Expedient Metrics to Describe Plant Community Change Across Gradients of Anthropogenic Inﬂuence

Environmental Management (2014) 54:1121–1130 DOI 10.1007/s00267-014-0321-z Expedient Metrics to Describe Plant Community Change Across Gradients of Anthropogenic Influence Jose´ A. P. Marcelino • Everett Weber • Luı´s Silva • Patrıćia V. Garcia • Antońio O. Soares Received: 14 January 2014 / Accepted: 18 June 2014 / Published online: 22 July 2014 Ó Springer Science+Business Media New York 2014 Abstract Human influence associated with land use may two anthropogenic gradients were determined. A new cause considerable biodiversity losses, namely in oceanic metric, ComVal, was developed to assess the similarity of islands such as the Azores. Our goal was to identify plant an uncategorized vegetation plot toward a reference com- indicator species across two gradients of increasing munity type, based on (i) the percentage of pre-defined anthropogenic influence and management (arborescent and indicator species from reference communities present in herbaceous communities) and determine similarity the vegetation plots, and (ii) the percentage of indicator between plant communities of uncategorized vegetation species, specific to a given reference community type, plots to those in reference gradients using metrics derived present in the vegetation plot. Using a data resampling from R programming. We intend to test and provide an approach, the communities were randomly used as training expedient way to determine the conservation value of a or validation sets to classify vegetation plots based on given uncategorized vegetation plot based on the number ComVal. The percentage match with reference community of native, endemic, introduced, and invasive indicator types ranged from 77 to 100 % and from 79 to 100 %, for species present. Using the metric IndVal, plant taxa with a herbaceous and arborescent vegetation plots, respectively. significant indicator value for each community type in the Both IndVal and ComVal are part of a suite of useful tools characterizing plant communities and plant community change along gradients of anthropogenic influence without Electronic supplementary material The online version of this a priori knowledge of their biology and ecology. article (doi:10.1007/s00267-014-0321-z) contains supplementary material, which is available to authorized users. Keywords Plant community ecology Á Indicator species Á J. A. P. Marcelino (&) Á P. V. Garcia Á A. O. Soares Change detection Á R programming Á Metrics CIRN, Department of Biology, University of the Azores, Rua da Ma˜e de Deus, 13-A, 9501-801 Ponta Delgada, Azores, Portugal e-mail: [email protected] Introduction J. A. P. Marcelino Á P. V. Garcia Á A. O. Soares Biodiversity Group of the Azores (GBA), Platform for Anthropogenic influence is one of the major forces shaping Enhancing Ecological Research & Sustainability (PEERS), University of the Azores, 9700-042 Ponta Delgada, Azores, ecosystems worldwide through land conversion from nat- Portugal ural into homogenized herbaceous land (Foley et al. 2005). Land use change can negatively impact biodiversity and E. Weber ecosystem balance, by reducing the number of species Department of Biology, Murray State University, Murray, KY 42071, USA contributing for ecosystem function and ecosystem resil- ience to environmental and anthropogenic impacts, as well L. Silva as by increasing species invasiveness, both in continental Centro de Investigaçaõ em Biodiversidade e Recursos Gene´ticos, land (Hawksworth and Bull 2010; Laliberte´ et al. 2010) and CIBIO/InBIO, Po´lo dos Açores, Departamento de Biologia, Universidade dos Açores, Apartado 1422, in insular ecosystems (Castro et al. 2010; Kueffer et al. 9500-321 Ponta Delgada, Azores, Portugal 2010). Identifying changes in land cover composition in the 123 1122 Environmental Management (2014) 54:1121–1130 context of rising anthropogenic influence helps better order to describe the composition of vegetation plots in understand the structural impact of human activities in terms of the presence of indigenous vs. non-indigenous species turnover following land conversion. Methodologies biota. capable of monitoring these changes are increasingly This simple statistical methodology provides an accu- popular (Bartha 2004; Winter 2012) and can contribute to a rate, cost effective, and expedient way to classify uncate- sustainable and strategic management of natural and arti- gorized vegetation plots, by inventorying only indicator ficial biotic communities, counteracting the decline of species previously defined in reference communities. The biodiversity (e.g., Engler et al. 2004; Peres et al. 2006; new metric provides an additional tool to complement Dupouey et al. 2010). methodologies characterizing plant communities with For instance, the use of indicator species