Contour map of Western Ecuador. Both the western Andean slopes and the much lower coastal Montañas de Mache appear. The isolated foothill range, including Centinela ridge, found in southern Pichincha and northern Los Ríos provinces, has been outlined with a box. Figura 2. Mapa topográfico del Occidente del Ecuador. Se ve ambos las faldas Andinas occidentales y a largo de la costa el más bajo Montañas de Mache. 

Contexts in source publication

Context 1

... 1991; Sierra 1999; Valencia et al. 2000). Until now there have been few detailed studies of larger representative groups of plants or animals that may demonstrate the extent of extinction or endangerment apparently caused by habitat destruction in western Ecuador. A large component of the vegetation of Western Ecuador is the Gesneriaceae, a flowering plant family of mostly herbs, sub-shrubs, and epiphytes, often constituting a large and colorful element in tropical and subtropical rain- and cloud forests. The family has more than 2500 species with under half of them in the Neotropics, and in Ecuador there occur more than 210 species of Gesneriaceae (Skog & Kvist 1997), and 107 of these are or were native to the elevations below 1000 m in western Ecuador. Of the 107 species nearly half are usually epiphytic, and 23 are endemic to western lowland Ecuador (i.e. below 1000 m). A closer look at these 107 species has shown that more than a third of the Gesneriaceae flora of western Ecuador is already threatened, and that these species mainly occurred in low-elevation cloud forests and moist lowland forests, now mostly converted to agriculture. The present study was stimulated partly by the revision of the Gesneriaceae genus Gasteranthus (Skog & Kvist 2000), a work which itself was inspired by the impressive number of apparently narrowly endemic taxa of Gasteranthus in western Ecuador. For example, six species of Gasteranthus had been reported to be endemic to the cloud forest at the same isolated ridge at 600 m elevation known as Centinela (Gentry & Dodson 1987; Gentry 1989, 1992; Dodson & Gentry 1991). The work on Gasteranthus confirmed that the genus has its diversity center in western Ecuador, and that many of its species are endangered. In addition, the recent discovery of another low elevation cloud forest in the Cordillera Mache-Chindul (Parker & Carr 1992) with many Gesneriaceae, e.g., five species of Gasteranthus (Skog & Kvist 2000) illustrated the richness of the former forest cover probably prevalent throughout much of Western Ecuador, as well as the threat that exists to the remaining remnant vegetation. This forest, surrounding the Bilsa Biological Reserve, is located in the coastal mountain range, Cordillera Mache-Chindul, south of the town of Esmeraldas. In 1996 the Bilsa Biological Reserve was included in the newly established 70000 hectare large Mache-Chindul Ecological Reserve. Dodson & Gentry (1991) defined western lowland Ecuador (Figure 1) as the area between the Pacific to the west, the 900 m contour line of the western Andean Cordillera to the east, the Colombian border to the north, and the Peruvian border to the south, for a total area of ca. 80000 km2. The inclusion of the Gesneriaceae found up to 1000 m elevation only expands the size of the study area marginally. By looking at the status of the Gesneriaceae in western Ecuador, and investigating the total distribution patterns of the species found in the area, we can demonstrate the extent to which the Gesneriaceae may be representative of the status of the entire flora in western Ecuador, as well as conservation priorities for the region. Topography, climate, and phytogeographic isolation can together explain the unique vegetation of western lowland Ecuador. The Andes isolate the coast from the extensive Amazonian forests to the east. To the south the arid Peruvian coast is nearly devoid of any vegetation, except desert shrubs and dry forests near the Ecuadorian border. To the north, the Pacific coastal Chocó region of Colombia, is among the most humid places in the world, receiving annually more than 8000 mm of precipitation, resulting in wet/pluvial forest cover. The gradient between the climatic and vegetational extremes found in Peru and Colombia is consequently found in the relatively small intervening area of western lowland Ecuador. The driest areas in Ecuador along the Peruvian border and the southwestern coast are covered with desert thorn scrub forests (Figure 1). Further to the north, as well as closer to the Andean slopes, these desert scrub forests are first replaced by strongly seasonal, deciduous dry forests and thereafter by increasingly humid semi-evergreen and evergreen moist forests. Finally, wet forests defined as having more than 3000 mm of annual precipitation (according to Gentry 1978, 1982) stretch along the Andean slopes. The wet forests are extensive in the north near the Colombian border, but further to the south they gradually reduce to a narrow belt on the lower Andean slopes. Pluvial forests, defined as having more than 5000 mm of annual precipitation, are only found on the lower Andean slopes near the Colombian border. Local topography adds further variation to the climatic