Pak. J. Bot., 39(5): 1717-1724, 2007.
IMPACT OF MICROHABITAT ON SURVIVAL OF
SERIPHIDIUM QUETTENSE SEEDLINGS
SHAMIM GUL*, SARFRAZ AHMAD**, ABDUL KABIR KHAN ACHAKZAI*
AND MOHAMMAD ISLAM**
*
**
Department of Botany, University of Balochistan,
Arid Zone Research Centre, Pakistan Agricultural Research Council Quetta, Pakistan.
Email: profakk@yahoo.com
Abstract
Two years study was conducted to examine the influence of microhabitats i.e., plant canopies
and interspaces on the seedling emergence and survival of Seriphidium quettense in relation to soil
temperature and soil moisture in natural habitat. The growth rate of first year seedlings are also
examined. Relative abundance of microhabitats was determined by using square quadrates. Soil
temperature and soil moisture of two microhabitats were recorded at 0-5, 5-10 and 10-15 cm depth.
Results showed that soil moisture in spring was found critical for seed germination while in summer it
had greater impact on the survival of first year seedlings. Precipitations in March and April promoted
seed germination while monsoon rains influenced seedling survival. Soil moisture and soil
temperature in different microhabitats were significantly different in different months, reflected
significant influence upon seedling emergence and their survival. Seedling emergence and survival
was higher under plant canopies than in open interspaces. Highest mortality rate of first year seedlings
were observed in June and August under high soil temperature and low soil moisture contents. High
soil moisture in July due to occurrence of precipitation decreased the mortality rate of first year
seedlings. After winter, no mortality occurred. Survived seedlings of the first year had high root to
shoot ratio. Results further depicted that conspecific plant canopies are favorable microsites for
seedling survival. Furthermore, high root to shoot ratio may enable them to survive in arid habitat.
Introduction
Seriphidium quettense (Podlech) synonym Artemisia quettensis is a dominant
shrublet in Hazarganji, Balochistan, Pakistan (Ghaphoor, 2002). It belongs to the plant
family Asteraceae. This shrub provides forage to small ruminants when other range
species produce limited dry matter particularly under drought conditions. Likewise, this
shrub provides many benefits to humans and animals including feed for livestock and
wildlife, erosion control and industrial products (McKell, 1989). However, rangelands of
Balochistan have been degrading very rapidly by overgrazing and removal of vegetation
for fuel purposes.
Native species have evolved under the prevailing stresses of the region and have the
ability to exploit limited available resources. In arid and semi arid rangelands, reestablishment of important native species is vital to maintain function, structure, diversity
and stability of the landscape. Seedling growth rate in their natural environment reflects
potential of their sustainability in their native habitat. Germination of seeds, their
establishment and survival are important parameters of colonization and population
dynamics of plants (Erikson & Ehrlen, 1992). Seed germination and growth of desert
plants are dependent greatly upon seedbed characteristics particularly soil moisture
(Owens & Norton, 1992) and temperature (Ren et al., 2005). In arid environment, any
microsite that prevents desiccation might be a suitable site for seeding survival (Harper,
1977). Information about these parameters can help range managers to re-habilitate native
plant species.
1718
SHAMIM GUL ET AL.,
Objectives of the research were to investigate: 1) the influence of two dominant
microhabitats (conspecific adult canopies and open interspaces) upon seedling emergence
and survival in relation to soil moisture and soil temperature and 2) growth rate of first
year seedling of the test plant.
Materials and Methods
Study site: The experiments were conducted in Chiltan National Park, Hazarganji,
Balochistan, Pakistan. Experiments were conducted in an extended area of the park that
was protected from livestock grazing since 1998. Dominant vegetations of the site are
Seriphidium quettense, Cymbopogon jawarencusa, Crysopogon aucheri, Berberis lycium
and annual grasses. Climate of the area is of Mediterranean type. Area receives rainfall
mostly in winter months, however rainfall occurs occasionally in summer season as well.
Mean annual rainfall of over 19 years is 200mm. Soil of the area is sandy-to-sandy loam
(Marwat et al., 1992).
