The effect of fire on the structural and functional characteristics of vegetation (case study: Astragalus spp. habitat of Kabodeh, Kermanshah)

Borzou Yousefi ¹ ( Department of Natural Resources Research, Kermanshah Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Kermanshah, Iran )
Mohammad Gheitury ² ( Department of Soil Conservation and Watershed Research, Kermanshah Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Kermanshah, Iran )
Mosayeb Heshmati ³ ( Department of Soil Conservation and Watershed Research, Agriculture and Natural Research Center, Agricultural Research, Education and Extension Organization (AREEO), Kermanshah, Iran, Iran )
Reza Siahmansour ⁴ ( Department of Soil Conservation and Watershed Reasearch, Lorestan Agricultural and Natural Resources Research and Education Center, Agricultural Research, Education and Extension Organization (AREEO), Khorramabad, Iran )

تاريخ الإرسال : 25 السبت , رجب, 1443 تاريخ التأكيد : 30 السبت , جمادى الأولى, 1444

الکلمات المفتاحية: Canopy cover, production, Density, Range condition, Range trend, Rangeland fire,

ملخص المقالة :

Wildfires annually occur as a threatening factor in natural resources at a large scale. This study was conducted with the aim of determining the effects of fire on the structural and functional characteristics of vegetation in the Kaboudeh range site, Kermanshah province, Iran during three years (2018-2020). An unburned range (control) was selected near the burned range. Both sites had the same characteristics. Sampling was preformed at a stratified random with four 50 m transects and 20 m distances as well as 10 fixed quadrates (1 m2). The spatial correlation was performed between quadrates.Data were collected for plant density (no/m2), canopy cover (%), and production (g/cm) for species and palatability classes. The range condition and range trend were evaluated using four factors and balance methods. The results showed that the palatable plants in the fire site were decreased with density (1.7 no/m2), production (4.1 g/m2), and canopy cover (3.9 %) compared to the control. In the first years after the fire, the fire decreased the number of palatable plants, and decreased the average values of production and canopy cover both by approximately 75%, butthe class II plants had not significantly decreased.In the burned site, the invasive plants (Class III), dominated by annual grasses, have spread rapidly across the range.The range condition in the burned area was poor andrange condition trend was positive, but in the control area,range condition was medium and range condition trendwas constant.In the short term, fire drastically caused the increase of annual grasses,decrease of species diversity, and subsequentlyled to a decrease in the stability of the range.

نص كامل:



The effect of fire on the structural and functional characteristics of vegetation (case study: Astragalus sp. habitat of Kabodeh, Kermanshah)

 

Abstract

Wildfires occur as a threatening factor in natural resources at a large scale annually. This study was conducted with the aim of determining the effects of fire on the structural and functional characteristics of vegetation in the Kaboudeh range site, Kermanshah province, Iran that was carried out during three years (2018-2020). An unburned range (control) was selected near to burned range. Both of these sites had the same characteristics. Sampling preformed at a stratified random with four 50 m transects and 20 m distances as well as 10 fixed quadrates (1 m2). The spatial correlation was performed between quadrates. The range structural and functional characteristics were evaluated. The plant density (n/m2), canopy cover (%), and production (gr/cm) were determined for species and palatable classes. The range condition and range condition trend were evaluated by 4 factors and balance methods. The results showed that the palatable plants in the fire site were decreased with density (1.7 n/m2), production (4.1 gr/m2), and canopy cover (3.9 %) compared to the control. In the first years after the fire, the fire leads to a decrease in the number of palatable plants and the average values of production and canopy cover by approximately 75%, but the class II plants had not significantly different. In the burned site the invasive plants (Class III), dominated by annual grasses, have spread rapidly across the range. The range condition in the burned area was poor and range condition trend was positive, but in the control area, range condition was medium and range condition trend was constant. In the short term, fire drastically caused increase of annual grasses, decrease of species diversity, and subsequently leads to a decrease in the stability of the range.

 

Keywords: Canopy cover, Density, Fire, Production, Range condition trend 

 

Introduction

Fire is one of the factors that greatly affect natural cycles and is one of the most important influencing factors on the structure and composition of plant communities, especially in arid and semiarid rangelands (Naghipour Borj et al., 2019).

