15 Ambientis 2017: 39-58.
Arthropod Diversity and Dynamics in Secondary Forests in the Jobos Bay Area, Salinas, Puerto Rico SM Encarnación-Rodríguez1,2, MF Barberena-Arias1,3 1School of Natural Sciences and Technology, Universidad del Turabo 2School of Medical Technology, University of Puerto Rico, Medical Science Campus. Corresponding author:
[email protected] Abstract. Natural disasters and human activities are responsible for the loss of biodiversity in the Jobos Bay, Salinas. To assess how arthropod diversity was affected we used two sampling methods: active search and butterfly net. Data were collected during dry and wet seasons from 2011 to 2013. The specific study areas represent sequential stages of forest recovery: agricultural field, 5 y, 10y, 15y and 40y forests, and a reference forest: mangrove. In the laboratory, collected arthropods were counted and identified to order. A total of 4544 individuals were collected, that represent 22 orders. Of these, 9 were common to all areas, and 5 were unique to specific habitats. We found that abundance and richness of arthropods varied among habitats and seasons. The species composition of arthropods varied among habitats, specifically mangrove arthropods were significantly different from other habitats, arthropods in the agriculture area differed from the majority of other areas, and sequential stages of recovery had sequential similarity in species composition. These results suggest that the arthropod community is made up of common and unique species that are present yearlong or only in specific seasons. Furthermore, mangroves are unique habitats that harbor a specific arthropod community, while nearby forests in sequential stages of recovery harbor sub groups of associated arthropods. As a consequence, mangroves are sensitive areas that should be preserved because associated arthropods are absent from recovering areas and any loss in mangrove cover will negatively affect their survival. Key words: abundance, active search, butterfly net, mangroves, secondary forests
Resumen. Los desastres naturales y actividades humanas son responsables de la pérdida de biodiversidad en la Bahía de Jobos, Salinas. Para evaluar como la diversidad de artrópodos fue afectada en este lugar usamos dos métodos de muestreo: búsqueda activa y jama. La data fue recolectada durante estaciones húmedas y secas desde el 2011 al 2013. Las áreas de estudio especificas representan estadios secuenciales en la recuperación de bosques: campo agrícola, y bosques de 5, 10, 15 y 40 años, y uno de referencia: manglar. En el laboratorio, colectamos los artrópodos los cuales fueron contados e identificados según su orden. Un total de 4544 individuos fueron recolectados, los cuales se representaron entre 22 órdenes. De estos, 9 fueron comunes para todas las áreas, y 5 fueron únicos para hábitats específicos. Encontramos que la abundancia y riqueza de artrópodos variaba entre estaciones y hábitats, mientras que la composición de especies de artrópodos variaba entre hábitats, especialmente los artrópodos del manglar, los cuales fueron significativamente diferentes de los otros hábitats. Los artrópodos del campo agrícola diferían de las otras áreas, y los estadios secuenciales de recuperación tenían similitud secuencial en composición de especies. Estos resultados sugieren que la comunidad de artrópodos está hecha de especies únicas y comunes que se presentan todo el año o solo en estaciones específicas. Además, los manglares son hábitats únicos que albergan comunidades de artrópodos particulares, mientras que los bosques cercanos que están en etapas secuenciales de recuperación hospedan sub grupos asociados de artrópodos. Como consecuencia, los manglares son áreas sensitivas que deben ser preservadas porque los artrópodos asociados están ausentes en las áreas de recuperación y cualquier pérdida en la cobertura de los manglares va a afectar negativamente su sobrevivencia.
© Copyright 2017, The Authors and Ambientis
16 Ambientis 2017: 39-58.
Introduction Puerto Rico modern landscape includes a mosaic of vegetation patches in different successional stages intermixed with forest patches of typical vegetation (e.g. mangroves). Secondary forests are characterized by being dominated by few fast growing species in early stages of forest recovery, and slow growing species later on (Brown and Lugo 1990) where insect play a fundamental role due to their participation in many ecosystem processes (Didham et al. 1996). Secondary forests are home to a variety of flora and fauna that in turn provide habitat and resources for many organisms, such as arthropods. Terrestrial arthropods play an important role in forest recovery because they participate in processes such as pollination where bees move gametes from one flower to another, and decomposition where arthropods influence soil nutrient dynamics (Didham et al. 1996). In addition, coastal forest ecosystems, such as mangroves are also threatened by human activities, despite being tied to terrestrial, marine and freshwater ecosystems (Lugo 1999a), and providing ecosystem services such as coastal protection, control of erosion, habitat for fishery species (Barbier et al. in press), nutrient sink, sediment capture (Lugo 1999b) and ecosystem products such as wood for construction (e.g. wood for boats), food (e.g. vegetables, tea substitutes), combustion materials (e.g. charcoal), and textile (e.g. fabric dye) (Lugo 1999b). Also mangrove forests are habitat for many species, for example in Puerto Rico, migratory and residential birds use this habitat either for nesting or for feeding (Laboy et al. 2008), as well as threatened species such as carrucho, juey comun and langosta espinosa, and endangered species such as mariquita de Puerto Rico, palometa and pelicano pardo (JBNERR 2011). On the other hand, coastal ecosystems are very sensitive to changes in the environment due to anthropogenic and natural disturbances which pose a threat to these ecosystems. In particular in Puerto Rico, coastal areas, such as Jobos Bay, are facing potential sea level rise and anthropogenic pressures on the landward side because of urban/agriculture development. Changes in Puerto Rico’s economy during the last century have resulted in an increase in the amount of abandoned agricultural lands that regain vegetation cover through secondary succession resulting in a mosaic of patches in different successional stages (Ewel and Whitmore, 1973; Thomlinson et al., 1996). In Jobos Bay National Estuarine Research Reserve in Salinas, Puerto Rico, the reserve includes mangrove forests that are surrounded by lands that represent habitats in different stages of recovery. These situation provides an opportunity to study arthropod communities associated to successional forests, and to reference habitats such as mangroves. Specifically, we addressed the following two questions: 1. How does the abundance and richness of arthropods change during succession among habitats and seasons as compared to reference habitats? According to Barberena-Arias and Aide (2003) richness increase as vegetation recovers, and according to Garrison and Willig (1996) the rainy season triggers biological activity, as a consequence we expected abundance and richness to increase among sequential stages of vegetation recovery and in the wet season. 2. How does species composition of arthropods change during succession as compared to reference habitats? According to Barberena-Arias and Aide (2002), arthropod composition differed between early and late successional stages in a chronosequence of secondary forests, therefore we expected arthropod to follow a similar pattern. Methodology
© Copyright 2017, The Authors and Ambientis
17 Ambientis 2017: 39-58.
Study Site The Jobos Bay National Estuarine Research Reserve is located in Salinas, at the southern of Puerto Rico. According to Laboy et al. (2008), natural disasters and human activities have resulted in a significant loss of biodiversity in this natural reserve. Similar to Puerto Rico, the forests in this reserve have been disturbed by both natural events and human activities, resulting in protected forests inside the Reserve surrounded by patches of disturbed forests that are in different stages of recovery, and that are located outside just in the limit of the Reserve. Specifically, this study was conducted in six habitats, i.e. inactive agricultural field, 40 yr recovery forest, and mangrove. The agricultural field was a cleared forest where agriculture was previously practiced and eventually was abandoned while the