Changes in seasonal vegetation and sustenance of tussocky arid rangelands under different grazing pressures

Abstract

Perennial vegetation provides ecological and economic
stability to livestock based production systems in the arid
regions. But, role of herbaceous annual and seasonal
vegetation is poorly understood. In order to understand
this, grazing experiments [T1: Control (no grazing); T2:
Optimum carrying capacity with supplemental feed (6
sheep grazing); T3: Optimum carrying capacity without
supplemental feed (6 sheep grazing); T4: Double the
carrying capacity with supplemental feed (12 sheep
grazing) and T5: Double the carrying capacity without
supplemental feed (12 sheep grazing)] were conducted
for two consecutive years in Lasiurus sindicus dominated
rangelands at Chandan, Jaisalmer. Study revealed that
irrespective of supplemental feed, 70-80% of L. sindicus
cover declined in paddock with double the carrying capacity
(T4 and T5). Further, the preferential consumption of
seasonal and low perennials such as Ochthochloa
compressa and annual Cenchrus biflorus in monsoon
and post-monsoon helped to defray the consumption of
perennials and inter-alia prolonged the duration of rangeuse.
It was concluded that spatial heterogeneity imparted
by seasonal vegetation in an overall matrix of perennial
tall grasses and woody perennials need to be managed
optimally by grazing management of both seasonals and
perennials.

Full text

Range Mgmt. & Agroforestry 38 (1) : 35-42, 2017
ISSN 0971-2070
Changes in seasonal vegetation and sustenance of tussocky arid rangelands under
different grazing pressures
Suresh Kumar1*, J.P. Singh2, K. Venkatesan2, B.K. Mathur1 and R.K. Bhatt1
1ICAR-Central Arid Zone Research Institute, Jodhpur-342003, India
2ICAR-Central Arid Zone Research Institute, Regional Research Station, Jaisalmer-345001, India
*Corresponding author e-mail: sk_ecology@yahoo.co.in
Received: 9th March, 2016 Accepted: 16th March, 2017
Abstract
Perennial vegetation provides ecological and economic
stability to livestock based production systems in the arid
regions. But, role of herbaceous annual and seasonal
vegetation is poorly understood. In order to understand
this, g razing experiments [T1: Control (no grazing); T2:
Optimum carrying capac ity with sup plemental feed (6
sheep grazing); T3: Optimum carrying capacity withou t
sup plem ental feed (6 sheep grazing); T4: Dou ble the
carryin g cap acity with supplemen tal feed (12 sheep
grazing) and T5: Double the carrying capacity without
supplemental feed (12 sheep grazing)] were conducted
for two consecutive years in Lasiurus sindicus dominated
rangelands at Chandan, Jaisalmer. Study revealed that
irrespective of supplemental feed, 70-80% of L. sindicus
cover declined in paddock with double the carrying capacity
(T4 and T5). Further, the preferen tial con sum ptio n of
seaso nal and low peren nials su ch as Oc ht ho ch loa
compressa and annual Cenchrus biflorus in monso on
and post-monsoon helped to defray the consumption of
perennials and inter-alia prolonged the duration of range-
use. It was concluded that spatial heterogeneity imparted
by seasonal vegetation in an overall matrix of perennial
tall grasses and woody perennials need to be managed
optimally by grazing management of both seasonals and
perennials.
Keywor ds: Arid zone, Grassland , Grazing, Las iurus
sindicus, Rainfall, Seasonal vegetation
Introduction
The area under permanent pastures (PP) and grazing
lands (GL) in India has declined from 120 to 102 lakh ha
during 1980-81 to 2007-08. However, livestock population
in the country has increased from 4230 to 5297 lakh
between years from 1982 t o 200 7 (Dixit et al., 2015).
Farming community in arid zone of Rajasthan earns 28-
42% of their agricultural inco me from livestock rearing
(Kar, 2014), the highest being in extreme arid part of
Barmer, Jaisalmer, Bikaner, Jodhpur and Churu. Human
population density is 67 per km² while livestock density
is 2 4. 4 p er km². From 1901 to 20 10 , t he reg ion
experienced drought in 52% of the years (severe 11%,
large 19% and mo dera te 22%). Tho ugh cropping is
increasing by 1-6% from 1981-1983 to 2006-2008, yet
the twelve extreme arid districts have 67.2% area under
cultivable waste which is used as grazing ground. While
livestock pro vides insurance against drought in arid
regions, it also provides highest quantum of meat, milk,
and wool to the country from an area (36%) which is
largely deg raded wasteland, since 62% of these areas
are very severely degraded,14% are severely degraded
and 5-7% are moderately degraded. Encroachmen t of
these grazing lands for both public and private purposes
is too well kno wn. Thus grazing area is shrinking and
quality of the feed is also declining. How these continually
sh rink ing a nd d eg rad in g graz ing lan ds with le ss
perenn ial grasses, s us tai n en ha nc ing livestoc k
pressure has been a paradox. This is specially so when
its botanical diversity is known i.e., 682 spp., habitat plant
cover relationship is studied , successional trends,
economic uses and extent are well do cumented (Kumar,
1998). Compositionally, climax vegetation in rangelands
in arid Raj asthan would have dominance of perennial
tussocky grasses like Las iurus sindicus and Panicum
turgidum i.e., their dominance or RIV exceeding at least
40 (Kumar, 1992).The remainder of the range community
has com pon ents like annuals and biennials amongst
legumes, sedges, weeds, grasses and others (Kumar,
20 05 ). Research ers, by and larg e, also arg ue th at
maintaining wide variety of such vegetation and diverse
hab itats in range productio n systems is essential for
sustainable production by way of enriching biological
co mp lexity and diversity (Bosc h and Kelln er, 1991;
Whitford , 1996). Though Snyman (1998) discussed in
great detail about their dynamics in terms of stability,
resilience and equilibrium for sustainab le utilization of
southern African rangelands, yet the role played by

