International conference of the Israeli Society of Ecology and Environmental

Sciences. Jerusalem, 1999

ROCK AND SOIL SYSTEM AS THE MAJOR ECOLOGICAL

FACTOR AFFECTING THE WATER REGIME IN QUERCUS

ITHABURENSIS FOREST IN ALONIM-SHFAR’AM REGION

N. Herr *, A. Singer *, J. Riov **, E. Sass ***

*Department of Soil and Water, The Hebrew University of Jerusalem,

76100 Rehovot, Israel.

**Department of Horticulture, The Hebrew University of Jerusalem, 76100

Rehovot, Israel.

***Institute of Earth Sciences, The Hebrew University of Jerusalem, 91904

Jerusalem, Israel.

ABSTRACT

Quercus ithaburensis forest in Alonim-Shfar’am region (Lower Galilee, Israel) exists

only on specific sites. The structure of the sub-soil in the forested sites consists of

chalky rock covered with Nari, brown shallow Rendzina, and soil pockets up to 1.5

meter deep which interrupt the Nari layer. The tree root-system is composed of a

dense root mat located at the bottom of the shallow soil layer and deeper root system

concentrations that are located in soil pockets. In the adjacent limestone and Terra

Rossa area, where the forest doesn’t grow, there are no significant soil pockets and

the soil lies above cracked rock.

The main factor responsible for the difference between the two soil-rock systems is

their different water regimes, due to the structure of the soil layer, the presence of soil

pockets and the hydraulic characteristics of the subsoil rock. Differences in nutrient

availability are the result of the different water regime in both habitats. Improved

water economy as the main factor and improved nutrient supply as a secondary

factor, lead to improved conditions which enable growth of trees in the chalk habitat

that is covered with Nari and Rendzina soil with its soil pockets.

KEWORDS

Brown rendzina; chalk; Quercus ithaburensis; soil moisture; soil pockets;

water regime

INTRODUCTION

In the Alonim-Shefar’am region of the Lower Galilee of Israel, the Quercus ithaburensis

forest thrives only in limited areas. The climate and the topographic conditions seem to

be quite similar throughout the region, and preliminary observations suggested that

factors related to soil and rock could be the reason for this phenomenon. The forest exists

on a chalky rock that is covered by Nari hardpan and Rendzina soil, and is absent on

limestone and associated Terra Rossa soil. The objective of this work was to examine in

detail the hypothesis that soil and rock are responsible for the limited distribution of Q.

ithaburensis in this region.

Q. ithaburensis in Israel occurs discontinuously in specific regions from the Golan Hights in

the north to the Sharon Plain in the center of the country. This species probably reached

Israel about 10,000 years ago, after the last Ice period, from south Turkey (Zohari, 1973;

Stiller et al., 1984; Bar-Matthews et al., 1998). Its distribution in the past was broader than

today. Cutting, grazing and temporary utilization of the land for cultivation of olives and

vineyards probably affected the distribution of Q. ithaburensis. It seems that the forest

(especially in the research region) regenerated again in the same boundaries after each

disturbance of the natural situation. This is due to good regeneration by stump sprouts as

well as regeneration from seed in the same suitable niches. Most of the forest in the region

was cut during World War I, regenerated (Eig, 1933), partly cut during World War II, and

regenerated in the same boundaries.

METHODS

The research region

Alonim-Shefar’am is a region of moderate hills up to 250 m above sea level. The geological

base consists of chalky rocks of the Maresha formation (middle Eocene) in the west, changing to

the west by interfingering with limestone of Timrat formation (Greenberg, 1963; Sneh, 1988).

The chalk is covered by Nari calcrete hardpan (Greenberg, 1963; Yaalon & Singer, 1974; Wieder

et al, 1994) and brown Rendzina soil, while the limestone is covered with Terra Rossa soil

(Singer, 1969).

On the chalk that is homogenous in the west, natural vegetation consists of a maquis, while on the heterogeneous chalk in the transition zone grows a park-forest of Q. ithaburensis (without any accompanying species of trees and shrubs). On the limestone landscape there are no trees at al. In this research the park-forest is compared to the bare area.

