A Floristic Study of Polylepis Forest Fragments in the Central Andes of Ecuador
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A FLORISTIC STUDY OF POLYLEPIS FOREST FRAGMENTS IN THE CENTRAL ANDES OF ECUADOR Ulrika Ridbäck Examensarbete i biologi, 15 hp, 2008 Handledare: Bertil Ståhl ___________________________________________________________________________ Institutionen för kultur, energi och miljö Högskolan på Gotland/Gotland University, SE-621 67 Visby www.hgo.se CONTENTS RESUMEN/ABSTRACT ……………………………………………………….....2 INTRODUCTION……………………………………………………...…....…......3 Background……………………………………………………...……………….....3 The genus Polylepis ……………………………………………………...………....3 Earlier studies……………………………………………………...………………..4 Why are Polylepis forests important? ………………………………………...…....5 Objectives……………………………………………………...……………...……5 STUDY AREA……………………………………………………...………...........6 Oyacachi……………………………………………………...…………………….6 Climate……………………………………………………...………………………7 MATERIAL AND METHODS………………………………………………...…..8 RESULTS…………………………………………………………………………...9 Observations of the remnants of Polylepis pauta forests…………………………...9 Species richness of vascular plants………………………………………………....9 Phytogeography…………………………………………………………………....10 Endemism………………………………………………………………………….10 Remnant of Polylepis microphylla forest at Achupallas…………………………..10 DISCUSSION……………………………………………………...………...........11 Species richness…………………………………………………………………...11 Conservation………………………………………………………………………11 Different Polylepis forests………………………………………………………...13 Reforestation……………………………………………………………………....13 Further studies…………………………………………………………………….14 ACKNOWLEDGEMENTS………………………………………………………14 REFERENCES.…………………………………………………………………...14 SAMMANFATTNING…..……………………………………………………….16 APPENDIXES……………………………………………………...………..........19 Appendix 1: Plant species of Polylepis forest and their distribution……………...19 Appendix 2: Páramo plant species and their distribution………………………....24 Cover picture: Calceolaria ericoides (Scrophulariaceae) Photo: Ulrika Ridbäck Denna uppsats är författarens egendom och får inte användas för publicering utan författarens eller dennes rättsinnehavares tillstånd. Ulrika Ridbäck 1 RESUMEN La presencia de los seres humanos ha afectado a los bosques de Polylepis desde hace mucho tiempo en los Andes de Ecuador. El objetivo de este estudio es la examinación de la flora de plantas vasculares en los bosques dominados por Polylepis pauta . Especies conocidas de plantas vasculares fueron registradas y especies menos conocidas fueron recolectadas. Todos los datos incluyendo coordenadas y altitud fueron analizados en el Herbario QCA. Se han registrado un total de 104 especies de plantas vasculares, el número de especies recogidas varía entre 16 y 36 en cada estudio local. Principalmente especies andinas dominan los bosques de P. pauta , 75 de las cuales están restringidas a los Andes. Se encontraron un total de 20 especies endemicas del Ecuador. Los bosques de Polylepis son un tipo único de hábitat por lo que vale conservar como un único tipo de hábitat. Polylepis puede contribuir con habitat y protección para los animales y las plantas, especialmente epífitas. Programas de reforestación con Polylepis podrían ser una buena alternativa para la zona de Oyacachi. ABSTRACT Human activity during several thousands of years has considerably changed the forests of Polylepis in the central Andes in Ecuador. The objective of this study was to examine the flora of vascular plants in forest fragments dominated by Polylepis pauta in the Oyacachi area in central Ecuador. Known species of vascular plants were recorded, and species not identified in the field were collected. All data, including coordinates and altitudes, were stored in the QCA Herbarium database. A total of 104 species of vascular plants were recorded. The number of species found varied from 16 to 36 between different localities. The P. pauta forests are dominated by Andean species, 75 of the recorded species being restricted to the Andes. Of these, 20 are endemic to Ecuador. The Polylepis forest as such is worth conserving as a unique kind of habitat, and can contribute with shelter and protection for many animals and plants, especially epiphytes. Reforestation programs based on Polylepis could be a good alternative in the Oyacachi area. 2 INTRODUCTION Background One of the richest floras in the world is found in South America. The Andes is a relatively young mountain chain that runs through the continent. The setting with a geologically recent uplift and a tropical and fluctuating climate has generated a plethora of species on and below the Andean slopes. Deforestation in the Andes has a long history, and different ethnic groups inhabited the Andean highlands many generations before the Spanish conquistadors arrived (Lippi 2004). Since humans entered this region the forests have