for analysis of limited a priori knowledge of their biology and ecology, biodiversity change or for defining conservation strategies such as cluster analysis using PC-ORD (McCune and is commonly reported and widely accepted (Paoletti 1999; Mefford 1999), TWINSPAN (Hill 1979), and COINSPAN Lindenmayer et al. 2000; Basset et al. 2004; Niemi and (Carleton et al. 2009), as well as canonical correspondence McDonald 2004; McGeoch 2006; Muramoto and Gliess- analysis, redundancy analysis, and other methods using R man 2006; Pearsall 2007;DeCaćeres et al. 2010). Vascular packages (see Borcard et al. 2011). plants are good indicators of biodiversity change because The Azores islands are a good model system to test this of their structural importance in ecosystems, their rele- methodology, considering the different conservation stages vance as keystone species in nutrient and carbon cycling, of the islands and the detailed information already avail- and their continuous presence in many terrestrial habitat able on biodiversity (Borges et al. 2010; Castro et al. types (Nordeń et al. 2007; Zerbe et al. 2007; Billeter et al. 2010), namely plants (Silva and Smith 2004, 2006; Silva 2008; Marignani et al. 2008; Aavik and Liira 2009; Odland et al. 2009; Costa et al. 2014; Queiroz et al. 2014). We 2009). Using indicator species to characterize vascular expect to find more native and endemic plant taxa as plant communities can reduce the time, cost, and difficulty indicators of the more preserved communities and intro- associated with comprehensive community surveys (Hilty duced or invasive plant taxa as indicators of the more and Merenlender 2000; Nordeń et al. 2007). altered and human influenced communities. The proposed There is considerable work currently done using statis- new metric, ComVal, is expected to give a measure of tically derived indicator species to characterize communi- similarity between reference community types and uncat- ties (Podani and Csańyi 2010; Urban et al. 2012; Vilches egorized vegetation plots, based on indicator species ana- et al. 2013), namely plants (e.g.,Nimis et al. 1993; De- lysis, and of their conservation value. Keyser et al. 2003;DeCaćeres et al. 2012). Although community classification based upon species sensitivity to habitat change is a powerful approach to detect ecological Materials and Methods impacts to an ecosystem, the required prior expertise in the biology and ecology of a species can make this method- Study Site ology difficult to implement. We intend to test a quantitative metric, IndVal (Dufrene The archipelago of the Azores (368350–398430 N, 248450– and Legendre 1997;DeCaćeres et al. 2010), as an expe- 318170 W) comprises nine volcanic islands, forming three dient tool to characterize plant communities, along a priori- main groups, on a WNW–ESE quadrant alignment across defined gradients of anthropogenic influence (Marcelino the Mid-Atlantic ridge. The Azores support a considerable et al., 2013), i.e., a herbaceous gradient of plant commu- variety of plant communities (Sjo¨gren 1973; Dias 1996), nities (corn, pasture, semi-natural pasture, natural mead- namely several types of scrubland (coastal, mountain, ows) and an arborescent gradient of plant communities pioneer), natural forest (e.g., Laurel forest, Juniper wood- (orchards, production forest, exotic woodland, native for- land), natural meadows (e.g., Festuca, Holcus, Des- est) based on indicator plant species. We then developed a champsia), coastal vegetation, and several types of new metric, ComVal, to measure the degree of similarity of wetlands. As a result, the Azores are recognized as an uncategorized vegetation plot to these reference plant important conservation hotspots (Myers et al. 2000; communities, based on shared indicator species. Using this UNESCO World Heritage; Biosphere and Natura 2000 methodology, we expect to identify changes in land cover Networks). composition resulting from anthropogenic influence based Sampled islands were selected on the basis of the rela- on the presence/absence of indicator species. In addition, tive proportion of land cover allocated to agriculture we attributed an ecological conservation category to the (LAA,) and to natural communities (Island Natural Parks, indicator species (e.g., endemic, native, introduced) in INP, source: Costa et al. 2014) as follows: 123 Environmental Management (2014) 54:1121–1130 1123 Table 1 Description and characteristic plant species by community Table 1 continued type Code Identification Description Characteristic plant Code Identification Description Characteristic plant species species CRY Production Dominated by Monocultural stands Herbaceous communities forest introduced taxa, of Cryptomeria MED Natural Dominated by Holcus rigidus, with high japonica meadow indigenous

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