Summer is already upon us, bringing heat waves and dry desert winds. Though some nights are still cool, the temperature of the sea is still relatively low, and the suffocating humidity that accompanies the blazing temperatures of midsummer has yet to arrive, the relentless sun and the parched soil radiating their warmth upon us tell us that summer is definitely here.
This past winter was the driest one since climatic conditions were first measured in most parts of the land of Israel. Until the start of May, there were only about 270 mm. of rainfall -- less than half the multi-year average temperature. Other than the serious downpours that fell in December (while snowstorms raged in the hills in the north and centre of the country), the only instances of precipitation were short and isolated. Two of the main winter months, January and February, were almost totally dry everywhere in the country.
How do these vagaries of climate influence plant life? Will they change the composition of the Mediterranean landscape or in its appearance? How will potential changes in vegetation impact the ecosystem? How will they affect the animals of the area?
Every plant has its own cycle of growth, leafing, flowering, fruiting and seeding. The science that deals with this cycle is known as phenology. In November, 2013, we wrote about the desiccation of the oak trees at Ramat Hanadiv after continuous years of low rainfall. Numerous studies have shown that the amount of precipitation and its distribution play a decisive role in phenological processes, and thus on ecosystem functioning and the essential services it provides to humankind, such as the production of shade and oxygen; carbon fixation; and nutrient recycling.
For ecologists, it is therefore extremely important to be able to determine the condition of trees, shrubs and other organisms in nature before symptomatic changes are visible to the naked eye. Otherwise, by the time we are able to see that a tree or shrub is dehydrating, for instance, the process of dehydration itself has exacerbated the situation, severely affecting the amount of moisture within a plant and its overall health.
Until just a short while ago, it was hard to imagine being able to determine what was happening inside a tree or shrub before it showed the effects of dehydration. Now let's set out on a journey into the world of research that goes on at Ramat Hanadiv, and see for ourselves how some of the innovative, unique studies of nature being conducted today may bring us answers to urgent questions about fluctuations in the climate and its effects.
Hikers in Ramat Hanadiv, alongside the dry riverbed of Nahal Hanadiv, have no doubt noticed the new metal tower that has been installed here during the past months. No ordinary observation post, this: it is a research tower. Its sophisticated equipment runs on renewable solar energy, which fits in with the Ramat Hanadiv's 'green' vision and its implementation throughout the Nature Park.
At the top of the tower is a camera that provides visual information and data daily via a multi-spectral camera, which can produce photographic images utilizing light waves that are beyond the vision of the human eye. These images make it possible to follow the processes occurring within a tree, providing early warnings about such processes long before external symptoms of dehydration can be observed and helping scientists understand these processes.
The pictures here portray identical parts of Nahal Hanadiv's north-facing slope. In the ordinary digital photograph we can distinguish the slope's tree canopy and green shrubbery. The multi-spectral photo, however, shows us the same landscape as it appears through different light waves (differentiated by the various colours in the photo). Generally speaking, the light red sections of the picture represent healthy vegetation, while the darker sections (brown) document those plants that are in the process of dehydrating.
This ongoing and innovative surveillance, which will be carried out for years as part of Ramat Hanadiv's long-term ecological research programme, will make a significant contribution to our understanding of how climate change affects Mediterranean flora. Testing trees and other vegetation in 'real time' with continuous follow-up gives researchers invaluable information and data, enabling them to do further studies.
The current research is being conducted in cooperation with the Remote Sensing Lab of the Institutes for Desert Research at Ben-Gurion University of the Negev.