Small Mammal Community Structure and Composition in the Cerrado Province of Central Brazil
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CORE Metadata, citation and similar papers at core.ac.uk Provided by UNL | Libraries University of Nebraska - Lincoln DigitalCommons@University of Nebraska - Lincoln Faculty Publications from the Harold W. Manter Laboratory of Parasitology Parasitology, Harold W. Manter Laboratory of 1986 Small mammal community structure and composition in the Cerrado Province of central Brazil Michael A. Mares University of Oklahoma Norman Campus Kristina A. Ernest University of Arizona Donald D. Gettinger University of Oklahoma Norman, [email protected] Follow this and additional works at: https://digitalcommons.unl.edu/parasitologyfacpubs Part of the Parasitology Commons Mares, Michael A.; Ernest, Kristina A.; and Gettinger, Donald D., "Small mammal community structure and composition in the Cerrado Province of central Brazil" (1986). Faculty Publications from the Harold W. Manter Laboratory of Parasitology. 679. https://digitalcommons.unl.edu/parasitologyfacpubs/679 This Article is brought to you for free and open access by the Parasitology, Harold W. Manter Laboratory of at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for inclusion in Faculty Publications from the Harold W. Manter Laboratory of Parasitology by an authorized administrator of DigitalCommons@University of Nebraska - Lincoln. Mares, Ernest & Gettinger in Journal of Tropical Ecology (1986) 2. Copyright 1986, Cambridge University Press. Used by permission. Journalof TropicalEcology (1986) 2:289-300. With5 figures Small mammal community structureand composition in the Cerrado Province of central Brazil MICHAEL A. MARES, KRISTINA A. ERNEST* and DONALD D. GETTINGER StovallMuseum and Departmentof Zoology, Universityof Oklahoma, Norman,Oklahoma 73019 USA ABSTRACT. Communitystructure, macrohabitat selection, and patternsof species co-occur- rence were examined duringa 14-monthstudy of small mammalsin the Cerrado Provinceof central Brazil. Data were collected frommark-recapture grids in brejo and galleryforest, and fromlive-trapping and specimen collection in all habitat types withincerrado (campo limpo, campo sujo, cerrado [s.s.], cerradao,brejo, valley-sidewet campo, and galleryforest). Gallery forest supported the highestspecies richness,most complex verticaldistribution of species, highestlevel of trophicdiversity, and highestmacroniche diversity. Degree of habitatselection varied widely. All habitat types supported both rodentsand marsupials,although marsupials tended to be much less common in the grasslands(campos) than in woodlands (cerrado) and forests(cerradao, gallery forest). Some species, such as Didelphis albiventris,occurred in all habitat types, while others were much more restricted.Oryzomys bicolor, for example, ocur- red only in galleryforest. No habitat type had a completelydistinct fauna: overlap in species composition always occurredwith at least one other habitat type. Because of the greatvaria- bility of habitats, and the fact that subsets of the mammal fauna were frequentlyhabitat specific,the overall species richnessof any portion of mixed cerrado vegetationis remarkably high. KEY WORDS: Brazil, communitystructure, gallery forest, habitat selection,marsupials, neo- tropics,rodents, tropical savanna. INTRODUCTION South Americasupports many habitats,but two major phytogeographicpro- vinces,both tropical,predominate. The Amazon rainforest, a mosaicof forest communities,encompasses about 5-6 million kmi2,while the cerrado,a com- plex of savanna grasslandsand forestedareas, extends over 1.5 millionkm2 (e.g. Eiten 1974, Fearnside1982). Together,these areas comprise42% of the South Americancontinent. The flora of both areas has been examinedcur- sorily,while their faunas remain largely unknown (e.g. Alho 1982a, Mares1982, 1986). The taxonomyof the mammalsin these habitatsis poorlyknown, and little ecological researchhas been conductedon thisgroup (Mares 1982, Pine 1982). Both the Amazon Basin and cerrado are experiencingrapid develop- ment (Goodland & Irwin 1977, Myers1980) and theirfaunas are considered * Present address: Departmentof Ecology and EvolutionaryBiology, Universityof Arizona, Tucson, Arizona85721, USA. (289) Mares, Ernest & Gettinger in Journal of Tropical Ecology (1986) 2. Copyright 1986, Cambridge University Press. Used by permission. 