Growth Strategy and Population Structure in a Threatened Herb (Neopicrorhiza scrophulariiflora) in Alpine Himalaya

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.