Abundance, biomass production, nutrient content, and the possible role of terrestrial salamanders in Missouri Ozark forest ecosystems

Abstract

The transfer of energy and nutrients largely depends on the role of animals in the movement of biomass between trophic levels and ecosystems. Despite the historical recognition that amphibians could play an important role in the movement of biomass and nutrients, very few studies have provided reliable estimates of abundance and density of amphibians to reveal their true importance. Here, we provide robust estimates of abundance and density of a dominant species, the Southern Redback Salamander (Plethodon serratus Grobman, 1944), in the oak forest ecosystem of the Ozark Highlands in Missouri. We then use the abundance and density estimates to calculate biomass and nutrient content of salamanders at our study sites in the Ozark forests. Salamanders at the Sinkin Experimental Forest comprise a large amount of protein, energy, and nutrients that greatly exceed estimates derived some 35 years ago in the Hubbard Brook Experimental Forest, New Hampshire. Our estimates (7 300 -12 900 salamanders·ha −1 ) are 2-4 times greater than the values reported by Burton and Likens (1975a, Ecology, 56: 1068-10801975b , Copeia, 1975. Furthermore, we show that density estimates of other small plethodontid species reported in the literature are nearly an order of magnitude greater than that reported by Burton and Likens. We believe this indicates that previous results have underestimated the importance of salamander biomass, nutrient, and energy flux, and their functional role in regulating invertebrates and carbon retention in forest ecosystems. Résumé :Le transfert d'énergie et de nutriments dépend en bonne partie du rôle des animaux dans le mouvement de biomasse entre niveaux trophiques et entre écosystèmes. Même s'il est reconnu depuis longtemps que les amphibiens pourraient jouer un important rôle dans le mouvement de biomasse et de nutriments, très peu d'études ont fourni des estimations fiables de l'abondance et de la densité des amphibiens qui permettraient d'en révéler l'importance réelle. Nous fournissons des estimations robustes de l'abondance et de la densité d'une espèce dominante, la salamandre rayée du Sud (Plethodon serratus Grobman, 1944), dans l'écosystème de la forêt de chêne des hautes terres des monts Ozark, au Missouri. Nous utilisons ensuite les estimations d'abondance et de densité pour calculer la biomasse et le contenu en nutriments des salamandres dans les sites d'étude des forêts des Ozark. Les salamandres dans la forêt expérimentale de Sinkin renferment une grande quantité de protéines, d'énergie et de nutriments qui dépasse de beaucoup les estimations obtenues il y a quelque 35 ans dans la forêt expérimentale de Hubbard Brook, au New Hampshire. Nos estimations (7 300 -12 900 salamandres·ha −1 ) sont de 2 à 4 fois supérieures aux valeurs rapportées par Burton et Likens (1975a, Ecology, 56: 1068-10801975b , Copeia, 1975. En outre, nous montrons que les estimations de la densité d'autres espèces de petits pléthodontidés rapportées dans la littérature dépassent par presque un ordre de grandeur les estimat...

Aquatic biodiversity in forests: a weak link in ecosystem services resilience

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“…Although diet analyses show all these stream predators to be gapelimited, and hence prey are partioned by body size, ties to ecosystem processes are not well-grounded. However, insights from salamander studies in terrestrial contexts suggest their effects on arthropods breaking down forest litter and general energy transfer are significant, potentially having a signature on carbon sequestration (Best and Welsh 2014;Semlitsch et al 2014). …”

“…Relative to energy flow, forest amphibians, in particular, are notable due to their large cumulative community biomass, which may exceed that of birds, mammals, and fishes (Peterman et al 2008;Semlitsch et al 2014). In other regions, instream amphibians have been shown to play a role in water quality, by their trophic effects on invertebrates, algal biomass, nitrogen, and stream respiration (Whiles et al 2013).…”

Evidence for asymmetric competition among headwater stream vertebrates

“…Even with great variability of basal resources, some aquatic species, in particular salamanders, can reach exceptionally high densities in aquatic systems (Petranka & Murray, 2001;Peterman et al, 2008;Semlitsch et al, 2014). Due to sheer abundance of some salamander species, they likely play critical ecological roles in aquatic food webs (functioning as both predator and prey; Wilbur, 1972;Burton & Likens, 1975;Holomuzki et al, 1994;Regester et al, 2006;Gido & Jackson, 2010;Vanni, 2010) and ecosystem resilience-resistance (Davic & Welsh, 2004).…”

Silver-white Variants of the Eastern Red-backed Salamander, <i>Plethodon cinereus</i>, from Eastern Canada

“…Like other terrestrial plethodontid salamanders, it plays an important role in forest ecosystems (Hickerson et al 2012;Walton 2013;Semlitsch et al 2014). This salamander's striking colour polymorphism has long attracted the attention of herpetologists and naturalists.…”