|Year : 2015 | Volume
| Issue : 2 | Page : 66-70
The Assessment of Carrying-Capacity of Persian Gazelle in Sorkh-E-Hesar National Park, Iran
Elmira Kazemi Jahandizi1, Mohammad Kaboli2, Mahmoud Karami2, Mahmoud Soufi3
1 Department of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran, Iran
2 Department of Environment Sciences, Faculty of Natural Resources, University of Tehran, Karaj, Iran
3 J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August-University of Gottingen, Germany
|Date of Web Publication||27-Nov-2015|
Elmira Kazemi Jahandizi
PhD student, Department of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran
Source of Support: None, Conflict of Interest: None
Introduction: Understanding food resources of large herbivores and their interactions with habitat is crucial for effective wildlife conservation in arid environments. However, the carrying capacity (CC) value may be influenced by a variety of human-induced perturbations, e.g., habitat fragmentation and potential competitors. The goitered gazelle (Gazella subgutturosa) inhabits a wide range of semi-desert and desert habitats in Iran. Materials and Methods: To estimate the CC of the species in Sorkh-e-Hesar National Park (SHNP), four different habitats were surveyed during the winter period in 2011-2012. The grazing behavior was recorded by direct observations. The grazing spots were identified and studied for vegetation types in 6 sites. In total, 80 plots and 10 T-square random points were sampled. Results: About 15 herbal species were identified in gazelle diet, with the main contribution of the family Poaceae. Dry weight and density of herbal species preferred by the gazelle were estimated. Moreover, the nutritional CC of the habitats and available forage during the winter period was determined using the cutting-weighting technique. The CC value of the goitered gazelle population was estimated as 56-107 individuals over 91.68 km 2 (0.62-1.17 individuals/km 2 ), which was estimated with the inclusion and exclusion of competitive herbivorous species, respectively.
Keywords: Carrying capacity, dietary, Gazella subgutturosa, Iran
|How to cite this article:|
Jahandizi EK, Kaboli M, Karami M, Soufi M. The Assessment of Carrying-Capacity of Persian Gazelle in Sorkh-E-Hesar National Park, Iran. J Earth Environ Health Sci 2015;1:66-70
|How to cite this URL:|
Jahandizi EK, Kaboli M, Karami M, Soufi M. The Assessment of Carrying-Capacity of Persian Gazelle in Sorkh-E-Hesar National Park, Iran. J Earth Environ Health Sci [serial online] 2015 [cited 2020 Dec 2];1:66-70. Available from: https://www.ijeehs.org/text.asp?2015/1/2/66/170590
| Introduction|| |
The Gazella genus has two extinct types and 8 living species throughout the world.  Today, only three species of them exist in Iran called Gazella gazelle, Gazella bennetti,  and Gazella subgutturosa. ,
In general, the Persian gazelle is bigger and heavier than the other gazelle species in Asia.  This species is native and roaming across the Middle East and central and Eastern parts of Asia. The species have been listed by the IUCN as (VU).  The geographical distributions of this species are restricted to the arid area of Yemen up to the Eastern and Southern parts of Turkey, Eastern part of the Caucasus, Turkmenistan, Baluchistan, Kazakhstan, and also throughout the Western and Northern parts of China. According to some evidences, the species has probably faced extinction in Georgia, Iraq, Kuwait, Syria, and Yemen (IUCN 2008). Yet, there are some small populations in Southern and Western parts of Pakistan and Afghanistan, and now some larger populations exist in South of Turkey, Northern part of Saudi Arabia, and also Jordan.  The Gazelles are mainly occurring in protected areas controlled by the Iranian Department of Environment; these areas are located on the border of Kavir-e-Markazi (the central desert) and extend toward in the Khark Island in the Persian Gulf.  The species often prefers the altitudes between 1000 and 2100 m a.s.l. in Afghanistan and Iranian landscapes,  respectively. Altitudinal distribution of this species during summer months in Mongolia and China might reach to circa 2700-3000 m a.s.l. In general, the dominant plant species in gazelle habitats embraces: Artemisia sp., Astragalus sp., Haloxylon sp., Anabasis sp., Stipa sp., Salsola sp., Suaeda sp., Kraschennekocina sp., Artrophyton sp., and Stipagrostis sp. , The goitered gazelle usually feed on variety of plant taxa grasses bushes and halophytes such as Asteraceae, Fabaceae, Polygonaceae, Tamaricaceae, Ephedraceae, Boraginaceae, Cucurbitaceae, Plumbaginaceae, and Zygophyllaceae. 
| Materials and Methods|| |
SHNP is one of the oldest parks in Iran and covers an area of 91.68 km 2 . This region is mainly covered by knoll hills and semi-mountainous areas at 1200-2800 m a.s.l.  The temperatures can fluctuate between 40°C and 30°C and the precipitation varies between 200 and 700 mm per year (Bomabad Consulting Engineers, 1381). The area is mainly covered by Artemisia sieberi and Stipa spp. and other shrubby species including: Pistaca atlantica, Amygdalus lycioides, Amygdalus scoparia, Juniperus excelsa, Berberis sp., A. sieberi, Crataegus azarolus, Tamarix sp., Haloxylon sp., Astragalus sp., the (SHNP) is home to many endemic mammalian species such as: Wild sheep (Ovis orientalis), wild goat (Capra aegagrus), wild boar (Sus scrofa), Persian leopard (Panthera pardus saxicolor), striped hyena (Hyaena hyaena), wild cat (Felis silvestris), Pallas's cat (Felis manul), caracal (Caracal caracal), and wolf (Canis lupus). 
