The savannization of moist forests in the Sierra Nevada de Santa Marta, Colombia

In the Rio Ranchería watershed of the Sierra Nevada de Santa Marta, between 500 and 1500 m, savanna vegetation is interspersed with moist forests. The savannas are composed of native savanna grasses like Aristida adscensionis L., Arundinella sp., Panicum olyroides Kunth, and Schyzachyrium microstachyum (Desv.) Roseng., Arrill & Izag and the African Melinis minutiflora P. Beauv. There is also Curatella americana L. and Byrsonima crassifolia (L.) H.B.K., two typical tree species of the neotropical savannas. Although moist forest patches occur more often on lower slopes and narrow valley bottoms, they can also be found on mid- and upper-slopes and less often on ridges. Thus, these forest patches are not gallery forests as are found throughout the neotropics, but the result of deforestation and fractionation of a continuous forest. A comparison of soil profiles between the savannas and remnant forest patches on the same slope, showed the disappearance of the A and B horizons (approx. 50 cm) under savanna vegetation. The sharp difference between the savanna and forest soils at the Rio Ranchería does not appear to be due to a change in soil water status along a toposequence or differences in the underlying bedrock. We hypothesize that the savannas of the Rio Ranchería watershed, are the result of deforestation and land practices on infertile soils derived from granite. The savannization process was likely initiated by Amerindians by means of the frequent use of fire or clearing lands for the cultivation of maize. The introduction of cattle by Spaniards (c. 1530) and the frequent use of fire to maintain grazing fields, contributed to further degradation of the habitat. While some tropical landscapes recovered their forest cover when human pressure was removed approximately 500 years ago, areas such as the Rio Ranchería watershed have suffered permanent damage. The savannas of this region are likely to remain unless fire is suppressed and soil restoration practices implemented.     

Pronophiline butterflies (Satyridae) of the Sierra Nevada de Santa Marta, Colombia

Abstract. The twenty-four species of Pronophilini known from the Sierra Nevada de Santa Marta, a small, isolated and very high north Colombian mountain range, are listed. The ecology of the tribe in northern South America, where these butterflies are exclusively montane, is described. The evolutionary relationships of the thirteen endemic species are analysed. Three new genera, three new species, and four new subspecies are described. Four new synonymies are established, the status of three taxa revised, six new combinations made, lished, the status of three taxa and one original combination re-instated.     

Barriers to Lowland Tropical Forest Restoration in the Sierra Nevada de Santa Marta, Colombia

Extensive areas of the tropics have been converted into pasture for cattle ranching. Frequently, abandoned pasture does not revert to forest. The goal of this project was to identify barriers to lowland moist forest regeneration in highly degraded grasslands in the Sierra Nevada de Santa Marta, Colombia. The barriers we considered were seed source, seed predation, competition with grasses, microclimate and soil limitations on plant growth, and fire. Seed dispersal into the grasslands is limited to within 10 meters of forest fragments, but this barrier can be overcome by sowing seeds and planting seedlings and by establishing perches to attract dispersers. In these degraded grasslands, seed predation was lower than in the adjacent forest patches, and there was no evidence that grasses inhibited the establishment of woody species. The most important barrier was the severe degradation of the soils. In much of the area, the A and B horizons have been eroded away, leaving saprolite at the soil surface. Seedlings of two fast-growing pioneer species, Ochroma pyramidale and Cochlospermum vitifolium, grew to a maximum height of only 2.5 and 12 cm, respectively, during the first eight months. The slow plant growth in the degraded grassland soils compared to forest soils was associated with lower levels of cation-exchange capacity, calcium, magnesium, and potassium. Even if these barriers could be overcome, the frequent and extensive use of fire in the region must be controlled to avoid killing established woody plants.     

A New Species of Terrestrial Isopoda from the Sierra Nevada de Santa Marta,Colombia (Crustacea: Oniscidea: Crinocheta)

A new species of the neotropical genus Ischioscia Verhoeff, 1928 is described from the Sierra Nevada de Santa Marta, Colombia: Ischioscia curvaculeus spec. nov. It is characterised by a hook on the merus of the male pereopod 7 not found in any other species of this genus. It was found in the rain forest at an altitude of 1700 m. The phylogeny of the new species is discussed and a note on the biogeography of the Santa Marta region is given.     

