Absence of Howlers Emphasis Type="Italic"Alouat

Authors: Alberto AnzuresDadda Ellen Andresen María Luisa Martínez Robert H Manson

Publish Date: 2011/02/02

Volume: 32, Issue: 3, Pages: 634-651

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Abstract

The disappearance of frugivorous primates in fragmented forests can potentially lower the rates of seed dispersal and recruitment of endozoochorous tree species thus altering plant community structure We quantified seedling density for 7 tree species that are common in the feces of mantled howlers Alouatta palliata in 6 rain forest fragments in northern Chiapas Mexico Howlers were present in 3 of the fragments and absent in the other 3 We compared seedling density in primate sleeping sites in inhabited fragments with control sites which were structurally similar to sleeping sites but where we did not find monkey feces in both inhabited and uninhabited fragments For each tree species we determined the relationship between seedling density and the local density of seeds and adult trees In fragments where howlers were present seedling density for 4 of the focal tree species Brosimum alicastrum Dialium guianense Manilkara zapota and Nectandra ambigens was greater in sleeping sites than in control sites found in the same fragments Moreover seedling density of Dialium guianense was greater in the control sites of fragments inhabited by howlers than in fragments where this primate is absent Seedling density of these 4 species correlates positively with seed density on the forest floor however we observed no correlations between seedling density and the density of adult trees Our results suggest that the diversity of the seedling community of tree species dispersed by howlers may decline in fragments where this seed disperser is absent These findings together with the fact that only 5 of the study region is currently covered by forest and 81 of the forest remnants are uninhabited by mantled howlers suggest that the potential longterm recovery of associated populations of tropical tree species dispersed by this primate species is highly uncertain Conservation and restoration efforts should be aimed at restoring or replacing the ecological role played by this important seed disperser in the regionA Birke L Guillén D Garibay A MartínezRamírez J León J BenítezMalvido JC SerioSilva J Laborde L AbdaláRoberts A CastroLuna C Gallardo and B Vera contributed valuable comments to earlier versions of the manuscript We also thank 3 anonymous reviewers for their many useful suggestions We thank R Morales and M Gil for field assistance This study was financed by a PhD scholarship to A AnzuresDadda provided by the Mexican Consejo Nacional de Ciencia y Tecnología 159285 through the Instituto de Ecología AC INECOL as well as by SigmaXi GrantsinAid of Research and Iberostal Hotels Resorts Logistic support was provided by the Ayuntamiento de Juarez Chiapas the Instituto de Historia Natural de Chiapas Organic Export Lom Lek Café Aleph Construcciones as well as by the AnzuresDadda GilRamos GuichardRomero and EscobarPadilla families and the landowners of the field sites A AnzuresDadda thanks M Aluja and the AlujaGuillén family for their support during the preparation of the manuscript E Andresen was on sabbatical leave during the time of manuscript preparation she thanks DGAPAUNAM for financial support through a sabbatical fellowship and the University of Washington for hosting her This article is part of the PhD dissertation of A AnzuresDadda directed by R H Manson We thank L AbdaláRoberts for translation of the manuscript

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