High litterfall in old-growth and secondary upper montane forest of Costa Rica

Abstract

Tropical upper montane forests usually comprise trees of small stature with a relatively low aboveground productivity. In contrast to this rule, in the Cordillera de Talamanca (Costa Rica), tall trees ([35 m in height and more than 60 cm in diameter) are characteristic for the upper montane old-growth oak forests which are growing at an altitude of almost 3,000 m close to the alpine timberline. For these exceptional forests, productivity data are not yet available. In this study, we analyzed litterfall and its components (tree leaves, litter of epiphytic vascular and non-vascular plants, mistletoes, twigs and other canopy debris) in three forest stands belonging to different successional stages and related seasonal changes in litterfall to micrometeorological variables. The studied stands were early-successional forest (10-15-year-old), mid-successional forest (40-year-old), and old-growth forest. The stands are dominated by Quercus copeyensis and are located at 2,900-m altitude. Total litterfall was highest in the mid-successional forest (1,720 g m -2 y -1 ), and reached 1,288 g m -2 y -1 in the old-growth forest and 934 g m -2 y -1 in the earlysuccessional forest. Litter mass was dominated by leaves in all stages (56-84% of total litterfall). In the oldgrowth forest, however, twigs and small canopy debris particles (33%), epiphytes (6%), and mistletoes (5%) also contributed substantially to litter mass. Leaf litterfall showed a clear seasonal pattern with a negative correlation to monthly precipitation and highest values in the dry season (January-April). However, the strongest correlation existed with minimum air temperature (negative), probably because temperatures already dropped at the end of the rainy season, when precipitation had not yet declined and leaf shedding already increased. In contrast, litterfall of epiphyte mass, and twigs and other debris was mostly dependent on occasional strong winds. We conclude that the upper montane oak forests of the Cordillera de Talamanca are exceptional with respect to the large tree size and the relatively high productivity as indicated by litterfall. Litter mass was especially high in the mid-successional and old-growth forests, where the observed annual totals are among the highest recorded for tropical forests so far.

Litterfall Production at Different Successional Stages in a Tropical Rain Forest in Southern Brazil

“…The results of this study do not corroborate other studies, which observed that the production of the leaf fraction decreased with the advance of the successional phase in tropical forests (PEZZATO;WISNIEWSKI, 2006;ROCHA, 2006;KÖHLER et al, 2008). Investigating the litterfall in different successional stages of a Subtropical Forest in Paraná, Dickow et al (2012) found a higher leaf deposition in initial stages of succession in relation to the medium and advanced stages of natural regeneration.…”

Produção de serapilheira em diferentes fases sucessionais de uma floresta subtropical secundária, em Antonina, PR

“…Essa porcentagem, normalmente situa-se acima dos 60-70% (CUEVAS; MEDINA, 1986;CUNHA et al, 1993;CUSTÓDIO FILHO et al, 1996;LUIZÃO;SCHUBART, 1986;MACHADO et al, 2008;MARTIUS et al, 2004;MORAES et al, 1999;MARQUES, 2003;ROCHA, 2006;SCHEER, 2006;SILVA et al, 2009;VARJABEDIAN;PAGANO, 1988;VOGEL et al, 2007). A diminuição na porcentagem de folhas (de 77 para 68%), com o avanço da fase sucessional, já foi observada por outros autores em florestas tropicais secundárias em diferentes fases de sucessão (CUNHA, 1997;KÖHLER et al, 2008;PEZZATO;WISNIEWSKI, 2006;MARQUES, 2003;ROCHA, 2006;TOLEDO et al, 2002) e pode estar associada a uma maior produção de serapilheira foliar pelas espécies pioneiras presentes nas fl orestas secundárias em processo inicial de regeneração (MARTINS; RODRIGUES, 1999). Luizão e Schubart (1986), investigando a produção de serapilheira em fl oresta de terra fi rme da Amazônia Central, encontraram maior porcentagem de folhas na capoeira jovem em relação às fl orestas originais de platô e baixio.…”

Litterfall dynamics in a iron-rich rock outcrop complex in the southeastern portion of the Iron Quadrangle of Brazil

“…Despite this variability, the seasonal variation of litterfall found in the SFA was not as pronounced as that reported for other seasonal forests (Lawrence 2005;Köhler et al 2008;Terror et al 2011). At the ecosystem level, a greater diversity of plant species and functional groups with different phenological patterns can lead to more uniform litter deposition throughout the year (Köhler et al 2008).…”

“…At the ecosystem level, a greater diversity of plant species and functional groups with different phenological patterns can lead to more uniform litter deposition throughout the year (Köhler et al 2008). In tropical forests, pulses of litterfall, with a high proportion deposited in a short time, can occur in formations with one or a few dominant species, reflecting the phenological pattern of these species (Villela & Proctor 1999;Köhler et al 2008;Terror et al 2011). Pulses of litter deposition can also occur in forests with high species diversity, such as semideciduous and deciduous forests, in response to changing environmental conditions.…”

“…We showed that the miscellaneous fraction of litter production was correlated with rainfall in all habitats (R 2 >0.42) and that the peaks in that fraction occurred mainly at the beginning of the rainy season (in October, November and December). After the leaf fraction, fragments of branches and trunks are the largest contributor to total litterfall in an ecosystem (Martins & Rodrigues 1999, Dent et al 2006Cianciaruso et al 2006, Köhler et al 2008, Valenti et al 2008. During the dry season, twigs and branches can show xylem cavitation, which results in death from embolism (Tyree & Sperry 1989).…”