As Yin et al. (2004) reported, wildfires are one of the most pervasive factors destroying natural ecosystems. Fire is a powerful ecological and evolutionary force that regulates organismal traits, population sizes, species interactions, community composition, carbon and nutrient cycling and ecosystem function (McLauchlan et al., 2020). Studying the effects of fire regimes and behavioral patterns improves understanding of range ecosystems and management strategies (Tainton and Mentis, 1984).

In the report of Corbin and D'Antonio (2004), fire has rapidly reduced perennial grasses and has been cited as an effective factor in controlling shrubs and woody shrubs. Davies et al. (2008) reported that fires in the cold season of the year cause rapidly grow the grasses and provide good vegetation in the range. Severe fires, such as wildfires, generally have several negative effects on soil. They cause significant removal of organic matter, deterioration of both structure and porosity, considerable loss of nutrients through volatilization and etc (Certini, 2005).

Some species are very sensitive to fire and do not regenerate after the fire (Ravi et al., 2009). The effect of fire on vegetation in different habitats is varied and the spatial effect of fire on its consequences is undeniable (Siah Mansour, 2013). In grasslands with hardy and non-palatable perennial herbaceous species, cold fires improve palatability and increase their nutritional value (Bond and van Wilgen, 1996). According to Wood and Blackburn (1981), a part of the effects of fire occur underground. Garnier et al. (2002) believe that frequent fires create an impermeable layer under the surface soil and reduce water infiltration. The fire reduces the depth of soil surface layers and reduces the amount of organic carbon (OC), nitrogen, and organic matter in the soil surface, and increases the amount of phosphorus, calcium, and soil pH (Snyman, 2004). Also, the fire caused reduces in the amount of soil carbon sequestration (Faraji et al., 2019) and severe impact of vegetation in range (Fattahi and Tahmasebi, 2010). Siah Mansour et al. (2015) were reported that woody plants, including shrubs, suffered more fire damage than herbaceous species, and their density and regeneration were greatly reduced. The density, canopy cover percentage, and forage production of various palatability plants unless shrubs were increased significantly by fire (Mirdavoodi et al., 2019). The fire significantly reduced the vegetation cover and litter, increased the bare soil surface, decrease the shrubs, and increase the proportion of perennial grasses, annual grasses, and annual forbs (Naghipour Borj et al., 2019).Sharifi and Imani (2006) stated that fire reduces the percentage of canopy cover in palatable plants (Class I) but increases it in invader plants (Class III). The number of plant individual, the index of Menhinick's richness and the Shannon diversity index were significantly affected by fire in Sirachal research station of Iran (Hamzeh’ee et al., 2020).

Fire and its subsequent negative effects on soil and vegetation are important for rangeland sustainability (Stavi, 2019). In range management, it is important to manage the factors of fire severity, fire season, and its recurrence (Snyman, 2004). According to Stubbenddieck et al. (2007) report, the effective factors on fire behavior include the amount of grass, the weather conditions in the past and present, and the target of the fire. Trollope (1999) stated that effects of fire on savanna grassland depend on wind intensity, humidity, amounts of fuel materials and etc.

The different conclusions in literature and observations show that the effects of fire on ecosystems are very diverse and its consequences are also different. Interactions between fire and other disturbances, such as drought are likely to be the primary drivers of ecosystem change in a warming climate (Halofsky et al., 2020).

Therefore, the study of the effect of fire on plant species and its consequences in different range habitats has research value as a method of improving rangelands in different ecological conditions. It should be noted that the challenge is the conservation, preventative and remedial action and ongoing management of ranges to protect biological diversity and maintain the ecological processes which provide the productive capacity of its natural resources (Mapiye et al., 2008). The unintentional or intentional fires usually occur in some area of zagross rangeland every year by humans and affect range conditions and stability. Accidental fires (wild burning) increase fire hazards which could destroy wildlife and protected rangelands (Trollope, 1999), causes environmental problems and affects the livelihood of the Livestock and indigenous people. There is need to validate and provide more evidence of the damage or probably benefits of fires to rangeland productivity. This study was designed to investigate sensitivity of vegetative forms to fire, effect of fire on density, canopy cover, and production of palatable classes and the role of fire on vegetation dynamics in semi-steppe range of Zagros region. What kind of quantitative and qualitative changes does the wildfire cause in the rangelands? What destructive or positive effects does wildfire have on range conditions?