Methods of research

A comparative mapping of rock, soil and vegetation was carried out by projecting the tree area from areal photographs on topographic map, and the forest distribution was analyzed using topographic, geologic and pedologic data by GIS. Sub-soil structure and location of

roots in relation to this structure were examined in hundreds of field sections. Moisture regime in the Rendzina and Terra Rossa soil was measured continuously for 3 years using gypsum soil moisture sensors and data loggers. There were two measurement stations in each of the two soil systems studied, one on a hill top and the other on the southern slope. In each station there were 5 sensors at a depth of 20 cm. The soil moisture data complemented by periodical gravimetric measurements at 10 sites in the research region. Gravimetric soil water content in soil pockets was measured at the end of the summer. Soil temperature was measured near each of the soil moisture sensors in the same system. Air temperature, humidity and precipitation were measured in the same stations. Other aspects that were examined included soil and rock characteristics, chemical composition of the soil and soil solution, tree water tension in trees, transpiration and stomatal conductance.

RESULTS AND DISCUSSION

Forest distribution has been found to be largely dependent on the rock and soil

characteristics. The topographic effect is minor and is in evidence only by the fact that in

the northern aspect the percentage of the tree coverage increases with increase in slope

up to an optimal degree, but the average percentage of coverage in the northern aspect is

not higher than that in the other slopes, and the forest borders cross various aspects and

slopes.

The structure of the sub-soil in the forest sites consists of chalky rock covered with Nari,

brown or red-brown shallow Rendzina, and soil pockets up to 1.5 meter deep which

interrupt the Nari layer. The tree root-system is composed of a dense root mat located at the

bottom of the shallow soil layer and a deeper root system which is concentrated in soil

pockets. Each tree occupies at least one soil pocket. In the limestone and Terra Rossa areas,

where the forest does not grow, there are no significant soil pockets but the soil is somewhat

deeper and lies above cracked rock. The soil-rock system varies greatly due to rock

variations that were caused by the original sedimentation process and subsequent sliding,

bending of layers and many faults. The rock variation leads to variations in the Nari

structure and development of soil pockets. As a consequence, the root environment may

differ considerably from one tree to another.

Water regime in the shallow soil. There were notable differences between the desiccation

processes of the Terra Rossa and Rendzina soils during spring and summer (Fig. 1). The

desiccation process in Terra Rosa was enhanced by events of hot and dry weather. The

effect of spring showers on delaying the drying of this soil was short and limited. Terra

Rossa usually reached complete dryness (a situation close to “air dryness”) by the end of

August. In Rendzina, soils, in contrast, the desiccation rate was more moderate. The

effect of spring showers in slowing down the drying process was more noticeable and

lasted longer after each rain, while the effect of hot and dry weather was less pronounced

compared with the Terra Rossa. Soil moisture persisted in Rendzina until the end of the

summer and was observed at depths of 20 cm with tensions of about 20-40 bar. At this

tension, tree roots are able to survive.

Moisture levels in soil pockets were high (tension of 1-4 bar), mainly at the bottom of the

pockets, in cracks inside the walls and under large stones. This situation allows the tree

to continue water uptake during the whole summer. In response to the first fall showers,

the Rendzina soils become wet more quickly and fully, and stayed wet longer than Terra

Rossa. Therefore, the dry period of the upper soil layer ends earlier.

The reasons for the quicker and more thorough wetting of the Rendzina, and

subsequently, its saturation over longer periods of time compared with Terra Rossa are:

Relatively large Nari areas on the surface, which extend into the shallow

subsoil, lead to formation of runoff water even after light rains, that allow the

wetting of the root environment at the bottom of this layer. Continued downward

penetration of water is probably limited by the laminar crust of the Nari hardpan.