Persian gazelle distribution in (SHNP) was determined based on the available gazelle habitat distribution map and their grazing behavior was observed by binoculars with two observers.  The grazing (s) locations were recorded with GPS. The plant species eaten by the species were listed according by direct observation of grazing gazelles. Among the seasons, we have chosen the winter as a critical period for this species given the fact that less availability of food, monthly lower average temperature, and snow cover which make harsh condition for the species of interest. Critical period was considered about 90 days.  In addition, continuous monitoring of gazelle fresh footprints on snow, grazed plants, and also direct observation of the species were allowed to determine the grazing spots of the target species during the cold season. Moreover, those spots were treated for conducting plot sampling and grazing measurements. The GPS records from the direct observation of gazelle's habitats was fitted to the available vegetation map of the study area, then 6 different sites were selected using ESRI (Environmental Systems Resource Institute) 2009. ArcMap 9.2. ESRI, Redlands, California [Figure 1]. 
|Figure 1: Vegatative types and Gazelle subguttrosa dispersal map in Sorkh-e-Hesar National park by GIS|
Click here to view
Although we used the available vegetative map which has been classified to 7 different vegetation types, of which 6 classes were overlapped in this study. It has to be noted that, we omitted one of those selected habitat (K4, [Figure 1]) because it was occupied by the military. Therefore, the habitats which occurred in military were ignored during nutritional carrying capacity (CC) calculations because of error increase during sampling such as military use and occupation by domestic animals in habitats 4 and 7, respectively. Therefore, 4 stations were chosen for this species [Figure 1]. Snowfall average during 90 days of winter was 10 cm and this value was not considered in CC assessments because its amount (i.e., height of snow) had no effect on grazing function of gazelles on the herbaceous plant species. After preparation of herbaceous species eaten by the species, their branches diameters were determined by caliper and then the average values for each species were calculated. The heights of foraging (browsing) by gazelle were measured from plant collar positions. In total about 30 stalks from uneaten species were collected and kept in plastic bags. The samples were then dried out in oven at 68°c for continuous 48/h, and finally, the average of biomass in each habitat of dried species for each plant was calculated, biomass (kg/ha) (H 1 : 1934, H 2 : 1700, H 3 : 3093, H 4 : 1416) [Figure 2].
|Figure 2: The comparing average of dried weight plant species that eaten by gazelles in each habitat|
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Eighty plots are sampling with 1 m × 1 m was conducted to determine grass species density across the sites. To estimate the density of shrubs and bushes, T-square sampling method was performed as recommended by Krebs (1999). Field procedures related to density measurements were carried out in all winter period, as well as in April 2010. The following equations were used in this regard: 
where is estimated T-square of population density, n is the number of samples, and Zi is the interval of T-square to randomized point i.
More powerful estimators of population density have used the following formula for species density measurements, which is made by a combination of and formula.
The standard error of was calculated by the following equation:
where is the average intervals between random points and the organism (mean of xi ), is the mean of distances, which occur between the organism and the nearest living organism (mean of zi ), N is the number of samples, S 2x is the variance of xi , Sxz is the covariance of xi.
Random points were used to determine herbal species density. These points were characterized by plotting. In total, 20 plot (1 m × 1 m) in each habitat type were established (numbers of total plot) and density of herbaceous species in each unit was calculated. Total density of herbaceous species, consumed by the gazelle, were calculated by adding bushes, shrubs, and gramineous densities together. The amount of production and biomass of each habitat was determined using dried - weight technique and herbal species density (the amount of plant production could be calculated by fraction of dried weight to density; multiplying density by consumption percentage of herbivorous, the biomass would be achieved.  Ultimately, the CC for each habitat was calculated using weight average, metabolism of each species, foraging (browsing), the proportion of herbivorous in each habitat [Table 1], animal unit, and valuing each herbivorous  (animal unit: This mean each animal eat a certain amount of food, for example, sheep and goat 1.5 kg/day they requires food intake, and animal unit for Gazella in (SHN) was calculated (1.328 kg/day) [Table 2].
|Table 2: Percentage of availability Persian Gazella in 4 stations were chosen|
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| Results|| |
According to the climatology report and amiable information from the environmental game wardens, the duration of critical period was determined about 90 days. It should be mentioned that during past 10 years, there has been no heavy snowfall in this region. Hence, the snowfall average of this period was calculated ~ 10cm, thus this depth because of not having affected on herbivory behavior, especially the gazelles. This value was not considered in our analysis.