Data collection: Two dominant microhabitats interspaces and plant canopies of
Seriphidium quettense were evaluated for seedling recruitment and survival from the soil
seed bank. At the study site, two 160 m long transect lines, parallel to each other with the
distance of 15 m apart were established. Sixteen points, 10 m apart were marked on each
transect line and 5 x 5 m plots (total 32 plots) were established. Twenty-six plots were
used for checking seedling emergence and survival in different microhabitats, three for
soil moisture content, and three for soil temperature. Plots were randomly assigned for
recording of seedlings emergence and survival. One meter square quadrate (sub-divided
into 20 x 20 cm cells) was used to determine the relative abundance of microhabitats of
26 plots of seedling survival.
Seedling emergence was recorded in April 4, 2003. Within experimental plots,
seedlings were located using one-meter square quadrates (sub-divided into a grid with 20
x 20 cm cells). Each emerged seedling was marked with thin wires of different colors.
Seedling survival was recorded at 30 days interval. Seedling development was assessed
by measuring root and shoot length of the seedlings at 30 days interval. Seedlings were
dug from the area out side of 26 plots. Soil water content was measured by gravimetric
method. Soil samples were collected from 0-5, 5-10 and 10-15 cm depths from each
microhabitat of the soil moisture plots. Soil samples were collected at 30 days interval.
Soil temperature was also measured from the three soil temperature plots at 30 days
interval by using thermocouples attached to a hand held digital thermometer (HANNA,
HI 9055 K). Soil temperature reading was taken from each microhabitat at a depth of 0-5,
5-10 and 10-15 cm. Soil temperature was recorded in morning, mid day and at evening
times. Rainfall data were also obtained from the Arid Zone Research Center’s automatic
weather station.
Three and four factorial Randomize Complete Block Designs (RCBD) were used for
soil moisture and soil temperature data, respectively. MSTAT-C computer software
package for statistical analyses was used for calculation of analyses of variance
(ANOVA). Descriptive analysis was used for seedling survival due to very low number
of emerged and survived seedlings.
IMPACT OF MICROHABITAT ON SURVIVAL OF SERIPHIDIUM QUETTENSE
1719
Results
Rainfall distribution and seedling recruitment: The monthly rainfall distribution was
noted to be much lower than those of long-term average rainfall (except during the month
of January, 2004). The year 2003 growing season had comparatively better rainfall
distribution in spring and summer seasons (Fig. 1). A total of 79, 10 and 15 mm of
rainfall was recorded in February, March and April, respectively, which is the optimal
time for seedling recruitment of many plant species in high land of Balochistan. Monsoon
rains in July i.e., 24 mm had no impact on recruitment of Seriphidium quettense
seedlings. However, these rains played a key role in their survival (Table 4). In year 2004
season, only 68 and 16 mm rainfall was received in the months of January and February
respectively while no rainfall occurred in the months of March and April. Similarly no
seedling recruitment was observed in the same year.
Soil moisture and soil temperature: Moisture contents of soil were significantly
different (p<0.01) among months during the year, 2003 and 2004 (Fig. 2). It was higher
in April and July 2003, and in March and May 2004. Soil moisture between microhabitats
was found non-significant (p>0.05) during both years. However, moisture contents were
high in spaces under plant canopies than those in open interspaces Soil moisture contents
among various depths were also found significant (p<0.05) in year 2003 and 2004. There
was a direct relationship between soil moisture and depths (Tables 1 and 2).
For soil temperature, main factors viz., months, microhabitats and depths were found
significant (p<0.05). Interspaces had comparatively high soil temperature than
Seriphidium quettense plant canopies. There was inverse relationship between soil
temperature and soil depth (Table 3).
