EcoRubric 15:39 06 Jun 2024

Unique willow forest thrives in Ukraine's dried-up reservoir one year after Kakhovka Dam destruction

A year ago, after Russian forces blew up a dam in the occupied Kherson region, the emptied Kakhovka Reservoir was expected to become a dead desert contaminated with dangerous sediments. However, it has become a unique willow and poplar forest, the only one of its kind in Europe. If preserved, this forest could attract investment to Ukraine and positively affect the climate.

What's the problem?

On June 6, 2023, the Russian forces committed a terror attack by blowing up the Kakhovka Hydroelectric Power Plant (HPP) dam. The explosion led to the emptying of the reservoir, which held an amount of water equal to that of the Great Salt Lake in the US state of Utah. It also caused massive flooding in the surrounding areas, with about 16,000 people affected and around 80 towns flooded. 

The water covered agricultural fields, private homes, industrial enterprises, and infrastructure. Initial estimates of the losses amounted to about $2 billion. The dam's destruction led to an environmental catastrophe. At least four national nature parks, a biosphere reserve, and areas protected by the Ramsar and Bern Conventions were affected.

Immediately after the tragedy, experts made the worst predictions, one of which was that the bottom of the former Kakhovka Reservoir would turn into a desert. They talked of sandstorms and the spread of dangerous bottom sediments accumulated over the years. However, these predictions have yet to come true.

We spoke with Ukrainian scientists who participated in expeditions to the Kakhovka Reservoir to find out what happened at the site of the century's most enormous environmental catastrophe over the past year.

What's the solution?

Difficult and dangerous journey to bottom of reservoir

Research to access the environment in the southern Kherson region began even before the destruction of the Kakhovka dam. Following the liberation of the part of the region on the right bank of the Dnipro River after the nine-month-long Russian occupation, Ukrainian scientists were studying the war's effects on the landscape and other consequences until the Kakhovka catastrophe.

The first expedition to the reservoir was three weeks after the Russian destruction of the hydroelectric power plant. Researchers went to the de-occupied Kamianska Sich National Nature Park, located on the banks of the former Kakhovka Reservoir.

Наслідки підриву Каховської ГЕС

Environmental scientist Kateryna Polianska and other scientists in the Kamianska Sich National Nature Park, October 2023, near the former reservoir. Photo: NGO "Environment. People. Law"

"It was quite difficult to get to the territory of Kamianska Sich, but we managed, although it was quite dangerous," says Anna Kuzemko, doctor of science in biology who participated in the expeditions with her colleagues.

The trips were organized by Ivan Moisienko and Oleksandr Khodosovtsev, members of the Ukrainian Nature Conservation Group and professors at Kherson State University, as well as geobotanist and ecologist Yakiv Didukh, academician of Ukraine's National Academy of Sciences. Despite the importance and necessity of the research, the scientists had to spend much time obtaining permits and going through bureaucratic procedures, but eventually, the expeditions took place.

Skeptical fears did not materialize 

Anna told us that with each subsequent trip, there were fewer concerns about nature. All the pessimistic predictions that appeared after the catastrophe gradually faded away.

У якому стані Каховська ГЕС

Oleksandr Khodosovtsev, Doctor of Science in Biology, Professor of the Botany Department at Kherson State University, at the site of the former Kakhovka Reservoir three weeks after the dam explosion. Photo: Ivan Moisienko

"There were concerns that the silt accumulated at the bottom of the reservoir over the years contained many different chemicals, including dangerous ones, that they would dry up and be dispersed," Anna says. "But when we first went there, three weeks after the dam explosion, we saw that the soil was very dense and unlikely to be dispersed when dried. We still had concerns that invasive plant species, such as Robinia, commonly known as black locust, false indigo-bush, and boxelder maple, would start growing there. These concerns were finally dispelled when we went there in October last year and saw this young willow forest."

Anna Kuzemko told us that they only saw tiny sprouts in June 2023, and four months later, there were continuous thickets of willow trees up to two meters high. Some trees reached over three meters in height.

Наслідки підриву Каховської ГЕС

Kakhovka Reservoir in mid-April 2024 on the Kamianska Sich National Nature Park territory. Photo: Ivan Moisienko

Even then, the skeptical researchers couldn't have believed what would happen to the former Kakhovka Reservoir in just six months:

"They said the willow forest wouldn't survive the winter, that there would be no spring flooding, and it would dry up," says Anna. "[In the spring, — ed.] we returned and saw the willow forest on the left bank. We saw that the growth from last year was about 30%, and these willow thickets were in excellent condition, growing strong and dense! We also saw poplar thickets near the nearby island of Khortytsia. All the fears about dust storms, deserts, and invasive species have not come true so far."

Наслідки підриву Каховської ГЕС

Kakhovka Reservoir in late April 2024. Photo: Ivan Moisienko

Forest with no analogs anywhere in Europe

Based on field research, scientists created a map of the Kakhovka Reservoir's biotopes or habitats using remote sensing and machine learning, or artificial intelligence. As of November last year, about 40% of the former reservoir was covered with willows, poplars, and other floodplain vegetation, and this forest continues expanding. Researchers are now awaiting the results of another study, which will show in numbers how much the forest area has increased from October to May.

The young willow-poplar forest that covers the vast exposed area, predicted to become a desert, is unique for Ukraine. No similar forests can be found anywhere in Europe. According to Anna Kuzemko, such a floodplain forest was typical for this area before the reservoir was created.

