Effects of Spatial Patch Characteristics and Landscape Context on Plant Phylogenetic Diversity in a Naturally Fragmented Forest
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Research Article Tropical Conservation Science Volume 10: 1–11 Effects of Spatial Patch Characteristics and ! The Author(s) 2017 Reprints and permissions: Landscape Context on Plant Phylogenetic sagepub.com/journalsPermissions.nav DOI: 10.1177/1940082917717050 Diversity in a Naturally Fragmented Forest journals.sagepub.com/home/trc Amaranta Arellano-Rivas1,2, Miguel A. Munguı´a-Rosas2, J. Arturo De-Nova1,3, and Salvador Montiel2 Abstract Phylogenetic diversity is a reliable predictor of taxonomic and functional diversity and of biodiversity option value. During forest fragmentation, forest patches that vary in size, degree of isolation, and shape are formed. Identifying the spatial characteristics of forest remnants that maximize phylogenetic diversity could be useful to conservationists when prioritizing areas to be protected if resources are limited. In this study, we assessed whether spatial patch characteristics (size, edge density, and shape) and the context of the patch in the surrounding landscape (i.e., isolation degree) affect plant phylogenetic diversity in 19 naturally shaped forest patches. Owing to the age of the forest patches, the study system allowed us to assess the long-term effects of spatial variables on phylogenetic diversity. We found that patch size has a positive effect on phylo- genetic diversity, presumably because environmental heterogeneity and niche opportunities are greater in bigger patches. Also, phylogenetic diversity was positively affected by edge density. The convergent evolution of traits which confer tolerance to prevailing edge conditions in phylogenetically distant species may explain this result. We suggest that patch size is a reliable predictor of plant phylogenetic diversity and could be used as a prioritization criterion in conservation strategies, at least in the study area. Keywords edge effect, forest fragmentation, habitat loss, phylogenetic diversity, plants Introduction for conservationists; for example, it may help identify land areas with a longer evolutionary history, those Biodiversity conservation is particularly urgent in the tro- with the most prolific lineages or the taxa most prone pics where a highly diverse biota exists in the context of to extinction (Brooks, Mayden, & McLennan, 1992; massive rates of habitat loss (Achard et al., 2002). The Faith, 1992; Faith et al., 2010). Despite the relevance assessment of biodiversity and how human-driven dis- phylogenetic diversity may have in fundamental and turbances affect it have mostly focused on taxonomic applied fields of ecology, it was not until recently that diversity (e.g., species richness; Fahrig, 2003). However, ecologists started looking at the effects of human-driven taxonomic diversity assumes that species are homoge- neous entities and neglects the evolutionary history of 1 species. Phylogenetic diversity, understood as the evolu- Instituto de Investigacio´n de Zonas Dese´rticas, Universidad Auto´noma de San Luı´s Potosı´,Me´xico tionary history contained in a biotic community (Faith, 2Departamento de Ecologı´a Humana, Centro de Investigacio´n y Estudios 1992), may be a more informative metric of biodiversity Avanzados del Instituto Polite´cnico Nacional, Me´rida, Me´xico because it is a reliable predictor of the main ecological 3Facultad de Agronomı´a, Universidad Auto´noma de San Luı´s Potosı´,Me´xico processes that structure biotic communities (Cadotte, Received 22 March 2017; Accepted 3 June 2017 Cardinale, & Oakley, 2008; Faith et al., 2010; Flynn, Corresponding Author: Mirotchnick, Jain, Palmer, & Naeem, 2011), and of Miguel A. Munguı´a-Rosas, Laboratorio de Ecologı´a Terrestre, Cinvestav- biodiversity option value (Faith et al., 2010). Me´rida, KM 6 Antigua carretera a Progreso, C.P. 97203 Me´rida, Me´xico. Phylogenetic diversity may also provide a useful tool Email: [email protected] Creative Commons Non Commercial CC BY-NC: This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage). 