Ability of plants to escape from climate change is lower than expected

Date: 8 November 2017

Introduction: According to an international consortium of natural scientists, we currently overestimate the ability of plants to avoid climate change effects by moving Northward.

As ecosystem productivity is higher in warm climates compared to more northerly ecosystems, climate warming is often expected to increase the plant productivity in the latter. In a recent study in Nature Ecology and Evolution, an international consortium of natural scientists including UAntwerp researcher Ivan Janssens (Global Change Ecology Centre of Excellence (GCE), Plants and Ecosystems research group) now challenge that hypothesis, and show that there is a mismatch between the velocity of temperature increase on the one hand, and productivity increase on the other.

Ivan Janssens: “Our observation casts a whole new light on the ability of vegetation to cope with climate change. As ecosystems warm up, plants are confronted with circumstances that are not ideally suited for their growth. Traditionally, it is assumed that vegetation can move North when confronted with warming conditions, where they would still encounter their ideal temperature niche. Our study now shows that reality is far less straightforward. There was an increase in productivity in Northern regions, but nearly not as high as expected from the temperature increase.”

This has far-reaching implications: it means we currently overestimate the ability of plants to avoid climate change effects by moving Northward. And we also overestimate the amount of carbon that will be sequestered by Northern vegetation in the future, as we overestimate productivity.

But what causes this mismatch between temperature increase and vegetation productivity? Another recent study in AoB Plants shows that poor seedling establishment in northern ecosystems might be the key. Ann Milbau (Research Institute for Nature and Forest, INBO) and GCE-scientists Ivan Nijs, Nicolas Vandeplas and Fred Kockelbergh performed an experiment where they investigated whether germination and seedling survival increased with warming, in species common to subarctic regions, such as European goldenrod and European blueberry.

European goldenrod (Photo: Ivar Leidus)

Ann Milbau and Ivan Nijs: “The colder the climate, the lower the recruitment rate from seeds becomes. We asked ourselves whether this recruitment could increase with climate warming. This is necessary for species to be able to follow their climatic niche. We however observed that there was no general positive response of seedling establishment to neither warming nor fertilization in Northern ecosystems.  Predictions of future species distributions in arctic regions solely based on abiotic factors, such as temperature, may therefore overestimate species’ ranges due to their poor establishment.”

The latter observation also provides an explanation for the observed mismatch between temperature and productivity increase in the earlier study. The combined studies show that there are currently unknown factors at work that prevent species from easily following their temperature preference Northward. The increase in temperature, and associated higher availability of nutrients, is not able to trigger the increasing seedling establishment that is needed.

Arctic soils were artificially heated in the experiments.