The chalky rock and the Nari hardpan maintain a high level of water saturation

during the whole summer due to their high water holding capacity. The high

effective saturation of the chalk and the Nari, their low water tension and

moderate hydraulic conductivity permit water to move from the rock to the drying

0

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Average soil temperature

Terra Rossa 1: top of the hill

Rendzina 1: top of the hill

Terra Rossa 2: southern slope

Rendzina 2: southern slope

Hourly rain (mm)

Terra rossa 2

Terra rossa 1

Rendzina 1

Rendzina 2

S o i l t e m p r e t u r e

Spring rain Outomn-winter rain

Soil water content, soil temperature and precipitation

in Terra Rossa on limestone and Rendzina on chalk with Nari

measured continuously from spring to winter, 1995

Fig. 1 :

Date, 1995 . The points are every hour

soil, and thus retard the process of drying of the shallow soil and allow to maintain

high levels of moisture in the soil pockets (Fig. 2). Thus the soil pockets function

as a “plant-pot” that is almost saturated with water.

Fig 2: Water flow in the rock-soil-tree system. Calculated by using data of soil and rock moisture

measurements, retention curves of soil and rock hydraulic conductivity. Transpiration rate and water

tension in leaf measured directly. The main water storage and main water flow is coming from the

chalk under the soil pocket.

In contrast, the Terra Rossa has no continuous rock exposure next to the

surface, and the subsoil rock is cracked and dense. Soil pockets do not exist and

the limestone does not absorb moisture.

The Rendzina has a higher water holding capacity than Terra Rossa.

Tree responses to the soil water regime. Soil moisture, water availability in the soils at

different sites, and tree responses are all related. In a habitat where soil moisture is high, the

water tension in the leaves will be lower and stomatal conductance, growth parameters,

acorn formation and the timing of leaf shedding are indicative of a better situation. When

soil moisture is low, the tree water tension rises and tree activity decreases to a minimum. In

general, due to dry soil conditions, the stomata closing mechanism is activated in order to

regulate the water tension in the trees during the day and during the season (Tenhunen et al.,

1987; Davies and Zhang, 1992). Transpiration rate decreases with the advancement of the

summer, and is compatible with water movement from the rock to the soil pockets.

Nutrient availability – a secondary factor. The type of moisture regime of the soil-rock

system leads to differences in mineral availability in the different soils. During winter the

chalky rock is saturated with water and therefore aeration conditions in the soil pockets

and the Rendzina are impaired. The nitrification process of the decomposable organic

matter slows down, and because of the limited leaching in this system, the accumulated

ammonium is not removed. In spring, when temperatures rise and the aeration conditions

improve, the nitrification process is more complete, and the concentration of available

nitrogen rises. The ratio ammonium/nitrate, that is high in winter, and high levels of

nitrogen in spring, make the Rendzina habitat superior. In contrast, in the drying Terra

Rossa, it can be assumed that the mobility of potassium and phosphorus decreases, and

therefore absorption of these elements decreases toward the end of summer (as it found

in the leaf chemical composition of seedlings). The drying up process apparently

damages the selective uptake of the roots and leads to uncontrolled uptake of damaging

elements.

CONCLUSIONS

In summary, it seems that the main cause of variation that is responsible for the difference

between the two soil-rock systems is their different water regimes, due to the structure of

the soil layer, soil pockets and the hydraulic characters of the subsoil rock. The differences

in the mineral availability are the result of the water regime in both habitats. Improved

water economy as the main factor and improved nutrient element supply as a secondary

cause, lead to improved conditions for tree growth in the chalk habitat that is covered with

Nari and Rendzina soil with its soil pockets.

REFERENCES

Bar-Mattews M., Ayalon M., Kaufman A. (1998). Eastern Mediterranean paleoclimate

during the last 60,000 years as derived from cave deposits. In: Israel Geological Society,

Annual Meeting, Mitzpe Ramon, Laser Pages Publishing.

Davies W. J., Zhang J., 1992. Root signals and the regulation of growth and development

of plants in drying soil. Annu.Rev.Plant Physiol. Plant Mol. Biol., 42: 55-76.