 

Materials and methods

Study area
The study area at the latitude of 34◦ 15′ 69″ and longitude of 47◦ 5′ 60″ is located 10 km from the southeast of Kermanshah (Figure 1). Apart of this rangeland (17.7 ha) was accidentally burned by some indigenous people in 2017. The land use map of the surrounding area of the studied site is shown in Figure 2. The average annual rainfall of the study area is 470 mm, indicating a cold semi-arid region as outlined by the Köppen climate classification method.

The average slope is 25% with southwest aspect. The altitude varies from 1300 to 1500 meters above the sea level. The site has moderately-deep soil and loam-clay texture (Ahmadi, 2008). This site is one of the summer rangelands of Kermanshah province that has caught fire in June, 2017. Before the fire, the rangeland type was Astragalus verus Olivier – Festuca. ovina in both control and fire areas, but after the fire, the rangeland type in the fire area changed to Teaniatherum caput medusae- Avena barbata- Agrostema gittago (Gheituri, 2005). The control area with Topographic, climatic and soil conditions almost similar to the burned area (rescued rangeland section) was 60 hectares and attached to the burned area.

 

 

Fig. 1. Geographical location of the burned and control site in Kermanshah province

 

 

Fig. 2. The land use map for the surrounding area of the studied site in Kermanshah province

 

Research Methods
Measurement of structural and functional traits of vegetation

In the three years (2018-2020) based on Systematic random sampling method, the four transects with 50 meters long and 20 meters distances accomplished and the 10 fixed quadrates (1m2) on each transect were used for measurements of plant density, canopy cover and production traits. The spatial correlation was performed between quadrates. The size of quadrates was calculated using the minimal area method on the bases of vegetation size and distribution. All four transects formed a sample unit. A homogeneous area was selected in burned site and control area. For the study of the type changes, by survey method, the dominant species and the new type were determined and the floristic list of the area was recorded. The percentage of cover, plants composition, and density were determined. Forage production calculated by Estimation and Double Method (Arzani, 1994) during (2018-2020).

The species variations was studied by preparing floristic lists by survey method and comparing them with each other and the presence or absence of species in control and burned site. To determine the plant composition at the plot level, statistics methods were performed. The canopy cover of each species was recorded along transects and then examined by summing and averaging the share of each species in the plant composition of the burned and control area. The canopy cover was determined using the vertical image of the plants on the ground by each species separately within quadrates along transects. The production (growth rate of rangeland plants in the growing season) was calculated at each plot. Also, the density of plants was measured by counting the number of perennial plants by species within the quadrates along each transects (Arzani and Abedi, 2014).

The amount of production for each species and palatability classes in the control area is determined by cutting and weighed with the Estimation and Double Method (Arzani, 1994) and then repeated in the burned area. The amounts of production decrease were determined for species and forage classes by calculating the difference between fire and control treatments during two vegetation periods. In the first year after the fire, the species removed under the influence of fire indentified by comparing the floristic list in the control and burned area. 

The condition of the rangeland determined by the four-factor method (Soil erosion, canopy cover, plant composition, and plant vigor) and the range condition trend by the balance method (Arzani and Abedi, 2014; Borhani et al., 2010)

 

Statistical analysis

The data recorded for three years. The analysis of variance, T-test and factor analysis was done using SPPS software (ver.16). The mean squares were compared using the Duncan test (Fotohi and Asgari, 2008). 

 

Results

Plant composition in burned and control sites

The study areas including both control and burned sites comprise 57 plant species belonging to 23 vegetation families. However, 44 and 30 plant species were distinguished in unburned and burned sties, respectively (Table 1). Furthermore, the respective more frequent plant species in unburned and burned sties belonged to the Poaceae and Fabaceae families. In the burned area, seven species, and in the control area, nine species belong to the Poaceae family were growing. From the Fabaceae family, three species in the fire area, and eight species in the control area were found. In the burned site, no class І plant grew, but in the control area, the seven class І species were grown (Table 1).