36
seasonals is not high lighted. W e, therefore, undertook
this study and designed grazing experiments to assess
the role of annual and seasonal vegetation in sustenance
of arid grazing lands.
Materials and Methods
Experime ntal ar ea: The st ud y was conduc ted at
Experimental Area, Chandan, CAZRI, RRS, Jaisalmer,
Rajasthan, India (latitude 26o 59’ 31.32 N and longitude
71o 20’ 29.59 E) having elevation of 196 meters (640
feet) and is 40 km away from golden city Jaisalmer. The
Jaisalm er distric t is sit uated in the extreme west of
Rajasthan and forms the major part of the Great Indian
Desert. It is located between 26º 29' to 28º 02' north
latitudes and 6 9º 29' to 72 º 20' east longitudes. The
rainfall in the district is scanty, uneven and highly variable.
Chandan received 164.5 mm rain during the year 2013
against the average rainfall of 157 mm. The average
rainfall of the district was 150 mm but in the year 2013
the total rainfall recorded in the district was 296 mm.
The d ay tem pe rat ur e sometime goes up to 47 ºC
through out the summer (May-J une) with intense heat
waves . So uth- we st m on so on in Ju ly co ols th e
temperatu re that starts risin g again when monsoo n
withdra ws in th e end of Sep tem be r. Tem perature s
decrease gradually in Octob er onwards. January is the
cold es t mo nt h when the mean daily m aximu m
temperature is 23.6º C and the mean daily minimum 5-
6ºC, often experiencing frosts and cold waves. The soil
of the experimental site was sandy loam and slightly
alkaline (pH 7.5) with 0.36% organic carbon, electrical
conductivity (-0.16 mmhos cm-1), available nitrogen (285
kgha-1), available phosphorus (24 kg ha- 1), availab le
po tas h (356 kg ha- 1). L. sin dicus with sprink ling of
Prosopis cineraria forms the dominant landscape in this
area.
Graz ing trial s an d methods of an al ys is : A field
experiment w as conducted from 2012-2013 at Chandan
farm which is protected for last 25 years. Five plots of
one hectare each were fenced for following five grazing
treatments (Table 1).
T1
T2
T3
T4
T5
Control
Optimum carrying capacity with supplemen tal feed
Optimum carrying capacity without supplemental feed
Double the carrying capacity with supplemental feed
Double the carrying capacity without supplemental feed
No grazing
6 sheep grazing
6 sheep grazing
12 sheep grazing
12 sheep grazing
Sheep were allowed to g raze from morning to noon (8
AM to 12 Noon ) and then from 3 to 6 PM all the year
aroun d. They were given water and salt ad li bit um.
Vegetation parameters were recorded on monthly basis.
Sequential observations were recorded on cover, density
an d heig ht of p lan t f oll ow ing standar d eco lo gic al
methods (Mueller-Dombois and Ellen-berg, 1974) in
perm an ently laid ou t quad ra te (1 0 m × 10 m, five
quadrates per plot) and line transact (10 m long five lines
per plot) (Misra, 1968). Herbaceous vegetation was also
sampled in 1m × 1m quadrate. Biomass was estimated
in 2 m x 2 m quadrates at the end of growing season i.e.
Octo ber. D ata was analyz ed for co mp os ition an d
dominance of different species following Ludwig and
Reynolds (1988).
Results and Discussion
Changes in ve ge ta tion: Ind ian arid landscap e is
characterized by a free range grazing with no control over
livestock nu mbe r and frequency of livestock visit for
grazing. Consequently 70% of the grazing lands in Indian
arid zone are severely degraded, while other 14% are
fair, 13% of good and 2-3% excellent class (Shankar et
al., 1988).These 70% degraded grazing lands are under
continuous grazing. We aimed in this study to document
changes in long-time protected paddocks due to optimal
an d su pra-o pt imal grazin g co nt inuously by sheep .
Results revealed that decline in L. sindicus cover and
dominance was much less in paddocks where sheep
grazing with sup plemental feed (T2, T4) than without
su pp lemen t fee d ( T3, T5) ( Fig 1 ). Irrespe ct ive of
sup plemental feed, 70-8 0% of L. sindic us cover was
declined in paddock with double the carrying capacity
(T4, T5) in two years (Fig 1). Seligman and Perevolotsky
(1994) and Kerven et al. (2003) also conc lude d that
degradation in North African, Middle East and Central
Asian ra ng eland s w as d ue t o larg e am ou nts o f
su pp lemen tary fe ed provided to the anim als. The
variation in rainfall during monsoon period was evident
fr om range of rainf all per day (0 to 88 .0 mm) and
cumulative rainfall (133.5 mm for 2012; 164.9 mm for
2013) and this c aused the changes in L. sindicus cover
as per time, d uration and quantity of rainfall.
Sustenance of arid rangelands
Table 1. Grazing treatments with sheep

