Species zonation in Corroios salt marsh in the Tagus estuary (Portugal) and its dynamics in the past fifty years

The objective of this study was to understand the main factors controlling salt marsh plant species structure and dynamics. So, we determined plant cover and composition across a permanent transect, 450 m long and 1 m wide, defined in 1951 in Corroios salt marsh, in the Tagus estuary (Portugal) and we characterized the physicochemical variables every 50 m along this transect. Based on those results we discuss the dynamic and evolution of salt marsh vegetation during the last 50 years comparing former and recent data. The results showed that differences in salinity and flooding were determinant factors in plant species composition and distribution along the studied transect. In addition, long-term variations of these factors as a consequence of vertical accretion and sea level rise seem to be responsible for the evolution in plant structure and vegetation zonation patterns, during the last 50 years in the Tagus estuary salt marshes.     

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.     

Physical and biological processes influencing zonation patterns of a subtidal population of the marine snail, Astraea (Lithopoma) undosa Wood 1828

The population density and size distribution of the marine gastropod, Astraea (Lithopoma) undosa Wood 1828, at Bird Rock, Santa Catalina Island, CA, reveal an inverse relationship between population density and mean individual size, over a depth gradient. This trend may be correlated with physical and biological differences between habitats for parameters such as water motion, competitive interactions, and predation.

The potential effect of hydrodynamic forces on the zonation patterns of Astraea undosa was tested in laboratory and field experiments. Based on theoretical predictions of the relationship between shear force and water velocity on different-sized snails, large snails are subjected to greater shear forces, as a result of water motion, than medium or small snails. Results of dislodgment experiments conducted in the laboratory indicated that for a given force per unit area, all snails dislodged at nearly the same frequency, with 50% of snails predicted to dislodge at about 4 m/s, and 100% of snails predicted to dislodge at about 8 m/s velocity. These results suggest that hydrodynamic forces may be an important factor in the shallowest subtidal zones.

A factorial-designed caging experiment was used to test the effects of snail population density on growth rates of snails of three different size classes. For small and medium size classes, results indicated an inverse relationship between population density and growth rates, which was especially pronounced for smaller snails. These data, in conjunction with long-term patterns of population density and size distribution in the field, suggest that intraspecific competition also plays a role in determining size-specific zonation patterns.

Tethering experiments, used to estimate predation rates in different algal-cover zones, suggest that there are no differences in survival rates among different snail size classes; however, survival rates differ among zones and may contribute further to the observed zonation patterns. Overall, data indicate that a combination of physical and biological processes controls the population density and size-distribution of Astraea undosa over a depth gradient at Santa Catalina Island, California.     

Sequential colonization and diversification of Galapágos endemic land snail genus Bulimulus (Gastropoda, Stylommatophora)

Species richness on island or islandlike systems is a function of colonization, within-island speciation, and extinction. Here we evaluate the relative importance of the first two of these processes as a function of the biogeographical and ecological attributes of islands using the Galápagos endemic land snails of the genus Bulimulus, the most species-rich radiation of these islands. Species in this clade have colonized almost all major islands and are found in five of the six described vegetation zones. We use molecular phylogenetics (based on COI and ITS 1 sequence data) to infer the diversification patterns of extant species of Bulimulus, and multiple regression to investigate the causes of variation among islands in species richness. Maximum-likelihood, Bayesian, and maximum-parsimony analyses yield well-resolved trees with similar topologies. The phylogeny obtained supports the progression rule hypothesis, with species found on older emerged islands connecting at deeper nodes. For all but two island species assemblages we find support for only one or two colonization events, indicating that within-island speciation has an important role in the formation of species on these islands. Even though speciation through colonization is not common, island insularity (distance to nearest major island) is a significant predictor of species richness resulting from interisland colonization alone. However, island insularity has no effect on the overall bulimulid species richness per island. Habitat diversity (measured as plant species diversity), island elevation, and island area, all of which are indirect measures of niche space, are strong predictors of overall bulimulid land snail species richness. Island age is also an important independent predictor of overall species richness, with older islands harboring more species than younger islands. Taken together, our results demonstrate that the diversification of Galápagos bulimulid land snails has been driven by a combination of geographic factors (island age, size, and location), which affect colonization patterns, and ecological factors, such as plant species diversity, that foster within-island speciation.     

The evolution of extreme shell shape variation in the land snail Ainohelix editha: a phylogeny and hybrid zone analysis

Ainohelix editha from Hokkaido, Japan, exhibit great geographical variation in their shell morphology. In particular, A. editha in two quite separate locations, Shimamaki and Samani, are striking because they are extremely flat and have a sharp keel, whereas at adjacent sites the shells are globular or depressed-globular. We used mitochondrial 16S rRNA and nuclear ITS-2 sequences to infer a phylogeny among 47 snails from 29 locations. Snails from the two keeled-flat populations clustered separately in the phylogeny, suggesting that this unusual shell form could have evolved independently. A morphological analysis of shells collected along a transect between keeled-flat and globular snail sites showed a cline for shell shape and the angle of the keel. Two different mtDNA lineages were found across the transect, with a cline for an ITS-2 single nucleotide polymorphism. Together, the results may suggest a lack of reproductive isolation between keeled-flat and globular snails, with possible introgression by hybridization.     

