Cryptogamic epiphytes in primary and recovering upper montane oak forests of Costa Rica – species richness,community composition and ecology

Species richness, community composition and ecology of cryptogamic epiphytes (bryophytes, macrolichens) were studied in upper montane primary, early secondary and late secondary oak forests of the Cordillera de Talamanca, Costa Rica. Canopy trees of Quercus copeyensis were sampled with the aim of getting insight in patterns and processes of epiphyte succession and recovery of diversity in secondary forest following forest clearing. Species richness of cryptogamic epiphytes in secondary and primary forests were nearly the same, showing that primary forests are not necessarily more diverse than secondary forests. High species richness of secondary forests was presumed due to the closed canopy, resulting in permanently high atmospheric humidity in these forests. Similarity in species composition of secondary and primary forests increases with forest age, but after 40 years of succession one third (46 species) of primary forest species had not re-established in the secondary forest. Community composition in primary and secondary forests differed markedly and indicates that a long time is needed for the re-establishment of microhabitats and re-invasion of species and communities adapted to differentiated niches. Genera and species exclusive to primary forests are relevant as indicator taxa and conservation targets. Forty percent (68 species) of all species recorded are restricted to secondary forests, indicating the important contribution of secondary forest diversity to total species richness of the oak forests of Costa Rica.     

Invertebrate drift along a longitudinal gradient in a Neotropical stream in Serra do Cipó National Park,Brazil

The diversity and composition of drift invertebrate assemblages were evaluated along a longitudinal gradient of an altitudinal stream in southeastern Brazil. The main goal of this study was to evaluate the influence of seasonality, stream order, and some abiotic factors on invertebrate drift and the use of drifting invertebrate assemblages to assess aquatic invertebrate diversity. Drift samples were collected over a 24 h period using nets (open area of 0.08 m²; mesh 0.250 mm), partially submerged (60%) in the water column. Taxonomic richness, Pielou evenness (J), Shannon–Wiener diversity (H), and total density of drift invertebrate assemblages were used in unpaired t-tests, Kruskal–Wallis and stepwise multiple regression analysis. The results showed a high taxonomic richness of aquatic invertebrates, with 91 taxa found. Chironomidae and Ephemeroptera represented together c. 80% of the total density of drift organisms. The drift approach allowed the collection of new and rare taxa, besides the knowledge of pupae stage of several chironomid genera. Significant differences in the taxonomic richness and diversity of drift invertebrate assemblages were found between the rainy and dry periods, indicating a significant influence of seasonality. An increase in water flow and electrical conductivity were associated with the increase in the taxonomic richness and diversity in the rainy period. No significant differences were found among the other abiotic variables among the stream orders.     

Spatial ecology and conservation of two sloth species in a cacao landscape in limón,Costa Rica

The spatial ecology of sloths was studied in an agricultural landscape in Limón Province, Costa Rica. Two sloth species, the three-toed sloth (Bradypus variegatus) and the two-toed sloth (Choloepus hoffmanni), actively used and traveled through a cacao agroforest and its contiguous living fence rows and riparian forests. This agroecosystem was embedded in an agricultural landscape dominated by banana and pineapple plantations and pastures with dispersed trees. The two-toed sloth (C. hoffmanni) was found in 101 tree species and used 34 for food; the three-toed sloth (B. variegatus) was found in 71 tree species and used 15 for food. Choice of preferred species differed between the two sloth species. Trees commonly used by sloths for food and/or refuge in the cacao agroforest included Erythrina poeppigiana, Cecropia obtusifolia, Leucaena leucocephala; in the living fence rows, Cordia alliodora, Erythrina poeppigiana, Ocotea sinuata and Trophis racemosa; in the riparian forests, Coussapoa villosa, Cecropia obtusifolia, Hura crepitans, Pterocarpus officinalis and Spondias mombin; and in the pastures with dispersed trees, Cordia alliodora, Coussapoa villosa, Erythrina poeppigiana, Ocotea sinuata and Hura crepitans. This study demonstrates the importance of the cacao agroforest as well as arboreal elements in other land uses in providing resources for sloth conservation in a larger agricultural landscape.     