Structural and functional traits of vegetation

The predominant vegetative form at the burned site was annual species, especially annual grasses such as Bromus tectorum, Avena barbata, Bromus danthonia, Agrostamma gihtago (annual herb), Teaniatherum caput-medusae, and poa annua. In contrast, forbs and shrub species have been severely reduced by fire. Mean comparison of production, density and canopy cover for vegetative forms between fire treatments (1 to 3 years after fire) showed that grasses have not significant mean difference for production in burned area and control but have a significant mean difference for canopy cover and density. While the shrubs and herbaceous forbs in terms of density, canopy cover and production had a significant difference at the level of 1% between burned site and control (Table 2).

Mean comparison between vegetative forms (Table 2) showed that there was significant differences for density, canopy cover and production and grasses had the maximum density (25.2 n/m2), canopy cover 27.4 %) and production 24.6 (gr/m2). The minimum density (0.24 n/m2), canopy cover (3.00 %) and production (1.32 gr/m2) were observed for shrub plants in the burned site.

Comparison of means between treatments (burned area and control) showed significant difference for density, canopy cover and production. The highest density (21.3 n/m2), canopy cover (21.5 %), and production (22.8 g/m2) were observed in control area for class П plants and the lowest of them for class І plants in the burned site (Table 3).

There was a significant difference between the fire treatment and the control in all years for the amount of forage production. The highest production rate was 160 kg/ha for class I plants in the control treatment in 2019, which was even higher than in 2020, and the reason is probably the appropriate rainfall in 2019. For Class II plants, the highest yield of 190 kg/ha and the highest harvestable forage (76 kg/ha) were obtained in 2019. Also, for class III plants, the highest production (235 kg/ha) was obtained in 2018 and the highest harvestable forage (65 kg/ha) was obtained in 2019 (Table not provided). 

 

 

 

 

Table 1. The list of range plant species in burned and unburned site(control)
Family	Species	Palatable class	Presence		Family	Species	Palatable class	Presence
			Burned site	Unburend site				Burned site		Unburend site
Apiaceae	Eryngium thyrsoideum Boiss.	III	+	+	Caryophyllaceae	Agrostemma githago L.	II	+		-
	Prangos ferulacea (L.) Lindl.	I	-	+		Velezia rigida L.	III	+		-
	Scandix stellata Banks & Sol.	II	+	-		Crassolaceae	Rosularia sempervivum (M. Bieb.) A. Berger.	III	-		+
	Smyrniopsis aucheri Boiss.	II	-	+			Umbilicus intermedius Boiss.	III	-		+
Asteraceae	Anthemis odontostephana Boiss.	II	+	-	Euphorbiaceae	Euphorbia cheiradenia Boiss. & Hohen.	Ш	+		+
	Centaurea intricate Boiss.	III	+	+	fabaceae	Astragalus verus Olivier	Ш	-		+
	Senecio vernalis Waldst. & Kit.	II	+	+		A. gossypinu Fischer	Ш	-		+
	Crupina crupinastrum (Moris) Vis.	II	+	+		A. laguriformis Freyn	Ш	-		+
	Gundelia tournefortii L.	II	+	+		A. rhodosemius Boiss. & Hausskn.	Ш	+		+
	Tanacetun polycephalum (L.) Schultz-Bip.	I	-	+		A. macroplematus	Ш	-		+
Boraginaceae	Onosma microcarpum DC.	II	-	+	A. hamosus L.	Ш	+		+
Brassicaceae	Auberitia parviflora Boiss.	Ш	+	+	Pisum sativum L.	III	+		+
	Fibigia macrocarpa (Boiss.) Boiss.	II	+	+	Vicia variabilis Grossh.	I	-		+
Campanulaceae	Campanula perpusila A. DC.	II	+	-	Fagaceae	Quercus libani G.Olivier	II	-		+

 

 

 

 

