.jpg)
Spring is starting earlier and earlier. Is that a problem?
Spring in the Netherlands starts three weeks earlier than it did 100 years ago, according to KNMI. How does this affect nature? And what will the Dutch landscape look like in, say, 100 years? “The question remains whether animals and plants can keep up with the speed of a changing climate.”
.jpg)
In late January, blackthorns were already blooming in Frankendael Park in East Amsterdam. In early February, crocuses were also in bloom, as were yellow dogwood, wild daffodil, speck weed, and summer bells.
Nature wakes up earlier and earlier, but UvA biologist Gerard Oostermeijer can’t recall it ever being as early as this year. “It is true, however, that in the city spring starts even earlier than in the countryside because it is a few degrees warmer and the species are not all wild.”
Evolution
What impact does this early budding have on nature? In the news, the mismatch between flowering plants and insects that come into action later in the season is often discussed. This year too, Oostermeijer—apart from a stray winter butterfly and an occasional chilled-out bumblebee queen—has yet to see insects in action. But the mismatch story is more nuanced, according to the biologist, who researches endangered and invasive species.
“Plants do not simply die out when pollination does not take place. Most plants like the daffodil bloom year in, year out and it only takes one successful pollination to reproduce. For plants that only flower once, nature has found all kinds of ways for plants to get around this through evolution, by building a seed bank in the soil or by self-pollinating. Plus, the relationship between plant and insect is constantly changing through evolution, but you seldom read about this in the media or scientific literature.”
Migration pattern of the bar-tailed godwit
Animals are also reacting to the warm temperatures. Blue herons are already nesting and storks are also busy, Oostermeijer reports from his visit to Frankendael on Tuesday morning. “I even thought I saw collared parakeets busy at nest cavities.” Warm temperatures are also causing the toad to wake up earlier from its hibernation. A few degrees rise in temperature causes toads to breathe faster, consume more energy, and lose weight, a recent European study in pre-print shows.
An increasingly earlier spring due to climate change may also make species disappear. UvA ecologist Eldar Rakhimberdiev investigated this for two subspecies of the ruddy godwit, the Limosa lapponica taymyrensis and the Limosa lapponica yamalensis, which he tracked using transmitters.
“Spring in the Arctic is only brief,” says Rakhimberdiev, “which is why the red-tailed godwit arrives a few days before the snow melts to lay its eggs. When they hatch, insects are abundant. Not long after that, summer comes and nature turns into a dry plain.”
Right now the two populations still breed at two different breeding sites in the Arctic, because the ice there melts at a different time, but that is about to change. Rakhimberdiev saw that change with his own eyes in the Arctic. When he visited the Taimyr Peninsula, the breeding grounds of the black-tailed godwit Limosa lapponica taymyrensis every year as a student at the turn of the century, the snow there melted in late June. Meanwhile, the snow melts as early as May. “At about two degrees per year, the Arctic is warming much faster than the rest of the world, a phenomenon we call Arctic amplification.”
That melting process is not occurring at the same rate throughout the Arctic. Both breeding areas are expected to be snow-free simultaneously by 2030, with the result that the migration pattern of the two godwit populations will synchronize and they will encounter each other more often. Says Rakhimberdiev: “The subspecies will probably disappear. This applies not only to the black-tailed godwit but also to many other animals. Climate change may thus lead in the long run to a homogenization of animal species. And that is worrisome because it comes at the expense of biodiversity.”
Southern France
If the Netherlands has a Mediterranean climate in, say a hundred years, animal and plant species from southern France will flourish here, although the question remains as to how those species will get here. Oostermeijer explains: “We have created a landscape with highways, railroads, and canals. This has fragmented the habitat of animals and plants, making it difficult for them to move around. Tunnels and natural bridges can help, but the question remains whether species can keep up with the speed of climate change.”
For that reason, UvA biogeographer Kenneth Rijsdijk advocates bringing back the natural landscape. “The landscape in the Netherlands has been increasingly altered in the interest of higher crop yields with hedges, rows of trees, and old orchards. The landscape that has been created is ill-suited to handling climatic extremes; it warms up faster and is less able to retain water. This increases the risk of drought and flooding.”
Climate change will also cause sea levels to rise. Salty seawater will then push up the groundwater and mix with the top layer of fresh water. Rijsdijk adds: “This will make the groundwater saline and we will no longer be able to grow certain crops. Crops will then have to be made salt-resistant. Research into this is already underway.”
Hedges of braided cactus
The more common animal and plant species will probably fare better in such a future than rarer ones, Oostermeijer expects. “And that, in turn, will be at the expense of biodiversity and the robustness of the ecosystem.” In forestry, people are already planting trees from central France in the Netherlands. This is not yet the case with wild plants, although that discussion is ongoing. Oostermeijer adds: “I think it would be a good idea to introduce plants from France here, first as an experiment.”
Introducing climate-resistant species also seems like a good idea to Rijsdijk. Next week he already has an appointment with someone who works on the Caribbean islands with hedges of braided cacti, in case our current hedges can no longer withstand the climate. “So in that respect, we can still move forward.”