Distribution and abundance of Caiman crocodilus in the Caño Negro National Wild Life Refuge, Costa Rica

The distribution and abundance of a population of Caiman crocodilus fuscus were estimated by monthly counting of eye-shines at night, from February 1999 to March 2000 in six transects of Río Frío in the Ca?o Negro National Refuge (RNVSCN), Northern Costa Rica. March was the month with the greatest abundance of caimans observed. The visible fraction of the population (PV2 index) fluctuated between 42.59% to 54.71% during the wet season and 35.49% to 53.93% in the dry season. The transects of river with greater abundance of caimans were Terrón-Sabogal and Sabogal-Playuela. Significant differences were determined in the abundance of caimans between transects, except the transects Entrada San Sebastían-Las Cubas and Las Cubas-Entrada Ca?o Los Patos and Entrada Ca?o Los Patos-Terrón and Boca Sabogal-Playuela. The population of estimated brown caiman in this study was 2283.48 +/- 313.5. The statistical analysis by seasons did not show significant differences in the number of caimans observed. Estimated mean number of caimans per km of river was 74.36/km for 30.7 km of habitat. The results of this study indicated that the fluctuation in population density during the seasons is attributable to local movements.     

Canopy dieback in lower montane forests of Alto Urimán,Venezuelan Guayana

Canopy dieback in patches was discovered in an otherwise undisturbed very humid lower montane forest on a quartzitic sandstone plateau of the middle Caroní river basin, Venezuela. The patches vary in size from about 0.1 to 2 ha (50 to 700 upper story dead trees per ha). Preliminary inventories were carried out at 3 selected sites comparing 4 dieback patches (M) with adjacent not affected (V) forests. In the M plots, 40 to 61% of all trees with dbh 10 cm were dead. They consisted mostly (81–100%) of the endemic tree species Terminalia quintalata of the upper story (dbh > 20 to 60 cm, height up to 30 m), which is much sparser in the V stands. Data on stand structure and species composition are presented. They seem to indicate a spatial variation in the density of Terminalia quintalata, but also of other dominant species, and reproductive problems of Terminalia, which is hardly present in the diameter classes below 10 cm dbh. V and M stands grow on similar soils with a perched high water table. They are practically free of clay and rich in humus. The exchange complex is dominated by H⁺. Low pH and dilution of base cations represent the main chemical stress factors. Different concepts of the dieback process are discussed, including cyclic reproductive patterns, nutrient sequestering and drought frequency.     

A survey of homopteran species (Auchenorrhyncha) from coffee shrubs and poró and laurel trees in shaded coffee plantations,in Turrialba,Costa Rica

A survey of homopteran species (Auchenorryncha) was conducted in coffee plantations with no shade (C), and in those with shade of either poró (Erythrina poeppigiana) (CP) or poró plus laurel (Cordia alliodora) (CPL), in Turrialba, Costa Rica. A total of 130 species in ten families were collected, dominated by Cicadellidae (82 species). Species richness was highest in the CP system (88), followed by CPL (74) and C systems (60). Five most common species for all systems were Fusigonalia lativittata, Hebralebra nicaraguensis, Neocoelidia sp., Oliarus sp. and Clastoptera sp. Diversification of the coffee agroecosystem favors some species while limiting others, and have no effect on the majority of species. Thus, only F. lativittata, Neocoelidia sp. and Scaphytopius ca. latidens were well represented in all systems, but were more abundant in coffee shrubs. Additionally, the following were the dominant species in each system: Graphocephala sp. 1 (C), F. lativittata (CP) and H. nicaraguensis (CPL). Four species abundant on laurel trees, including H. nicaraguensis, appeared almost exclusively on these tree species. Species similarity was highest on the CP and CPL systems (51% of the species in common), followed by the C and CP (39%) and the C and CPL systems (38%). These findings show that even disturbed systems can harbor many insect species, so that they deserve attention from conservation advocates and biologists.     