Kumar et al.
Fig 1. Trends in percent cover and dominance [in terms of relative importance value (RIV)] of Lasiurus sindicus under
different grazing treatments in line transect (10m) method
The trend of dominance (RIV; Relative Importance Value)
of L. sindicus indicated the consumption of companion
vegetation such as Ochthochloa compressa, Cenchrus
biflorus more passionately by sheep so much so that
this companion vegetation cover /dominance declined
by 100% over 2-years period (Figs 1 to 3 ). In contrast,
sh eep in o ptim um c arrying c ap ac ity and g iven
sup plemen tal feed (T2) nearly maintained the perce nt
cover of L. sindicus though cover decline was 60-70% in
T3 paddock grazed by sheep and not given supplemental
feed (Fig 1). This decline however did not aggravate with
passage o f time du e to adeq uate c om pe ns ato ry
regeneration of this grass favoured by adequate rains in
20 13. Do min anc e (R elat ive Impo rtance Value) of L.
sindicus in all the four treatments over two years period
either maintained (as in T2) or increased by 50% in T5,
200% in T3 and 240% in T4 (Fig 1). This indicated that
companio n vegetat ion w as also consumed more
preferentially over L. sindicus and though overall cover of
L. sindicus declined, its RIV increased. If rains were less
or failed and grazing pressure co ntinues unabate d,
companion grass, O. compressa declined by 100% over
two years both in terms of percent cover and dominance,
trends in both being rain driven. The annual grass, C.
biflorus followed similar trend. Severity of changes in L.
sin dicu s bec ame visible from number of tussocks per
paddock over time in these treatments (Fig 4). Overall
decline in nu mb er of tu ssocks was mer ely 10 % in
pad docks grazed twic e the carrying cap acity while it
increased by 5 -10% in paddocks subjected to optimum
carr ying capacity grazing . This w as also confirmed by
trends in dominance (Fig 5). Though, tussocks stood on
the ground, but because of overgrazing their regenerated
biomass available for grazing declined by over 80% in all
the four treatment (Fig 6). Thus increasing stocking rate
an important variable in our study, predictably causes a
decline in biomass by 80% in two years i.e., from 461.5
(T2), 306.6 (T3), 450.5 (T4) and 341 ,1 (T5) kgh a-1 to 70.3
(T2), 29 .6 (T3), 28.7 (T4) and 15.4 (T5) kgh a-1. In an
eco logic ally frag ile arid zone, even small variations in
environmental variables such as rain have a major effect
on vegetat ion com po sitio n (Sn yman, 19 98 ) w ith
accompanying high drought risk and resultant sustainable
productivity of the rangeland eco system (Yunlong and
Smit, 1994 ).
37