The results show that the Persian gazelle exists mainly in Northwest of (SHNP) [Figure 2]. Production maximum/minimum was related to habitats 4 and 2 with amounts of 193 and 12.4 kg/ha, respectively [Table 3]. The amount of production in habitat 1 is more than habitat 3 [Table 3]. The amount of available grassy production might be lower than the calculated value. This probably due to some uncalculated parameters such as wind and rain that would destroy herbaceous species.  In relation to gazelle diet, 15 herbal species from 14 genera consumed by both wild sheep and gazelle were identified. Among 8 identified plant families, Poaceae with 8 species showed that has the greatest contribution to the gazelle diet. On the other hand, herbaceous families such as Astraceae, Plumbaginaceae, Caryophyllaceae, Lamiaceae, Chenopodiaceae, Polygonacea, and Papilionaceae, have shown that each family contributes with only one species, in both gazelle and wild sheep diets [Table 4].
We estimated the total carrying-capacity value (107, ind) for the gazelle by excluding the potential competitors: Rabbit and wild sheep. Meanwhile, the CC for each habitat (H) were estimated as (H 1 = 81 ind, H 2 = 7 ind, H 3 = 13 ind, H 4 = 6 ind). It was expected that (H 4 ) might support higher value of CC for the targeted species while the results showed that the (H 4 ) supplies the lowest value of CC for the species. This contradict might be due to more safety, lower latitude, and more sunshine in this area in contrast with other habitats. Indeed, the obtained results from CC estimations illustrates that (H 1 ) provides more forage for gazelle in the critical period. More importantly, considering the existence of other competitors such as rabbit and wild sheep, total CC for gazelle was estimated about 56 in [Table 5].
| Discussion|| |
According to Kingswood and Blank (1996), a community of Tamarix could provide a shelter, windbreaker and also food for gazelles during cold seasons. The 99% in the correlation of Tamarix and gazelle consuming from this plant in winter did not observable during autumn. These researchers showed that the desirability of Tamarix in winter is more than that of the autumn because the amount of salt in Tamarix boughs has a lower influence on thirst of the herbivorous in winter [Table 1]. However, there were no evidence found as to consumption of this species by gazelle in SHNP.
Some factors including the wind, temperature, and deep snow are obstacles to herbivorous life on the mountains. Snow coverage and other climatic parameters are effective factors to herbivorous species in the winter season.  These viewpoints are confirmed for gazelles in SHNP. The results showed that the carrying-capacity of the different habitats are not providing the equivalent quantity for the species of interest, this may be influenced by various ecological parameters, for example, the relative abundance of competitors, elevation, slope and the soil, and topographic reasons.
In addition, changes in food resources and availability could be due to nutritional overlapping in symbiotic herbivorous, especially the competitors.  If the nutritional overlapping is to be high among the species and the mount of forage is to be low, the competition for grass recourse could have greater impact on CC of the habitats.  Therefore, CC for all herbivorous species and their nutritional overlapping have been noticed in this research. However, this has not been mentioned in many studies. It has to be noted that it is so difficult to make decisions just according to the 1-year survey. Therefore, it is necessary for such studies to be conducted for several years to finally determine the CC of gazelle's habitat. On the other hand, this CC was calculated for critical months, it means the winter and it is obvious that the habitats in (SHNP) are able to hold this population in the other months that are not critical.
The question of why gazelles are seen in agricultural farms of (SHNP) is noticeable; it presumably, because of the real amount of herbal biomass is lower than what was estimated above. Another considerable point is that the herbal species diversity is not high in the area. Furthermore, the dominant species in this area is A. sieberi and although this species has a high amount of protein, it is not responsible for the gazelle's feeding requirements alone practically, the habitat of gazelle in this park is highly restricted by some human-induced reasons such as the military station of this area, highly building legal and illegal activities on the edges of this region, and some ongoing projects such as gas pipelines and livestock grazing are the main threats to the wildlife. In addition, because of migration constraints, gazelle's migration has drastically hindered by above-mentioned threats nowadays.  It is worthy of mention that during sampling in the study area, herds of domestic sheep and donkeys were observed and there is no doubt that they consume some nutrient biomass, and potentially these livestock can be a serious competitor for the herbivores in SHNP. Moreover, illegal hunting by the locals, being vicinity to closeness to the capital city, Tehran, and availability of this area, not excluded (unprotected from grazing), road construction and similar factors are main reasons of decreasing the number of this species (Bomabad Consulting Engineers, 1381).
According to the data or even total census data, the population size of the (G. subguttrosa) was about 40-50/ind. Therefore, our estimated value of carrying-capacity by including competitors indicates that the habitats seem are capable of supporting the existent gazelle populations in SHNP. To conclude, when evaluating the carrying-capacity, we strongly, recommend to study the dietary behavior (dung analysis) of the species, which could allow taking into account the potential food diversity intake and the livestock population sizes.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]