Eig A. (1933). A historical-phytosociological essay on palestine forests of Quercus

agilops L. ssp. Ithaburensis (Desc) in past and present. Beihefte Botanischem

Centralblatt, 51 B: 225-272.

Greenberg Y., 1963. The Geology of Kfar Hahoresh-Illut region. Isr. J. Earth Sci., 12.

Singer A., 1969. The soils of the Lower Galilee. Soil Map 1:20,000 (unpublished)

Sneh A., 1988. Regional litostratigraphy of the Eocene Avdat group, Israel. Report

GSI/26/88.

Stiller M., Erlich A., Poinqer U., Baruch U., Kaufman A., 1984. The late Holocene

sediments of lake Kinneret (Israel) – multi – disciplinary study of a five meter core. In:

Geological Survey of Israel, Current Research, 1983-1984, A. Erlich (ed.), 83-87.

Tenhunen J. D., Pearcy R. W., Lange O. l., 1987. Diurnal variation in leaf conductance and

gas exchange in natural environments. In: Stomatal function, E. Zeiger ed., Stanford

University Press, Calif.,USA

Zohari M.(1973). The geobotanical foundations of the middle east. Stuttgart: Gustav

Fischer.

The conference of the Israel Seological Society. Eilat, 2001

Use of GPR in mapping and evaluating the rock-soil structure

as a part of an ecological research

Herr, N.,1 Kofman, L.

2

1. Department of Soil and Water, Hebrew University of Jerusalem, Rehovot 76100

2. Laboratory for field systems, Technion Institute for Research and Development, Technion

City, Haifa 32000

Surveys were made with GPR in the Alonim-Shefar’am region. The purpose of these

surveys was to obtain data on the 3D structure of the complex rock-soil system prevailing

in the area. The work performed was a stage of ongoing research its main purpose being

the understanding of the relationship between ground factors and the growth of the forest

and the maquis.

In the research area, a transition zone is exposed between the chalk and limestone facies of

Timrat formation, and the chalk of Maresha formation (Avdat group). The chalk is covered

with Nari hardpan and reddish-brown rendzina soil. The rock-soil system varies greatly

due to rock variations of the original sedimentation and mass transport, bending of layers

and faults. 3 layers of Nari are observed: The laminar crust, the upper Nari and the lower

Nari. The laminar crust forms a sequence of surface that are partly covered by shallow soil.

The rock variation leads to variations in the Nari structure. In weakness joints of it, many

soil-pocket were formed.

The big diversity caused formation of various systems of rock-soil structure. These

systems are habitats to various types of vegetation. Thus, it is on Timrat chalk covered

with well-developed Nari and soil pockets that Quercus ithaburensis park-forest has

developed. On the more porous chalk of Maresha formation the Nari is less developed, the

soil is scarce and Quercus caliprrinos maquis has grew, its root going deep into the rock

cracks.

Due to the complexity of the structure of the subsoil, the evaluation of its details is not

easy by usual mapping. Use of the GPR enables “seeing” the subsoil structure with high

resolution in variable depth ranges according to the frequency of the antenna used and the

electrical conductivity of the rock and soil layers. Surveys carried out in park-forest on

Timrat formation and in maquis on Maresha formation. The GPR equipped with two

antennae: Antenna 500 MHz enabling imaging at very high resolution up to depth of 2.5 m

and antenna 300 MHz up to of 4 m. surveys were performed along lines at intervals of 2-3

m and in lines broadside. Additional profiles were made later along strike and dip lines of

layers and perpendicular to faults.

After the interpretation it was possible to determine changes between soil, rock and Nari

layers thickness, inclination and lateral changes, joints, faults and soil pockets. This

information was used for planning a series of drillings at depth of 5 m. A correlation

between the drilling and the GPR data enable understanding of the properties of the layers

and their continuity in various directions as well as evaluation of the rock-soil system

structure and its properties.

In continuation, it is planned to measure changes in the water content of the soil and rock

between the drilling by means borehole antenna radar. This measurement, based on the

knowledge of the rock-soil structure describe, will enable obtaining the water flow system

in the rock toward the soil and roots by the hydraulic properties of the various layers.