and vegetational variation in western Ecuador. Parallel to the coast stretches a range of coastal hills that rarely exceed 800 m in elevation, and along the Andean slopes isolated front ridges also rise nearly to this elevation (Figure 2). These ridges are almost constantly shrouded in clouds due to the orographic uplift of warm air from the Pacific Ocean. The constant layer of clouds may explain how forests having a unique higher elevation physiognomy are here present at remarkably low elevations. Foster (in Parker & Carr 1992) noticed that western Ecuador usually has two layers of clouds resulting in distinct low- and high elevation cloud forests. The low elevation cloud forests are located between ca. 500 and 900 m elevation and the latter from ca. 1800 m elevation and up to the tree limit. The low elevation cloud forests, in particular, are fairly small and for the most part geographically isolated. An example is Centinela Ridge, an isolated front range located approx. 20 km west of the Andean slopes (see (Figure 2), which formerly was covered with low elevation cloud forest, which now has been converted to agriculture (Dodson & Gentry 1991). Extant low-elevation cloud forests are found above 500 m in the Bilsa Biological Station area located in the coastal mountain range, the Cordillera Mache-Chindul (see (Figure 2). Nearer the see, however, clouds may condense at even lower elevations on exposed slopes and hills rising less than 100 m above the surrounding landscape. Even the driest parts of southwestern Ecuador otherwise dominated by cacti and dry deciduous forests, may include small and scattered patches of luxuriant and green, more humid vegetation on low hills. Deforestation and extant forests Since World War II the Ecuadorian population has nearly quadrupled from about three million to more than 12 million inhabitants with the subsequent increase in demand for farmland. This demand in combination with intensive road construction has resulted in colonization and extensive deforestation throughout the coastal region (Dodson & Gentry 1991). Thus, more than 95 % of the semi-deciduous and moist forests of the central and southern parts of the coast forests have disappeared because the climates and the soils of these areas are particularly suitable for intensive agriculture. Today these fertile soils are used mostly for large-scale, export-oriented production of bananas, cacao, and palm oil, rather than small-scale subsistence farms. The drier deciduous forests are protected to some extent by an unpredictable and scanty precipitation, but nearly all-extant dry forests are severely disturbed by grazing, firewood collection, charcoal production, lumber extraction, annual burning, and subsistence agriculture. Only in parts of Esmeraldas province and northern Manabí do some tracts of moist forest remain, while only small patches persist to the south. Apart from the established Sistema de Areas Protegidas the only protected areas are small patches of forest such as the Río Palenque Science Center [87 hectares] (Dodson & Gentry, 1978), Jauneche [130 hectares] (Dodson et al. 1985), La Perla Forest [250 hectares] and the Reserva ENDESA [85 hectares]. Just 25 years ago there still remained much wet forest in western Ecuador, but since then lumbering and road building have been particularly devastating. Logging operations were followed by colonization, which converted large tracts of forest to farming and cattle raising. Numerous scattered palms, however, still bear witness to the recent deforestation. What wet forest still remains begins north of the Guayllabamba River, on the border between the provinces of Pichincha and Imbabura, and stretches along the Andean foothills northward through Imbabura, Esmeraldas and Carchi provinces (Figure 3). Much of these forests are in an ecological reserve protecting the eastern, higher parts of the Cayapa River watershed, but wet forests also remain further down-river mostly in areas reserved for the Cayapa indigenous peoples. Further to the north on the Colombian border an established reserve, protecting the Awa indigenous people, may protect most of the Ecuadorian pluvial forests, as well as adjacent areas in Colombia, although a new road to the coast has facilitated encroachment into the remaining wet and pluvial forests outside the reserve, and very possibly also inside the reserve. There now remains only one significant tract of humid forest south of the Esmeraldas-Guayllabamba River-system (Figure 3). In 1992 Conservation International reported the presence of ca. 200 km2 of very humid forests in the Montañas de Mache south of the town of Esmeraldas, and the forest was rapidly being cut in from all sides. More recently CDC [Centro de Datos para la Conservación] (1995) reported 400 km of extant forest in this area. This forest has since become known as Bilsa for the river (headwaters of Río Bilsa) from where researchers first entered the area. Areas in Bilsa above ca. 500 m elevation are covered with low-elevation cloud forest. Fortunately a considerable part of this area has been purchased by the private conservation foundation "Jatun Sacha", to establish the currently 3000 ha Bilsa ...

