Introduction

The Himalayan region is known for its unique and diverse flora and fauna. The biodiversity of the region is utilised by people for various uses like fodder, fuel wood, medicine  and timber. Forest fire is very common problem in various forests in world  and are the main cause of changes in population of plants and animals. It even affects the biodiversity and environment. Forest fires are important component of disturbance regime of various forests of the world and altering composition and structures of vegetation types (Elliot et al., 1999; Barden and Woods, 1976; Harmon, 1982; Buckner, 1989; Van Lear and Waldrop, 1989; De Vivo, 1991; Van Lear, 1991).

The sub-tropical pine forest occupy 18,102 km² area, which constitute 2.36 % of the total forest area of the country (FSI, 2019). The sub-tropical pine forest are found in Jammu & Kashmir, Himachal Pradesh, Haryana, Punjab, Uttrakhand, Assam, Manipur, Mizoram, Meghalya, Nagaland and Arunachal Pradesh (FSI, 2011)

Himalayas are home to pines with history of forest fires as old as the forests themselves. The health of the forests is the indicator of ecological condition present in any site. The repeated forest fires of different intensity are the main cause of habitat’s modification of flora and fauna in any landscape.  Chirpine forests are prone to forest fire every year and forest fire is one of important cause which does incalculable harm to chirpine forests.  The main cause of damage to forest after deforestation is forest fire. The occurrence of forest fires destroy or degrade forest and even finish the hard work of forest managers of generation. The cause of forest fire can be divided into three classes i.e. natural, people’s carelessness and due to  deliberate and intentional action. Fire has been used as a silviculture treatment in various landscapes to restore productivity and diversity (Swift et al., 1993 and Elliott et al., 1999). Forest fire affects the diversity of herbaceous flora. The physical environment has been modified for our benefit by human being since long time and fire is one tool used for gaining the benefits (Schmerbeck and Fiener, 2015, Pyne, 1995).

Controlled burning is a tool in management of chirpine forest to reduce incidence of forest fire.  The burning treatments are used throughout the world to reduce the fuel load (Cronan, et al., 2015, Schwilk et al., 2009 and Stephens et al., 2012) to mitigate the uncontrolled fire. Various workers have conducted study on impact of burning in various landscapes of world (Alcaniz et al., 2018; Borja et al., 2016; Butnor et al., 2020; Catherine and Andersen, 2006; Eales et al., 2016; Elliot et al., 1999; Fernandes and Botelho, 2003; Hood et al., 2020; Huisinga et al., 2005; Magallanes, et al., 2020; Rawat, 1949 and Zhan et al., 2020). Forest fires generally occur in summers in these forests but sometime it is reported in other seasons also. The controlled burning is practiced in winter in chirpine forests in Western Himalaya. The lower cost and easiness may be the main reasons to use the controlled burning in winter to reduce the damage caused by forest fire of high intensity to environment in summer in chirpine forests.

The database on controlled burning and its impact on the diversity of herbs and natural regeneration of woody species in Chirpine forest is not sufficient in India. There is a need for understanding the impact of controlled burning on herbaceous vegetation in Chirpine forest, hence, the present investigation was carried out to study the effect of controlled burning on herbaceous diversity including regeneration of trees and shrubs.

Materials and Methods

2.1.  Study area

The investigation was carried out at altitude zone (>1200 m amsl) of chirpine forests in three forest divisions of Nahan and Solan Forest Circles of Himachal Pradesh, India.  One site each in three forest divisions was selected i.e. Mangotimor in Solan Forest Division, Bagpashog in Rajgarh Forest Division, Lawasachowki in Nahan Forest Division. The details of study sites is given in Table 1.

Table 1: The geo-coordinates and other details of study sites

The study area of 2 ha in each site was selected. Controlled burning was carried out once (B₁) in 1.5 ha during winter in 2017 with 0.50 ha areas kept as control (C) in all three sites. The geographic details of study sites are given in Table 1. Maximum temperature (°C) ranged from 16.4 to 30.50 and the minimum temperature (°C) ranged from 3.1 to 20.4. Average humidity (%) varied from 45 to 82 and total rainfall (mm) ranged from 7.6 to 233.8 (Source Meteorological Center, Department of Environment Science, Dr. YSP, UHF, Nauni, the meteorological data has been taken for January, 2017 to September, 2017). These study sites fall in upper or Himalaya, Chirpine forest (9/C1b) forest type (FSI, 2011).

