Reciprocal transplants reveal asymmetric local adaptation of Himalayan Rhododendron approaching elevational range limit
- Conservation Innovation Center, Chesapeake Conservancy Annapolis Maryland USA, Department of Integrative Biology The University of Texas at Austin Austin Texas USA
- Department of Entomology, Plant Pathology and Nematology University of Idaho Moscow Idaho USA
- College of Applied Sciences Nepal Kathmandu Nepal
- Theoretical and Experimental Ecology Station (SETE), CNRS Moulis France
- Department of Biology Baylor University Waco Texas USA
- Theoretical and Experimental Ecology Station (SETE), CNRS Moulis France, Department of Geological Sciences The University of Texas at Austin Austin Texas USA, School of Biological and Marine Sciences University of Plymouth Plymouth UK
Abstract As plant species expand their upper limits of distribution under current warming, some retain both traditional climate space and biotic environment while others encounter novel conditions. The latter is the case for Rhododendron campanulatum , a woody shrub that grows both above and below treeline at our study site in the Eastern Himalayas where a very conspicuous, stable treeline was defined by a nearly contiguous canopy of tall Abies spectabilis trees, many of which are over a century old. Prior work showed that treeline had remained static in this region while R. campanulatum expanded its elevational range limit. We tested local adaptation of R. campanulatum by performing reciprocal transplants between the species' current elevational range limit (4023 m above sea level [asl]) and just above treeline (3876 m asl). Contrary to expectation, the coldest temperatures of late winter and early mid‐spring were experienced by plants at the lower elevation: R. campanulatum at species' limit (upper site) were covered by snow for a longer period (40 more days) and escaped the coldest temperatures suffered by conspecifics at treeline (lower site). The harsher spring conditions at treeline likely explain why leaves were smaller at treeline (15.3 cm 2 ) than at species limit (21.3 cm 2 ). Contrary to results from equivalent studies in other regions, survival was reduced more by downslope than by upslope movement, again potentially due to extreme cold temperatures observed at treeline in spring. Upslope transplantation had no effect on mortality, but mortality of species limit saplings transplanted downslope was three times higher than that of residents at both sites. A general expectation is that locals should survive better than foreign transplants, but survival of locals and immigrants at our species limit site was identical. However, those species limit saplings that survived the transplant to treeline grew faster than both locals at treeline and the transplants at species limit. Overall, we found asymmetric adaptation: Compared with treeline saplings, those at species limit (147 m above treeline) were more tolerant of extremes in the growing season but less tolerant of extremes in winter and early mid‐spring, displaying local adaptation in a more complex manner than simply home advantage, and complicating predictions about impacts of future regional climate change.
- Research Organization:
- US DOE National Institute for Climate Change Research (NICCR), Washington, DC (United States)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 1989491
- Journal Information:
- Ecosphere, Journal Name: Ecosphere Journal Issue: 7 Vol. 14; ISSN 2150-8925
- Publisher:
- Wiley Blackwell (John Wiley & Sons)Copyright Statement
- Country of Publication:
- United States
- Language:
- English
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