Continuum or zonation? Altitudinal gradients in the forest vegetation of Mt. Kilimanjaro

Based on the analysis of 600 vegetation plots using the method of Braun-Blanquet (1964) the composition of the whole vascular forest plant flora with about 1220 species was studied in the forests of Mt. Kilimanjaro. The altitudinal distribution of all strata (trees, shrubs, epiphytes, lianas and herbs) along a transect of 2400 m is discussed with respect to altitudinal zonation and ecological factors. With uni-dimensionally constraint clustering significant discontinuities were revealed that occurred simultaneously in the different strata. Thus even in structurally highly complex, multilayered tropical montane forests distinct community units exist that can be surveyed and classified by the Braun-Blanquet approach. This observed zonation was significantly correlated with altitude, temperature and soil acidity (pH); rainfall was of importance in particular for the zonation of epiphytes. Other key factors were humidity (influenced by stable cloud condensation belts) and minimum temperature (in particular the occurrence of frost at 2700 m altitude upslope). The contrary results of other transect studies in East Africa in respect to continuity of change in floristic composition appear to be caused by different sampling methods and intensities or mixing of data from areas with different climate conditions, whereas species richness did not influence the clarity of floristic discontinuities on Kilimanjaro and other parts of East Africa.     

Ichthyoplankton from the pier area in Limón, Costa Rica

Four sampling stations were set 200-500 m off Limon Port, Costa Rica, at an average depth of 20 m. From October 1996 to May 1997 horizontal subsuperficial trawls were done for 12 minutes at a speed of about 2 Km/h, with a 1,000 microns plancton net. A total of 28 samples were processed and 104 physical-chemistry parameter measurements were taken. Average salinity was 30.1 +/- 3.7 and dissolved oxygen 6.9 +/- 0.6 mg l-1 reflecting good aeration throughout the sampling period. This suggests good mixture and a highly dynamic hydrography. Temperature showed no drastic variations (28.0 +/- 1.7 degrees C), possibly because of the constant mixing with shallow water. The highest larval counts were for November and early January and include families common to reefs and estuaries (Balistidae, Lutjanidae) and to coastal areas (Centropomidae, Gerreidae, Haemulidae, Carangidae, Engraulidae, Hemiramphidae, and representative Pleuronectiformes) existing in a common area.     

A multiscale analysis of canopy structure in Fagus sylvatica L. and Quercus cerris L. old‐growth forests in the Cilento and Vallo di Diano National Park

Abstract

Broadleaved forest is one of the most severely exploited and threatened ecosystems worldwide such that many authors have highlighted the scarcity of undisturbed old‐growth broadleaved forests, especially in southern Europe. From an ecological perspective, old‐growth forests are considered to be significant for their structural diversity and complex ecological relationships among species. In this paper, we compare ground measurements of leaf area index (LAI) and the remotely sensed normalized difference vegetation index (NDVI) autocorrelation pattern of two old‐growth forest stands in the Cilento National Park (southern Italy) with two nearby managed forests stands of the same type. Results show that old‐growth forests have higher fine‐scale variability in both LAI and NDVI values and longer autocorrelation ranges than the corresponding managed forests. The potential relevance of these findings for the single large or several small (SLOSS) debate is also briefly discussed.     

Linking vegetation pattern to hydrology and hydrochemistry in a montane river floodplain, the Šumava National Park, Central Europe