Context 2

... lowland forests, now mostly converted to agriculture. The present study was stimulated partly by the revision of the Gesneriaceae genus Gasteranthus (Skog & Kvist 2000), a work which itself was inspired by the impressive number of apparently narrowly endemic taxa of Gasteranthus in western Ecuador. For example, six species of Gasteranthus had been reported to be endemic to the cloud forest at the same isolated ridge at 600 m elevation known as Centinela (Gentry & Dodson 1987; Gentry 1989, 1992; Dodson & Gentry 1991). The work on Gasteranthus confirmed that the genus has its diversity center in western Ecuador, and that many of its species are endangered. In addition, the recent discovery of another low elevation cloud forest in the Cordillera Mache-Chindul (Parker & Carr 1992) with many Gesneriaceae, e.g., five species of Gasteranthus (Skog & Kvist 2000) illustrated the richness of the former forest cover probably prevalent throughout much of Western Ecuador, as well as the threat that exists to the remaining remnant vegetation. This forest, surrounding the Bilsa Biological Reserve, is located in the coastal mountain range, Cordillera Mache-Chindul, south of the town of Esmeraldas. In 1996 the Bilsa Biological Reserve was included in the newly established 70000 hectare large Mache-Chindul Ecological Reserve. Dodson & Gentry (1991) defined western lowland Ecuador (Figure 1) as the area between the Pacific to the west, the 900 m contour line of the western Andean Cordillera to the east, the Colombian border to the north, and the Peruvian border to the south, for a total area of ca. 80000 km2. The inclusion of the Gesneriaceae found up to 1000 m elevation only expands the size of the study area marginally. By looking at the status of the Gesneriaceae in western Ecuador, and investigating the total distribution patterns of the species found in the area, we can demonstrate the extent to which the Gesneriaceae may be representative of the status of the entire flora in western Ecuador, as well as conservation priorities for the region. Topography, climate, and phytogeographic isolation can together explain the unique vegetation of western lowland Ecuador. The Andes isolate the coast from the extensive Amazonian forests to the east. To the south the arid Peruvian coast is nearly devoid of any vegetation, except desert shrubs and dry forests near the Ecuadorian border. To the north, the Pacific coastal Chocó region of Colombia, is among the most humid places in the world, receiving annually more than 8000 mm of precipitation, resulting in wet/pluvial forest cover. The gradient between the climatic and vegetational extremes found in Peru and Colombia is consequently found in the relatively small intervening area of western lowland Ecuador. The driest areas in Ecuador along the Peruvian border and the southwestern coast are covered with desert thorn scrub forests (Figure 1). Further to the north, as well as closer to the Andean slopes, these desert scrub forests are first replaced by strongly seasonal, deciduous dry forests and thereafter by increasingly humid semi-evergreen and evergreen moist forests. Finally, wet forests defined as having more than 3000 mm of annual precipitation (according to Gentry 1978, 1982) stretch along the Andean slopes. The wet forests are extensive in the north near the Colombian border, but further to the south they gradually reduce to a narrow belt on the lower Andean slopes. Pluvial forests, defined as having more than 5000 mm of annual precipitation, are only found on the lower Andean slopes near the Colombian border. Local topography adds further variation to the climatic and vegetational variation in western Ecuador. Parallel to the coast stretches a range of coastal hills that rarely exceed 800 m in elevation, and along the Andean slopes isolated front ridges also rise nearly to this elevation (Figure 2). These ridges are almost constantly shrouded in clouds due to the orographic uplift of warm air from the Pacific Ocean. The constant layer of clouds may explain how forests having a unique higher elevation physiognomy are here present at remarkably low elevations. Foster (in Parker & Carr 1992) noticed that western Ecuador usually has two layers of clouds resulting in distinct low- and high elevation cloud forests. The low elevation cloud forests are located between ca. 500 and 900 m elevation and the latter from ca. 1800 m elevation and up to the tree limit. The low elevation cloud forests, in particular, are fairly small and for the most part geographically isolated. An example is Centinela Ridge, an isolated front range located approx. 