The conference of the Israel Seological Society. Eilat, 2001

Detection and mapping of fault zones and karst caves

by GPR and Borehole Radar System

Kofman, L.1

Herr, N.,2

1. Laboratory for field systems, Technion Institute for Research and

Development,

Technion City, Haifa 32000

2. Department of Soil and Water, Hebrew University of Jerusalem, Rehovot

76100

A great part of the construction in Israel is made in the mountains regions where

geological faults (including active faults) and karstic phenomena are found as a result

endangering the stability of structures. Construction above underground caves is highly

dangerous as the pressures developing in the caves’ roof during an earthquake are liable

to cause its collapse.

The GPR method has proven to be the most effective method detection of caves, voids

and areal of faults and cracks in progress. This ability is mainly achieved by the highest

resolution of this method – the highest among all geophysical methods, operating on

ground surface.

In the survey in Alon Hagalil and Timrat (Alonim-Shefar’am region) characteristic

imaging of faults lines were obtained. Geological faults observed on ground surface were

identified by the GPR also in places that were not visible on surface level. The image thus

obtained is one of diffraction development along the fault line and considerably more

visible than that of rock cracks.

Locating underground caves and voids is done by identifying on the GPR data the

reverberation picture generally occur in places, where the towed antennas pass during

survey over some form of sub-surface opening. The reverberation picture is expressed by

increase in amplitude of the reflections and the decrease in their frequency. It is logical to

suppose, that the occurrence of the reverberation above the voids can be observed in

cases when the antenna wavelength is similar to magnitude of the void diameter.

Numerous voids were detected in surveys of various regions of Israel and actually found

after digging or drilling.

Clay lenses in the rock may sometime cause a multireflection effect similar to the

reverberation image. By combined use of the GPR survey using antennas towed on the

ground surface, with the Borehole Antennas System (BAS), an absolute differentiation

between voids and clay lenses can be achieved. The BAS method emits and receives

impulses passing between two antennas being lowered into the borehole. It is possible to

obtain accurate data on size of caves and their location by analysis of the changes

occurring in the parameters of the signals. Actual experiments in the Rafiah region

proved the possibility of void detection ranging from 0.5 m in diameter and at depths of

1-10 m.

We suppose that the continuos voluminous GPR data on cave/void location below

building sites, by combining the two georadar technologies, will considerably contribute

to reinforcing of foundation existing and planned buildings and prevent construction of

new ones above or in the vicinity of active faults.

The conference of the Israel Seological Society. Ma'agan, 2002

Mg in carbonate rocks as a major factor controlling rock-

soil relationship in Judea and Avedat Groups,

Mediterranean zone, Israel

Herr, N.,1 Frumkin, A.,

2 Azaize, H.

3

1. Soil and Water Department, The Hebrew University of Jerusalem, 76100 Rehovot

2. Geography Department, The Hebrew University of Jerusalem, 91905, Jerusalem

3. Research and Development Center the Galilee Society, 20200 Shefa’amr

Geomorphic and pedologic observations in the Mediterranean climatic zone of

Israel show that limestone and dolomite display a different soil-rock

interaction. The difference is reflected in karren-field structure, soil pockets-

rock-karren interaction, and the relationship between shallow and deeper karst

features. Dolomites apparently develop larger karren formations, deeper soil

pockets, and intensive karstification. Micritic limestone of Avdat Group tends

to support thicker homogenic soil cover, almost without soil pockets. The

rock-soil interaction apparently dictates the floral ecosystem and species

distribution.

Limestone and dolomite Mg content of Bina and Sakhnin Formations

seems to control the forest structure of the Upper Galilee. Additional

observations of forest and maquis in lower Galilee, Karmel and

Samaria indicate similar behavior in these regions too within Judea and

Avedat Groups. Comparison of rock-soil systems and meteoric water

composition along the route from surface to groundwater, indicate that

the Mg influence is not direct but rather involves variable dissolution

processes associated with variations of Mg content.

