Growth Strategy and Population Structure in a Threatened Herb (Neopicrorhiza scrophulariiflora) in Alpine Himalaya
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Authors
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Department of Botany
Abstract
Variation in growth strategy, plant performance and population structure was studied in a threatened longlived clonal medicinal herb [(Neopicrorhiza scrophulariiflora (Pennell) .Y. Hong)] in relation to altitude and other environmental variables. Seven populations were
selected from lower alpine and upper alpine habitats in Walangchung Gola and Ghunsa sectors within Kangchenjunga Conservation Area, East Nepal.The two sectors differ in terms of degree of protection at landscape level (Ghunsa sector being more protected than Walangchung Gola sector) and level of precipitation (higher precipitation in
Ghunsa sector). The habitat of N. scrophulariiflora ranged from shrubland to open rocky/scree or grassy slopes on increasing altitude. There were strong geographical (sectorial) and altitudinal differences in the relative contribution of sexual and vegetative growth strategies in population persistence. Altitude was also related to the inter-population variation in other plant performance traits as well as in population size and
structure.Sexual allocation and sexual reproductive effort were high in lower alpine populations. As compared to Ghunsa sector (moist sites); populations from alangchung
Gola sector (drier sites) produced large-sized genets (except in highly disturbed site). hunsa populations on the other hand showed significantly Variation in growth strategy, plant performance and population structure was studied in a threatened longlived
clonal
medicinal
herb [(Neopicrorhiza
scrophulariiflora
(Pennell) D.Y. Hong)] in
relation to
altitude
and
other environmental
variables.
Seven
populations were
selected
from
lower
alpine and upper alpine
habitats
in Walangchung Gola
and Ghunsa sectors within
Kangchenjunga
Conservation Area, East Nepal.
The
two sectors
differ
in terms
of
degree of protection at landscape
level (Ghunsa sector being more
protected
than
Walangchung
Gola sector) and level
of
precipitation (higher precipitation in
Ghunsa
sector).
The habitat
of N.
scrophulariiflora
ranged from
shrubland to open rocky/scree
or grassy
slopes
on
increasing
altitude. There were strong geographical (sectorial)
and altitudinal differences
in the relative
contribution
of sexual and
vegetative growth strategies in
population persistence.
Altitude
was also related
to
the inter-population
variation in other plant performance
traits
as
well as in
population size and
structure.
Sexual
allocation
and sexual reproductive effort were
high
in lower alpine
populations.
As
compared
to Ghunsa
sector
(moist
sites); populations
from
Walangchung
Gola sector (drier
sites)
produced
large-sized genets (except in highly
disturbed
site). Ghunsa populations
on the
other hand
showed
significantly
large number
of flowering
ramets
per genet than
did by
Walangchung
Gola
populations.
This
shows that
at high
altitudes
and at
drier sites, plants
tend to invest
less in sexual
fecundity
and more
in traits ensuring
persistence
of
vegetative offshoots. Populations from
Walangchung
Gola
sector showed
higher proportions of juvenile
and
vegetative
adult ramets,
with poor representation of
very
young
and reproductive adult ramets.
In highly
disturbed populations,
proportion of reproductive
adult
was even greatly
reduced.
On the other hand, populations
from
Ghunsa
sector showed almost
equal
proportions
of young,
juvenile and vegetative adult ramets.
Proportion of
adult reproductive
ramets
was
also
significantly
high in Ghunsa populations
than in Walangchung
Gola
populations.
This showed
that
Ghunsa
populations were stable in density
and self-replacing.
The strong relationship between
environmental
conditions and
plant growth strategy,
adult
performance
and population
structure of
N.
scrophulariiflora
has important
implications
for its in
situ management.
The lower performance
of plants
(in
terms
of
growth-related
traits),
and low
sexual reproductive efforts in higher alpine
sites (especially
Walangchung
Gola sector) indicate
that these
populations
need immediate
action to protect
them
from
illegal
and premature
harvesting.
In such
populations management
should focus on increasing seedling
recruitment
and
reducing damage
to the reproductive
adults.
Thus long-term
plan
with
a strong measure
for
sustainable
utilization system
is
needed
to manage
the target
species
populations simultaneously
respecting
traditional
access rights of the
local users.
Extremely
low seedling recruitment
makes
this
species
highly vulnerable if
harvesting
is
applied at fairly
higher level,
because in such condition
population
genetic
diversity can be expected
to be very
low. Thus applying
low level of harvesting with
fairly
long rotation is a good
strategy
for
population
persistence. Level of harvesting should be even
low
in
harsh
higher alpine
habitats of Walangchung Gola sector.
Key words: altitude, disturbance, medicinal plant, plant performance, soil variable, sustainable management.
large number
of flowering
ramets
per genet than
did by
Walangchung
Gola
populations.
This
shows that
at high
altitudes
and at
drier sites, plants
tend to invest
less in sexual
fecundity
and more
in traits ensuring
persistence
of
vegetative offshoots. Populations from
Walangchung
Gola
sector showed
higher proportions of juvenile
and
vegetative
adult ramets,
with poor representation of
very
young
and reproductive adult ramets.
In highly
disturbed populations,
proportion of reproductive
adult
was even greatly
reduced.
On the other hand, populations
from
Ghunsa
sector showed almost
equal
proportions
of young,
juvenile and vegetative adult ramets.
Proportion of
adult reproductive
ramets
was
also
significantly
high in Ghunsa populations
than in Walangchung
Gola
populations.
This showed
that
Ghunsa
populations were stable in density
and self-replacing.
The strong relationship between
environmental
conditions and
plant growth strategy,
adult
performance
and population
structure of
N.
scrophulariiflora
has important
implications
for its in
situ management.
The lower performance
of plants
(in
terms
of
growth-related
traits),
and low
sexual reproductive efforts in higher alpine
sites (especially
Walangchung
Gola sector) indicate
that these
populations
need immediate
action to protect
them
from
illegal
and premature
harvesting.
In such
populations management
should focus on increasing seedling
recruitment
and
reducing damage
to the reproductive
adults.
Thus long-term
plan
with
a strong measure
for
sustainable
utilization system
is
needed
to manage
the target
species
populations simultaneously
respecting
traditional
access rights of the
local users.
Extremely
low seedling recruitment
makes
this
species
highly vulnerable if
harvesting
is
applied at fairly
higher level,
because in such condition
population
genetic
diversity can be expected
to be very
low. Thus applying
low level of harvesting with
fairly
long rotation is a good
strategy
for
population
persistence. Level of harvesting should be even
low
in
harsh
higher alpine
habitats of Walangchung Gola sector.
Key words:, disturbance, medicinal plant, plant performance, soil variable, sustainable management.