20 km west of the Andean slopes (see (Figure 2), which formerly was covered with low elevation cloud forest, which now has been converted to agriculture (Dodson & Gentry 1991). Extant low-elevation cloud forests are found above 500 m in the Bilsa Biological Station area located in the coastal mountain range, the Cordillera Mache-Chindul (see (Figure 2). Nearer the see, however, clouds may condense at even lower elevations on exposed slopes and hills rising less than 100 m above the surrounding landscape. Even the driest parts of southwestern Ecuador otherwise dominated by cacti and dry deciduous forests, may include small and scattered patches of luxuriant and green, more humid vegetation on low hills. Deforestation and extant forests Since World War II the Ecuadorian population has nearly quadrupled from about three million to more than 12 million inhabitants with the subsequent increase in demand for farmland. This demand in combination with intensive road construction has resulted in colonization and extensive deforestation throughout the coastal region (Dodson & Gentry 1991). Thus, more than 95 % of the semi-deciduous and moist forests of the central and southern parts of the coast forests have disappeared because the climates and the soils of these areas are particularly suitable for intensive agriculture. Today these fertile soils are used mostly for large-scale, export-oriented production of bananas, cacao, and palm oil, rather than small-scale subsistence farms. The drier deciduous forests are protected to some extent by an unpredictable and scanty precipitation, but nearly all-extant dry forests are severely disturbed by grazing, firewood collection, charcoal production, lumber extraction, annual burning, and subsistence agriculture. Only in parts of Esmeraldas province and northern Manabí do some tracts of moist forest remain, while only small patches persist to the south. Apart from the established Sistema de Areas Protegidas the only protected areas are small patches of forest such as the Río Palenque Science Center [87 hectares] (Dodson & Gentry, 1978), Jauneche [130 hectares] (Dodson et al. 1985), La Perla Forest [250 hectares] and the Reserva ENDESA [85 hectares]. Just 25 years ago there still remained much wet forest in western Ecuador, but since then lumbering and road building have been particularly devastating. Logging operations were followed by colonization, which converted large tracts of forest to farming and cattle raising. Numerous scattered palms, however, still bear witness to the recent deforestation. What wet forest still remains begins north of the Guayllabamba River, on the border between the provinces of Pichincha and Imbabura, and stretches along the Andean foothills northward through Imbabura, Esmeraldas and Carchi provinces (Figure 3). Much of these forests are in an ecological reserve protecting the eastern, higher parts of the Cayapa River watershed, but wet forests also remain further down-river mostly in areas reserved for the Cayapa indigenous peoples. Further to the north on the Colombian border an established reserve, protecting the Awa indigenous people, may protect most of the Ecuadorian pluvial forests, as well as adjacent areas in Colombia, although a new road to the coast has facilitated encroachment into the remaining wet and pluvial forests outside the reserve, and very possibly also inside the reserve. There now remains only one significant tract of humid forest south of the Esmeraldas-Guayllabamba River-system (Figure 3). In 1992 Conservation International reported the presence of ca. 200 km2 of very humid forests in the Montañas de Mache south of the town of Esmeraldas, and the forest was rapidly being cut in from all sides. More recently CDC [Centro de Datos para la Conservación] (1995) reported 400 km of extant forest in this area. This forest has since become known as Bilsa for the river (headwaters of Río Bilsa) from where researchers first entered the area. Areas in Bilsa above ca. 500 m elevation are covered with low-elevation cloud forest. Fortunately a considerable part of this area has been purchased by the private conservation foundation "Jatun Sacha", to establish the currently 3000 ha Bilsa Biological Reserve. In 1996 a total of 70000 ha, including the Bilsa Biological Reserve, was included in the newly established Mache-Chindul Ecological Reserve, which should end the granting of timber concessions. However, the impact of colonists may not be significantly reduced as most of the reserve area was already disturbed and privately owned. Recently, too, a new road was completed on the western borders of the Reserva Ecológica Mache-Chindul along the coast of Esmeraldas, which will allow access for logging and colonization on the western side of the reserve. The flora at Bilsa Biological Station and surrounding areas has been intensively collected since 1994 (Clark 1997), and many species originally known only from the Centinela Ridge or other recently destroyed low elevation cloud forests, have been found to occur at the Bilsa Biological Reserve, as well as some apparently endemic species. According to Parker & Carr (1992) there also remain a few other low-elevation cloud forests in the coastal hills further to the south of Bilsa, as well as along the Andean slopes. Relatively few ...

