous biodiversity. Similarly, climate change has been predicted to affect global food provision and the stability of ecosystems. Many studies assess the direct effect of either of these issues facing today’s world; however, of course they operate in tandem and this can create complex effects. While it is well established that climate change may facilitate the abundance and/or range expansion of invasive species, it is less known that it may also impact the ability to control and manage this invasion. If, for example, climate change results in the increase in abundance of an invertebrate crop pest, and at the same time in a decrease of a natural pest control agent (for example, insectivorous birds), then climate change can accelerate the impacts of invasions, and create a ‘double whammy’ for the receiving ecosystem. Similarly climate change may alter the effectiveness of ways to control invasive species.

(c) wikipedia

(c) wikipedia

In a recent article, we show that increasing air temperatures over >60 years in New Zealand has reduced the window of opportunity to effectively control an invasive mammalian pest (European rabbit Oryctolagus cuniculus – using Central Otago, South Island, as an example).

Latham ADM, Latham MC, Cieraad E, Tompkins DM, Warburton B 2015. Climate change turns up the heat on vertebrate pest control. Biological Invasions 17(10): 2821-2829. doi: 10.1007/s10530-015-0931-2

Anthropogenic control of invasive vertebrate species is most effective in times when natural food is limiting. In the case of rabbits in temperate southern New Zealand, the most effective period of control is during the coldest period in winter, when temperatures are sustained below approximately 5°C and the above-ground palatable vegetation available to rabbits reaches an annual low. Our study found that the milder winters in recent years resulted in the window of control starting later and ending earlier in the year, and that those windows are increasingly punctuated by warm temperatures. Overall this has resulted in suboptimal conditions for poisoning because of the higher availability of natural foods.

While longitudinal records detailing the effectiveness of control operations are not available, this study suggests that the trend towards warmer winters over the past >60 years has significantly reduced the window of time for effective control of rabbits in temperate New Zealand. As winters are likely to continue to warm, alternative methods of management warrant investigation.

Climate change may thus exacerbate the unwanted impacts of invasive species by reducing our ability to manage them effectively.