Table 1. (Continue). The list of range plant species in burned and unburned site(control)
Family	Species	Palatable class	Presence		Family	Species	Palatable class	Presence
			Burned site	Unburend site				Burned site		Unburend site
Iridaceae	Cerasus microcarpa (C.A.Mey.) Boiss.	III	_	+	Poaceae	Hordeum bulbosum L.	II	+		+
Lamiaceae	lamium amplexicaule L.	II	+	-	Melica persica Kunth	II	-		+
	Salvia multicaulis Vahl.	II	+	+	Noaea mucronata (Forssk.) Asch. & Schweinf.	III	-		+
	Stachys lavandulifolia Vahl.	I	-	+	Poa bulbosa L.	Ш	+		+
	Stachys kurdica Boiss. & Hohen.	I	-	+	Stipa arabica Trin. & Rupr.	II	-		+
	Teucrium polium L.	II	-	+	Taeniatherum caput- medusa (L.)	III	+		+
	Ziziphora clinopodioides L.	II	-	+	Rhamnaceae	Rhamnus pallassi Fisch. &C.A.Mey.	Ш	-		+
Moraceae	Ficus carica L.	II	+	-	Rosaceae	Amygdalus orientalis (Lam.) Rehder	Ш	-		+
Plumbaginaceae	Acantholimon olivieri (Jaub. & Spach) Boiss.	II	+	-	Rosaceae	Cerasus microcarpa (C.A.Mey.) Boiss.	Ш	-		+
Poaceae	Agropyron intermedium (Host) P. Beauv.	II	-	+
	Arrheratherum elatius (L.) P. Beauv. ex J. Presl & C. Presl	II	+	-	Rubiaceae	Callipeltis cucullaria (L.) Steven	Ш	+		-
	Avena barbata Pott ex Link	Ш	+	-	Sapindaceae	Acer monspessulanum L.	Ш	-		+
	Bromus tomentellus Boiss.	I	-	+	solanaceae	Hyoscyamus niger L.	II	+		-
	Festuca ovina L.	I	+	+	Thymelaceae	Daphena mucronata Royle.	III	+		+
	Heteranthelium piliferum (Sol.) Hochst. ex Jaub. & Spach	II	+	-	Urticaceae	Parietaria judaica L.	II	-		+

 

 

 

Table 2. Comparison of means between treatments (burned and control site) for density, canopy cover and production based on plant life forms in burned area and control with Duncan multi-range test
Vegetative forms	(Mean± standard deviation)
	Density (n/m2)		Canopy cover (%)		Production (gr/m2)
	Fire	Control	Fire	Control	Fire	Control
Forbs	2.7±0.56 b**	4.1±0.6 a	7.2±2.7 b**	12.8± 2.6 a	6.1± 0.9 b**	10.7±1.4 a
Shrubs & Tress	0.24±0.04 b**	1.3±0.7 a	3.0±1.6 b**	16.6± 4.3 a	1.32±0.22 b**	20.7±2.4 a
Grasses	25.2±2.1 a**	10.6±1.3 b	27.4±1.3 a**	15.5 ± 1.7 b	24.6± 4.1 a	22.7±3.1 a
The letters show the difference in the mean classes. * and **, significant difference at the level of 5% and 1% respectively.

 

Table 3. Means Comparison of forage production in different palatable classes using Duncan test
Palatable classes	(Mean ±Standard deviation)
	Canopy cover (%)		Density (n/m2)		Production (g/m2)
	Control	Fire	Control	Fire	Control	Fire
Class І	9.7 ± 0.9 a**	3.9 ± 0.6 b	8.0 ± 1.2 a**	1.7 ± 0.9 b	18.2 ± 2.8 a**	4.1 ± 1.1 b
Class П	21.5 ± 1.80 a**	21.2 ± 0.6 a	21.3 ± 2.2 a	23.1 ± 2.9 a	22.8 ± 2.7 a**	15.1± 2.3 b
Class Ш	18.1 ± 1.30 a**	10.2 ± 1.3 b	7.1 ± 1.4 a**	5.2 ± 0.5 a	13.7 ± 1.4 a**	5.7 ± 0.7 b
The letters show the difference in the mean classes. * and **, significant difference at the level of 5% and 1% respectively.

 

The study revealed that the range condition in burned site was poor during three years of the study indicating the severe effects of fire occurrence on rangelands. In contrast, range condition trend at first year after the fire incidence (2018) was negative, while, there was changed to positive in the second and third years after the fire (2019 and 2020). In the control area, the range condition was medium and the range condition trend was constant in all three years of the study (2018-2019).

