Abstract
Summary Despite significant interest in the sustainable use of medicinal plants, the population ecology of many medicinal plant species remains unstudied. Also, few demographic studies have compared effects of harvesting across habitats. We studied the demography of a highly threatened perennial Himalayan medicinal herb, Nardostachys grandiflora , in two habitats and examined effects of indigenous harvesting regimes on its population dynamics. In a rocky‐outcrop population in 1998, different levels of rhizome harvesting were applied directly by the local users. In meadows, we sampled an unharvested population and another population that was commercially harvested. Data on recruitment, growth and survival of individuals classified by size were gathered over 4 years. Population growth rate (λ) was significantly higher in the unharvested meadow population than in control subplots of the outcrop population. Harvesting significantly reduced λ. Matrix model projections revealed that the size of outcrop populations would return to initial values within ≈5 years, only after 10% rhizome harvesting. In other treatments, recovery time varied from 17 (25% harvesting) to 33 (75%) years. In contrast, in the commercially harvested meadow population (with harvesting levels >25%), projected recovery time was 6 years. Higher growth rates and faster recovery in meadow populations appear to be due to higher recruitment and faster vegetative growth. In outcrops, slow growth and low fecundity slow down recovery after harvesting. Synthesis and application . Nardostachys grandiflora is extremely sensitive to harvesting of rhizomes, but this sensitivity is higher in outcrop than in meadow habitats. Given the constraints on its population growth and its high sensitivity to harvesting, N. grandiflora should be strictly managed, with low harvest rates (<10% in outcrop and <25% in meadow) and fairly long rotations (at least 5 years) between successive harvests. This work shows the importance of considering demographic variation across habitats when formulating specific management plans for threatened medicinal plants. It also demonstrates the importance of integrating local harvesting practices in ecological research for informing management. A large proportion of high‐altitude perennial medicinal plants may be expected to be similarly sensitive to exploitation, requiring careful management to achieve sustainable harvesting.
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Claims 9
Claim · model-written summary
Unharvested meadow population growth rate exceeded the outcrop control.
Verbatim
e0“Population growth rate (λ) was significantly higher in the unharvested meadow population than in control subplots of the outcrop population.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Harvesting significantly reduced population growth rate.
- Taxon
- Nardostachys grandifloraNardostachys jatamansit0
- Treatment
- Harvestinge0
- Outcome
- λe0
- Direction
- reducede0
Not reportedComparator
Verbatim
e0“Harvesting significantly reduced λ.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Outcrop populations were projected to regain initial size within about five years only after 10% rhizome harvesting.
- Taxon
- Nardostachys grandifloraNardostachys jatamansit0
- Treatment
- 10% rhizome harvestinge0
- Outcome
- return to initial valuese0
- Value
- ≈5 yearse0
- Setting
- outcrope0
Not reportedDirection
Verbatim
e0“the size of outcrop populations would return to initial values within ≈5 years, only after 10% rhizome harvesting.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Projected outcrop recovery took 17 years after 25% harvesting.
Verbatim
e0“recovery time varied from 17 (25% harvesting) to 33 (75%) years.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Projected outcrop recovery took 33 years after 75% harvesting.
Verbatim
e0“recovery time varied from 17 (25% harvesting) to 33 (75%) years.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Commercially harvested meadow population recovery was projected at six years.
- Taxon
- Nardostachys grandifloraNardostachys jatamansit0
- Outcome
- projected recovery timee0
- Value
- 6 yearse0
- Setting
- meadowe0
Not reportedDirection
Verbatim
e0“in the commercially harvested meadow population (with harvesting levels >25%), projected recovery time was 6 years.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Higher recruitment and faster vegetative growth appeared to explain faster meadow recovery.
Verbatim
e0“Higher growth rates and faster recovery in meadow populations appear to be due to higher recruitment and faster vegetative growth.”
t0“Nardostachys grandiflora”
Claim · model-written summary
Outcrop slow growth and low fecundity delayed recovery after harvesting.
Verbatim
e0“In outcrops, slow growth and low fecundity slow down recovery after harvesting.”
t0“Nardostachys grandiflora”
Claim · model-written summary
The authors recommend low rhizome harvest rates and rotations of at least five years.
- Taxon
- Nardostachys grandifloraNardostachys jatamansit0
- Outcome
- low harvest rates (<10% in outcrop and <25% in meadow) and fairly long rotations (at least 5 years)e0
Verbatim
e0“N. grandiflora should be strictly managed, with low harvest rates (<10% in outcrop and <25% in meadow) and fairly long rotations (at least 5 years) between successive harvests.”
t0“Nardostachys grandiflora”