2.2.  Field sampling and data collection

Sampling for phytosociological observations was carried out after rainy season in 2017 by laying 40 quadrates of 1×1 m² in each treatments i.e. C and B₁. Natural regenerations of trees and shrubs have also been included in phytosociological analysis with herbs.

2.3.  Data analysis

Density, frequency and abundance was calculated by Curtis and McIntosh (1950). Importance value index (IVI) was estimated by addition of relative values of density, frequency and basal area. The distribution pattern was estimated by calculating the abundance to frequency ratio (A/F) for different species. The ratio indicates contiguous (>0.050), random (0.025 to 0.050) and regular (<0.025) distribution (Curtis and Cottam, 1956).

The plant diversity was calculated by using Shannon- Wiener diversity index (H) (Shannon-Wiener, 1963).

         S

H=   ∑(ni/N) ln(ni/N)

         i=1

Concentration of dominance (Cd) was calculated by Simpson’s index (Simpson, 1949).

        S

Cd= ∑(ni/N)²

        i=1 

Where ni= importance value of species i and N= total importance value of all the species in both the indices.

Richness Index (R) was measured by using following formula (Margalef, 1958).

 R=S-1/ln N

Evenness index (E) was estimated as per following formula (Hill, 1973)

E=H/In S

Where S= total number of species, N= total number of individuals of all the species, H= Index of diversity.

Results and Discussion

Total 41 species belonging to 41 genera and 26 families were observed in all three sites. The number of species was 32 and 41 in control (C) and burnt (B₁), respectively.  Total number of species varied from 21 at Lwasachowki and Mangotimor to 24 at Bagpashog in control (C) whereas burnt site (B₁) it varied from 23 at Lwasachowki to 30 at Bagpashog.

3.1.  Site-mangotimor

At Control (C) area, total 21 species of herbs were recorded at Mangotimor (Table 2).

Table 2: Density/m2 of control and burnt area in selected study sites in chirpine forests

Table 2: Continue...

Maximum frequency % was observed for Chrysopogon montanus (40.00) and Heteropogon contortus (40.00) followed by Carex meiogyna (37.50), Adiantum lunulatum (17.50), Fragaria vesca (12.50), Oxalis corniculata (12.50)and minimum value (5.00) was observed for seedlings of Pinus roxburghii and Pyrus pashia as well as Parthenium hysterophorus (Table 3).

Table 3: Frequency (%) of control and burnt area in selected study sites in chirpine forests

Table 3: Continue...

Maximum abundance was observed for Carex meiogyna (8.00) followed by Heteropogon contortus (6.31), Adiantum lunulatum (6.00), Chrysopogon montanus (5.69),and minimum value (1.50) was observed for Pyrus pashia (Table 4).

Table 4: Abundance/m2 of control and burnt area in selected study sites in chirpine forests

Table 4: Continue...

Carex meiogyna (38.26) was dominant species on the basis of IVI at C followed by  Heteropogon contortus (35.42), Chrysopogon montanus (33.73), Adiantum lunulatum (20.71) and least dominant was Pinus roxburghii (5.10) (Table 5).  

Whereas, at burnt (B₁) area, total 25 species of herbs were recorded at Mangotimor (Table 2). Ageratum conyzoides showed highest value for density/m² (3.10) followed by Chrysopogon montanus (2.53), Lantana camara seedlings(2.25), Heteropogon contortus (2.13),and lowest value(0.13) was observed for Sapium insigne (Table 2).  Maximum frequency % was observed for Chrysopogon montanus (40.00) and Heteropogon contortus (40.00) followed by Ageratum lunulatum (25.00), Adiantum lunulatum (22.50), Lantana camara seedlings(22.50), Carex meiogyna (20.00), Hydrocotyl asiatica (20.00)and minimum value (7.50) was observed for Pinus roxburghii, Pyrus pashia and Sapium insigne (Table-3).  Maximum abundance was observed for Ageratum conyzoides (12.40) followed byby Carex meiogyna (10.75), Lantana camara seedlings (10.00), Adiantum lunulatum (6.44) and minimum value (1.67) was observed for Sapium insigne (Table 4). Ageratum conyzoides (25.42) was dominant species on the basis of IVI at B₁ followed Chrysopogon montanus (21.50), Lantana camara seedlings (20.85), Heteropogon contortus (19.51) and least dominant was Sapium insigne (6.14) (Table 5).

