Ecosystems and climate change

e e ects of climate change has had, and will continue to have, an impact on ecosystems and wildlife communities. Climate change a ects individual species and their interactions with other species. But why some communities are able to resist the e ects of climate change better than others remains unclear, but it may be bu ered by community diversity. Climate change can a ect whole communities by increasing the number of warm versus cold loving species and impact their interactions and resources. However, the processes that regulate the community level resources remain unclear. In a study carried out by researchers from the University of Helsinki, Finland, covering nearly all North American bird species over a y-year period, it was found that communities of birds with a higher species richness changed less radically in community composition following climate change.

e leading researcher Emma-Liina Marjakangas, explained that for example, if a community contained birds of prey, insectivores, and seed-eaters rather than birds from just one feeding guild, it was better safeguarded against the negative impacts of climate change.

Community-level diversity works as a bu er against negative climate change impacts, especially during winter, the season that has shown strongest climatic warming across the Northern Hemisphere. On the other hand, biodiversity played a smaller role during the breeding season. Indeed, earlier studies have shown that bird communities change faster during winter than summer, which explains this pattern.

Habitat and the availability of food determines a species’ exibility for changing its breeding and wintering areas. For example, grassland species have shi ed their distributions northwards slower than forest species, such as the American robin, or habitat generalists, such as the mourning dove, explained senior curator Aleksi Lehikoinen from the University of Helsinki. Diverse bird communities help maintain ecosystems via plant seed dispersal, pest insect control and even pollination of owering plants. Climate change reshu es the composition of these important bird communities and therefore threatens their ability to provide ecosystem services. eir results strengthen the understanding that biodiversity safeguards ecosystem functioning and that the biodiversity and climate crises need to be mitigated simultaneously to avoid multiplier e ects. e method used to measure the climate change response of bird communities was thermal variability. e variability over time in the ‘thermal niche’ of communities can be measured as a trend compared to the temperature preference of di erent species. Invariability in the average thermal niche indicates that species within the community are resisting temperature related changes. ermal variability used the community temperature index (CTI). e CTI is a method where rst the species temperature index (STI) is determined. is is the average temperature a species experiences across its range, or the temperature preference of a species. e STI can then be combined or weighted with the abundance of each species within a community. is can then be used to look at how communities are responding to climate changes. e STI of a species represents a long-term average temperature for a season and is a useful tool as climate change is a long-term pressure on ecosystems, not just a single occurring event. As well as birds this method of measurement is also a useful tool for measuring changes in sh and insect communities. e technique does have limitations, however, as it cannot take into account other pressures happening at the same time, in the same area such as habitat loss and disturbance. But it does nonetheless prove to be a useful tool for measuring the e ects of climate change within communities and strengthening our understanding around the importance of biodiversity within the pressures of climate change. e study is based on a community science database from 1966–2016 covering all of North America, and it was published in the international journal Scienti c Reports. https://www.helsinki. /en/news/climate-change/biodiversitysafeguards-bird-communities-under-changing-climate https://www.nature.com/articles/s41598-022-26248-1

IRISH

By Tim Clabon