Leaf Litterfall and Decomposition ofPolylepis reticulatain the Treeline of the Ecuadorian Andes

Aldemar Carabajo,Carlos Gracia,Ashley Studholme,Juan Pinos

doi:10.1659/mrd-journal-d-16-00004.1

Aldemar Carabajo, Carlos Gracia + Show 2 more

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https://doi.org/10.1659/mrd-journal-d-16-00004.1

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Abstract

Leaf litterfall contributes significantly to carbon fluxes in forests. A crucial open question for the sustainability of mountain forests is how climate change will affect this and other carbon fluxes (eg photosynthesis and respiration). Leaf litterfall and decomposition of Polylepis reticulata, an endemic species of the Andes, were analyzed during a period of 1 year at 6 experimental plots located in the Andean paramo between 3700 and 3900 m above sea level in Cajas National Park, Ecuador. Litterfall was collected in each plot using 5 randomly distributed traps. Every trap had a 40-cm diameter (0.125 m2) and was suspended 0.8 to 1.0 m above the ground. The decomposition rate of the leaf litter was analyzed using litter bags. Eighteen bags with approximately 20 g of dry litter were placed in the litter layer in each experimental plot and collected 30, 60, 90, 150, 210, 300, and 365 days after they were installed. The mean annual litterfall recorded was 3.77 Mg ha−1, representing 51% of the leaf biomass present in the canopy, so the leaf life span of P. reticulata in Cajas National Park is 1.98 years. Litterfall occurred all year, with no significant seasonal pattern. The mean decomposition rate (k) obtained for this study period was 0.38 year−1. This study contributes to the information gap on litterfall and decomposition in natural forests located at the highest elevations in the world.

Highlights

Polylepis reticulata, an endemic threatened tree species of the Central Andes (Goldstein et al 1994; Romoleroux et al 2008), is distributed throughout Ecuador and in some remote areas in northern and central Peru (Mendoza and Cano 2011; Zutta et al 2012)
Six 10 3 10 m2 experimental plots were selected near the center of different forest patches to avoid any edge effect, which may affect the appropriate estimation of litterfall and decomposition rates (Sizer et al 2000)
This study contributes to the knowledge regarding ecological processes like leaf litterfall and decomposition in forests dominated by Polylepis reticulata, which is one of the few species adapted to elevations above 3700 masl

Summary

Introduction

An endemic threatened tree species of the Central Andes (Goldstein et al 1994; Romoleroux et al 2008), is distributed throughout Ecuador and in some remote areas in northern and central Peru (Mendoza and Cano 2011; Zutta et al 2012). Highland mountain areas are more sensitive to variations in climate conditions and are expected to experience stronger temperature fluctuations in the future than other parts of the planet (Beniston 2003). Treelines have been proposed as potential indicators of the response of ecosystems to climate change (Kimball and Weihrauch 2000). Regional climate models project changes in temperature and precipitation patterns, which would affect ecosystem processes such as net primary production (NPP) and respiration (Melillo et al 1993; Cao and Woodward 1998). Leaf litterfall, and decomposition rates are showing changes in different ecosystems across the globe (Zhang et al 2008; Chave et al 2010)

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