Seedling growth and survival: Densities of emerged seedlings of Seriphidium quettense
were higher under plant canopies than in open interspaces. Similarly, the densities of
survived seedlings were also higher under plant canopies than in interspaces. At the end
of the first growing season (August 2003), only 0.39 and 0.036 seedlings/m2 were
surviving under plant canopies and in interspaces, respectively. All of the seedlings
survived during the winter months and no cold mortality was recorded in the spring of
second year. At the end of second growing season, density of survived seedlings was
further reduced to 0.034 and 0.011 under adult conspecific plants and in open interspaces,
respectively (Table 4). It was also found that survived seedlings had very slow growth
rate. At the end of August 2003, survived seedlings attained a mean height of 2.94 cm
with 38.8 cm root length and 21 secondary roots plant-1. Seedlings attained maximum
growth rate in April and May (Fig. 3).
Discussion
Spring season is the optimal time for seed germination of Artemisia species (Bai &
Romo 1996; Booth & Bai, 1999) if soil moisture is adequate enough to allow their
germination. Bai & Romo (1995) reported that seedlings of Artemisia frigida emerge
only when soil moisture is above 1.5 M pa. In the present study, lack of precipitations
during the months of March and April for the year 2004 may be one of the reasons for no
seedling recruitment of the species.
SHAMIM GUL ET AL.,
1720
Table 1. Mean (± S.E.) Soil moisture contents (%) of different parameters
(microhabitats and soil depths) during 2003 in different months.
Microhabitat
Depth (cm)
Month
Canopy
Interspace
0-5
5-10
10-15
April
1.988 ab
2.956 a
1.133 bc
2.875 a
3.407 a
May
0.571 c
0.422 c
0.185 c
0.485 bc
0.82 bc
June
0.521 c
0.447 c
0.583 bc
0.343 bc
0.525 bc
July
1.456 bc
0.744 c
0.733 bc
1.253 bc
1.313 b
Values within a column represented by different letters are significantly different at p<0.05
Table 2. Mean Soil moisture contents (%) of different parameters (microhabitats
and soil depths) during 2004 in different months.
Microhabitat
Depth (cm)
Month
Canopy
Interspace
0-5
5-10
10-15
March
1.447 a
1.423 a
0.0789 cde
0.224 ef
0.245 ef
April
0.338 c
0.45 bc
0.32 ef
1.52 b
2.51 a
May
1.351 a
1.059 ab
0.13 f
0.31 ef
0.75 def
June
0.55 bc
0.415 c
0.85 cde
1.37 bcd
1.42 bc
Values within a column represented by different letters are significantly different at p<0.05
Table 3. Mean Soil temperature (oC) of different parameters (microhabitats and
soil depths) during 2004 in different months.
Microhabitat
Depth (cm)
Month
Canopy
Interspace
0-5
5-10
10-15
March
26.21 e
30.85 d
28.06 e
29.01 e
28.52 e
April
35.00 c
37.98 bc
35.99 d
36.82 d
36.67 d
May
39.43 ab
42.1 a
43.8 a
40.68 abc 37.81 bcd
June
38.13 bc
40.29 ab
41.01 ab
39.25 bcd
37.35 cd
Values within a column represented by different letters are significantly different at p<0.05
Table 4. Mean (± S.E.) densities of emerged and survived seedlings of Seriphidium
quettense in different microhabitats during 2003 and 2004 seasons.
Emerged seedlings /m2 (2003)
Survived seedlings /m2 (2003)
May, 2003
June, 2003
July, 2003
August, 2003
Survived seedlings /m2 after winter 2003
(April, 2004)
Survived seedlings /m2 by the end of the
second growing season (August, 2004)
Canopies
(20) 1.31± 0.23
Interspaces
(2) 0.14 ± 0.03
(15) 0.99 ± 0.19
(10) 0.68 ± 0.15
(9) 0.57 ± 0.15
(6) 0.39 ± 0.12
(6) 0.39 ± 0.12
(2) 0.12 ± 0.02
(1) 0.07 ± 0.016
(1) 0.07 ± 0.01
(0.54) 0.036 ± 0.001
(0.54) 0.036 ± 0.001
(1) 0.034 ± 0.030
(0.23) 0.011 ± 0.0075
Numbers in parenthesis indicate total number of emerged and survived seedlings.
