The impact of red howler monkey latrines on the distribution of main nutrients and on topsoil profiles in a tropical rain forest

Abstract

Scarcity of organic matter and nutrients in the topsoil is a typical feature of lowland primary tropical rain forests. However, clumped defecation by vertebrate herbivore troops and further dung beetle processing may contribute to locally improve soil biological activity and plant growth.We studied the impact of clumped defecation by the red howler monkey (Alouatta seniculus), a frugivorous primate, on the vertical distribution of topsoil (0-6 cm) main nutrients and microstructures in a tropical rain forest (French Guiana). Three latrines, where monkey troops regularly defecate, were sampled, together with adjoining controls for carbon, nitrogen, phosphorus and microscopic components.The vertical distribution of C and N was affected by clumped defecation: nutrients were mostly restricted to the top 2 cm in control areas while latrines exhibited homogeneously distributed C and N, resulting in higher C and N content below 2 cm. No marked effect of defecation was registered on Olsen P. A small although significant increase in pH (0.1-0.3 pH units) and a marked increase in soil respiration (¥1.5-2.5) were registered in latrines. Soil microstructures were studied by the small-volume method. Variation according to depth, site and clumped defecation was analysed by Redundancy Analysis. The three latrines were characterized by an increase in root-penetrated mineral-organic assemblages, mainly composed of recent and old earthworm faeces. The local stimulation of plant roots, microbial and earthworm activity was prominent, together with an increase in soil fertility. Consequences for the regeneration of tropical rain forests in the Amazonian basin were discussed, in the light of existing knowledge.

Urine as an important source of sodium increases decomposition in an inland but not coastal tropical forest

“…Initial reductions in soil fauna after urea application are commonly reported and followed by rapid recoveries at as early as 4 weeks (Marshall 1974;Lohm et al 1977). Natural latrines are typically nutrient-rich sites where nutrient mineralization and decomposition occur rapidly and shock effects are likely insignificant because cell-free ureases can accumulate in areas of frequent urine deposition and accelerate mineralization (McNaughton et al 1997b;Dos Santos et al 2010). It is likely that we would have seen increased invertebrate abundance and enhanced decomposition on urine-fertilized plots had we sampled after a longer period.…”

The impact of seed dispersal by black and gold howler monkeys on forest regeneration

“…Additionally, compared to outside of latrines, the micromorphology of the soil in latrines is more favorable for the development of roots (Feeley 2005;Dos Santos Neves et al 2010). While transitional probabilities remain constant in controls, they increase noticeably in latrines from tall saplings shorter than 1 m to those taller than 1 m, denoting that another mechanism could be involved.…”

Short-term sodium inputs attract microbi-detritivores and their predators

“…This allowed us to examine both rapid effects that mimic a migrating mammal excretion event (1 day), and longer term subsidies that mimic latrines where mammals such as howler monkeys (as well as other primates) common throughout the Neotropics display excretion site-fidelity and deposit daily both urine and feces (Feely, 2005;Dos Santos Neves et al, 2010). Prior to each harvest, we measured litter depth 1 cm inside the four plot corners of both treatment plots using a wire gently inserted into the litter down to mineral soil.…”