Table 5: Importance Value Index (IVI) of control and burnt area in selected study sites in chirpine forests

Table 5: Continue...

3.2.  Site-bagpashog

Total 24 species of herbs were recorded at Bagpashog at control (C) area (Table 2). Chrysopogon montanus showed highest value for density/m² (2.30) followed by Heteropogon contortus (2.13), Adiantum lunulatum (0.50), Ajuga bracteosa (0.50)and lowest value (0.15) was observed for seedlingsof Pinus roxburghii (Table 2). Maximum frequency % was observed for followed by Chrysopogon montanus (30.00), Heteropogon contortus (25.00), Adiantum lunulatum (10.00), Ajuga bracteosa (10.00), Viola serpens (10.00), Berberis lycium seedlings (7.50), Fragaria vesca (7.50), Myrsine africana seedlings (7.50), Oxalis corniculata (7.50), Pyrus pashia seedlings (7.50), Solanum nigrum (7.50), Sonchus asper (7.50)and minimum value (5.00) was observed for Anaphalis triplinervis, Artemisia vulgaris, Cirsium wallichii, Cissampelos pareira, Dicliptera bupleuroides, Geranium wallichianum, Leucas lanata, Pinus roxburghii seedlings, Rubia cordifilia, Rubus ellipticus seedlingsand Zanthoxylum armatum seedlings(Table 3). Maximum abundance was observed for Chrysopogon montanus (38.51) followed by Heteropogon contortus (34.86), Ajuga bracteosa (19.93), Adiantum lunulatum (15.18)andminimum value (6.61) was observed for Pinus roxburghii seedlings(Table 4). Chrysopogon montanus (38.51) was dominant species on the basis of IVI at C followed by Heteropogon contortus (24.86), Ajuga bracteosa (19.93), Adiantum lunulatum (15.18) and least dominant was Pinus roxburghii seedlings(6.06) (Table 5).  

Whereas at burnt (B₁) area, total 30 species of herbs were recorded at Bagpashog (Table 2). Chrysopogon montanus showed highest value for density/m² (3.40) followed by Heteropogon contortus (2.30), Leucas lanata (0.85), Pteris cretica (0.85), Solanum nigrum (0.85), Anaphalis triplinervis (0.75), Berberis lycium seedlings (0.750and lowest value (0.25) was observed for Zanthoxylum armatum seedlings(Table-2). Maximum frequency % was observed for followed by Chrysopogon montanus (47.50), Heteropogon contortus (45.00), Adiantum lunulatum (22.50), Berberis lycium seedlings (20.00)and minimum value (7.50) was observed for Artemisia vulgaris, and Zanthoxylum armatum seedlings(Table 3). Maximum abundance was observed for Heteropogon contortus (7.33) followed by Chrysopogon montanus (7.16), Leucas lanata (5.67), Myrsine africana seedlings (5.50)andminimum value (2.00) was observed for Cissampelos pareira (Table 4). Heteropogon contortus (27.23) was dominant species on the basis of IVI at B₁ followed by Chrysopogon montanus (26.84), Pteris cretica (12.65), Myrsine africana seedlings(12.39) and least dominant was Myrica esculenta seedlings (4.98) (Table 5).

3.3.  Site-Lwasachowki

Total 21 species of herbs were recorded at Lwasachowki at control (C) area (Table 2). Chrysopogon montanus (1.88) showed highest value for density/m² at C followed by Heteropogon contortus (1.50), Leucas lanata (0.63), Dicliptera bupleuroides (0.55) and least dominant (0.08) was recorded for Geranium wallichianum (Table 2). Maximum frequency % was observed (385.00) for Heteropogon contortus followed by Chrysopogon montanus (37.50), Adiantum lunulatum (10.00), Ageratum conyzoides (10.00), Cheilanthes farinosa (7.50), Dicliptera bupleuroides (7.50), Leucas lanata (7.50), Myrsine africana seedlings (7.50), Oxalis corniculata (7.50), Pinus roxburghii seedlings (7.50), Sonchus asper (7.50), Viola serpens (7.50) and minimum value (2.50)was observed for Geranium wallichianum (Table 3).Maximum abundance was observed for Leucas lanata (8.33)followed by Murraya koenigii seedlings (8.00), Dicliptera bupleuroides (7.33), Oxalis corniculata (6.67)andminimum value (0.39) was observed for Heteropogon contortus (Table 4). Heteropogon contortus (90.10) was dominant species on the basis of IVI at C followed by Chrysopogon montanus (31.39), Ageratum conyzoides (17.64), Viola serpens (13.37) and least dominant (5.29) was recorded for Rubus ellipticus seedlings (Table 5).

