González Et Al. Predicting the Climatic Distribution of the Colombian
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Novedades Colombianas, 11(1) – 2011 1 Predicting the climatic distribution of the Colombian oak Quercus humboldtii Bonpl. (Fagaceae) Carlos E. González-Orozco¹, Andy Jarvis² and Juan D. Palacio³ ¹ 25 Walker Crescent, Jerrabomberra, 2619, New South Wales, Australia. [email protected] ² International Centre for Tropical Agriculture (CIAT), A.A 6713, Cali, Colombia; [email protected] ³ The University of Texas at Austin, USA; [email protected] Abstract Spatial analyses of climate are important for understanding the potential adaptation of species to unstable environments. This paper reports on the potential climatic distribution of the Colombian oak or Q uercus humboldtii (Q. humboldtii) . A predictive model was used to analyse data on the Q. humboldtii , calculating the habitat suitability on the basis of 36 climate variables using a Principal Component Analysis. Our analysis found that the Q. humboldtii is distributed through the west, central and eastern mountain ranges and some lowland inter-Andean regions. Q. humboldtii has a wide climatic adaptation, with a particular o o preference for environments that have a mean temperature between 9.3 C to 27.9 C and annual rainfall between 788mm/year and 2681mm/year. Q. humboldtii grows at elevations of 1.100 meters above the sea level and is well-adapted to wet and dry environments. There is however, no climatically unique and geographically succinct cluster of Q. humboldtii populations. The Q. humboldtii population is split into two climatic envelopes with a differing mean temperature for populations located in low and high elevations. A population of Q. humboldtii never collected prior to our study was reported at 1,100 m above sea level in the Serranía de San Lucas. This new record is relevant because it represent the lower elevation range of the species in the northern part of the country. Therefore, it is essential for future studies on conservation of the species because it suggest the possibility of finding new populations even further north of San Lucas. Our results prove to be useful for identifying potential climatic risk to the species and locating suitable environments in Colombia and some neighbouring countries where the Q. humboldtii could potentially grow. Key words: Q. humboldtii, FloraMap, species distribution, Colombian oak Gonzállez-Orozco et all. Prediictiing the clliimatic diistriibutiion of the Collombian oak 2 Resumen Análisis espaciales de variables climáticas son importantes para entender la posible adaptación de las plantas a condiciones ambientales inestables. Este articulo presenta la distribución climática potencial de Q. humboldtii Bonpland en Colombia. Datos de colecciones de herbario fueron usados para generar el mapa de distribución. Los datos de distribución fueron cargados en el paquete de simulación FloraMap, el cual usó 36 variables climáticas para generar un mapa de predicción climática. La predicción está basada en análisis de componentes principales, los cuales interpolan la latitud y la longitud de cada uno de los registros de herbario con respecto a la elevación sobre el nivel del mar y cada una de las 36 variables de clima. Se reporta que Q. humboldtii se distribuye a lo largo de las tres cordilleras desde el sur de Panamá hasta el norte de Nariño. Se demostró que está adaptado a gran variedad de condiciones climáticas, con adaptación a rangos de temperatura que varían entre 9.3 y 27.9 grados centígrados y una cantidad de lluvia anual promedio entre 788 y 2.681 milímetros. Altitudinalmente, el Roble se distribuye desde 1.100 m sobre el nivel del mar hasta más o menos 3.000 m. Aunque no se identificó una condición ambiental específica, se detectaron dos tipos climáticos que están condicionados por la temperatura promedio: un clima seco de zonas bajas y otro húmedo de elevaciones altas. Como resultado de estas condiciones, es posible argumentar que la especie presenta una amplia adaptación climático-ambiental a lo largo y ancho de los Andes colombianos. Se reporta una nueva colección de la especie en el Departamento de Bolívar, Serranía de San Lucas a 1.100 m. Este registro de distribución es importante porque sugiere la posible existencia de más poblaciones en zonas aun más al norte. Esto es un incentivo para realizar más expediciones en las cuales se podría colectar la especie y así plantear estudios de conservación de poblaciones aisladas. Palabras clave: Q. humboldtii , cambio del clima, Biogeografía, FloraMap, Colombia INTRODUCTION Climate change poses a real threat to the natural the Colombian Oak require so that scientist can distribution of species. Therefore it is crucial to know the climate under which the species can characterise the climatic adaptability