Context 3

... half are usually epiphytic, and 23 are endemic to western lowland Ecuador (i.e. below 1000 m). A closer look at these 107 species has shown that more than a third of the Gesneriaceae flora of western Ecuador is already threatened, and that these species mainly occurred in low-elevation cloud forests and moist lowland forests, now mostly converted to agriculture. The present study was stimulated partly by the revision of the Gesneriaceae genus Gasteranthus (Skog & Kvist 2000), a work which itself was inspired by the impressive number of apparently narrowly endemic taxa of Gasteranthus in western Ecuador. For example, six species of Gasteranthus had been reported to be endemic to the cloud forest at the same isolated ridge at 600 m elevation known as Centinela (Gentry & Dodson 1987; Gentry 1989, 1992; Dodson & Gentry 1991). The work on Gasteranthus confirmed that the genus has its diversity center in western Ecuador, and that many of its species are endangered. In addition, the recent discovery of another low elevation cloud forest in the Cordillera Mache-Chindul (Parker & Carr 1992) with many Gesneriaceae, e.g., five species of Gasteranthus (Skog & Kvist 2000) illustrated the richness of the former forest cover probably prevalent throughout much of Western Ecuador, as well as the threat that exists to the remaining remnant vegetation. This forest, surrounding the Bilsa Biological Reserve, is located in the coastal mountain range, Cordillera Mache-Chindul, south of the town of Esmeraldas. In 1996 the Bilsa Biological Reserve was included in the newly established 70000 hectare large Mache-Chindul Ecological Reserve. Dodson & Gentry (1991) defined western lowland Ecuador (Figure 1) as the area between the Pacific to the west, the 900 m contour line of the western Andean Cordillera to the east, the Colombian border to the north, and the Peruvian border to the south, for a total area of ca. 80000 km2. The inclusion of the Gesneriaceae found up to 1000 m elevation only expands the size of the study area marginally. By looking at the status of the Gesneriaceae in western Ecuador, and investigating the total distribution patterns of the species found in the area, we can demonstrate the extent to which the Gesneriaceae may be representative of the status of the entire flora in western Ecuador, as well as conservation priorities for the region. Topography, climate, and phytogeographic isolation can together explain the unique vegetation of western lowland Ecuador. The Andes isolate the coast from the extensive Amazonian forests to the east. To the south the arid Peruvian coast is nearly devoid of any vegetation, except desert shrubs and dry forests near the Ecuadorian border. To the north, the Pacific coastal Chocó region of Colombia, is among the most humid places in the world, receiving annually more than 8000 mm of precipitation, resulting in wet/pluvial forest cover. The gradient between the climatic and vegetational extremes found in Peru and Colombia is consequently found in the relatively small intervening area of western lowland Ecuador. The driest areas in Ecuador along the Peruvian border and the southwestern coast are covered with desert thorn scrub forests (Figure 1). Further to the north, as well as closer to the Andean slopes, these desert scrub forests are first replaced by strongly seasonal, deciduous dry forests and thereafter by increasingly humid semi-evergreen and evergreen moist forests. Finally, wet forests defined as having more than 3000 mm of annual precipitation (according to Gentry 1978, 1982) stretch along the Andean slopes. The wet forests are extensive in the north near the Colombian border, but further to the south they gradually reduce to a narrow belt on the lower Andean slopes. Pluvial forests, defined as having more than 5000 mm of annual precipitation, are only found on the lower Andean slopes near the Colombian border. Local topography adds further variation to the climatic and vegetational variation in western Ecuador. Parallel to the coast stretches a range of coastal hills that rarely exceed 800 m in elevation, and along the Andean slopes isolated front ridges also rise nearly to this elevation (Figure 2). These ridges are almost constantly shrouded in clouds due to the orographic uplift of warm air from the Pacific Ocean. The constant layer of clouds may explain how forests having a unique higher elevation physiognomy are here present at remarkably low elevations. Foster (in Parker & Carr 1992) noticed that western Ecuador usually has two layers of clouds resulting in distinct low- and high elevation cloud forests. The low elevation cloud forests are located between ca. 500 and 900 m elevation and the latter from ca. 1800 m elevation and up to the tree limit. The low elevation cloud forests, in particular, are fairly small and for the most part geographically isolated. An example is Centinela Ridge, an isolated front range located approx. 