Whereas total 23 species of herbs were recorded at Lwasachowki at burnt (B₁) area(Table 2). Chrysopogon montanus (3.40) showed highest value for density/m² followed by Heteropogon contortus (3.30), Leucas lanata (0.85), Murraya koenigii seedlings (0.85), Cheilanthes farinosa (0.75) and least dominant (0.25) was recorded for Sonchus asper (Table 2).  Maximum frequency % was observed (47.50) for Chrysopogon montanus followed by Heteropogon contortus (45.00), Adiantum lunulatum (22.50), Cheilanthes farinosa (20.00) and minimum value (7.50)was observed for Carrisa carandas seedlings and Sonchus asper (Table 3). Maximum abundance was observed for Heteropogon contortus (7.33)followed by Chrysopogon montanus (7.16), Geranium wallichianum (5.50), Anaphalis triplinervis (5.00)andminimum value (2.78) were observed for Adiantum lunulatum (Table 4). Heteropogon contortus (33.48) at B₁ was dominant species on the basis of IVI followed by Chrysopogon montanus (33.01), Murraya koenigii seedlings (15.62), Geranium wallichianum (15.30) and least dominant (6.41) was recorded for Flacourtia indica (Table 5).

3.4.  Distribution pattern

The abundance to frequency ratio (A/F) for herbs was > 0.05 in C as well as B₁ in all the three sites which indicate that the distribution pattern of all the species was contiguous.

3.5.  Concentration of dominance (Cd)

The value of concentration of dominance (Cd) was highest (0.12) at Lwasachowki (C) followed by 0.07 at Mangotimor (C)  and lowest (0.04) at Bagpashog (B₁) (Table 6).

3.6.  Diversity index (H)

The maximum value of diversity index (H) was 3.30 at Bagpashog (B₁) followed by 3.13 at Mangotimor (B₁) and minimum was 2.63 at Lwasachowki (C) (Table 6).

3.7.  Species richness index (R)

The richness index (R)was highest (4.30) at Bagpashog (B₁) followed by 3.80  at Bagpashog  (C) and lowest was 3.22 at Mangotimor (C) (Table 6). 

3.8.  Evenness index (E)

The value of eveness index (E) was maximum (0.974) at Mangotimor (B₁) followed by 0.971 at Bagpashog (B₁) and minimum (0.863) at Lwasachowki (C) (Table 6). 

Table 6: Concentration of dominance (Cd), diversity index (H), richness index (R) and evenness index (E) of control and burnt area in selected study sites in chirpine forests

The total density was higher in burnt sites compared to control. The general pattern of plant distribution is contiguous in nature and has been observed by many workers (Kershaw, 1973: Singh and Yadava, 1974 and Kunhikannan et al., 1998) which means plants are adapted in chir pine forests due to frequent occurrence of forest fire. The greater value of concentration of dominance in control site (C) indicate homogenous nature of the community and vice versa (Kohli et al., 2004 and Verma, 2014). The diversity was higher in B₁ as compared to C  and various research workers (Elliot et al., 1999; Royoet al.,2010 and Agra et al., 2018) have reported the variation in diversity of ground flora due to treatments of burning. 

Conclusion

The density and diversity of herbs including regeneration of trees and shrubs were higher in burnt sites as compared to control. There is a need of conducting research to study long term impact of controlled burning on vegetation in chirpine forests.

Acknowledgement

Authors are thankful to Director, HFRI for guidance and thankful to Indian Council of Forestry Research and Education, Dehradun for providing financial support for the study. The authors are also thankful to Divisional Forest Officers of Nahan, Solan and Rajgarh Forest Divisions and frontline staff of Himachal Pradesh Forest Department for their assistance during the study.  

Reference

Agra, H., Schowanek, S., Carmel, Y., Smith, R.K., Ne’eman, G., 2018. Forest conservation. In: Sutherland, W.J., Dicks, L.V., Ockendon, N., Petrovan, S.O., Smith, R.K. (Eds). What Works in Conservation 2018. Open Book Publishers, Cambrige, U.K., 285-328.

