Distribution of the genus Cedrela in Ecuador

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Distribution of the genus Cedrela in Ecuador

Silvia Alejandra Llerena1, Natalia Salinas2, Luiz Orlando de Oliveira3, Monica Jadan-Guerrero4, Claudia Segovia-Salcedo4

1 Department of Ecology. Peoples Friendship University of Russia

2 Department of Horticultural Sciences University of Florida

3 Department of Biochemistry and Molecular Biology Federal University of Vicosa

4 Departamento de Ciencias de la Vida y Agricultura. Universidad de las Fuerzas Armadas ESPE

The genus Cedrela in Ecuador has four species: C. odorata, C. montana, C. fissilis and C. nebulosa. Cedrela was one of the economically most important timber in the past, due to its wood properties. The genus has a long history of overharvesting and selective logging; as a consequence a substantial genetic degradation have occurred in Ecuador. Currently, three species of Cedrela are included in the IUCN Red List. C. odorata and C. nebulosa are listed as vulnerable species and C. fissilis as endangered species. In spite of their conservation status and priority, few studies related to geographical distribution have been done. Then, the geographic distribution at local level had been carried out to provide a valuable tool to the conservation and management of these species. Field sampling and herbarium compilation showed C. montana is restricted to the Ecuadorian highlands in the western and eastern Andean montane region between 805 to 3200 masl (meters above sea level). Cedrela nebulosa is located in Andean region about 1400 to 2300 masl. C. odorata is the most widely distributed, occupying areas in the Amazon (200--1300 masl), Pacific (330--825 masl) and insular regions (350 masl). While, Cedrela fissilis is only found in the Amazon Region about 200 to 510 masl. This basic information about current distribution and abundance of cedar species is primordial to generate sufficient tools to formulate the strategies of management and conservation of these species in the country. The widespread distribution of C. odorata have been found in the Amazonian and Pacific regions, indicating that it is adapted to tropical rainforest and tropical monsoon climates. To prove if there are adaptations to both habitats morphological, ecological and phylogenetic studies must be carried out.

Key words: Cedrela, endangered species, ecoregion, altitude

INTRODUCTION

Each year between 2010 and 2015, worldwide 7,6 million hectares (ha) of forest were lost due to the deforestation. South America is not an exception, is one of the continents with the highest rate of deforestation (2 million ha/year) [6]. Same as Ecuador with one of the highest rates of the Continent according to the Food and Agriculture Organization of the United Nations (annual rate of 1.8% for the 2001--2010 period) and the main causes are related to urban sprawl, expansion of agricultural and pasturelands, lack of adequate government policies, high demand for timber products, logging and forest fires [15; 16; 26].

Although, the annual rate of deforestation in Ecuador has been reduced in recent years, it continues affecting a large range of species, such as Cedrela. Cedar is demanded by the timber and construction industries due to the high quality of its wood in terms of color, fragrance, strength and durability [3; 8; 17).

In Ecuador, the genus Cedrela P. Browne (Meliaceae) includes 4 species: Cedrela odorata, C. fissilis, C montana and C. nebulosa [21]. These species have shown a huge decrease in their population size and distribution due to their high quality timber. According to CITES data between 2002 to 2009, Ecuador exported 342 m3 ofcedar wood, however in the international market, this wood replaced collapsed sales of other species such as mahogany, this lasted a couple ofyears before collapsing the exports. Furthermore, the selective logging of big and better formed trees is a common practice in Ecuador, which erodes the genetic quality of the remain populations [21; 25]. Other threats to the future survival of this genus are the expansion of human settlements, conversion of land for agricultural and livestock use, the construction of highways and the extraction of oil and minerals [26]. All of these threats trigger the genetic diversity diminish and generate problems in the conservation and management policies of these plants. As a consequence of the selective logging of cedar, C. fissilis is an endangered species and Cedrela odorata is considered as a vulnerable species [10].

Despite the economic and ecological relevance of the genus Cedrela, studies on the current status and the distribution of its species in Ecuador are scarce [11; 21; 22]. This study provides information about the distribution of Cedrela genus in Ecuador, which can be a valuable contribution to the management of these species.

METHODS

The map of geographical distribution of the genus Cedrela in Ecuador was generated using data collected and vegetable formations division of the continental Ecuador [2; 12; 20; 23]. ArcGIS 10.3 Software was used in this study.

