Seed-dispersal and seedling recruitment patterns by the last Neotropical megafaunal element in Amazonia, the tapir

Abstract

Tapirs (Tapiridae) are the last representatives of the Pleistocene megafauna of South and Central America. How they affect the ecology of plants was examined by studying the diversity, abundance, and condition of seeds defecated by the lowland tapir (Tapirus terrestris) in Amazonian Brazil. Additionally, the spatio-temporal pattern of the seed-rain and seed-shadows generated by tapirs was recorded. Three hundred and fifty-six tapir faeces were examined. Eleven per cent were found in water (n = 41), while 88% were located on dry land (n = 315). Of those found on dry land, 84% were located at sites that flood seasonally, while 14% of the total were encountered at forest sites that do not flood. In 127 faeces checked in the laboratory over 12 906 seeds of at least 39 species were found. Seed viability ranged from 65% for Maximiliana maripa to 98% for Enterolobium schomburgkii. Of nine seed species planted in the laboratory, seven germinated within 4 wk, with one species achieving an 89% germination rate. For many species recruitment to the seedling stage was also high under natural conditions, with 13 plant species occurring as seedlings in older faeces. Tapir generated seed-rain occurred throughout the year, with seeds defecated in all months. Two temporal patterns in species seed rain occurred: (1) contiguous monthly occurrence with peaks in abundance, and (2) discontinuous occurrence (time clumped) with small (a few months) to large (many months to more than a year) temporal gaps. The highest diversity of seeds appeared in April, at the end of the dry season. As the last of the Pleistocene megafauna of the region, tapirs may have particular importance as dispersers of large seeds and generators of unique seed dispersion patterns.

Thieving rodents as substitute dispersers of megafaunal seeds

“…Communities of stealing rodents can provide long-distance dispersal comparable to other vertebrates that are considered good seed dispersers (45,46). Although this seed movement is not as far as provided by large-bodied frugivores, such as megafauna that can transport seeds over multiple kilometers (47,48), the survival potential of scatter-hoarded seeds is likely superior to that of hundreds of seeds deposited together in megafauna dung piles (48)(49)(50). Our results make it conceivable that secondary seed dispersal by rodents can be sufficiently effective to substitute for primary dispersal of megafaunal seeds by large mammals.…”

Clumped dispersal and species coexistence

“…a scrub in an open landscape or a rock in the sea. Using biotic dispersal agents, patchy dispersal can emerge due to the behaviour of the agent (Heard and Remer, 1997;Wenny and Levey, 1998;Fragoso and Huffman, 2000;Hartley and Shorrocks, 2002;Wehncke et al, 2003). Secondary dispersal processes such as scatter hoarding may also be an important source of patchy dispersal (Nathan and MullerLandau, 2000;Wang and Smith, 2002;Roth and Vander Wall, 2005).…”

Interactive effects of flooding and treefall gap formation onterra firmeforest andvárzeaforest seed and seedling mechanisms and tolerances in the Ecuadorean Amazon

“…For example, 86% of Cecropia monostachya predation in an old field located in an Ecuadorian upland forest was from insects rather than mammals (Myster 2004). Finally in the flooded forest and gaps, larger mammals such as tapirs could be significant seed dispersers on seeds larger than those used in this study (Fragoso and Huffman 2000).…”