Reproduction of Joturus pichardi and Agonostomus monticola (Mugiliformes: Mugilidae) in rivers of the Sierra Nevada de Santa Marta, Colombia

The freshwater mugilids Joturus pichardi and Agonostomus monticola, have been documented on ecological and distribution aspects, mainly for Central American populations, nevertheless, little information is available on their reproductive aspects, specifically in Colombian freshwater environments. Reproductive biology of the mugilids J. pichardi and A. monticola from Sierra Nevada de Santa Marta (SNSM) rivers was studied between July 2005 and December 2006. A total of 14 specimens of J. pichardi and 320 of A. monticola were collected. The reproductive biology was analyzed by means of: sexual proportion, gonadosomatic index, and mean size at maturity, fecundity and oocyte diameter. Additionally, a bioassay was carried out to evaluate the effect of salinity on spermatic motility and its possible relationship with the species' spawning area. These mugilids share habitats with similar ecological characteristics, in which strong currents; clear water and stony areas stand out. Gonadal maturity indicators and indirect evidence are presented to support the relationship between reproductive maturity and higher rainfall levels in the area (September, October and November), as well as the catadromous migration of J. pichardi and A. monticola. This last species females outnumbered males with a sex ratio of 2.3:1. Females mean size at maturity was 172mm of their total length (TL) and 108mm TL for males. Fecundity (F) was 23 925 +/- 4 581 eggs per gram of gonad, and was related to size by the equation F = 395.1TL(1.281); besides, the mean oocyte diameter was 362 +/- 40 microm. Considering the salinity effect on sperm motility in both species, results suggested that J. pichardi spawned in estuarine environments but the species did not migrate to fully marine environments; however, A. monticola withstood a broad range of salinity, suggesting a spawning from intermediate to total saline environments. Both species have high culturing potentials, considering that their feeding is based on plant and macroinvertebrates, their meat quality and the size they are able to reach. These species represent an interesting resource to the fisher groups of the region and should be integrally assessed.     

Multi-criteria spatial identification of carnivore conservation areas under data scarcity and conflict: a jaguar case study in Sierra Nevada de Santa Marta,Colombia

Human–wildlife conflict, habitat loss, and prey hunting are the main threats to carnivore species worldwide. Forest conversion as consequence of deforestation and agricultural expansion increases the proximity between carnivores and humans, thereby escalating conflicts. Knowledge about carnivore species in data-poor countries, such as Colombia, is scarce which has the potential to result in poor landscape planning decisions. For many species, the only existing spatial information resides in expert-driven approaches which result in coarse-resolution ‘extent-of-occurrence’ maps. There is an increasing need for the development of methodologies to identify conservation and management areas at appropriate scales. Multi-criteria approaches will allow the inclusion of diverse species attributes enabling environmental institutions to address complex landscape decisions that result in conservation and management of carnivore habitat. We present a multi-criteria spatial identification tool for conservation and management areas, focused on Jaguars (Panthera onca) in the Sierra Nevada de Santa Marta, in northern Colombia. Our approach identifies areas based on the relationship between three spatial criteria: (1) suitable habitat patches, (2) habitat connectivity, and (3) zones of higher likelihood of human–jaguar conflict. We identified areas with the presence of at least one spatial criteria in 32% of the study area. Only 16.28% of these occur within protected areas (PAs) and the remaining fall on private lands (83.72%), either within (35.68%) or outside (48.04%) buffer zones of PAs. Our results highlight the need for multi-stakeholder collaborative approaches given that most proposed conservation areas fall on private rather than public lands.     

Relative abundance and microhabitat use by the frog Geobatrachus walkeri (Anura: Strabomantidae) in two habitats of Sierra Nevada de Santa Marta, Colombia

Geobatrachus walkeri belongs to a monotypic frog genus endemic to the San Lorenzo area, Sierra Nevada de Santa Marta, Colombia. This species has been categorized as endangered because of its small distribution area and the decline in the extent and quality of its habitat. It inhabits two forest types with different composition and structure, the native secondary forest and a pine plantation (dominated by Pinus patula). To compare the relative abundance and microhabitat use of this species in these habitat types, 30 quadrants/environment were distributed randomly. The individual number, microhabitat use and other aspects of its natural history were registered using visual encounter surveys in both sites, including non-sampled areas in the quadrants. The relative abundance of frogs was significantly different between habitats and among seasons. The highest abundance of G. walkeri relative to the total area was found in the pine plantation, being 2.3 times higher than in the natural forest. More frogs were significantly found during the rainy season; nevertheless, active individuals were also found during the dry season. Significant differences were found in the microhabitat use with respect to the forest type and season. The most frequently microhabitat used in the two forest types was the pine leaf-litter; besides, in the native forest, the microhabitat occupied more frequently presented medium and large size stones. Geobatrachus walkeri is a successful species in pine plantations, associated permanently to its leaf-litter environment where it seems to develop its entire life cycle. The clear modifications in the soils and water, derived from the introduction of the pine plantation in this area, seem not to have negatively affected the conservation and successful maintenance of this species.     