IMPACT OF MICROHABITAT ON SURVIVAL OF SERIPHIDIUM QUETTENSE
1721
2002
90
80
2003
Rain fall (mm)
70
2004
60
50
Average rain fall in last
19 years
40
30
20
10
0
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Fig. 1. Monthly rainfall distribution during the years 2002, 2003, 2004 and average rain fall for the last 19 years.
3.00
2003
a
(%) soil moisture
2.50
2004
2.00
1.50
a
a
b
1.00
b
0.50
b
b
b
0.00
March
April
May
June
Fig. 2. Monthly (%) soil moisture in year 2003 and 2004. Values with the same subscript are not significantly
different among months of the same year.
Density of new seedlings was quite low as compared to the average density of adult
plants (4-5 plants/m2). Low seedling recruitment in established stands of Artemisia has
also been reported for Artemisia rothrockii (Bauer et al., 2002) and for Artemisia herba
alba (Friedman & Orshan, 1975). Friedman & Orshan (1975) found average density of
Artemisia herba alba seedlings in Negev deserts of Israel quite low than the density of
adult conspecifics and ranged from 1.1 to 0.6/m2. Low seedling emergence may be
attributed to low soil moisture and small size of the seeds. Because of the very small size,
they may burry in the soil in substantial number (Harper, 1977), which can hinder their
germination and emergence probably because of their high sensitivity towards light for
germination (Silvertown & Doust, 1993).
SHAMIM GUL ET AL.,
1722
45.00
Shoot length
Root length
Number of roots
40.00
Seedling growth (cm)
35.00
30.00
25.00
20.00
15.00
10.00
5.00
0.00
April
May
June
July
August
Fig. 3. Growth rate of shoot, main root and number of lateral roots of Seriphidium quettense
seedlings during 2003.
Survival rate decreased with decreasing soil moisture. High mortality rates in the
months of June and August when high soil temperature and paucity of precipitations
severely depleted water from the soil and low mortality rate in the month of July when
area received precipitations, which increased though non-significantly soil moisture,
implies that survival of seedlings are dependent greatly upon soil moisture. The moisture
contents of soil, indicates that summer precipitations are critical for survival of first year
seedlings. In this connection, our results are also in agreement with the findings described
by Owens & Norton (1992).
High density of survived seedlings of Seriphidium quettense was found under plant
canopies. Most of the established seedlings were also observed in the vicinity of adult
conspecific plants (personal observation). Survival rate of Gutierrezia microcephala, an
arid land shrub was also found higher in the vicinity of adult plants than in bare
interspaces (Paker, 1982). It reflects that plant canopies are more favorable microhabitats
for seedling survival as compared to open interspaces. More open microsites have
slightly higher diurnal temperature fluctuations than microsites under plant canopies
(Thompson et al., 1977; Pierson & Wight, 1991). Factors that alter environment of
individual seedlings may also alter their probability of survival and successful
establishment (Owens & Norton, 1992). Moreover, in desert plant communities,
evapotranspiration in warm conditions can severely affect seedling survival and adult
plants may facilitate them by providing shade and nutrients (Fowler, 1988; Guo, 1998).
As observed in present findings that in warm conditions, soil moisture and soil
temperature was comparatively better under plant canopies than compared with open
interspaces. The accumulation of soil under plant canopies and high organic matter may
also be the reason for comparatively high survival rate of the seedlings under or near
adult plants in arid habitats.
IMPACT OF MICROHABITAT ON SURVIVAL OF SERIPHIDIUM QUETTENSE
1723
Seedlings attained high growth rate in early growing season and with high root to
shoot ratio. It can be attributed to high osmotic potential in early growing season
(Shereen et al., 2005) due to high soil moisture contents. Seriphidium quettense seedlings
invested most of the resources for belowground root growth rather than aboveground
shoot growth. Achievements of maximum growth rate early in growing season when
conditions are more favorable for plant growth and high root to shoot ratio seems to be
adaptive feature of these species to survive in arid environment (Booth et al., 1990).