We compared Ca and Mg concentrations of meteoric water on bare

rocks, runoff, soil, karst shafts, caves and springs. Dissolution on bare

rocks and in the soil is more intensive on limestones compared with

dolomites. Most dissolution occurs at the soil-rock interface. On

limestones, dissolution capacity seems to be exosted in this interface,

and solute concentration does not increase much further down. On

dolomites, dissolution is less intensive at the upper unsaturated zone,

and solute concentrations increase significantly downwards through the

shallow karst towards caves and springs.

Suggested hypothesis: In Judea Group micritic limestone, intensive dissolution

close to the surface renders the water almost saturated with carbonates, and

little aggressiveness is left for deeper dissolution. The lower dissolution rate of

dolomites allow the infiltrating water to remain aggressive, enlarge fractures

and create deeper soil pockets. High-Mg limestones are thus associated with

deeper soil-pockets compared with low-Mg limestones. Mg content is even

lower in the Eocene Timrat Formation micritic limestone, whose Mg/Ca ratio

is 1:250, supporting deep soil development with almost no pockets. The depth

of soil pockets and their water capacity potential control local forest and

maquis richness.

The conference of the Israel Seological Society. Hagoshrim, 2004

The water dynamics in the soil-rock system

of the Avdat group chalk in the Lower Galilee

Herr N. 1, Makovsky Y.

2, Shani U

1.

1. Department of Soil and Water, Hebrew University of Jerusalem, Rehovot 76100

2. Department of Geophysics and Planetary Sciences, Tel Aviv University, Ramat Aviv 69978

Spatial and temporal moisture distribution in a given rock-soil system is a major factor influencing

vegetation type and habitat properties. The current work presents an integration of Geobotanics,

Soil-Rock-Water continuation, Geology and Hydrology, and includes a multidimensional study of

the water system in the habitats of oak forests and maquis. The research was based on direct and

comprehensive measurements of the water status in the soil and rock formations.

Measurements of soil and rock moisture content were conducted during the past three years at three

sites in the Alonim-Shefar’am hills. At each site, we drilled a network of 8 m deep boreholes for

water content measurements using a neutron probe, borehole antennas and soil moisture sensors.

The research sites included two locations of Quercus ithaburensis park-forest in Alon Hagalil: (i) on

the Timrat formation (chalk covered by Nari calcrete hardpan, with intermediate layers of limestone

with soil pockets); and (ii) on Adulam formation (alternate hard and soft chalk and marl, and soil of

variable depths); and another location of Quercus calliprrinus maquis in the Timrat settlement on

soft chalk of Maresha formation. Meteorological data, including soil and rock temperatures at

various depths, were monitored. 3-D structures and features of the subsoil were analyzed by GPR

net, and from rock cores.

At this stage, we analyzed the data and some conclusions may already be established:

In habitat of chalk covered by Nari hardpan with limestone and marl layers,

the upper soil and the rock to a depth of 2.5 m becomes dry towards the end

of the summer. Water percolation, during and following the rainy season

during an average year, does not reach the bottom of the dry area. The

wetting slowly progressed towards this depth in a few months, and at the

same time, the shallower area became dry. Later, all the wetted area became

dry.

Deeper rock moisture has almost no seasonal changes. There are quite sharp

interfaces between the upper dry area and the lower wet area.

When the annual rainfall is high, the moistening is deeper and remains so for

a longer period. In rainy years, the wetting front may break through the dry

area bottom and unite with the lower wet area.

Moisture fluctuation along the section can reflect an intermediate layer of

limestone, marl and soil, and the Nari layers. The influence of these layers is,

in particular, during the time of percolation and wetting.

The 3-D soil-rock system in each site has a high influence on the water distribution

along the section. Our aim is to examine and compare the influence of various soil-rock

systems on the water system dynamics in the ecosystems in the same sites. This study of

the water system in the rock serves as a tool in understanding the hydraulic properties of

the rock in the section and the hydrologic processes in this region.