been used as a source for building material and fuel (Fjeldså & Kessler 1996). Much of the forests were also cleared to produce farm land and pastures. The best known ethnic group before the Spanish colonisation, the Incas, used a terrace system which successfully kept the horizontal fields from erosion (Jørgensen & Ulloa 1994). To obtain more land for cultivation additional forests were cleared, which led to a reduction of natural vegetation. New agricultural techniques where introduced by the Spanish colonists and they abandoned the terraces used by the Incas. The deforestation continued and the Mediterranean type of agriculture practiced by the Europeans contributed to land degradation through soil erosion. The high Andean landscape seen today is dominated by grass páramos. Remnants of high Andean forests, which have been conserved to present time, consist largely of Polylepis spp., which often inhabit inaccessible steep slopes outside the inter-Andean plateau. The genus Polylepis Polylepis is a genus in the family Rosaceae and is restricted to the high Andes. Seven species of Polylepis are known from Ecuador (Romoleroux 1996), of which Polylepis incana, P. pauta and P. sericea are found in the Oyacachi valley (Ståhl et al. 1997). Polylepis is well adapted to the harsh climate in the mountains, having reduced flowers and leaves covered with woolly hairs (Fjeldså & Kessler 1996). The trunks wear thick and rough bark, a protection against nocturnal frost. At altitudes between 3500 and 4000 m, Polylepis is the only resource of wood in a zone where other tree species are unable to grow (Fjeldså & Kessler 1996). Some species of Polylepis even occur at an altitude of 4850 m (Braun 1997). The Polylepis forests are most common in mountain slopes, deep canyons and ravines, often among rocks and boulders. The growth of Polylepis has been hypothesised to be limited to favourable microclimatic conditions, which occur on rocky isolated slopes (Velez et al. 1998). However, today most scientists believe that the high Andean vegetation largely is anthropogenic. The practice to burn large areas to create and improve pastures has reduced Polylepis forests to a few percentage of their original extent (Kessler 2002). Remaining patches of Polylepis forests are spread out in an open landscape, separated by huge areas of grass páramo. The borders between the forests and the páramos are usually sharp. 3 Fig. 1. Map of Ecuador, showing the location of the Cayambe-Coca Ecological Reserve, nr 14 ( Mapa físico, República del Ecuador 1999 ). Earlier studies Little is known about the floristic diversity within Polylepis forests (Fernández & Ståhl 2002). In Ecuador, earlier studies of Polylepis forests have been done in the vicinity of Oyacachi in the Cayambe-Coca Ecological Reserve (Fig. 1), an area protected since 1970 (Morales & Schjellerup 1997). The DIVA-project (1996-1997) studied the interactions between the people in the village Oyacachi and the environment, to estimate the biological consequences caused by present and potential future land use (Skov 1997). Focusing on a few target taxa (ferns, Rubiaceae, Piperaceae) the Polylepis forests were also studied within the DIVA-project, but only at a few sites near the village. Studies of Polylepis near Oyacachi have also been carried out by Cierjacks et al. (2007) in Polylepis stands at Páramo de Papallacta. They studied the 4 capacity of lateral expansion and focused on the possibility of recovering to dense Polylepis forest stands. Cierjacks et al. (2007) made transects to examine the cover of herbaceous vegetation in Polylepis incana and P. pauta forests. In a follow-up study, Cierjacks et al. (2008) investigated reproductive traits, site conditions and stand structure of P. incana and P. pauta in Páramo de Papallacta, with the effects of altitude and cattle as limiting factors. Fehse et al. (2002) examined the possibility of carbon offsets at a P. incana forest, by quantifying aboveground biomass. The study took place near Pifo, 20 km southwest of Oyacachi. Several floristic and biogeographic works on Polylepis forests have been done in Bolivia. One study, which gave inspiration to this present work, was carried out in the Andes of south- central Bolivia by Fernández & Ståhl (2002). They investigated the conditions for vascular plants in Polylepis forests at different localities in the Cordillera de Cochabamba. Why are Polylepis forests important? The forests of Polylepis have a unique biological diversity and provide many important ecological functions (Fjeldså & Kessler 1996). The trees harbour many species of epiphytic vascular plants, mosses and lichens, as well as animals, including mammals and birds. In a landscape dominated by open páramos, the forests give shelter, nesting sites, and food to many mammals and birds. Being native to the Andes,