Alcaniz, M., Outerio, L., Francos, M. and Ubeda, X. 2018. Effects of prescribed fires on soil properties: A review. Science of the Total Environment, 944−957.

Barden, L.S., Woods, F.W., 1976. Effects of fire on pine and pine hardwood forests in the southern Appalachians. Forest Science 22, 399−403.

Borja, M.E.L., Madrigal, J., Candel-Perez, D., Jimenez, E., Moya, D., Heras, J.D.L., Guijarro, M., Vega, J.A., Fernadez, C., Hernando, C., 2016. Effects of prescribed burning, vegetation treatment and seed predation on natural regeneration of Spanish black pine (Pinus nigra Arn. Ssp. salzmannii) in pure and mixed forest stands. Forest Ecology and Management 378, 24−30

Buckner, E.R., 1989. Evolution of Forest types in the South East. In: Waldrop, T.A. (Ed.), Proceedings of pine- hardwood mixtures: A symposium on management and ecology of the type, 18-19 April 1989 at Atlanta, GA. United State Forest Service General Technical Report.  SE-58, 27−33.

Butnor, J.R., Johnsen, K.H., Maier, C.A., Nelson, C.D., 2020. Intra-Annual Variation in Soil C, N and Nutrients Pools after Prescribed Fire in a Mississippi Longleaf Pine (Pinus palustris Mill.). Plantation. Forests, 11, 1−14 

Catherine, L.P., Andersen, A.N., 2006. Patch mosaic burning for biodiversity conservation:  A critical of the pyrodiversity paradigm. Conservation Biology 20 (6), 1610−1619.

Cronan, J.B., Wright, C.S., Petrova, M., 2015. Effect of Dormant and growing season burning on surface fuels and potential fire behaviour in Northern Florida longleaf pine (Pinus palustris) flatwoods. Forest Ecology and Management 354, 318−333.

Curtis, J.T., Cottam, G., 1956. Plant ecology work book- laboratory field reference manual.  Burgess Publishing Co., Minnesota, 193.

Curtis, J.T., Mclntosh, R.P., 1950. The interrelations of certain analytic and synthetic phytosociological characters. Ecology  1,  434−455.

DeVivo, M.S., 1991. Indian use of fire and land clearance in the Southern Appalachians. In: Nodvin, S.C., Waldrop, T.A.(Eds), Fire and the environment: Ecological and cultural perspectives. United State Forest Service General Technical Report. SE-69, 306−312.

Eales, J., Haddaway, N.R., Bernes, C., Cooke, S.J., Jonsson, B.G., Kouki, J., Petrokofsky, G., 2016. What is the effect of prescribed burning in temperate and boreal forest on biodiversity, beyond tree regeneration, pyrophilous and saproxylic species? A systematic review protocol. Eales et al., Environmental Evidenc, 5, 24. DOI 10.1186/s13750-016-0076-5.

Elliot, K.J., Hendrick, R.L., Major, A.E., Vose, J.M. and Swank, W.T., 1999. Vegetation dynamics after a prescribed fire in the southern Appalachians. Forest Ecology and Management 114, 199−213.

FSI, 2011. Atlas Forest Types of India. Forest Survey of India. Ministry of Environment & Forest, Government of India, Dehradun.

FSI, 2019. India State of forest report. Forest Survey of India. Ministry of Environment forest and climate change. Kaulagarh road, Dehradun.

Fernandes, P.M., Botelho, H.S., 2003. A review of prescribed burning effectiveness in fire hazard reduction. International Journal of Wildland Fire 12, 117−128.

Harmon, M.E., 1982. Fire history of the western most portion of Great Smoky Mountains National Park.  Bull. Ton. Bot. Club. 109, 74−79.

Hill, M.O. 1973. Diversity and its evenness, a unifying notation and its consequences. Ecology 54, 427-432.

Hood, S. M., Keys, C. R., Bowen, K. J., Lutes, D. C., Seielstad, C., 2020.
Fuel treatment longevity in ponderosa pine-dominated forest 24 years after cutting and prescribed burning. Frontiers in Forests and Global Change 3, 1−16. Doi: 10.3389/ifgc.2020.00078

Huisinga, K.D., Laughlin, D.C., Fule, P.Z., Springer, J.D., McGlone, C.M., 2005. Effects of an intense prescribed fire on understory vegetation in a mixed conifer forest. The Journal of the Torrey Botanical Society 132(4), 590−601.