290 MICHAEL A. MARES, KRISTINA A. ERNEST AND DONALD D. GETTINGER threatened.In this paper, we examine habitat selectionby small mammals, especiallyrodents, in the CerradoProvince of centralBrazil. Most of our data weregathered in one of the Cerrado'smost unusual habitats, the galleryforest. Most descriptionsof tropicalforest in South Americaconsider the lowland Amazon forest,the montanetropical forest rimming the Amazon Basin,or the montanerain forestof the east coast of Brazil. However,there is an extensive evergreentropical forest that occurs along many thousands of kilometersof the cerradowatercourses and extendsthroughout the regionin a serpentinefashion. Ultimately,this galleryforest joins the Amazon or Atlantic coastal forest (Eiten 1972, 1974), and so it is not surprisingthat many floral and faunalele- mentsare shared among these sylvanhabitats (Alho 1982b, Cerqueira1982). Little ecological work has been done on the mammalsof the galleryforest (Paula 1983), althoughsome cerrado mammals have been examinedecologically (Alho 1981a, 1981b, 1981c, Dietz 1983, Souza & Alho 1980). The habitat selection of tropical mammals,forest or otherwiseis largely unknown,but it has been suggestedthat habitatspecificity in tropicalregions is more pronouncedthan in temperateareas (MacArthuret al. 1966). This has been especiallytrue forresearch done on birds (MacArthuret al. 1972). Here we presentpreliminary data on habitatselection, species richnessand macro- niche compositionof the small mammalfauna of fourhabitats of the cerrado of Brazil. We comparethese data to otherstudies conducted in the cerradoand point out the importanceof havingdetailed information on speciescoexistence beforegeneralizations on diversitypatterns can be made. Our resultsapply to both ecologicaland biogeographicstudies of thisregion. STUDY AREA Cerrado(sensu lato) is a majorphytogeographic province located in the central plateau region of Brazil (Figure 1; Cabrera & Willink1973). The climate is tropical,with distinct wet (October-April)and dry (May-September)seasons. Annualprecipitation ranges from 750-2000 mm (Eiten 1974). Cerrado(s. 1.), the dominantflora of the province,is a mosaic of xeromorphicupland vegeta- tion typesranging from open grasslandsto closed woodlands.Trees and shrubs withcontorted trunks, thick bark, twisted limbs, and broad,thick leaves give a characteristicappearance to these upland formations.Edaphic factors,such as soil depth,drainage, and nutrientquality, influence the structureof the flora, and often produce physiognomicgradients (Eiten 1972). The upland florais commonlydivided into fivephysiognomic types (Eiten 1972, Goodland 1971): (1) cerradao,a forestof largeand moderatelytall trees,usually with a closed canopy and few shrubs;(2) cerrado(sensu stricto), a shortertree/shrub wood- land withan open canopy and sparsegrass understory; (3) campo cerrado,an open tree/shrubwoodland with a groundcover of grasses;(4) campo sujo, a grasslandwith scattered trees and shrubs;(5) campo limpo,an open grassland withfairly low grasses. Mares, Ernest & Gettinger in Journal of Tropical Ecology (1986) 2. Copyright 1986, Cambridge University Press. Used by permission. Mammalecology in theBrazilian cerrado 291 -20 -10 -0 -10 -20 -30 -40 -50 Figure1. Map showingthe limitsof the Cerradophytogeographic Province in South America. The flora changesdrastically along the drainagelowlands, where the water table is close to the surface.The dominantcerrado vegetation is replacedby mesophyticevergreen forest, which formscorridors along streamsand rivers. These galleryforests often ascend the slopes of the valleyand are usually50- 200 m wide (Eiten 1974). Two typesof lowlandmarshes are frequentlyfound along the edge of gallery forest: brejo, a sedge-dominated,permanently- inundatedmarsh; and valley-sidewet campo, a grass-dominated,seasonally- inundatedmarsh that grades into upland cerrado vegetation. In thispaper, we group the vegetationaltypes of the CerradoProvince into fourhabitats (Figure 2) for purposes of statisticalanalysis. We will consider cerradao,cerrado, and campo cerradoas a singlehabitat, cerrado. Further, we combine campo limpo,campo sujo, and valley-sidewet campo into the single habitat,campo. Membersof these habitat sets grade imperceptiblyinto one another,and our collectingeffort was not sufficientlyfine-grained to distin- guishbetween the relatedhabitat pairs. Brejo and galleryforest are considered separatehabitats. Data presentedhere were collected near Brasilia, Districto Federal ( 150 56' S, Mares, Ernest & Gettinger in Journal of Tropical Ecology (1986) 2. Copyright 1986, Cambridge University Press. Used by permission. 292 ,0 0 U 1 1"~~~~~~~~~~ Mares, Ernest & Gettinger in Journal of Tropical Ecology (1986) 2. Copyright 1986, Cambridge University Press. Used by permission. Mammalecology in theBrazilian cerrado 293 470 53' W). Althoughcerradao is poorly representedin this area, all other vegetationtypes were common. Most field work was done on the Ecological Reserveof the InstitutoBrasilieiro de Geografiae Estatisticaand the Fazenda Agua Limparesearch station of the Universidadede Brasilia. METHODS BetweenAugust 1983 and November1984, smallmammals were sampled from all vegetationtypes: cerradao,cerrado