of trees and survive and therefore adapt to a changing predict the climatic conditions that endemic and climate. Unfortunately, little information exists threatened species emblematic species such as about the geographical regions in Colombia Novedades Colombianas, 11(1) – 2011 3 where the most suitable climatic for Q. the environmental conditions surrounding the humboldtii exists to make it able to grow. The sampling point. Predictive distribution modelling purpose of this study is to predict the climatic uses occurrence observations of a species to distribution of the Q uercus humboldtii Bonpland understand the biophysical adaptation of the (Q. humboldtii ). In this paper, we specifically species in question and then extrapolate the investigate the capabilities of using the software potential distribution to larger regions. FloraMap to predict the potential climatic conditions that the Colombian oak relies on to Point and predictive methods are usually applied exist. FloraMap has been used in different case separately, in our study, we combine both studies (Upadhyay et al. 2011; Segura et al. methods using FloraMap. FloraMap is one of 2003; Laderach et al. 2008; Jones and Gladkov many climatic envelope models tools available 1999; Jones et al . 2002; Jarvis et al. 2002; Jones that produces a predicted layer composed of grid 1991; Jones et al . 1997). Theoretical background cells with assigned high or low values of can be found in the FloraMap manual, which is prediction. These prediction values are based on available online at http://www.floramap-ciat.org the interpolation of climatic variables. The http://www.floramap-ciat.org/ . output data are used to analyse the potential distribution of species based on their original The relationship between climate and spatial location. There are numerous statistical geographical distribution of trees is an important models that have been developed to analyse aspect of forest ecology and habitat distribution output data, including genetic algorithm models (Guisan and Zimmermann 2000). (Anderson et al. 2002) and logistic regression Biologists or ecologist are presented with two (Draper et al. 2003) . FloraMap uses a Principal methods for assessing species distribution: point Component Analysis (Jarvis et al. 2003b; observations and predictive distribution models. Robertson et al. 2001) commonly known as Point observations can be used to examine the “PCA” as its main statistical method. distribution of a species at the local scale but this method tends to underestimate the true In our study, we focus on the use of FloraMap to distribution if observations are an incomplete investigate to what extent the variations in representation of the geographic range of the elevation, rainfall and temperature influence the species (Anderson et al. 2002) . Spatial potential spatial distribution of the population of predictive modelling has received particular Q. humboldtii in Colombia. Our specific focus in ecology in recent years (Guisan y objective is to predict the habitat suitability of Zimmerman 2000) because it takes account of such variables on the current distribution of Q. humboldtii. Gonzállez-Orozco et all. Prediictiing the clliimatic diistriibutiion of the Collombian oak 4 endangerment (Salinas and Cardenas 2007). MATERIALS AND METHODS Studied taxa Data set Figure 1 shows the spatial distribution of the 132 The genus Quercus has 500 species distributed accessions of Q. humboldtii used in this study. in the northern hemisphere with a mid- latitude Each accession was georeferenced and any holartic origin (Manos et al. 1999). It belongs to spatial errors were corrected. This dataset covers the Fagaceae family and has a Laurasian origen 95 percent of the species distribution range. The (Hernandez et al. 1980). The closest genus, data set was compiled gathering information Trigonobalanus , comes from the northern from different herbaria in Colombia and also hemisphere of the new world (Palacio 2001). In online international databases. We visited Colombia, Q. humboldtii is widely distributed herbariums at the national university of across the country with large populations found Colombia located in Bogota; the University of in specific areas of the Andean region forests. Q. Antioquia in Medellin; the Humboldt Institute in humboldtii is a woody tree commonly known as Villa de Leyva; the University of Valle in Cali; “Roble”. The species has other common names, the University of Cauca in Popayan and the including Roble Amarillo, Roble Negro, and University of Nariño in Pasto. Our main Roble Blanco (Pacheco and Pinzon 1997). In international sources were the online datasets of previous studies by Lozano and Torres (1974), the Missouri Botanical Garden and the New seven Colombian Quercus species were cited York Botanical Garden (See Annex