Kershaw, K.A., 1973. Quantitative and Dynamic Plant Ecology. Edward Arnold Ltd., London, 308.

Kohli, R.K., Dogra, K.S., Batish, D.R., Singh, H.P., 2004. Impact of Invasive plant on the structure and composition of natural vegetation of Northwestern Indian Himalayas. Weed Technology 18, 1296−1300.

Kunhikannan, C., Verma, R.K., Verma, R.K., Khatri, P.K.,  Totey, N.G., 1998. Ground flora, soil microflora and fauna diversity under plantation ecosystem in bhata land of Bilaspur, Madhya Pradesh. Environment and Ecology 16(3), 539−548.  

Margalef, R., 1958. Temporal succession and spatial heterogeneity in phyto-plankton.In: A. A. Buzzati-Traverso. (Ed.). Perspective in Marine Biology. University of California Press, Berkeley.  323−347.

Magallanes, S.R.S., Giongo, M., Carvalho, E.V.deC., Rotili, E.A., Fernandes, A.C., Cachoeira, J.N.,  Santos, G. R. D., 2020. Immediate effects of Prescribed Burning on Chemical Properties of the Cerrado Soil. Floresta e Ambiente 27(3), e20180253. https://doi.org/10.1590/2179-8087.025318

Pyne, S.J., 1995. World fire: the culture of fire on earth. University of Washington Press, Scattle, London

Rawat, A.S., 1949. Results of controlled burning in the sal plantation of Bengal. Indian Forester, 69−86.

Royo, A.A., Collins, R., Adams, M.B., Kirschbaum, C., Carason, W.P., 2010.  Pervasive  interactions between ungulate browsers and disturbance regimes promote temperate forest herbaceous diversity. Ecology 91, 93−105.

Schwilk. D.W., Keeley, J.E., Knapp, E.E., Mclver, J., Bailey, J.D., Fettig, C.J., Fiedler, C.E., Harrod, R.J., Moghaddas, J.J., Outcatt, K.W., Skinner, C.N., Stephens, S.L., Waldrop, T.A., Yaussy, D.A., Youngblood, A., 2009. The national fire and fire surrogate study: Effect of fuel reduction methods on forest vegetation structure and fuel. Ecolgical Applications 19, 285−304.

Schmerbeck, J., Fiener, P., 2015. Wildfires Ecosystem Services and Biodiversity in Tropical Dry Forest in India. Environmental Management 56, 355−372.

Shannon, C.E., Wiener, W., 1963. The Mathematical Theory of Communication.  Univ. of Illinois Press.  Urbana, U.S.A.

Simpson, E.H. 1949.  Measurement of diversity. Nature, 163, 688.

Singh, J.S., Yadava, P.S., 1974. Seasonal variation in composition, plant biomass and net primary productivity of a tropical grassland at Kurukshetra, India. Ecology Monograph 44, 357−375.

Stephens, S.L., Mclver, J.D., Boerner, R.E.J., Fettig, C.J., Fontaine, J.B., Hartsough, B.R., Kennedy, P.L. Schwilk, D.W., 2012. The effects of forest fuel reduction treatments in the United States. Bioscience 62, 549−560.

Swift Jr., L.W., Elliott, K.J., Ottmar, D.A., R.D., Vihnanek, R.E., 1993. Site preparation burning to improve Southern Appalachian pine hardwood stands: fire charachterstics and soil erosion, moisture and temperature. Canadian Journal of Forest Research 23, 2242−2254.

Van Lear, D.H., 1991. Fire and oak regeneration in the Southern Appalchians. In: Nodvin, S.C., Waldrop, T.A. (Eds), Fire and the environment: Ecological and Cultural perspectives. United State Forest Service General Technical Report. SE-69, 15−21.

Van Lear, D.H., Waldrop, T.A., 1989. History, use and effects of fire in the Appalachians. United State Forest Service General Technical Report. SE-54, 20

Verma, R.K., 2014. Floristic Diversity along an Altitudinal Gradients in Hango Valley of Cold Desert in District Kinnaur, Himachal Pradesh. Biological Forum- An International Journal 6(2), 115−126.

Zhan, Y., Liy, F., Peng, X., Wang, G., 2020. The effects of different burning intensities on soil properties during recovery stage of forests in subtropical China. Journal of Soil and Water Conservation 75 (2), 166−176.