GERMANY - Land use change is a greater threat to river biodiversity than any other human impact, even climate change, according to new research from the Senckenberg Research Institute and Natural History Museum.
For the study, scientists modelled the effects of land use changes on the species diversity in rivers and stream, showing that the loss of biodiversity is caused to a significantly higher degree by changes in land use practices than by climate change.
In consequence, conservation concepts for this valuable ecosystem and the organisms that live in flowing water should be adapted accordingly.
Although they only cover a small percentage of the land area, in their natural state these ecosystems are home to a multitude of living organisms.
“At the same time, however, rivers and streams are the most endangered ecosystems on a global scale,” said Dr Mathias Kuemmerlen from the Department of Freshwater Ecology and Nature Conservation Research at Senckenberg.
“Rivers and streams are more sensitive to environmental changes than any other biotope.”
Together with colleagues from China and Germany, Dr Kuemmerlen studied the rivers and streams in a catchment area of approximately 1,700 square kilometres in Southern China, which is part of the drainage basin of the Yangtze River.
“For the first time, we modelled a future projection of the species diversity in connection with land use changes,” explained Dr Sonja Jähnig, who conducts research at the Leibniz Institute for Freshwater Ecology and Inland Fisheries in Berlin and who initiated this study.
“The loss of biodiversity is often studied in relation to climate change.
"Other important anthropogenic impacts on the environment, such as changing land use practices, are frequently neglected in this context.”
The team of scientists modelled three scenarios for the development of freshwater-dwelling macroinvertebrates for the years from 2021 until 2050: climate change, change in land use, and a combined climate change and land use change scenario.
“Our results will help us to better understand future changes in the invertebrate communities,” according to Dr Jähnig.
The 72 aquatic organisms that were studied display a wide range of different behaviours in the models.
“In all of our models, there are ‘losers’ and ‘winners’, both in the land use and climate change scenarios.
"However, across all species, it can be said that the changes in land use have the strongest negative effect on the species diversity in rivers and streams, in this model, the local biodiversity decreased by 20 per cent,” explained Dr Kuemmerlen.
“There is a close interaction between flowing water and the landscapes in the drainage basin. Therefore, the species diversity is strongly affected by land use practices.”
In addition, the modelling results show that the combined effect of changes in land use and climate may lead to a general decrease in local species diversity. Moreover, a shift in the distributions of many aquatic invertebrates can be expected.
Although changing land use practices, such as the clearing of forests for agricultural use, represent the most obvious change within an ecosystem, according to Kuemmerlen this factor is frequently neglected in the development of conservation concepts.
“In order to preserve the species diversity, we must consider both changes in climate as well as in land use,” he summarised.
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