Fig 2. Trends in percent cover and d ominance [in terms of relative importance value (RIV)] of Ochthochloa compressa
under different grazing treatments in line transect (10m) method
Fig 3. Trends in percent c over and dominanc e [in terms of relative importance value (RIV)] of Cenchrus biflorus under
different grazing treatments in line transect (10m) method
Sustenance of arid rangelands
38

Fig 4. Trends in number of tussocks of La siurus sindicus per 100 m2 in different grazing treatments
Kumar et al.
39
Sustenance of vegetation: It emerges from foregoing
that companion annuals and low spreading, herbaceous
per ennial grazable species as mediated by rain, give
temporary or seasonal rest to L. sindicus when it grows
and builds up cover and biomass. Such differences in
composition, structure, diversity and forage production
potential of vegetation under different grazing intensities
are widely understood and agreed (Vetter et al., 2006).
Th e reason , behind this is that, these seasonal and
herbaceous peren nials can draw water from whole soil
profile throughout the g rowing seasons where as climax
grasses with draw wate r from deeper layers of 2-5 m
during droughts (Snyman, 1998). Such a partitioning of
resources utilization actually increases the duration of
livestock grazing by providing resilience. Fynn (2012) also
reported that functional wet seasons habitats dominated
by short, nutritious grasses facilitate optimum intake of
nutrients and energy for lactating females, for optimal
calf growth and building body stores. He further argued
that rotational grazing compartm ents, negating these
functional range biomass d ynamics, had therefo re not
out p erformed the c onti nu ous g raz in g systems .
Importance o f hetero geneity in vegetation comp osition
was also emphasized for achieving optimum grazing use
by McGranahan and Kirkman (2013). There are conflicting
views on continuous versus rotational grazing as both
seem to affect rangelands equally good or equally bad
an d a bio tic factor consid ered res po ns ible for this
degradation (McGranahan and Kirkman, 2013).This will
also take into account the spatial patterns of landscape
created by patches of seasonal vegetation and temporal
patt erns of biomass (= pr od uc tivity) ava ila bil ity of
seasona ls in post monsoon and perennials in winter
and summer, as eviden t from pr esen t stud y. Similar
conclusions were also arrived at in decade-long detailed
grazing experiments conducted earlier in rangelands in
Jaisalmer in Indian Thar desert by Mertia (1984). It also
emerged from an excellent review of grazing studies by
Fynn (2012) that neither rotational nor continuous grazing
is ecologically sound and econ omically viable; rather
grazing based on spatial and temporal variability in forage
quality and quantity would be the best option. This would
allo w seasonal graz ing and seasonal rests for mor e
effective recovery periods, a conclusion also reached by
Mertia (19 84 ). Sin gh et al. (2 00 6) also proved that
seaso nal veg eta tio n had higher crude prot ein th an
perennial grasses and therefore meets the nutritional
needs of the livestock. It is therefore, important to realize
that seasonal vegetation that provides heterogeneity and
complexity prolonged the period of range use and delayed
the onset of degradation. Managing this heterogeneity
and com plexity in order to enhan ce resilien ce th us
becom es an imp ort ant man agemen t prio rity for arid
rangeland (Vetter, 2009).
Fynn (2012) recommends grazing distribution in such a
way so as to utilize above mentioned spatial and temporal
patterns. Our observation in the present study is that free
range anim als in mon soo nal rangelands themselves
do selective grazing based on seasonal availab ility of
biom ass i. e., th ey graze annuals first (Aug us t to
November) and then perennials (December to April) and