20 km west of the Andean slopes (see (Figure 2), which formerly was covered with low elevation cloud forest, which now has been converted to agriculture (Dodson & Gentry 1991). Extant low-elevation cloud forests are found above 500 m in the Bilsa Biological Station area located in the coastal mountain range, the Cordillera Mache-Chindul (see (Figure 2). Nearer the see, however, clouds may condense at even lower elevations on exposed slopes and hills rising less than 100 m above the surrounding landscape. Even the driest parts of southwestern Ecuador otherwise dominated by cacti and dry deciduous forests, may include small and scattered patches of luxuriant and green, more humid vegetation on low hills. Deforestation and extant forests Since World War II the Ecuadorian population has nearly quadrupled from about three million to more than 12 million inhabitants with the subsequent increase in demand for farmland. This demand in combination with intensive road construction has resulted in colonization and extensive deforestation throughout the coastal region (Dodson & Gentry 1991). Thus, more than 95 % of the semi-deciduous and moist forests of the central and southern parts of the coast forests have disappeared because the climates and the soils of these areas are particularly suitable for intensive agriculture. Today these fertile soils are used mostly for large-scale, export-oriented production of bananas, cacao, and palm oil, rather than small-scale subsistence farms. The drier deciduous forests are protected to some extent by an unpredictable and scanty precipitation, but nearly all-extant dry forests are severely disturbed by grazing, firewood collection, charcoal production, lumber extraction, annual burning, and subsistence agriculture. Only in parts of Esmeraldas province and northern Manabí do some tracts of moist forest remain, while only small patches persist to the south. Apart from the established Sistema de Areas Protegidas the only protected areas are small patches of forest such as the Río Palenque Science Center [87 hectares] (Dodson & Gentry, 1978), Jauneche [130 hectares] (Dodson et al. 1985), La Perla Forest [250 hectares] and the Reserva ENDESA [85 hectares]. Just 25 years ago there still remained much wet forest in western Ecuador, but since then lumbering and road building have been particularly devastating. Logging operations were followed by colonization, which converted large tracts of forest to farming and cattle raising. Numerous scattered palms, however, still bear witness to the recent deforestation. What wet forest still remains begins north of the Guayllabamba River, on the border between the provinces of Pichincha and Imbabura, and stretches along the Andean foothills northward through Imbabura, Esmeraldas and Carchi provinces (Figure 3). Much of these forests are in an ecological reserve protecting the eastern, higher parts of the Cayapa River watershed, but wet forests also remain further down-river mostly in areas reserved for the Cayapa indigenous peoples. Further to the north on the Colombian border an established reserve, protecting the Awa indigenous people, may protect most of the Ecuadorian pluvial forests, as well as adjacent areas in Colombia, although a new road to the coast has facilitated encroachment into the remaining wet and pluvial forests outside the reserve, and very possibly also inside the reserve. There now remains only one significant tract of humid forest south of the Esmeraldas-Guayllabamba River-system (Figure 3). In 1992 Conservation International reported the presence of ca. 200 km2 of very humid forests in the Montañas de Mache south of the town of Esmeraldas, and the forest was rapidly being cut in from all sides. More recently CDC [Centro de Datos para la Conservación] (1995) reported 400 km of extant forest in this area. This forest has since become known as Bilsa for the river (headwaters of Río Bilsa) from where researchers first entered the area. Areas in Bilsa above ca. 500 m elevation are covered with low-elevation cloud forest. Fortunately a considerable part of this area has been purchased by the private conservation foundation "Jatun Sacha", to establish the currently 3000 ha Bilsa Biological Reserve. In 1996 a total of 70000 ha, including the Bilsa Biological Reserve, was included in the newly established Mache-Chindul Ecological Reserve, which should end the granting of timber concessions. However, the impact of colonists may not be significantly reduced as most of the reserve area was already disturbed and privately owned. Recently, too, a new road was completed on the western borders of the Reserva Ecológica Mache-Chindul along the coast of Esmeraldas, which will allow access for logging and colonization on the western side of the reserve. The flora at Bilsa Biological Station and surrounding areas has been intensively collected since 1994 (Clark 1997), and many species originally known only from the Centinela Ridge or other recently destroyed low elevation cloud ...