Discussion and Conclusion

A case of human wildfire intentionally or accidentally occurred in the Kabudeh rangeland in Kermanshah province (Iran) in the 2017. In order to investigate the effects of this fire on plant vegetation and the range condition and trend, this area was studied for three years after fire.

The vegetative forms of shrubs and woody plants have been severely depleted in the burned site. The density at the level of 1% and canopy cover (p< 5 %) has a significant difference between the two areas and has higher values in the control area. In the shrubs and woody plants due to the presence of flammable woody branches and stems and the presence of buds and terminal meristems above the ground level, the susceptibility to fire is higher and its death rate is higher. Some authors reported that the fire is a strong deterrent to shrubs and woody plants (Fulé et al., 2007; Tizon et al., 2010; Stubbenddieck et al., 2007; Zimmerman et al., 2008; Reinwald, 2013).

The density of annual grasses and annual herbaceous plants in the burned site was higher than the control. The predominance of grass production in this area is related to annual grasses such as Bromus tectorum, Avena barbata, Bromus Danthonia, Agrostama githogo, Teaniatherum caput-medusae, and poa annua. Humphrey and Scoop (2001), and Rimer and Evans (2006) have reported an increase in annual plants in one year after the fire, but Reinwald (2013), Corbin and D'Antonio (2004), Humphrey and Scoop (2004) announced an increase in perennial plants by fire. The canopy cover, in the burned area is less than the control area. The annual alfalfa, Trigonella, Medicago, Crupina crupinastrum, Astragalus hanisus, especially Euphorbia cheiradenia, and annual species of the genus Centaurea were dominant share of the canopy cover in control and burned area. These plants have been able to re-establish the first growing season after the fire, due to abundant seed production and taking advantage of the available moisture. Dale et al. (2002), Snyman (2004), and Jones et al., (2000) reported an increase in herbaceous annual plants after the fire. In annual plants, the resistance and location of the seeds during the fire is crucial, and the greater heat can increase the seed mortality.

The fire, two years after onset, had severe affects on herbaceous forbs such as Prangus ferulacea with a sharp decline in average production. Bennett et al. (2002), Christopher (2009), Snyman (2004), Zimmerman et al. (2008), Boyd and Davis (2010), and Prevey et al. (2010) believe that herbaceous forbs are sensitive and vulnerable to fire.

In the burned area, annual plants (especially annual grasses) and invaders species (class III) had the higher production and canopy cover, and this superiority was maintained in every three years (2018-2020), while in the control area palatable plants (class I) were superior, indicating that fires in grassland increase invasive species and reduce the production and canopy cover of perennial palatable species in the short term. Boyd and Davies (2010), Dale et al. (2002), Snyman (2004), Bennett et al. (2002), Garnier et al. (2002) reported a decrease in the amount of decreasing plants (class I) in the short term. In each three years (2018-2020), in the control area, palatable species had a higher production and canopy cover than in the burned area. Mapiye et al. (2006) and Bebawi and Campbell (2002) reported reduced canopy cover and production of shrubs as a result of the fire. 

The density of Bromus tomentellus, between fire and control treatments was differing and decreased in the burned area. The Festuca ovina in 2018 (two years after the fire) was more dense than other perennial grasses and the average density of this species in the control field was higher than the burned site. The fire has led to the development and spread of annual grasses in the burned site. Hordeum bulbosum is almost completely was removed by the fire in 2018 due to being under the canopy cover of shrubs and Daphne mucronata, but its density has increased to some extent by propagation by seeds in the second and third years after the fire. Badia and Marty (2003), Bennett et al. (2002), Lesica and Martin (2003), and Zimmerman (2008) were emphasized the drastic reduction and elimination of batch grasses after the fire. Garnier et al. (2002) and Bennett et al. (2002) reported a decrease in the canopy cover for annual forbs, but vice versa, Medaniel et al. (2000), Dale et al. (2002) and Snyman (2004) reported an increase in annual canopy cover. Mirdavoodi et al. (2019) resulted that the density, cover percentage and forage production of perennial and annual forbs, and annual grasses were increased significantly by fire but density and cover percentage of shrubs decreased. The fire also was increased the proportion of high and moderate palatable species (class I and II) and reduced the proportion of class III species (Naghipour Borj et al., 2019). The fire significantly was increased the relative abundance of palatable grade III plants in soil seed banks but decreased the frequency of class III (Nabizadeh et al., 2020). The fire was caused increases in forage production, canopy cover and density of grasses and forbs but significantly decreased density and canopy cover of shrubs (Mirzaei Mossivand, et al., 2015). The results of this some newly studies are consist with our resalts. 

