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dc.contributor.advisorChinea, Jesús D.
dc.contributor.authorGarcía-Cancel, Juan Gilberto
dc.date.accessioned2018-04-09T14:26:55Z
dc.date.available2018-04-09T14:26:55Z
dc.date.issued2013
dc.identifier.urihttps://hdl.handle.net/20.500.11801/342
dc.description.abstractInvasive non-native species can reduce native species diversity, alter ecosystem structure and produce barriers to restoration. However little is known about how native and non- native grasses may differ in their effects on woody species diversity or seedling regeneration in a subtropical dry forest. I surveyed randomly selected patches dominated by native grasses or non–native grasses throughout randomly selected 1-km2 cells within the Guánica Dry Forest in Puerto Rico. There I assessed the effects of grass type and patch size on woody species diversity, stem diameter and stem density. Afterwards I conducted a field experiment to assess possible facilitation or inhibition effects of two grasses, one non- native (Megathyrsus maximus) and the other native (Uniola virgata), on native woody seedlings for six months. Thirty vascular families were sampled, with 58 species identified to the species level. Grass species presence was observed to correlate with woody stem density. Once this was observed I wanted to check if woody stem density was consistently different between native grasses and non-native grasses. For the native grass Uniola virgata woody stem density was associated with patch size. No patterns could be discerned for the other native and non-native grasses. Native woody species richness inside sampled plots was linearly related to grass patch size only for Uniola virgata patches. Seedlings planted near the edges of native or non-native grass clumps had a higher percentage survival than seedlings planted in bare exposed soil in the same sites. Between the two grass species, woody seedling survival was higher near native grass clumps than near non-native grass clumps, perhaps due to differences in phenology and root development that produced a more suitable microclimate near the native grass clumps. These results suggest that native grasses may be used during dry forest restoration to mitigate the negative effects of non- native grasses.
dc.description.abstractEspecies no-nativas y altamente invasivas pueden reducir diversidad de plantas nativas, alterar la estructura del ecosistema y crear barreras para restauración. Se conoce poco del efecto de pastos, tanto nativos y no-nativos en la diversidad de plantas leñosas nativas o regeneración de plántulas en bosques secos. Muestreé aleatoriamente parchos de pastos nativos y no-nativos dentro de celdas de 1-km de largo distribuidas por el Bosque Seco de Guánica en Puerto Rico. De este muestreo evalué el efecto del tipo de pasto y el tamaño del parcho en la diversidad de especies leñosas, diámetro de tallos y densidad de tallos. Luego llevé a cabo un experimento en el campo donde evalué el efecto de facilitación o inhibición de dos pastos, Megathyrsus maximus, un pasto no-nativo y Uniola virgata, un pasto nativo, en la sobrevivencia de plántulas de árboles nativos durante seis meses. Treinta familias de plantas vasculares fueron muestreadas con 58 especies identificadas. Se buscó si la presencia de gramíneas estaba correlacionada con la densidad de tallos nativos y la diversidad de plantas leñosas. No se encontró que la presencia de un pasto en particular fuera un factor determinante en la densidad de tallos y en la diversidad de plantas leñosas. Tan solo para parchos del pasto nativo de Uniola virgata fue observada una relación lineal con tamaño de parcho y diversidad de especies. Plántulas trasplantadas en el borde de pastos tuvieron mayor sobrevivencia que plántulas sembradas en suelo expuesto en ambos lugares. Entre los dos pastos sobrevivencia era mayor en el borde del pasto nativo Uniola virgata que en el borde del pasto no-nativo Megathyrsus maximus. Esto puede deberse a diferencias en fenología y desarrollo de raíces, los cuales afectan el microclima de las plántulas. Estos resultados sugieren el potencial uso de pastos nativos como herramientas de restauración de ecosistemas de bosques secos.
dc.description.sponsorshipJosé Gilberto Martinez and Fish and Wildlife Servicesen_US
dc.language.isoenen_US
dc.subjectInvasive non-native speciesen_US
dc.subjectnative grassesen_US
dc.subjectnon–native grassesen_US
dc.subjectGuánica Dry Forest in Puerto Ricoen_US
dc.subjectseedling regenerationen_US
dc.subjectwoody species diversityen_US
dc.subjectUniola virgataen_US
dc.subjectMegathyrsus maximusen_US
dc.subject.lcshTropical dry forests--Puerto Rico--Guánicaen_US
dc.subject.lcshWoody plants--Seeds--Puerto Rico--Guánicaen_US
dc.subject.lcshGrasses--Variation--Puerto Rico--Guánicaen_US
dc.subject.lcshForest restoration--Puerto Rico--Guánicaen_US
dc.titleEffects of native and non-native grasses on woody species regeneration in a Puerto Rican subtropical dry foresten_US
dc.typeThesisen_US
dc.rights.licenseAll rights reserveden_US
dc.rights.holder(c) 2013 Juan Gilberto García-Cancelen_US
dc.contributor.committeeThaxton, Jarrod
dc.contributor.committeeKolterman, Duane
dc.contributor.representativeRobles, Wilfredo
thesis.degree.levelM.S.en_US
thesis.degree.disciplineBiologyen_US
dc.contributor.collegeCollege of Arts and Sciences - Sciencesen_US
dc.contributor.departmentDepartment of Biologyen_US
dc.description.graduationSemesterFallen_US
dc.description.graduationYear2013en_US


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