Context 4

... of the rainy season. Another three species, Columnea manabiana , C. microsepala , and C. schimpffii , have also been collected mainly in areas with seasonal forests, but here they apparently grow in patches of more humid vegetation found on exposed hills and slopes. Low elevation cloud forests harbor more than half of both the endemic and the globally extinct and endangered species (Table 3). Judging from the local floras of Gesneriaceae, there actually exist two floristically different types of low-elevation cloud forests in western Ecuador. The cloud forests observed on an exposed hill west of San Marcos near the Colombian border were remarkable in having six different species of the terrestrial genus Cremosperma (Kvist & Skog 1988), including three that have not been collected elsewhere in Ecuador, but all six occur in western Colombia. Cremosperma species are otherwise relatively rare in Ecuador. In the cloud forests further to the south and west, including Centinela Ridge, Manta Real, and the Bilsa Biological Station, only a single Cremosperma species occurs, and there instead the dominant terrestrial Gesneriaceae genus is Gasteranthus . Unfortunately, cloud forests that may be rich in Cremosperma are poorly known, but the genus is diverse throughout Pacific slope Colombia, and here Cremosperma is also found mainly in low elevation cloud forests. Species found in low-elevation cloud forest with high Cremosperma diversity are thus likely also to occur in western Colombia. In contrast, the cloud forests where Gasteranthus is exceedingly well represented are apparently restricted to Ecuador, and have a particularly high percentage of endemic as well as endangered and species; e.g. , half of the 24 species recorded from Centinela Ridge (Table 4). The distribution patterns of the Gesneriaceae thus strongly substantiate the claim by Dodson & Gentry (1991) that Centinela Ridge was in fact unique. This cloud forest apparently had more endangered and endemic species than any other correspondingly small forest in western Ecuador, and at least one Gesneriaceae species, Gasteranthus extinctus , may never have occurred elsewhere (Skog & Kvist 2000). Bilsa Biological Station is the only other of the nine localities that probably has a truly endemic species, in this case a recently discovered undescribed Drymonia . In contrast, two species that only have been collected from San Marcos and Zapallo Grande (Table 4) are both likely to have wider distributions, since extensive relatively similar forests surround these two localities. in western Ecuador is truly remarkable. Of the 36 species in the genus 24 have been recorded from western Ecuador, and 15 of these from elevations below 1000 m elevation. Gasteranthus has actually both speciated below in the low-elevation cloud forests at approx. 600 m elevation, and above in the high-elevation cloud forests mostly between 1800 and 2200 m elevation. Ten species are adapted to low-elevation cloud forests and another different 12 species to high-elevation cloud forests, and the remaining few species have wider distributions in western Ecuador (Skog & Kvist 2000). The six species that were found at Centinela Ridge were all adapted to cloud forest, and five of them have also been found in other cloud forests mainly further to the south, including G. carinatus as far to the south as El Oro province. None of the six Centinela Ridge species, however, occur in the coastal hill cloud forests of the Bilsa Biological Station. Here, another four cloud forest adapted species occur, as well as a species that is more common and widespread in moist and wet forests. Three species found at the Bilsa Biological Station are endemic to the range of coastal hills, while the most common cloud forest species at Bilsa, G . crispus , has also been found along creeks in some wet and moist forests elsewhere in western Ecuador, e.g. , at Río Palenque and Congóma Grande. Dodson & Gentry (1991) suggest that there may have existed many "Centinelas" on isolated ridges along the Andean slopes, each with a large number of endemic and now mostly extinct species. If that statement is true a considerable number of Gasteranthus species may have gone extinct before they were ever collected. There may have existed a few more species of Gasteranthus in western Ecuador than those recognized in the recent revision (Skog & Kvist 2000), but we doubt that many unrecorded species have disappeared. Centinela Ridge and the Bilsa Biological Station cloud forest probably were the two richest low-elevation cloud forests in the region (ignoring possible extant more northern cloud forests along the still mostly unexplored lower western Andean slopes of the Imbabura, Esmeraldas and Carchi provinces). Contour maps of western Ecuador show that Centinela and adjacent ridges on the border between Pichincha and Los Ríos provinces, are the largest and most isolated low-elevation front ridges along the entire western Andean