Cover of higher plants (in 4 × 4 m plots), groundwater table height, and water chemistry in boreholes were sampled at 43 sites along three cross-sectional transects in a flat floodplain of the Upper Vltava River in the Šumava Mountains (Šumava National Park, Czech Republic). The goal was to describe the relationships between vegetation and alluvial environment. Correlations between hydrochemical and plant community characteristics were calculated, and Canonical Correspondence Analysis (CCA) was used to express relationships between the abiotic factors and vegetation. The following characteristics were significantly correlated with the vegetation pattern: mean height of the water table, distance from the river, pH, and concentration of NH₄ and humic acids in the groundwater. Two distinct zones were distinguished in the floodplain: Zone I was under direct influence of the river, and exhibited higher pH and ammonium content in a fluctuating groundwater table. Zone II, covering more than half of the floodplain extent, was under the prevailing influence of water coming from the adjacent upland, and exhibited lower pH, higher content of humic acids, and a higher and relatively stable groundwater table. A diverse mosaic of the riparian communities, especially of tall-sedge and tall-grass marshes and alluvial meadows, was typical for the former zone, while peatland vegetation characterised the latter one. The floodplain exhibited a rather oligo- to mesotrophic status with only very local eutrophication, and harboured diverse and valuable plant communities. The protection of this floodplain should be among the priorities of the National Park authorities.     

Lichens as air pollution indicators in the metropolitan area of San José, Costa Rica

Lichens were used as air pollution indicators in the metropolitan area of San José, Costa Rica. Transplants showed a positive correlation between the percentage of dead cells in the thallus and the ketone soluble substances deposited on it. Those parts of the city where pollution is greatest (industrial areas and heavy traffic) were also the ones where lichens suffered the most, and in some extreme cases the thallus died after 8 months of exposure. Besides this transplant experiment, the coverage of Parmelia lichens on the bark of several tree species was determined in some areas of the city. The results of these observations suggest that the city of San José has three different kinds of air environment in relation to lichen survival: normal, transitional and desertic, as reported for other cities of the world. The most frequent air pollutants in San José are: CO, CO2, C2H5OH, Cl2, HCl, H2S, H3PO4, H2CrO4, NO, NH3, NH4 Cl, SO2 and Zn.     

Ethnicity, gene flow, and population subdivision in Limón, Costa Rica

In this paper we examine the effects of ethnicity on the gene flow between two groups living in Limón, Costa Rica. Our main interest is to determine if ethnicity has acted as a barrier to the exchange of genes, and if the groups have remained distinct genetically. We report the admixture estimates, F(st) values, and inbreeding coefficients of the two samples. The data consist of blood samples and surnames obtained from 375 individuals. The subjects' two surnames were analyzed to determine the ethnicity of their parents (individuals carry their father's and mother's first surnames). We used the formula of Crow and Mange ([1965] Eugen Q 12:199-203) to compute F(t), F(n), and F(r) with the surnames. Admixture estimates were computed for both groups using the computer program ADMIX.PAS kindly provided by Jeffrey Long. The estimates for the Hispanic-Limonense group are M1 = 0.5866 European, M2 = 0.3383 Amerindian, and M3 = 0.0751 African ancestry. For the Afro-Limonense group, the admixture estimates indicate M1 = 0.1047 European, M2 = 0.1357 Amerindian, and M3 = 0.7595 African ancestry. The F(st) values are F(st) = 0.00558 for the Hispanic group and F(st) = 0.05137 for the Afro-Limonense group. These F(st) values indicate that the Afro-Limonense group has experienced more genetic drift than has the other group, possibly as a result of its long history of isolation in Costa Rica. Indeed, when plotted along a scaled eigenvector R matrix of Caribbean gene frequencies, the two Limonense groups did not cluster with each other. Thus we conclude that the two ethnic groups have remained distinct breeding populations.     

Species richness and diversity of a fish community in a temporal water body at Caño Negro National Wildlife Refuge, Costa Rica

We evaluated fish community, species richness and diversity in a temporal water body of Rio Frio, Ca?o Negro National Wildlife Refuge. These evaluations were done for three categories of water levels: low (below 1.5 m), intermediate (between 1.5 and 3.0 m) and high (deeper than 3 m). A total of 10,264 individuals were collected (nine families, 18 genera and 21 species). The most abundant species were Poecilia gillii (37%) and Astyanax aeneus (19%) and the least abundant were Ophisternon aenigmaticum (0.06%) and Rhamdia nicaraguensis (0.05%). The highest values in diversity (H' = 2.07), in the inverse of the Simpson index (1/D = 6.2) and of the Berger-Parker (1/d = 4.2), were recorded in the deepest water category. Diversity differed clearly among water levels (p < 0.001). The high and intermediate categories were the most similar (conglomerate analysis: 72.9%). Out of the 21 species captured, only O. aenigmaticum constitutes a new record for the ichthyofauna of Rio Frio in the Ca?o Negro National Wildlife Refuge. The temporal water body of the Rio Frio, considered in this study in the Playuela sector of Ca?o Negro National Wildlife Refuge is a nonhomogeneous ichthyological system.     

