Environment

Biodiversity the heart of ecosystems

With human activity threatening large numbers of animal and plant species with extinction, natural and social scientists have joined forces in the EU-funded ALARM project to look for global solutions.

Flies act as nature’s pollinators. Here on a fennel flower (Foeniculum vulgare). ©Josef Settele/UFZ. Flies act as nature’s pollinators. Here on a fennel flower (Foeniculum vulgare). ©Josef Settele/UFZ.
Global warming is leading species to adapt to new environments. Here palm trees starting to grow spontaneously in the Alpine foothills. © Walther, Gritti, Berger, Hickler, Tang, Sykes Global warming is leading species to adapt to new environments. Here palm trees starting to grow spontaneously in the Alpine foothills.
© Walther, Gritti, Berger, Hickler, Tang, Sykes
The widespread Nymphalis butterfly can be an excellent biodiversity indicator. ©Josef Settele/UFZ The widespread Nymphalis butterfly can be an excellent biodiversity indicator.
©Josef Settele/UFZ
Episyrphus balteatus Episyrphus balteatus
©Frank Dziock/TU Berlin
Eucera nigrescens Eucera nigrescens
©Nico Vereecken

You can find them in the heatstricken olive groves on the Greek island of Lesbos, in the giant geometrical maizefields of Veneto and in the pine forests of Tartu in Estonia. For the past three years scientists taking part in Europe’s largest ever research programme into biodiversity have criss-crossed Europe, capturing, classifying and mapping flora and fauna. With a € 24 million budget and a five-year timeframe, the ALARM (Assessing LArge-scale environmental Risks for biodiversity with tested Methods) project brings together 250 scientists from 68 institutions in 35 European countries, joined by teams from other continents.

A multi-faceted programme

The size of the project reflects the complexity of the research subject. Biodiversity is today a mainstream topic. But it remains a difficult concept to grasp, not lending itself to precise quantification.

Nature’s diversity can be measured on various scales. Species is the best-known of these. For most of us, biodiversity equates with the “number of different species in existence”. However, genetic diversity can vary greatly within a single species: from practically zero in a group of poplars originating from a single clone to very large in an untended South European oak forest.

Moving up a step we are confronted with ecosystem diversity, that is the ability of practically identical animal and vegetable species to interact and organise themselves in different combinations. At this level, biodiversity becomes difficult to study globally, simply because plants, birds, insects and bacteria each call for different skills and tools.

However, ALARM’s objective is not to map biodiversity in minute detail, but to grasp the extent of its decline and, above all, pinpoint the causes. We all know that responsibility for the degradation of nature lies with the human race, but we still need to clarify how humans act in different situations.

The variety of human impacts

Scientists have identified the main mechanisms behind this imbalance. The ALARM teams are focusing on four main research topics: global warming that makes habitats increasingly inhospitable for certain occupants; man-made environmental pollution (pesticides, heavy metals, fertilisers); a proliferation of invasive species, i.e. imported animals or plants multiplying at the expense of local species; and changes in land use (grubbing of hedges, reforestation of open spaces, concreting over of agricultural land, more and more roads and impediments to the movement of animals, etc). But which of these causes are the most damaging? How do they interact? What are the major risk factors for biodiversity? What practical conclusions can we draw from them?

To answer these questions and establish both general and local trends, the ALARM partners have built a network of experimental sites.

Cooperation between “hard” and “soft” sciences

This network covers the whole of Europe. Each site consists of two neighbouring plots. One is in a relatively good state of conservation; the other has undergone major change through human activity. “We have tried to bring together researchers from the natural and social sciences,” says project coordinator Josef Settele from the Helmholtz Centre for Environmental Research in Leipzig and Halle, Germany. “One team studies the socio-economic context of each human impact, using scenarios to try and predict the future.” The ultimate objective is to come up with a risk assessment toolkit for decisionmakers and to benefit from practical recommendations for slowing the decline of European biodiversity.

At mid-term, the project still has a lot of ground to cover. Researchers are continuing their experiments. Some are planting trees outside normal climatic conditions to anticipate their resistance to future warming. Others are combing their plots for little exotic plants of any species, tell-tale signs of an impending invasion. Sometimes, a particular invader is tracked down, like the dreaded Cameraria ohridella, a tiny moth which for the last twenty years has been relentlessly ravaging European chestnut trees, turning their leaves brown from July onwards. At the same time, social scientists are using studies and questionnaires in an attempt to define the external factors influencing their sites: advances in agriculture, housing expansion, leisure pursuits, environmental protection, etc.

Initial publications

ALARM researchers can already proudly point to a number of publications in leading journals. The pollination group made the front page of Science in July 2006 with an article quantifying the decline in wild pollinators in the United Kingdom and the Netherlands. “Of course, a decline in these two countries with their intensive agriculture – though not the only such countries in Europe – does not mean a widespread decline across the continent,” states William Kunin from Leeds University, one of the article’s authors. “Nevertheless it is the first time measurements have been taken on a national level and the decline, especially in wild bees, is significant. We also noted a decline in wild plants which are very dependent on particular insects for pollination. But we don’t as yet know which of the two declines has caused the other.”

Strangely, another family of pollinating insects included in the study – the hoverfly – shows much lower rates of decline than the bee. Work here is still in progress. “If we could identify territorial constellations that are more favourable to pollinators than others, that would be a very valuable data item from which to draw recommendations,” Josef Settele tells us.

Halting the decline in biodiversity is clearly beyond the power of scientists, but we do expect them to provide us with tools to aid decision-making. Our consumption, travel, agricultural and residential patterns are all at stake here. The cards are in the hands of responsible politicians and informed citizens.

Yves Sciama

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The extinction stakes

What difference does it make if a butterfly or beetle species becomes extinct, we hear asked again and again. And indeed, the disappearance of a single species is not dramatic, even if an irreversible loss of a part of our planet’s heritage. But when a second, third or more species becomes extinct, ecosystem stability is threatened. Specialists confirm that the more species there are and the more varied and redundant the interactions between them, the more natural resistance there is to any upheaval.

A high level of biodiversity therefore offers (relative) protection against the collapse or decay of ecosystems through which nature provides a wide range of services like crop pollination, waste disposal, soil maintenance, water filtering and carbon storage, as well as valuable compounds for pharmaceuticals and other industries.



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