Preprints
https://doi.org/10.5194/egusphere-2025-2032
https://doi.org/10.5194/egusphere-2025-2032
15 May 2025
 | 15 May 2025

Radial growth decline in a tropical Andean treeline in Bolivia

Rose Oelkers, Laia Andreu-Hayles, Rosanne D'Arrigo, Arturo Pacheco Solana, Milagros Rodriguez-Caton, M. Eugenia Ferrero, Ernesto Tejedor, Alfredo F. Fuentes, Carla Maldonado, and Daniel Ruiz-Carrascal

Abstract. Relative to research efforts in higher latitiudes, the impact of climate shifts in the tropical treeline remains understudied. Little is known about the tree growth dynamics and climate response at this treeline over the past few centuries, and at present under a rapidly changing environment. Here we provide information on recent changes in tree-ring patterns of Polylepis pepei BB.Simpson, a tropical tree species that grows in a monospecific forest at the elevational treeline in the Andes-Amazon ecotone of Bolivia and identify factors that limit its radial growth. We first developed a ring width (RW) chronology spanning 1867–2018 C.E. using dendrochronological methods and independently verified annual periodicity with radiocarbon dating. The RW chronology indicates a significant (p < 0.01) radial growth decline in P. pepei since 1997, a trend that mirrors a decrease reported in other Polylepis species from the drier central Andes of South America. P. pepei tree-ring width (RW) was mostly limited by mean, minimum, and maximum temperature and precipitation during austral summer (November–January). Over the instrumental period (1981–2019) prior-year temperatures negatively affected current-year tree growth (p < 0.05), while prior-year wet conditions were associated with higher growth (p < 0.05). Gridded temperature records (1901–2019) showed a significant increase in minimum temperatures and a decline in the diurnal temperature range since 1967, which may reduce orographic convection and water availability at higher elevations where our forest is located. In situ daily measurements from dataloggers in the forest recorded higher temperatures and lower relative humidity values when data was available. Our results suggest less moisture availability associated with warming conditions was related to the observed tree-growth decline. If temperature continues to rise at current rates, one of the highest-elevation tree species on the globe, P. pepei, could face severe consequences. This work provides insights into the past and historical trends of a tropical Andean treeline, which shows a recent decline also observed in other high-elevation forests (4657–4800 m.a.s.l.) of tropical South America (>17° S).

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
Share
Rose Oelkers, Laia Andreu-Hayles, Rosanne D'Arrigo, Arturo Pacheco Solana, Milagros Rodriguez-Caton, M. Eugenia Ferrero, Ernesto Tejedor, Alfredo F. Fuentes, Carla Maldonado, and Daniel Ruiz-Carrascal

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2025-2032', Anonymous Referee #1, 17 Jul 2025
  • RC2: 'Comment on egusphere-2025-2032', Anonymous Referee #2, 15 Aug 2025
Rose Oelkers, Laia Andreu-Hayles, Rosanne D'Arrigo, Arturo Pacheco Solana, Milagros Rodriguez-Caton, M. Eugenia Ferrero, Ernesto Tejedor, Alfredo F. Fuentes, Carla Maldonado, and Daniel Ruiz-Carrascal
Rose Oelkers, Laia Andreu-Hayles, Rosanne D'Arrigo, Arturo Pacheco Solana, Milagros Rodriguez-Caton, M. Eugenia Ferrero, Ernesto Tejedor, Alfredo F. Fuentes, Carla Maldonado, and Daniel Ruiz-Carrascal

Viewed

Total article views: 391 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
311 66 14 391 13 28
  • HTML: 311
  • PDF: 66
  • XML: 14
  • Total: 391
  • BibTeX: 13
  • EndNote: 28
Views and downloads (calculated since 15 May 2025)
Cumulative views and downloads (calculated since 15 May 2025)

Viewed (geographical distribution)

Total article views: 388 (including HTML, PDF, and XML) Thereof 388 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 05 Sep 2025
Download
Short summary
Alpine treelines are situated at the extreme biogeographic limits of Earth's forests and are sensitive to global environmental change. We analyzed annual ring-widths from Polylpeis pepei trees from the Andes Mountains and found reduced growth since the 1990s. Smaller rings occurred if the prior-year wet season was hotter and drier. Our findings provide a long-term context of forest growth near the Andes-Amazon and suggest regional drought may be driving this decline at a tropical treeline.
Share