RESULTS AND DISCUSION

On large scale, there was a clear division in the geographical distribution of Cedar species in Ecuador: Cedrela montana is distributed in the Andean Region between 805 and 3200 meters above sea level; C. nebulosa in the Andean Region in heights between 1420 to 2300 masl; Cedrela odorata was the most widespread species located in three regions: Pacific (330--825 masl), Amazonian (200--1300 mas) and Insular region at 350 m. Cedrela fissilis was found only in the Amazon Region at elevations between 200 and 510 masl (Fig. 1 and 2).

The Cedar distribution in the Ecoregions of Ecuador classified by [23; 20] showed a notorious preference of each species to different formations. As shown in Figure 2, the most widely distributed species was Cedrela odorata, found in the following Ecoregions: Lowland Evergreen Forest of the Amazon, and Flooded Lowland Forest of the Amazon at heights from 200 to 1300 masl. In the Pacific Region it was presented in Lowland Evergreen Forest, Piedmont Evergreen Forest of the Coast Mountains and Deciduous Forest of Lowlands, at heights from 330 to 825 masl. In Galapagos Islands C. odorata was found in the Xeric Scrub Ecoregion at 350 masl.

Fig. 1 . Scatter plot of Cedar species distribution by altitudinal range and region

Cedrela montana was restricted to the Andean Region in the following Ecoregions: Lower Montane Evergreen Forest and Montane Mist Forest of the Western Andes, Lower Montane Evergreen Forest of the North and Central Andes, and High Montane Evergreen Forest of the Eastern Andes in heights between 805 and 3200 masl. In the previous Ecoregion and in the Montane Mist Forest of the Eastern Andes, the species C. nebulosa was also located in heights between 1420 to 2300 masl. Cedrela fissilis appeared only in the Amazon Region in the Lowland Evergreen Forest and Flooded Forest of the Amazon at heights between 200 to 510 masl (Fig. 2).

The regions where Cedrela species were located are enclosed in three different biodiversity hotspots. C. odorata in the Coast Region (Mache Chindul Ecological Reserve and Maglares Churute Nature Reserve) is located in Choco-Darien-Western Ecuador Hotspot [4]. Both, Cedrela odorata and C. fissilis in the Amazon and Cedrela montana is in the Hotspot of the Tropical Andes (Table 1).

The C. odorata distribution determine that is adapted to two habitat types: tropical rainforest and tropical monsoon where the climate is warm dry and warm humid in the regions of the Central and Insular Coast and in the North Coast and Amazon Regions, respectively.

Fig. 2. Map of Cedrela Distribution in Ecuador based in the plant formations classification of Sierra et al (1999) and Olson (2002). Symbology: C. odorata, blue circle; C. montana, red circle; C. fissilis, yellow circle and C. nebulosa, green circle (ArcGis 10.3)

Adaptations due to growth in different regions have been recorded in previous studies [18; 19], where it was established that C. odorata populations of Xeric (high solar radiation and low humidity) and Mesics environments (higher humidity and lower radiation) of Costa Rica differ in morphological and adaptive characteristics such as seed weight, seedling size, root neck diameter (RND) of the seedling, leaf size, weight of the sheet. In Xeric environment C. odorata populations showed higher values in the morphological characteristics than C. odorata of Mesics habitat as an adaptation to survive in drought.

The leaves of C. odorata sampled in dry and humid environments showed differences in size. In addition, in the research developed by [14] about molecular phylogenetics of Cedar in Ecuador using chloroplasidic genes cpDNA and transcripted internal spacers (ITS) was suggested a possible incipient speciation and/or a subspecies status over C. odorata populations. The two lineages found for this species were correlated with the region of distribution, one from the Central Coast Region and Insular Region (dry climate) and the other from the North Coast and Amazon Region (humid climate). However, to corroborate this hypothesis it is suggested to perform morphological and ecological studies to determine the parameters on which the dry and humid environments caused a selective pressure and therefore its adaptation.

Table 1

[11] IUFRO, International Union of Forest Research Organizations in Brisbane, Australia. (2008). “Sustainable management of highvalue timber species of the Meliaceae: a global perspective”: Introduction. Forest Ecology and Management 255, 265--268.

[12] Josse, C., Navarro, G., Comer, P., Evans, R., Faber-Langendoen, D., Fellows, M., Kittel, G., Menard, S., Pyne, M., Reid, M., Schulz, K., Snow, K., & Teague, J. 2003. Ecological Systems of Latin America and the Caribbean: A Working Classification of Terrestrial Systems. NatureServe: Arlington, Virginia. USA.