Notes on the behavior and ecology of Reliquia santamarta,an Alpine butterfly (Lepidoptera: Pieridae) from the Sierra Nevada de Santa Marta,Colombia, with comparisons to Nearctic Alpine Pierini

Reliquia santamarta is an unusual Pierine butterfly endemic to the Sierra Nevada de Santa Marta of northeastern Colombia, where it flies above 3500 m. Its biology is of particular interest because of the possibility that it might be a relict derived from the otherwise Holarctic Pieris callidice group, which it strongly resembles phenotypically. Its behavior was studied afield for comparison with Nearctic members of that group. Male R. santamarta are vigorous hilltoppers, assembling to topographic prominences, while females are frequently encountered at lower elevations. Flight patterns, thermoregulatory postures, and interactions between and within the sexes are all virtually identical to high‐montane and alpine Nearctic Pieris. The natural host plant was not determined. The role of seasonality in the biology of R. santamarta is discussed. Behavior data alone are inadequate to determine whether R. santamarta is closely related to or strongly convergent with the Nearctic taxa.     

Seasonal variations of bacterial abundance and biomass and their relation to phytoplankton in the hypertrophic tropical lagoon Cienaga Grande de Santa Marta, Colombia

The seasonal development of bacteria was studied in the hypertrophiccoastal lagoon Ciénaga Grande de Santa Marta (Caribbeancoast of Colombia). This large but only 1.5 m deep lagoon issubject to strong seasonal variations of salinity from almostfully marine (April/May) to brackish conditions in October/November.Chlorophyll ranged from 6 to 182 µg L^–1, and grossprimary production amounted to 1690 g C m^–2 per year.Total bacterial number (TBN) ranged from 6.5 to 90.5 x 10⁹ cellsL^–1 and bacterial biomass (BBM) from 77 to 1542 µgC L^–1, which are among the highest ever reported for naturalcoastal waters. Neither TBN nor BBM varied significantly withsalinity, phytoplankton or seston concentrations. Only the bacterialmean cell volume showed a significant relation to salinity,being highest (0.066 µm³) during the period of increasingand lowest (0.032 µm³) during decreasing salinity. Bacterialprotein accounted for 24% (19–26%) and phytoplankton proteinfor 57% (53–71%) of total seston protein. The ratio (annualmean) of bacterial carbon to phytoplankton carbon was 0.44 (range0.04–1.43). At low phytoplankton abundance [chlorophylla (Chl a) < 25 µg L^–1], bacterial carbon wasalmost equal to phytoplankton biomass (i.e. the mean ratio was1.04). In contrast, at Chl a > 100 µg L^–1, BBMwas low compared to phytoplankton biomass (the mean ratio was0.16). In general, BBM varied less than phytoplankton biomass.Most probably, the missing correlation between bacterial andphytoplankton variables was due to (i) organic material partlyderived from allochthonous sources serving as food resourcefor bacteria and (ii) a strong resuspension of bacteria fromthe sediment caused by frequent wind-induced mixing of the veryshallow lagoon.     

Index to the vascular plant types collected by H. H. Smith near Santa Marta,Colombia

An index to 360 names based on specimens collected from 1898 to 1901 by H. H. Smith in Santa Marta, Colombia is provided. Each citation includes the plant name, author, place of publication, exact locality and date of collection, and, when possible, the location of the holotype and isotypes. Additional comments are provided to clarify the type status of specimens representing a single taxon and given a single collection number but collected on several different dates or from several different localities, and for truly mixed collections where two or more taxa were given the same number.     

A new species of Henriettea (Melastomataceae) from the Sierra de Baoruco, the Dominican Republic

Henriettea uniflora, which is known only from a diverse moist montane forest in the vicinity of Loma Trocha de Pey (or “Monteada Nueva”), Loma Pie de Palo, and Loma Remigio, the easternmost peaks of the Sierra de Baoruco, is described and illustrated. It is compared to species of the Henriettea squamulosa complex, especially H. squamulosa and H. ciliata. The species of this complex are characterized by an indumentum of ferruginous, stellate-lepidote hairs.     