The fire causes decrease in species diversity, canopy cover, rangeland production, and palatable plants, and subsequently, in the short term, leads to a decrease in the stability and richness of the rangeland. After the fire the population of Astragalus spp. decreased drastically but the annual grasses increased sharply.

 

Acknowledgment

The authors gratefully acknowledge the financial support for this work that was provided by RIFR, Tehran, Iran.

 

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تأثیر آتش­سوزی بر صفات ساختاری و عملکردی پوشش گیاهی (مطالعه موردی: گون­زارهای منطقه کبوده، کرمانشاه)

 

چکیده. آتش‌سوزی به‌عنوان یک عامل تهدیدکننده منابع طبیعی هر ساله در مقیاس وسیع رخ می‌دهد. این مطالعه با هدف تعیین اثرات آتش سوزی بر صفات ساختاری و عملکردی پوشش گیاهی در گون­زارهای منطقه کبوده در استان کرمانشاه، طی سه سال (1399-1397) انجام شد. این مرتع در سال 1396 دچار آتش سوزی شده بود. یک مرتع شاهد با ویژگی­های مشابه در مجاورت محل آتش­سوزی انتخاب شد و با استفاده از روش سیستماتیک- تصادفی، چهار ترانسکت 50 متری (با  فواصل 20 متر از یکدیگر) و 10 کوادرات ثابت با مساحت 1 متر مربع ایجاد و تراکم بوته­ها اندازه گیری شد، تاج پوشش گیاهان با استفاده از تصویر عمودی گیاهان روی زمین توسط هر گونه به­طور جداگانه در طول ترانسکت­ها و پلات­ها تعیین شد. سپس تاج پوشش هر گونه در امتداد ترانسکت­ها برداشت شد و سهم هر گونه در ترکیب پوشش گیاهی و میزان تولید در هر کرت محاسبه شد. وضعیت مرتع با روش 4 عاملی و گرایش مرتع به روش امتیازدهی به علائم قهقرا در پوشش گیاهی و خاک، ارزیابی شد. نتایج نشان داد که بین تیمارهای شاهد و آتش سوزی در سطح 1 درصد تفاوت معناداری وجود داشت. گیاهان کلاس I در مناطق شاهد و آتش­سوزی برای تولید و تاج پوشش در سطح 1 درصد و برای تراکم در سطح 5 درصد تفاوت معنی­داری نشان دادند. در سال­های اول پس از آتش­سوزی، گیاهان خوش خوراک در محل آتش سوزی با تراکم 7/1 (تعداد بر متر مربع)، تولید 1/4 (گرم در متر مربع)، و تاج پوشش (9/3 درصد) نسبت به شاهد 75 درصد کاهش نشان داد، اما گیاهان کلاس II تفاوت معنی­داری نداشتند و گیاهان مهاجم یا کلاس III (بیشتر گراس­های یکساله) غالب شده و به سرعت در سطح مرتع گسترش پیدا کردند. آتش­سوزی باعث کاهش مقدار تولید مرتع و کاهش پایداری گرایش مرتع شده بود. وضعیت مرتع در منطقه سوخته ضعیف و در منطقه شاهد متوسط بود. گرایش مرتع در منطقه سوخته مثبت و در منطقه شاهد ثابت بود. در نهایت می‌توان نتیجه گرفت که آتش­سوزی در کوتاه مدت باعث کاهش تنوع گونه­ای، کاهش تاج پوشش و تولید مرتع و متعاقباً کاهش پایداری و غنای مرتع می­شود. پس از آتش­سوزی، جمعیت گونه­های گون به شدت کاهش یافت اما گراس­های یکساله در مرتع به شدت افزایش یافتند.

 

کلید واژگان: آتش­سوزی، تاج پوشش، تراکم، تولید، گرایش مرتع

 

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