Original ArticleDendroclimatological assessment of Polylepis rodolfo-vasquezii: A novel Polylepis species in the Peru highlands
Introduction
Nineteen species of Polylepis grow in the Peruvian Andes between 1800 and 5100 m elevation (Mendoza and Cano, 2011). Some Polylepis woodlands represent the highest elevation tree formations in the world, reaching up to 5000 m a.s.l. in the humid and arid Andes, respectively (Kessler and Schmidt-Lebuhn, 2006). The Polylepis woodlands provide ecosystem services to local montane communities including water regulation and soil nutrient conservation. These woodlands also represent important refuges for biodiversity and an important carbon sink at high elevations (Fjeldsá, 2002; Zutta et al., 2012).
Compared to the subtropical and temperate regions along the Andes, tree-ring records in the tropics are scarce (Boninsegna et al., 2009). The Central Andes of Peru (6°-15 °S) sustain one of the most diverse forests in the world (Josse et al., 2009); however, the development of well-replicated chronologies from tree species has been limited. One of the most important dendrochronological advances in South America during recent decades has been the development of the Polylepis spp. tree-ring chronologies. This achievement was possible due to the presence of well-defined annual rings in several Polylepis species, their high climatic sensitivity, the longevity of some species and their unique geographical locations (Boninsegna et al., 2009). From a dendrochronological point of view, Polylepis tarapacana is the species most studied of the genus (Argollo et al., 2004; Christie et al., 2009; Solíz et al., 2009; Morales et al., 2004, 2012, 2015; Moya and Lara, 2011). Other Polylepis species used in tree-ring research include Polylepis besseri (Gareca et al., 2010), Polylepis pepei (Roig et al., 2001), Polylepis subsericans (Jomelli et al., 2012), Polylepis rugulosa (Jomelli et al., 2012), and Polylepis australis (Chartier et al., 2016; Marcora et al., 2017; Suarez et al., 2008). Therefore, the exploration of the dendrochronological potential in Polylepis species in the Peruvian Andes is of high scientific value due to its possible applications in ecological and paleoclimatic studies, at both local and regional scales.
The Peruvian Andes, the home of an extraordinary biological and cultural diversity, encompass three phytogeographic regions: The Yungas, the Wet and the Xerophytic Puna (Josse et al., 2009). In the Wet Puna, the precipitation shows a marked seasonality with a prolonged dry interval from May to October. The marked dry season induces a period of vegetative dormancy with the fall of leaves in most species and the cease of biomass production (Josse et al., 2009).
In this study, we present the first chronology of Polylepis rodolfo-vasquezii, a species recently discovered in the central Andes of Peru (Valenzuela and Villalba, 2015). Based on standard dendrochronological statistics (Cook and Pederson, 2011), we evaluate the quality of the chronology in the context of tree-ring records from different Polylepis species. Finally, we compared the chronology of P. rodolfo-vasquezii with instrumental records of temperature and precipitation to determine the climatic variables that influence the growth of this species.
Section snippets
Climate
Climate variability at different temporal scales in the tropical Andes is modulated by oceanic and continental climatic forcings. Sea-surface temperature anomalies in the Pacific Ocean related to El Niño-Southern Oscillation (ENSO) and the Pacific Decadal Oscillation, are major forcings of interannual- and decade-scale climatic variations, respectively, along the tropical Andes (Vuille et al., 2000; Garreaud et al., 2003). On the other hand, variations in the South American summer monsoon in
Results
The wood of Polylepis rodolfo-vasquezii shows clearly distinguishable growth rings (Fig. 3a) due to the presence of more abundant and large-diameter vessels at the beginning of the earlywood (semicircular porosity; Fig. 3b and c). Heterogeneous, uni-seriates and multi-seriates radii up to three-cell wide are observed (Fig. 3d and e). The delimitation of the growth rings is also facilitated by the occurrence of abundant fibers with thicker cell walls present at the end of the annual rings (Fig. 3
Discussion
We present here the first ring-width chronology of P. rodolfo-vasquezii from the humid Puna in the Central Andes of Peru. This tree-ring record, located in the tropics at 11 °S, extends towards the equator the coverage of dendrochronological records in the Andes. The P. rodolfo-vasquezii wood shows rings clearly demarcated by the semicircular arrangement with larger vessels at the beginning of the annual ring that contrast with abundant thick-wall fibers at the end of the latewood. The
Conclusions
The first P. rodolfo-vasquezii chronology at 4000 m elevation in the humid Puna of Peru represents a valuable record to infer past climate variability in the tropical Andes and their relationships with SST over the tropical Pacific and Atlantic oceans. This temperature-sensitive record provides climatic information of great paleoclimatic value in a region devoid of long-term instrumental records and tree-ring chronologies. Our tree-ring record shows significant relationships with SST variations
Declaration of Competing Interest
The authors whose names are listed immediately below certify that they have NO affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in
Acknowledgments
The authors are grateful for the collaboration of Harol Quispe and Luis Salome in the field work and Ricardo Ortega and Luis Santin in the preparation of histological cuts. Pomamnta community for facilities and permission to work the woodlands. This study was financed by the National Council for Science, Technology and Technological Innovation; CONCYTEC, Peru (Project N° 147-2015-FONDECYT-DE, Proyect N° 039-2019-FONDECYT-BM-INC-INV). M.S.M. and R.V. have been partially support by CONICET,
References (44)
- et al.