2 Tropical Conservation Science disturbance on phylogenetic diversity (e.g., Ribeiro et al., that of the habitat matrix, which is dominated by flood- 2016). Some studies have tested the prediction that tolerant species (Rico-Gray & Palacios-Rios, 1996). anthropogenic disturbance (e.g., agriculture [Dinnage, Because this forest has been fragmented for over a million 2009], chronic human disturbance [Ribeiro et al., 2016], years (CONANP-SEMARNAT, 2006), it offers an excel- and logging [Tamoya et al., 2015]) impoverish plant lent opportunity to study the long-term effects of spatial phylogenetic diversity, the underlying mechanism being patch variables on phylogenetic diversity (Montiel, identified as the phylogenetic conservation of functional Estrada, & Leo´ n 2006; Munguı´ a-Rosas & Montiel, 2014). traits associated with the vulnerability of plants to dis- Patch area is positively related to environmental het- turbance (e.g., shade tolerance, large seeds, and hard erogeneity, and smaller patches may represent a more wood; Laurance et al., 2006; Lopes, Gira˜o, Santos, restricted niche for a reduced number of potentially Peres, & Tabarelli, 2009; Silva & Tabarelli, 2000). As a more closely related species (Arellano-Rivas, De-Nova, result, plant communities in more disturbed habitats are & Munguı´ a-Rosas, 2017). Also, patch isolation may expected to be more phylogenetically related, a prediction filter plant species that have a long-distance dispersal frequently supported by data (Egorov et al., 2015; capacity, such as plants with zoochory, a phylogenetically Ribeiro et al., 2016; Tamoya et al., 2015). conserved trait (Rezende, Lavabre, Guimara˜es, Jordano, A major threat to biodiversity is habitat loss and frag- & Bascompte, 2007). Moreover, the amount of edge of a mentation, a process that encompasses several changes in patch increases with shape complexity, and edges have the spatial characteristics and configuration of habitat harsher environmental conditions (Murcia, 1995) where remnants at the patch and landscape levels (Fahrig, mostly pioneer-like, closely related plant species can sur- 2003). Although several studies have shown that habitat vive (Letcher, 2010; Tabarelli, Lopes, & Peres, 2009). loss at the patch level has a particularly strong negative And finally, because of the chronic flooding that prevails effect on taxonomic diversity (Bender, Contreras, & in the habitat matrix, patches with a lower elevation are Fahrig, 1998; Mazerolle & Villard, 1999; Valde´ s et al., at a higher risk of flooding; thus, a larger proportion of 2015), the few studies available have not found any flood-tolerant plants (a phylogenetically conserved trait effect of patch size, isolation, or shape on phylogenetic [Tanentzap & Lee, 2017]) is expected in these patches. It diversity in tropical plant communities (Arroyo- is not unreasonable to expect that plant communities in Rodrı´ guez et al., 2012; Santos, Arroyo-Rodrı´ guez, habitat patches with spatial variables associated with Moreno, & Tabarelli, 2010). Instead, previous studies harsher environmental conditions (reduced area, high iso- have found that phylogenetic diversity is influenced by lation degree, convoluted shape, and low elevation) the age of forest patches (Santos et al., 2010, 2014), sug- would have lower phylogenetic diversity. gesting that elapsed time since the fragmentation process began (from decades to just a few hundred years) was possibly not long enough to reveal any effect on phylo- Methods genetic diversity (Santos et al., 2010, 2014). Therefore, Study Area forest which has been fragmented for longer periods of time, such as naturally fragmented forests, are ideal The study area was the Petenes-Celestu´ n-El Palmar model systems for assessing the long-term effects of spa- Biological Corridor (19 530–21 110 N, 90 280–90 170 tial variables on phylogenetic diversity (Munguı´ a-Rosas W), located along the northwestern coast of the Yucatan et al., 2014). This information may both improve our Peninsula (Figure 1). The climate is tropical subhumid understanding of how spatial patch variables affect with summer rains. Precipitation ranges from 1,000 to phylogenetic diversity and help identify which spatial 1,200 mm yÀ1 and temperature from 26.1C to 27.8C attributes of habitat remnants would maximize the (Dura´ n, 1987). The study was conducted on patches of long-term conservation of phylogenetic diversity. semievergreen tropical forest locally known as petenes In this study, we evaluated whether the spatial charac- (singular: peten; Figure 1). These forest patches are teristics of forest patches (size, shape, and edge density) surrounded by a flooded matrix of shorter, less diverse and their context in the landscape (distance to the con- vegetation that is tolerant to flooding and dominated tinuous forest and distance to the nearest patch) predict by sedges and short mangroves (Rico-Gray, 1982; plant phylogenetic diversity in a naturally fragmented Rico-Gray & Palacios-Rios, 1996). The forest becomes tropical forest of the Yucatan. This forest is composed continuous as one moves inland. In our sample, patch of natural vegetation patches that vary naturally in size, size ranges from 1.6 to 320 ha, and shape index