slope (Figure 2). In addition, the higher montane forests and cloud forests at the Andean slopes west of Centinela are also extraordinarily rich in Gesneriaceae, including another six Gasteranthus species (Skog & Kvist 2000). To the south the diversity of the Gesneriaceae decreases. In the low elevation cloud forest of Manta Real located 200 km south of Centinela Ridge on the border between Cañar and Azuay provinces (Figure 1) occur 18 mostly common and widespread Gesneriaceae, including only two western lowland Ecuador endemics, in contrast to 11 at Centinela Ridge (Table 4). Manta Real has only one species of Gasteranthus , and only three species of this genus have been found in Andean low-elevation cloud forests in southeastern Ecuador (in the provinces of Cañar, Azuay and El Oro), while Centinela Ridge had eight Gasteranthus species. It can be argued that the Bilsa cloud forest is probably the richest cloud forest that has existed in the coastal hill range. The Bilsa Biological Station is located in the northern part of the coastal hill range surrounded by the wettest lowland forests (Figure 1). To the south the ridges become surrounded by increasingly dry forests with much fewer Gesneriaceae, and probably also with fewer species of the other plant families that tend to speciate in isolated cloud forests. Gasteranthus also exemplifies this trend in the coastal hill range. Five species occur to the north in the provinces of Esmeraldas and northern Manabí, but apparently only two Gasteranthus species occur in southern Manabí and adjacent northwestern Guayas (Figure 1). Our estimates of the status of the species of Gesneriaceae found in western lowland Ecuador are based on our present, in many ways somewhat limited, knowledge of their distribution, taxonomy, and ecology. Additional collections and discoveries will thus probably prove that some species are, in reality, more common and widespread, and consequently less at risk than estimated here. Despite that limitation, it is probably not too pessimistic to estimate that more than a third of the species found in western lowland Ecuador are extinct or endangered in the region. Three factors add to that conclusion: 1) we have been taxonomically conservative interpreting poorly understood complexes as a single widespread and variable species, e.g. , Monopyle macrocarpa and Napeanthus robustus , and future studies may thus circumscribe additional species in such complexes; 2) some additional rare and endemic Gesneriaceae will probably yet be discovered; and, 3) some extinct (or soon to be extinct) species may not be represented by any herbarium vouchers, or there may exist a few and relatively faulty vouchers that taxonomists will hesitate to assign species names. In the revision of Gasteranthus (Skog & Kvist 2000) a couple of odd, older collections are treated as extreme variants of recognized species, although these vouchers might in fact represent undescribed but probably already extinct species. In 1991 Dodson & Gentry estimated that 6300 species of flowering plants are native to western lowland Ecuador, and that 20 % of them (or ca. 1260 species) are endemic to the region. Similar to the estimations of Dodson & Gentry we find that approx. 20 % of the Gesneriaceae are endemic, and that more than 90 % of the endemic species (20 of 22 species) are extinct or endangered. However, in contrast to the 1991 estimates of Dodson & Gentry, Joergensen & León (1999) and Valencia et al. (2000) reported 4463 plant species native to western lowland Ecuador (defined as below 1000 m) and that only ca. 538 species (or 12%) were endemic to the coastal region. This estimation is significantly less than the percentage of endemic plans to Ecuador as a whole (26% on average for all of Ecuador). If the Gesneriaceae are representative of the entire flora of flowering plants using the estimates from Dodson & Gentry, then more than 1000 endemic species may thus already be extinct or endangered in western lowland Ecuador, but using the figures from the more recent reports by Joergensen & León and Valencia et al. we arrive at a total of somewhere between 400 and 500. In addition, we find that more than a third of all the Gesneriaceae native to lowland western Ecuador may be extinct or endangered in the region, corresponding to more than 2000 species in the entire flora using the Dodson and Gentry estimates, but much less using the more recent data. Is the Gesneriaceae, in reality, representative of the status of the entire flora of lowland western Ecuador? The family is very well-represented in the severely threatened cloud forests, as well as in the moist evergreen forests that also have been largely destroyed, suggesting that the Gesneriaceae may be even more endangered, than the average resident of the local flora, which is borne out by comparing the numbers of endangered Gesneriaceae with the more recent figures. However, we may also come to the opposite conclusion that may be ...