Dendroclimatological reconstructions in South America: a review
Paleogeography Paleoclimatol. Palaeoecol.
(2009) - et al.
El Niño-Southern Oscillation signal in the world’ s highest-elevation tree-ring chronologies from the Altiplano, Central Andes
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2009) - et al.
The climate of the Altiplano: observed current conditions and mechanisms of past changes
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2003) - et al.
Taxonomical and distributional notes on Polylepis (Rosaceae)
Org. Divers. Evol.
(2006) - et al.
A ‘“signal-free”’ approach to dendroclimatic standardisation
Dendrochronologia
(2008) - et al.
Spatio-temporal variations in Polylepis tarapacana radial growth across the Bolivian Altiplano during the 20th century
Palaeogeogr. Palaeoclimatol. Palaeoecol.
(2009) - et al.
RClimDex (1.0) User Manual. Climate Research Branch Environment Canada
(2004) - et al.
Changes in precipitation and temperature extremes in Central America and northern South America, 1961–2003
J. Geophys. Res. Atmos.
(2005) - et al.
Potencialidad dendrocronológica de Polylepis tarapacana en los Andes Centrales de Bolivia
Ecol. en Boliv.
(2004) - et al.
Anatomía de anillos de crecimiento de 80 especies arbóreas potenciales para estudios dendrocronológicos en la Selva Central, Perú
Rev. Biol. Trop.
(2013)
Response functions revisited
Tree-Ring Bull.
Interpreting high-resolution proxy climate data — the example of dendroclimatology
Uncertainties in climate change projections and regional downscaling in the tropical Andes: implications for water resources management
Hydrol. Earth Syst. Sci. Discuss.
Exposed roots as indicators of geomorphic processes: a case-study from Polylepis mountain woodlands of Central Argentina
Dendrochronologia
Uncertainty, emergence, and statistics in dendrochronology
ERA5: Fifth Generation of ECMWF Atmospheric Reanalyses of the Global Climate
Biodiversidad y cambio climático en los Andes Tropicales. Red Gloria-Andes, Lima-Quito
Tree-growth responses across environmental gradients in subtropical Argentinean forests
Plant Ecol.
Polylepis forests - vestiges of a vanishing ecosystem in the Andes
Ecotropica
Tree Rings and Climate
Dendrochronological investigation of the high Andean tree species Polylepis besseri and implications for management and conservation
Biodiversyti Conserv.
Evaluation crossdating accuracy: a manual and tutorial for the computer program cofecha
Tree-Ring Res.
Cited by (8)
Revealing Polylepis microphylla as a suitable tree species for dendrochronology and quantitative wood anatomy in the Andean montane forests
2022, DendrochronologiaCitation Excerpt :Specifically, the Central Andes in Peru sustain one of the most diverse forests in the world (Josse et al., 2009). Several dendrochronological studies in the region, and further south in the Altiplano, found significant relationship between tree growth and environmental variables such as temperature and precipitation (Solíz et al., 2009; Ballantyne et al., 2011; Brienen et al., 2012; Requena-Rojas et al., 2020, 2021; Crispin Dela Cruz et al., 2022; Rodriguez-Caton et al., 2021), as well as with El Niño Southern Oscillation (ENSO) variability (Christie et al., 2009; Li et al., 2013; Crispin Dela Cruz et al., 2022; Rodriguez-Caton et al., 2021), which explain much of the inter-annual hydroclimate variability in the Andes with reduced precipitation during ENSO warm phase and increase precipitation during ENSO cold phase (Garreaud et al., 2009). Despite significant progress, tree-ring based climate reconstructions are still scarce in the tropical Andes (see the International Tree-Ring Data Bank; Grissino-Mayer and Fritts, 1997).
Tree-ring isotopes from Araucaria araucana as useful proxies for climate reconstructions
2022, DendrochronologiaCitation Excerpt :Climate-sensitive Polylepis tarapacana in the Altiplano in South America provide the highest-elevation tree-ring chronologies worldwide spanning for centuries to millennia (Morales et al., 2012). Even closer to the Equator at 11ºS, but with shorter time span, Polylepis rodolfo-vasquezii have also shown climate sensitivity, in particular with growing season temperature (Requena-Rojas et al., 2020). Further south in the Central Andes in Chile (32°S - 36°S), centennial oscillations in precipitation were inferred from millennium-long records of Austrocedrus chilensis (Le Quesne et al., 2006, among others).
Dendroclimatic potential of the Adesmia pinifolia shrub growing at high altitude in the Andes foothills
2022, DendrochronologiaCitation Excerpt :Barichivich et al. (2009) showed the existence of strong relationships between the growth variability of shrubs and ENSO at elevations between 1900 and 2550 m.a.s.l. in the Chilean Central Andes. Furthermore, Li et al. (2013) developed an ENSO reconstruction with the Polylepis tarapacana trees growing at the Andes Altiplano and Requena-Rojas et al. (2020) observed the influence of surface sea temperature of the tropical ENSO region on radial growth of Polylepis rodolfo-vasquezii in the highlands of Perú. Recent studies indicate the large potential of shrubs to extract dendroecological information in large areas of the planet whose vegetation cover is restricted to this biological form (Myers-Smith et al., 2015a; Carrer et al., 2019; Quesada-Román et al., 2020; Yang et al., 2020; Camarero et al., 2021; Requena-Rojas et al., 2021).