The Fall of a 74 Year-Old Giant (Cont.)
A new building was constructed in 1977-1978 in place of the small house of my childhood; the large pine tree kept growing while many of its neighbors fell down in snow storms. We planted an ivy ([Hedera helix]) vine at its foot, which developed beautifully on the lower part of the pine; it developed its own trunks, flowered, and produced fruits every year. The width of the pine’s annual rings (discussed later) showed good and uniform growth rate throughout the years. During the 1980s dozens of pigeons adopted the crown of the tree and contributed their “gift” to the soil fertility of our garden below it. After cutting the lower branches of the pine the pigeons ceased their activity. As mentioned before, on January 8, 2013, at 19:00 the neighbors heard a loud noise on their roof. We did not hear the noise and only on the afternoon of the following day, one of the neighbors called us and suggested that we should go out to our garden and see what had happened.
During the sunset hours, Yankale Safian and his team came and estimated the work needed. On Thursday, after the snow-fall had stopped, they came equipped with the necessary saws and other tools. With mechanical saws they started to remove lateral branches. They started near the top of the tree, hanging by rock-climbing rappelling equipment. Towards the evening the giant landed on the ground between No. 3 Maalot Street (our home) and No.5 Maalot Street; the rail of the balcony of the lower apartment was damaged by the tip of the heavy giant. The lateral branches were cut by the experts and transported to a high pile that accumulated on HeHalutz Street. New mechanical saws were used by the team to cut the huge trunk into removable sections shorter than one meter. Before long people came and took the trunk sections to their cars. I assume that several people made some income from our tree trunk. Thanks to the cooperation of Yankale’s team it is possible that many houses have been warmed for many hours by the giant pine.
Among the trunk sections I found a thin piece with an almost complete cross-section. I took it home, and using a sharp knife (scalpel), I made a smooth face which enabled study of the annual rings. Checking it provided a surprise: the tree was 74 years old when it fell on my 74th birthday.
This is an opportunity to enlarge a little on the issue of annual rings of trees and shrubs. When I was a student at university in the 1960s we were fortunate enough to learn Plant Anatomy through the lectures and laboratories of the late Prof. Avraham Fahn. This subject is no longer included in the curriculum of the Hebrew University, and I feel that it is worth enlarging on it here. The main part of the pine trunk is built up from xylem tissue transporting fluids; the main component of the tissue is of hollowed elongated cells known as “tracheids”. Trunk anatomy is studied by microscopic sections. Luckily we (our nation and myself) have devoted friends in Switzerland; Walter and Verena Naenny, who have contributed many plant pictures to my website. They were happy to assist here as well. Walter bought the sophisticated equipment needed for botanical and microbiological research and devotes much time to various researches. The faithful readers of my website may read about the [http://flora.huji.ac.il/browse.asp?action=content&keyword=%D7%A9%D7%99%D7%9E%D7%95%D7%A9%D7%99%D7%A6%D7%9E%D7%97%D7%99%D7%9D%D7%98%D7%962 anatomy of the Rhamnus lycioides in this link, aided by Walter’s microscopic sections and photographs].
In order to emphasize various components, plant anatomists use artificial dyes in the preparation of the transect. The cross-section in Fig. 19.1.9 is in its natural colors; Figs 19.1.10-19.1.12 are dyed with Safranin, Fig. 19.1.13 by Acridin Orange, and Figs. 19.1.14 and 19.1.15 by Primulin. The cross section of a tracheid has a lumen in a circle or eliptical shape (Fig 19.1.10).Tracheids formed in the spring have a thin wall and a large lumen (70 micron diameter); they function as transporters of high quantities of water and salts from the roots to the canopy during the good growth season. Tracheids formed in the dry season and in the cold winter have thick walls and a small lumen (33 microns diameter; Figs. 19.1.11-19.1.13 right of the arrow and the letter S).
In Fig. 19.1.14 Walter Naenny measured the radial length of four cells of spring tracheids and compared them to four cells of summer-winter (Fig. 19.1.15). The cell rows right and left of the arrow in Figs. 19.1.11-19.1.13 and in 19.1.14 and 19.1.15 have direct continuity. The only difference between the two sides is the walls’ width and the lumen diameter. The xylem cells are formed as a result of division of the cambium cells. In most places their number remains the same. The result is that in the spring (left of the arrow) light colored xylem is formed whereas in the summer and winter dark colored xylem is formed. The new growth in spring and the development of light tissue brings about a big contrast in the wood. Between one growth season and the beginning of the next, there was one year of activity. The width of the upper ring in Fig. 19.1.9 is 1.38 mm whereas the width of the lower ring is 0.61 mm. If the activity year is blessed with a large quantity of rain water, the tree forms a wide annual ring and in a dry year, the tree forms a narrow ring. The good growth conditions of Jerusalem are expressed in my giant pine by a radius of 34.3 cm. The average growth rate of this pine is 4.63 mm per year.
I sampled a [Juniperus phoenicea] branch in 1968 in N Sinai; the mean annual rainfall there is less than 100 mm; the radius is similar to our pine tree and 1000 rings were encountered recently (in a laboratory in Cornell, USA; Fig. 19.1.16). The average growth rate of the entire tree is thus 0.34 mm per year. Although we deal with different species, the almost 10-fold difference in their growth rate reflects the dry conditions in Gebel Halal when compared to those of Jerusalem. Accurate investigations of the climate of the past (Dendrochronology) are studied in the USA in Tucson, Arizona and Cornell, New York.