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Local vegetation can point to the consequences of climate change, Israeli scientists say after extensive studies

A recent study by a team of researchers from Bar Ilan University suggests that endangered plants in water-saturated habitats can be taken as indicators for climate change in the Levant region. They present a picture particularly of the consequences of changes in precipitation.

“Israel is prepared to serve as a regional laboratory and centre of excellence to prepare for, and adapt to, changing climatic conditions,” Israel’s minister for environmental protection Gilad Erdan speaking at the UN Climate Change summit in New York late September, hailed his county’s expertise in preventing and combating desertification.

And, indeed, Israeli scientists on the ground are already trying to identify manifestations of climate change. Local vegetation, some of them say, reflects the changing weather patterns and might help in determining further consequences.

Nevertheless, these very recent studies mostly testify for the largely unexplored field of climate change and its various local implications. Accordingly, the effects of shifts in rainfall regimes – a critical aspect in this part of the world – turn out to be a bone of contention among Israeli botanists.

An earlier study led by archeologist Prof. Naama Goren-Inbar of Hebrew University in Jerusalem found the last known traces of ten plant species dating back to 780,000 years – all at a single site north of the Sea of Galilee. The species are now globally extinct.

Narcissus in Tel Aviv. Photo by Ido Liven

Their disappearance was attributed to ancient climate changes. Prof. Mordechai Kislev and fellow researchers Dr. Yoel Melamed, Dr. Orit Simchoni and Dr. Ehud Weiss decided to check whether contemporary Israeli flora is undergoing similar processes.

Their study tracked five endangered wetlands plant species – the most dryness sensitive of all plants in Israel, according to Kislev – over the past few decades, and found that their numbers are gradually declining. The reason, they believe, is a decrease in effective precipitation.

Sprouting evidence of waning plant cover and growing aridity – namely, increasing temperatures, decreasing air humidity and decreasing precipitation – have been recorded by the concerned scientists. A study by Dr. Joseph Sapir supports the correlation between the two, and adds overgrazing as a possible factor. His study highlights the contribution of a man-made forest on the desert edge to curbing desertification processes and their impacts on the surrounding natural vegetation.

Stretching over 30 square kilometers, his test case of the Yatir Forest between the Judean Desert and the Negev was planted in the 1960s by the Jewish National Fund (KKL). The findings showed that forestation reduced the productivity of all biomass at the site by 80 percent, thus dramatically depleting the forest’s flora.

However, not only does the forest function as an important carbon sink, says Sapir – who worked for the organization for 18 years until recently – KKL is “pushing the desert away by ‘savannization'”. In this process, the arid lands are gradually blanketed with herbaceous vegetation, “which will later be covered by the evolving forest,” he explains.

Examining aerial photographs, interviewing local shepherds and conducting field surveys, the study shows that in areas distant from the forest, average weighted plant cover dropped from 5 percent in 1945 to 0.1 percent in 2001 – as opposed to areas in the vicinity of the forest.

Sapir is confident this drastic decline has its implications. “This particular research wishes to demonstrate that not only that climate is changing,” he says, “but also, that the vegetation is gradually disappearing, pasture will diminish, there will be less cattle and people will suffer more famine.”

But conclusions of this kind are also subject to criticism. “It’s simply a fundamental mistake to think that what happened is what will happen,” says Dr. Marcelo Sternberg of Tel Aviv University. “The conditions 50 years ago are utterly not today’s conditions.”

The Bar Ilan University researchers admit that the scientific instrument they offer has its shortcomings and will require further study to base its validity. “We decided not to make conclusions, and instead to do with a suggestion for an instrument,” says Kislev. The main intention is to propose the idea, he says. Later, other species – such as beetles, crabs and other hydrophilic organisms – can be examined.

Yet Kislev is confident that the endangered wetlands plants can provide important information that cannot be retrieved using only meteorological data. The evidence of changing precipitation patterns shown by employing this method, he says, can help in structuring water management policies.

Altering precipitation regimes, adds Prof. Jaime Kigel of The Hebrew University of Jerusalem, will necessarily have direct implications for agriculture as well as in other fields. In turn, these could ultimately result in “less flowers, less bees, less honey”, as well as less grass for cattle and generally drier landscapes. All of these consequences, says Kigel, might lead to a push for more import and substantially different development planning.

However, herbaceous plants tend to prove stable, according to the ongoing study Kigel and Sternberg are part of. “You can see quite significant differences in the biomass created – as much as ten times between years – but you don’t see such changes in the species composition,” says Kigel. “This indicates the resilience of the vegetation in relation to possible changes in climatic conditions”.

As part of the German-funded GLOWA (Globaler Wandel des Wasserkreislaufs) project, which addresses water management aspects in climate change, a study conducted by an Israeli-German group of researchers aims at portraying a variety of possible impacts of climate change on Israeli flora.

Unlike the two other studies which track plants’ responses to climate change over time based on observations, in this case researchers actively increase and decrease the amount of water the plants receive in field conditions.

Even though the GLOWA project is the largest of its kind in the eastern Mediterranean region, financial constraints limit the research to studying the single parameter of water quantities out of numerous other climatic factors that might be as important.

The manipulations carried out by the researchers reflect climate change models for the region which project either increase or decrease of 30 percent of precipitation amounts. But after seven years of research, says Sternberg, “we see that the Mediterranean (eco-)systems in the semi-arid areas are relatively durable to the manipulations we perform, which are in the range of the expected climate change in our region.”

These findings came as a surprise for the researchers who have so far found these ecosystems to be more stabile than they had first assumed. The climate change scenarios for precipitation on which they based their initial assumptions have eventually proved to be within the natural variability for these ecosystems. “On a global scale,” says Sternberg, “the places where the climatic conditions are more stable are the most vulnerable ones”.

Nonetheless, he stresses, changes can take place beyond the ten-year timeframe for their research. Therefore, the very distinct role of long-term climate change, with its numerous different factors, in the shifts the Israeli flora is undergoing is still largely an enigma to local botanists.

“This is the importance of long-term climate studies,” says Sternberg. “There is still no national plan for climate change research in Israel” – any plan that could stand up for the declarations of the environmental protection minister.

Ido Liven is a journalist whose work has appeared in a variety of publications – both in print and online – in Israel, Germany, Canada, Austria, Switzerland and more. His web site is

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