Microcrustacean communities of high-elevation lakes in the Sierra Nevada, California

Seventy-five high-elevation lakes in the Sierra Nevada mountainsof California were sampled for microcrustacean species and majorion compositions. Cluster analysis was used to delineate fiverecurrent community types. Distributions of both individualspecies and of community types were related to chemical, morphometric,topographic and geologic variables, as well as fish presenceor absence, by stepwise logistic multiple regression. Fish distributionwas an important predictor of the distributions of all individualspecies for which significant regression models could be built;other common predictors included nitrate concentration, elevation,basin area and lake depth. One common community type (n = 22)consisted of Dapbnia rosea, Diaptomus signicauda, Bosmina longirostrisand Holopedium gibberum. A second, more species-rich, community(n = 27) included many of these same species, in addition toCyclopsvemalis, Diaphanasoma brachyurum, Polyphemus pediculis and/orCeriodaphnia affinis. Two further communities (n = 9 and n =6 respectively) contained Daphnia middendorffiana with eitherDiaptomus shoshone or Diaptomus eiseni. A fifth community type(n = 11) either lacked microcrustaceans or contained only Chydorusand/or Alona spp. The distributions of the first four of thesecommunity types could be well predicted on the basis of fishpresence and elevation (community types I and II), or fish absenceand lake depth (community types III and IV). The distributionof the fifth community type was independent of fish presenceor absence; phosphate concentration was the only significantpredictor of this community. ¹Present address: New York City Department of EnvironmentalProtection, PO Box 184, Valhalla, NY 10595, USA     

Fire Severity in Conifer Forests of the Sierra Nevada, California

Natural disturbances are an important source of environmental heterogeneity that have been linked to species diversity in ecosystems. However, spatial and temporal patterns of disturbances are often evaluated separately. Consequently, rates and scales of existing disturbance processes and their effects on biodiversity are often uncertain. We have studied both spatial and temporal patterns of contemporary fires in the Sierra Nevada Mountains, California, USA. Patterns of fire severity were analyzed for conifer forests in the three largest fires since 1999. These fires account for most cumulative area that has burned in recent years. They burned relatively remote areas where there was little timber management. To better characterize high-severity fire, we analyzed its effect on the survival of pines. We evaluated temporal patterns of fire since 1950 in the larger landscapes in which the three fires occurred. Finally, we evaluated the utility of a metric for the effects of fire suppression. Known as Condition Class it is now being used throughout the United States to predict where fire will be uncharacteristically severe. Contrary to the assumptions of fire management, we found that high-severity fire was uncommon. Moreover, pines were remarkably tolerant of it. The wildfires helped to restore landscape structure and heterogeneity, as well as producing fire effects associated with natural diversity. However, even with large recent fires, rates of burning are relatively low due to modern fire management. Condition Class was not able to predict patterns of high-severity fire. Our findings underscore the need to conduct more comprehensive assessments of existing disturbance regimes and to determine whether natural disturbances are occurring at rates and scales compatible with the maintenance of biodiversity.     

Forest Pattern, Fire, and Climatic Change in the Sierra Nevada

In the Sierra Nevada, distributions of forest tree species are largely controlled by the soil-moisture balance. Changes in temperature or precipitation as a result of increased greenhouse gas concentrations could lead to changes in species distributions. In addition, climatic change could increase the frequency and severity of wildfires. We used a forest gap model developed for Sierra Nevada forests to investigate the potential sensitivity of these forests to climatic change, including a changing fire regime. Fuel moisture influences the fire regime and couples fire to climate. Fires are also affected by fuel loads, which accumulate according to forest structure and composition. These model features were used to investigate the complex interactions between climate, fire, and forest dynamics. Eight hypothetical climate-change scenarios were simulated, including two general circulation model (GCM) predictions of a 2 × CO₂ world. The response of forest structure,species composition, and the fire regime to these changes in the climate were examined at four sites across an elevation gradient. Impacts on woody biomass and species composition as a result of climatic change were site specific and depended on the environmental constraints of a site and the environmental tolerances of the tree species simulated. Climatic change altered the fire regime both directly and indirectly. Fire frequency responded directly to climate's influence on fuel moisture, whereas fire extent was affected by changes that occurred in either woody biomass or species composition. The influence of species composition on fuel-bed bulk density was particularly important. Future fires in the Sierra Nevada could be both more frequent and of greater spatial extent if GCM predictions prove true. Received 5 May 1998; accepted 4 November 1998.     

Distribution of edaphic-endemic butterflies in the Sierra Nevada of California

Five edaphically-restricted or -endemic butterflies, mostly associated with serpentine, are shown to be distributed in the western foothills of the Sierra Nevada in addition to their previously documented areas of occupancy in the California North Coast Ranges. Two species are absolutely limited by the edaphic restriction of their host plants, while the other three seemingly are not. The controversies concerning the origins of serpentine endemism in plants apply to butterflies as well. Long-term relictualism can presumably apply only at the metapopulation level, not the local population level, due to the frequency of fire in these habitats. Development and habitat-conversion trends pose a high risk to the long-term survival of these species in the Sierra Nevada.