Fig 6. Trends in total dry biomass of Lasiurus sindicus per 100 m2 in different grazing treatments
Sustenance of arid rangelands
40
Fig 5. Trends in dominance of Lasiurus sindicus per 100 m2 in different grazing treatments

both litter and perennials in summer. A mix of cattle, goat
and sheep would further optimiz e to increase range
utilization. Similar results were also reported by Weber
an d H orst (2 011 ), wh ile examining t he ro les of
se dentarizatio n, m ob ility an d re st of live st oc k in
desertification caused by grazing. Further, a study by
Tasadoq et al. (2015) revealed degradation of soils of
the grazing lands under uneven grazing intensity (an
inh eren t feature of a tran shuman t grazing system in
Kashmir) b y means of decrease in soil organic carbon,
calcium and magnesium content.
Conclusion
It was concluded that a) arid rangelands have intrinsic
heterogen eity in spec ies compo sition, b) this mix of
se aso nal an d pe ren nials (= he te rogenei ty) is ab ly
sup port ed by the landscape by way of partitioning of
resources, c) lifecycle pattern of seasonal fits well to meet
the nutritional needs of livestock and d) grazing of such
se aso nal vegetatio n th us he lps su stain pe re nn ial
tussocky rangelands for longer rang e-use.
Acknowledgement
Authors thank the Director, ICAR-CAZRI, Jodhpur and
Indian Council of Agricu ltural Research, New Delhi for
fin anc ial sup port und er NICRA project and fac ilities
provided to carry out this study.
References
Bosc h, O. J . H. an d K. Ke lln er. 19 91 . Th e use of
degradation gradients for ecological interpretation
of rang e co ndition assessment. Jo urn al of Arid
Environment 21: 21-29.
Dixit, A. K., M. K. Singh, A. K. Roy, B. S. Reddy and N.
Singh. 2015 . Trends and contribution of grazing
resou rces to livestock in different states of India.
Range Management and Agroforestry 36: 204-210.
Fynn, R. W. S. 2012. Functional resource heterogeneity
increases livestock and ra ngeland productivity.
Rangeland Ecology and Management 65: 319-329.
Kar, A. 2014. Agricu ltu ral land use in arid Western
Raj asthan: Resource exploitation and emergin g
issues. Agropedology 24: 179-196.
Kerven, C., I. I. Alimaev, R. Beh nke, G. Devidson, L.
Franchois, N. Malmakov, E. Mathijs, A. Smailov, S.
Temirbekov and I. Wright. 200 3. Retraction and
expansion of flock mobility in Central Asia: costs
and co nsequences. In: Pro c. VIIth Internation al
Rangelands Congress (July 26-August 01, 2003),
Durban, South Africa. pp. 543-556.
Kumar, S. 1998. Vegetation resources in the Indian arid
zone. In: A.S. Faroda and Manjit Singh (eds). Fifty
Years of Arid Zone Res ea rch in Ind ia, CAZRI,
Jodhpur, 343 003, India. pp. 89-119.
Kumar, S. 2005. Monsoonal herbage- their ecology and
potential. In: R.C. Jakhmola, A. Joshi, R. K. Sawal,
S. C. Gill and D. Kumar (eds). Proceedings National
Semi na r on Co nse rvat ion, Proc essing a nd
Utilization of Mon soon Herbage for Augmenting
Animal Production, Indian Society for Sheep and
Goat Production and Utilization, Avikanagar, Jaipur,
Raj asthan.
Kumar, S. 1992. Assessment of vegetation degradation:
Status of methodological research. Annals of Arid
Zone 31: 53-62.
Ludwig, J. A. and J. F. Reynolds. 1988. Statistical Ecology:
A Primer on Methods and Computing. JohnWiley
and Sons, NY, USA.
McGranahan, D. A. and K. P. Kirkman. 201 3. Multi-
functional rangelands in southern Africa: Managing
for production, conservation and resilience with fire
and grazing. Land 2: 176-193.
Mertia, R. S. 1984. Studies on improvement and utilization
of ra ng ela nd s of Jaisalmer reg ion . In: CAZR I
Monogragh No. 25, CAZRI, Jodhpur. pp. 50.
Misra, R. 1968. Ecology Work Book. Oxford and IBH
Publishing Co., New Delhi. pp. 235.
Mueller-Dombo is, D. and H. Ellenberg. 1974. Aims and
Methods of Vegetation Ecology. John Willey and
Sons, New York. pp. 525.
Seligman, N. G. and A. Perevolotsky, 1994. Has intensive
grazing by do mestic livestock degraded the Old
W orld M edite rranean rangel an ds? In : M.
Arianoutsou and R.H. Groves (eds). Plant-Animal
Interactions in Mediterranean- Type Ecosystems.
Kluwer, Dordrecht. pp. 93-103.
Shankar, V., S. Kumar and R. K. Tyagi. 1988. Grazing
resources of arid and semi-arid regions. In: Pasture
and Forag e Crops Research- A State of Knowledge
Report. 3rd International Rangeland Congress, New
Delhi. pp. 63-85.
Singh, J. P., B. C. Mondal, M. L . Soni and R. K. Beniwal.
2006. Annual weeds add to the nutritional level of
forage from desert rangelands. Annals of Arid Zone
45: 189-193.
Snyman, H. A. 1998. Dynamics and sustainable utilization
of ran geland eco syst ems in arid and semi- arid
climate s o f so ut hern Afr ic a. Jou rn al of Arid
Environment 39: 645 -666.
Kumar et al.
41