After winter no seedlings died, which indicates their good capability of winter
tolerance. High survival rate of Seriphidium quettense may be due to low autumn
precipitation that probably strengthen the seedlings and enable them to survive in winter
season (Cawker, 1980). Our results suggest that winter temperature is not as critical as
soil moisture for the survival of Seriphidium quettense seedlings.
Results suggest that conspecific plant canopies are favorable microsites for seedling
survival. Soil moisture in spring is critical for seed germination while summer
precipitations have greater impact on the survival of first year seedlings. Furthermore,
high root to shoot ratio may enable them to survive in arid habitat.
References
Bai, Y. and J.T. Romo. 1995. Influence of temperature, light and water stress on germination of
fringed sage (Artemisia frigida). Weed Sci., 43: 219-225.
Bai, Y. and J.T. Romo. 1996. Fringed sagebrush response to sward disturbance. J. Range Manag.,
49: 228-233.
Bauer, K.M., E.L. Berlow and C.M. D’antonio. 2002. The relationship between climate and
rothrock sagebrush colonization patterns. J. Range Manag., 55: 620-625.
Booth, D.T. and Y. Bai. 1999. Inhibition temperature affects on seedling vigor: In crops and shrubs.
J. Range Manag., 52: 534-538.
Booth, G.D., B.L. Welch and T.L.C. Jacobson. 1990. Seedling growth rate of 3 subspecies of big
sagebrush. J. Range Manag., 43: 432-435.
Cawker, K.B. 1980. Evidence of climatic control from population age structure of Artemisia
tridentata Nutt. In southern British Columbia. J. Biography, 7: 237-248.
Erikson, O. and J. Ehrlen. 1992. Seed and microsite limitation of recruitment in plant populations.
Oecologia, 91:360-364.
Fowler, N.L. 1988. What is safe site? Neighbor, litter, germination date and patch effects. Ecology,
69: 947-961.
Friedman, J. and G. Orshan. 1975. The distribution, emergence and survival of seedlings of
Artemisia herba alba asso in the Negev desert of Israel in relation to distance from the adult
plant. J. Ecol., 63: 627-632.
Ghafoor, A. 2002. Flora of Pakistan. Asteraceae (1)-Anthemideae. In: Ali, S.I. and Qaiser, M.
(Eds.) Department of Botany, University of Karachi, Karachi-Pakistan.
Guo, Q. 1998. Microhabitat differentiation in Chihuahuan desert plant communities. Plant Ecol.,
139: 71-80.
Harper, J.L. 1977. Population Biology of Plants. Academic Press, New York.
Marwat, Q.U.D., M. Nisar and F. Hussain. 1992. Vegetation studies of Chiltan National Park
Hazarganji, Quetta. Pak. J. Agric. Res., 13: 71-79.
McKell, C.M. 1989. The Biology and Utilization of Shrubs. Academic Press, San Diego, California.
Owens, M.K. and B.E. Norton. 1992. Interactions of grazing and plant protection on basin big
sagebrush (Artemisia tridentata ssp tridentata) seedling survival. J. Range Manag., 45: 257-262.
Paker, M.A. 1982. Association with mature plants protects seedlings from predation in arid
grassland shrub (Gutierrezia microcephala). Oecologia, 53: 276-280.
SHAMIM GUL ET AL.,
1724
Pierson, F.B. and J.R. Wight. 1991. Variability of near surface soil temperature on sagebrush range
land. J. Range Manag., 44: 491-498.
Ren, J., J. Zixue and L Tao. 2005. Effect of temperature on seed germination of seven Calligonium
species. Pak. J. Bot., 37(3): 651-660.
Shereen, A., S. Mumtaz, S. Raza, M.A. Khan and S. Solangi. 2005. Salinity effects on seedling
growth and yield components of different inbred rice lines. Pak. J. Bot., 37(1): 131-139.
Silvertown, J.W. and J.L. Doust. 1993. Introduction to Plant Population Biology. Blackwell
Science.
Thompson, K., J.P. Grime and G. Mason. 1977. Seed germination in response to diurnal
fluctuations of temperature. Nature, 26: 147-149.
(Received for publication 5 June 2007)