Physical-chemical features and determination of pesticides in the lagoon water in Gandoca, Limón, Costa Rica.

Nutrients and chlorophylls concentrations, as well as salinity, temperature and Secchi disk depth were determined from November 1999 to April 2000, at three stations and two depths, at Gandoca lagoon, Gandoca-Manzanillo National Wildlife Refuge, Limón, Costa Rica. Salinity profiles indicated that the lagoon was a salt wedge estuary with a partially mixed region near the mouth. No processes of eutrophication were found. The distribution and abundance of nutrients and chlorophylls showed a slight influence of continental water and water circulation patterns in the lagoon. A preliminary study was done in order to analyze the presence of 20 organochlorated and organophosphorated pesticides along the Gandoca lagoon in February 2000. None of the pesticides were detected by the analysis of residues from liquid-liquid extractions. The absence of the pesticides may be due to the fact that they did not reach the lagoon or, if they did, they were washed away by the strong rains during the sampling period.     

Effects of climate on historical fire regimes (1451–2013) in Pinus hartwegii forests of Cofre de Perote National Park,Veracruz, Mexico

Cofre de Perote National Park (CPNP) in Veracruz, Mexico is part of the Transmexican Volcanic Belt, and its Pinus hartwegii forests reflect a balance between the various natural factors that represent the region's climatology and hydrology. Like many other areas in this region, the historical fire regimes of these forests and their relationship with climate are unknown, but are needed for sustainable management plans. The main objectives of this study were to reconstruct the historical fire regime in a Pinus hartwegii forest and decipher the influenced of climate. Our investigation focused in two study areas, Valle la Teta (VT) and Barranca Honda (BH). The VT study area was divided into three sites based on humidity and elevation: 1) Humid (VTH), 2) Dry Low (VTDL) and 3) Dry High (VTDH). The approximated area for each site was ​​30, 30, 35 and 50 ha, for VTH, VTDL, VTDH and BH, respectively. We collected 162 fire scarred samples to reconstruct the fire history for the last 550 years (1461−2013). The fire scarred samples contained 1240 fire scars, with most fires occurring in spring (95 %) or summer (5%). Prior to 1973, these sites were characterized by a frequent surface fire regime. In all four sites, the mean fire intervals ranged from 5 to 6 years (for fires that scarred ≥ 10 % of the samples) and 13–23 years (for fires that scarred ≥ 25 % of the samples). Extensive fires (≥ 10 %) coincided with significantly dry conditions based on the Standardized Precipitation Index (SPI), influenced by El Niño Southern Oscillation (ENSO) and the Pacific Decadal Oscillation Index (PDO). We also found a significant relationship between fire occurrence and ENSO, both in its warm phase, El Niño (21 fires ≥ 10 %) and in its cold phase, La Niña (32 fires ≥ 10 %). Synchronization of the cold phase of ENSO (La Niña) with the cold phase of the PDO (negative), facilitated severe drought conditions, resulting in fires with the greatest spatial extent. Since 1973, extensive fires have been absent from the study area most likely due to anthropogenic activities including active fire suppression. These results show a strong climate-fire relationship in these high elevation forests. The lack of fire in the last four decades is concerning and could potentially lead to unnatural stand-replacing fires, unless the historical fire regime is restored to maintain natural processes and increase forest resilience.     