Tasadoq, J. H., P. G. Saptarshi. and S. W. Gaikwad. 2015.
Impact of transh umant grazin g on physical and
chem ic al p ropert ies of s oils in temperat e
pastur eland s o f Ka sh mir H ima laya. R an ge
Management and Agroforestry 36: 128-13 5.
Vetter, S. 2009. Drought, change and resilience in south
Af ric a’s arid and semi-arid ran gelands. So ut h
African Journal of Science 105: 29-33.
Vetter, S., W. M. Goqwana, W. J. Bond and W. S. W. Trollope.
2006. E ffects of land ten ure, geol og y an d
to po grap hy o n vegetatio n and s oils o f tw o
grasslands types in south Africa. African Journal of
Range Forage Science 23: 1 3-27.
We ber, K. T. and S. Horst. 2011. Desertification and
livestoc k grazing : Th e roles of sedentarization ,
mobility and rest. Pastoralism: Research, Policy and
Practice 1: 19 (doi:10.1186/2041-7136-1-19).
Wh itford, W. G. 1996. The importance of the biodiversity
of soil biota in arid ecosystems. Biod iversity and
Conservation 5: 185-195.
Yun lo ng , C . and B . S mit. 1 994. S ustai na bility in
agriculture: a general review. Agriculture, Ecosystem
and Environment 49: 299-30 7.
Sustenance of arid rangelands
42