Combating the Forest Mortality Crises in Zagros Regions, Iran through Adaptive Approaches Solutions

1. Zagros forests (Quercus sp.) contribute to recharging groundwater, controlling air
pollution, ecotourism, by products, livestock grazing, sustaining agriculture, soil
conservation and flood control. Due to geological and topographical properties of Zagros
area, however, these forests are more vulnerable to deforestation agents mainly drought
driven die-off phenomenon. The effects of climate change are generally expected to
reduce the growth and survival of forests, which not only predisposes them to being
disturbed by insects and disease, but also increases the vulnerable ones to higher tree
mortality. As a consequence of continued climate change, forest mortality has spread
throughout Zagros areas inducing a severe environmental disaster. According to some
research, several biotic and abiotic factors, such as extreme weather conditions, drought,
storms, heat, and insect fluctuations, are responsible for oak reduction. Regarding rainfall
deficit, soil moisture storage and reduction in evapotranspiration should be considered as
the possible solutions through short term measures. Consequently, harvesting runoff by
micro-catchment construction such as crescent -shaped bund (CSB) is a possible adapted
measure in the semiarid regions for enhancement of soil moisture. In order to evaluate the effects of runoff harvesting on forest rehabilitation, the present research aimed to analyze the effects of CSB on soil soil moisture content.
2. Material and This study was conducted in Kalehzard site located in Kermanshah, west of Iran (UTM;
38S682887E, 3748385N). The respective annual precipitation and temperature are 440
mm and 15.2 ºC, indicating the semiarid region. The winter is so cold that the
temperature drops below zero on average for 90 days during December, January and
February. The summer is relatively hot and dry. A hill with a 15% slope and southeastern
aspect was chosen as the experimental site to represent the dieback phenomenonin Zagros forests. The experiment was a randomized complete block design with four
treatments and three replications. The experiment was conducted as a randomized
complete block design with four treatments including crescent shaped bund with
preservation (CSB), preservation treatment (PT), crescent shaped bund without
preservation (CSB-P) and control treatment (CT). CSB was constructed to assist
reduction in dieback rate and even re-vegetation of some dried forest trees through its
effects on harvesting runoff. This technique is perpendicularly in the slope direction
with the opening perpendicular to the flow of runoff, capturing runoff inside. The
frequency of both dieback and healthy trees was recorded twice a year, therefore, the
total number of trees was recorded before the construction of bunds within the plots
using 100% inventory method. Soil quality, soil moisture and plant canopy were
analyzed within treatments and repeated every year during the research period.
3. Results explored that the effects of CSB treatment on reduction of dieback rate and
re-growing of some dried trees was 36.7 and 19 tree ha-1 respectively (totally 55.7 ha-1
tree in the forest stand). Therefore, both the reduction of mortality rate and re-growing
of dried trees are two main positive effects demonstrated by CSB measure. PT
treatment has no effect on re-growing, while it contributes to the reduction of dieback
severity (37.7 tree ha-1). Finally, CSB-P was found the lower level on dieback
reduction was 6 tree ha-1, revealing the crucial importance of preservation for the
protection of built bund. As a result, micro-catchment and preservation have a
significant positive effect on forest restoration through soil moisture retention. also showed that the respective means SOC in the CSB, PT, CSP-P and CT
treatments were 2.35, 2.40, 1.90 and 1.80 %, indicating no significant difference among
them. However, the means significantly (p>0.05) increased in the CSB and P
treatments over time. CSB significantly reduced bulk density from 1.46 (1st yr) to
1.32 (3rd yr) enhancing soil moisture content. The crescent shaped bund was designed as the adaptive micro-catchment runoff harvesting system (MCRHS) and measured within
treatments plots. This technique has a lower soil and embankment movement than
earthy or stone dams which can be built perpendicularly in the flow of runoff. Besides,
it is arranged in staggered rows along the natural contour of the land with the open end
facing uphill. Consequently, these bunds slow down runoff enabling the harvested water
to be used in an effective way. This is particularly useful in increasing the soil moisture,
especially when precipitation is scarce.
4. It is concluded that CSB (first treatment) can be considered as the possible adaptation
approach for combating Zagros forest mortality induced by drought stress and climate
change. This technique is a possible measure for runoff harvesting and thereby
enhancement of soil moisture during dry season. However, proper and holistic
management of forests are needed to curtail forest dieback event. Furthermore, Zagros
forest soil should be protected from disturbance factors in terms of tillage practice, machinery traffic, grazing, logging and charcoal extraction. In our experience, runoff
harvesting through micro-catchment technique, forest preservation and sustaining SOC
are crucial short term measures for combating forest mortality in Zagros regions.