Rotifers in ephemeral ponds of Doñana National Park

32 ephemeral dune ponds were studied at the end of January 1990. 34 rotifer species were identified. The distribution of only a few species was related to salinity, suspended matter, chlorophyll-a and total water protein concentrations. However, most of the species seem to be better related to the colonization possibilities than to the environmental characteristics of the ponds.     

Regional variation in soil carbon and δ<Superscript>13</Superscript>C in forests and pastures of northeastern Costa Rica

Recent studies suggest that the direction and magnitude of changes in soil organic carbon (soil C) pools following forest-to-pasture conversion in the tropics are dependent upon initial soil conditions and local factors (e.g. pre-conversion soil C content, soil texture, vegetation productivity, and management practices). The goal of this study was to understand how landscape-scale variation in soil-forming factors influenced the response of soil C pools to forest clearing and pasture establishment in northeastern Costa Rica. We measured soil C and its stable isotopic composition in 24 paired pasture and reference forest sites distributed over large gradients of edaphic characteristics and slope throughout a 1400 km² region. We used the large difference in stable C isotopic signatures of C3 vegetation (rain forest) versus C4 vegetation (pasture grasses) as a tracer of soil C dynamics. Soil C pools to 30 cm depth ranged from 26% lower to 23% higher in pastures compared to paired forests. The presence of non-crystalline clays and percent slope explained between 27 and 37% of the variation in the direction and magnitude of the changes in soil C storage following pasture establishment. Stable carbon isotopes (¹³C) in the top soil (0–10 cm) showed a rapid incorporation of pasture-derived C following pasture establishment, but the vegetation in these pastures never became pure C4 communities. The amount of forest-derived soil C in pasture topsoils (0–10 cm) was negatively correlated to both pasture age and the concentrations of non-crystalline iron oxides. Together these results imply that site factors such as soil mineralogy are an important control over soil C storage and turnover in this region.     

Effects of the duration of flooding on species richness and floristic composition in three hectares in the Jau´ National Park in floodplain forests in central Amazonia

Rivers in Central Amazonia show annual water level fluctuations of up to 14m; the flooding period ranges from 50 to 270 days between the rising and falling phases. Differences in duration and type of flood in Amazonian floodplain forests result in a mosaic of habitats which include lakes, grasslands, forests, streams etc. To study the floristic composition, structure, variation on number of species and diversity in a forest that is seasonally flooded by a black-water river in Brazilian Amazonia, 200km NE of Manaus, I surveyed three hectares in habitats which included lake, river margin, and stream. The number of species per hectare ranged from 44 to 137. The number of trees varied from 796 to 1130. Total basal area ranged from 22.3m2 to 41.8m2. Leguminosae was the most abundant and dominant family in the river margin and stream plot, while Euphorbiaceae and Leguminosae were, respectively the most abundant and dominant families in the lake plot. The most dominant species in the river margin and stream plots was Aldina latifolia (Leguminosae), while Amanoa oblongifolia (Euphorbiaceae) was the most abundant and dominant species in the lake plot. Mean water level and flooding period decreased significantly from lake to the river margin to the stream. The mean number of species and the Shannon diversity increase significantly from the lake to the river margin to the stream habitats plots. Similarity indexes varied from 0.3 to 0.55% between the three plots sampled in this study.     

Batrachochytrium dendrobatidis infection of amphibians in the Doñana National Park, Spain

Amphibian chytridiomycosis, caused by infection with the non-hyphal, zoosporic chytrid fungus Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease recognised as a cause of recent amphibian population declines and extinctions worldwide. The Do?ana National Park (DNP) is located in southwestern Spain, a country with widespread Bd infection. This protected area has a great diversity of aquatic habitats that constitute important breeding habitats for 11 native amphibian species. We sampled 625 amphibians in December 2007 and February to March 2008, months that correspond to the early and intermediate breeding seasons for amphibians, respectively. We found 7 of 9 sampled species to be infected with Bd and found differences in prevalence between sampling periods. Although some amphibians tested had higher intensities of infection than others, all animals sampled were apparently healthy and, so far, there has been no evidence of either unusually high rates of mortality or amphibian population declines in the DNP.