У якому стані Каховська ГЕС

This is what the former Kakhovka Reservoir looks like a year after the catastrophe. The green sea is young willows, forming a unique forest. Photo: Ivan Moisienko

"Usually, these floodplain forests are very altered. They only form along watercourses because the surrounding area is either populated, plowed, or used for something else," the scientist explains. "Such large areas are truly unique. I think there is no other willow-poplar forest of this scale in Ukraine and Europe." 

The forest's growth rate is phenomenal. It's hard to imagine that just a year ago, this place was bare ground, and now, in May, there are trees almost five meters tall.

"Can you imagine? A willow that grew to 4.7 meters in less than a year! We compared this with other data and couldn't find any other place with such a growth rate," Professor Ivan Moisienko comments.

His colleague Yakiv Didukh, who studied the biomass of young willows and poplars, says that the willows in the Kakhovka Reservoir grow twice as fast as anywhere else. It can be explained by the fertility of the steppe soils in Ukraine's south and the large amount of nutrient-rich silt at the bottom of the former reservoir.

It's also important that the forest's conservation status rapidly increases as it grows. The site of the ecological disaster is now a home for a forming type of biotope that the Bern Convention protects.

"Over time, the value of these areas will only increase as the biotopes continue to form. Biodiversity will increase, and with it, the status of this area as part of the Emerald Network," Anna Kuzemko adds.

Of course, this will happen if nothing hinders the forest from forming.

Kakhovka willow forest can positively impact climate

The vast new forest will store carbon and accumulate harmful substances. All expedition members agree that the ecosystem services—benefits people derive from healthy nature—already provided by the young willow forest are superior to those offered by the artificial reservoir ecosystem. Thanks to the new willow-poplar forest, the climate in the region may improve even more.

"These willows, poplars, and other plants on the reservoir's bottom have already absorbed millions of tons of carbon dioxide — the main greenhouse gas that causes global warming," Ivan Moisienko explains. "I don't know if any other ecosystem in the world or Europe fights global warming more effectively. This definitely wasn't the case before when there was a reservoir. It was more like a hydro-desert."

Наслідки підриву Каховської ГЕС

Scientists on the bottom of the former Kakhovka Reservoir. Photo: NGO "Environment. People. Law"

"Before it disappeared, the reservoir absorbed water from the atmosphere. There's a theory that the climate might become more moderate now, and the number of droughts in the Kherson region will decrease," Anna Kuzemko supports her colleague's view.

"Speaking of the billion trees (Ukrainian President Zelensky's tree-planting program, — ed.), planted in unsuitable places like steppes and sands… Here, at the Kakhovka Reservoir, there might already be a billion trees. Maybe even more. And this doesn't require significant investments," says Kuzemko.

The benefit this area's ecosystem provides is hard to overestimate. Until recently, scientists only discussed the phenomenon, but now they have set a new goal—quantifying it. The spring expeditions in 2024 did just that.

Calculating clean air value, or how scientists use numbers to advocate for Kakhovka Forest

After the latest expedition, an online video showed four strong men trying together to uproot a several-meter-tall young willow in the young Kakhovka forest. It wasn't an act of vandalism but a necessary action for a scientific experiment.

Yakiv Didukh explained that the tree sample was needed for research to assess the role of willows and willow thickets, their impact on the climate, climatic indicators, soil formation, and how they consume carbon. The sample analysis allows scientists to make forecasts for 5, 10, or even 50 years ahead.

Such studies are crucial to explaining to economists, agrarians, hydrologists, and those who claim the reservoir's water-released territory the main point: that now and in the future, the former reservoir in its new natural state will be much more valuable than any infrastructure projects.

"Today, ecologists are trying to obtain quantitative arguments to show the greater significance of these forests than the role of water there and their impact on other needs," says Didukh. "Hydrologists, agrarians, and economists need numbers. To get these arguments, we are conducting such analyses today, making calculations, and soon publishing our data."

The team's research found that the ecosystem services of mature forests, if they form at least 30% of the reservoir area, will be 16 times greater than the benefits provided by the artificial reservoir.

With these ecosystem services, Ukrainians can get not only clean, improved environments, richer biodiversity, a better climate, and even a unique natural area but also money.

Ukrainians can receive substantial grants from global funds if they just leave reservoir nature untouched

Restoring vegetation and the natural riverbed of the Dnipro in the territory of the former Kakhovka Reservoir aligns with the European Green Deal, as other countries strive to return rivers to their normal, natural state.

The EU biodiversity program, "Bringing Nature Back into Our Lives," is a strategy for 2030, under which 25,000 kilometers of rivers are to be returned to their natural courses. This process involves the demolition of dams, so the plans to restore the reservoir contradict the European Green Deal — the Ukrainian hydropower generating company Ukrhydroenergo started discussing the reconstruction a month after the Kakhovka catastrophe. Considering the pace of reservoir restoration, the new project would negate all the benefits the new territories could provide us if left untouched.

The "untouched" option could attract investments to Ukraine. Global funds are ready to pay landowners for restoration. The owners themselves do not need to do anything—just leave the land alone and let nature take its course.

It seems there couldn't be a better solution for the Kakhovka Reservoir. For this beneficial scenario to happen, Ukraine needs to meet a few conditions. First, the war must end, as hostilities are almost the only factor keeping these territories somewhat suspended. Second, global funds need guarantees that a new hydroelectric power station, which Ukrhydroenergo dreams of, will not be built in this location.

"If these guarantees are provided, I think we could get this funding for nature restoration and receive it for many years. But both the first and second conditions are challenging tasks," Moisienko concludes.

Meanwhile, we can only follow the expeditions, await new research results, and observe how the Great Meadow, which existed in the area before the Kakhovka Reservoir, is reviving in the aftermath of the ecological catastrophe.


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