Taconic Foreland Basin graptolites: age zonation, depth zonation, and use in ecostratigraphic correlation

Late Middle Ordovician graptoloids are stratigraphically zoned by depth of deposition as well as by age along an 83 km long downslope transect through a roughly four million year long continental-shelf and outer-trench slope sequence in the Mohawk Valley, New York. The distribution of graptoloid assemblages parallels the distribution of sediment types and benthic macroinvertebratc assemblages in showing the general, convergence-related marine transgression, secondary transgressive and regressive pulses, and topographic irregularities related to syndepositional block faulting. The relationship of ordination scores for graptoloid assemblages (which arc based on relative abundances of genera) to the samples' positions on downslope transects along bentonite beds, and to depth-related ordination scores for benthic macroin-vertebrate assemblages in the same samples throughout the sequence, quantitatively demonstrates zonation by depth of deposition. Rather like modern pelagic colonial tunicates, graptoloids were evidently zoned by depth in the water column, with Orthograptus spp. predominating in offshore waters above the oxygen minimum zone, Climacograptus spp. near the top of the minimum zone at 300 to 500 m depths, and Corynoides spp. well within the minimum zone. Destruction of sinking rhabdosomes by decomposers evidently accentuated zonation by depth of deposition, and may have contributed to the strong, broad oxygen minimum zone thought to have been characteristic of graptolitic shale basins. Stratigraphic sections' approximate relative sea level curves, calibrated in terms of graptoloid assemblage ordination score, give ecostratigraphic correlations of 2–3 × 10⁵ year average accuracy when statistically cross-correlated between sections, and when cross-correlated with similar curves based on benthic macroinvertebratc assemblage ordination score. □Graptolithina, age zonation, depth zonation, paleoeco-logy, Middle Ordovician, ecostratigraphy, coenocorrelation.     

广东湛江红树林保护区大型底栖动物群落的空间分带

用生态样带研究了广东湛江红树林保护区高桥镇核心区大型底栖动物的空间分带。结果表明：德耀村红树剖面中出现的大型底栖动物优势种类为琵琶拟沼螺、悦目大眼蟹、扁平拟闭口蟹、宽身闭口蟹、黑口滨螺、等齿角沙蚕、弧边招潮和中华伪露齿螺。该剖面大型底栖动物从高潮位到低潮位可分为3个分布带：琵琶拟沼螺-弧边招潮-浓毛拟闭口蟹带；宽身闭口蟹．悦目大眼蟹．黑口滨螺带；扁平拟闭口蟹-珠带拟蟹手螺带。群落生物量的变化主要由软体动物所主导，栖息密度的变化主要由软体动物和甲壳动物所主导，多样性指数变化主要由软体动物所主导。红寨村红树剖面中出现的大型底栖动物优势种类为琵琶拟沼螺、蝼姑虾、扁平拟闭口蟹、宽身闭口蟹、耳螺科的一种、黑口滨螺、中华伪露齿螺、哈氏仿对虾、弧边招潮和等齿角沙蚕。该剖面大型底栖动物也可分为4个分布带：黑口滨螺-中华伪露齿螺-等齿角沙蚕带；琵琶拟沼螺-宽身闭口蟹-耳螺科的一种带；蝼蛄虾．扁平拟闭口蟹带；沈氏长方蟹-珠带拟蟹守螺带。群落生物量的变化也主要由软体动物所主导，栖息密度的变化主要由甲壳动物所主导，多样性指数变化主要由软体动物所主导。底栖动物群落的等级聚类和非参数多变量标序显示，大型底栖动物分带与红树植物群落类型相一致。大型底栖动物分带受红树植物群落类型影响的主要原因是不同红树植物群落间的群落特征、沉积物性质和所处潮位线存在差异。     

Habitat and zonation patterns of Littoraria species (Gastropoda: Littorinidae) in Indo-Pacific mangrove forests

The zonation of 15 species of Littoraria in the scabra group is described, using a transect method, at 13 mangrove localities in Australia, Thailand, Malaysia and Hawaii. At these localities the littorinids occurred only on trees, and showed both vertical and horizontal patterns of zonation, with broad overlaps between co-occurring species. It is suggested that vertical distribution is determined mainly by behavioural responses, while the landward limits of horizontal distribution may be set by physiological tolerance. Several species occurred predominantly on either leaf or bark substrates, but no consistent associations with tree species were found. On the basis of local distribution patterns, Littoraria species can be classified as continental or oceanic in character. Oceanic species may be less tolerant of sediment in the water or on the substrate.     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Spatial zonation of macrobenthic fauna in Zhanjiang Mangrove Nature Reserve, Guangdong, China

The spatial zonation of macrobenthic fauna in the core region of Zhanjiang Mangrove Nature Reserve was studied with two transects vertical to the shoreline. The first transect was near Deyao Village where three faunal zones of the mangrove swamp could be divided into the following types from the high tide part to the low tide part: the Assiminea lutea-Uca arcuata-Paracleistostoma crassipilum zone, the Cleistostoma dilatatum-Macrophthalmus erato-Littoraria melanostoma zone, and the Paracleistostoma depressum-Cerithidae cingulata zone. Mollusck and crustacean exhibited the highest individual density in this transect. Mollusck mainly influenced the dynamics of community biomass as well as the species diversity index. In the second transect near Hongzhai Village, the following four faunal zones could be determined: the Littoraria melanostoma-Pseudoringicula sinensis-Ceratonereis burmensis zone, the Assiminea lutea-Cleistostoma dilatatum zone with a dominant species belonging to the Ellobiidae, Upogebia sp.-Paracleistostoma depressum zone, and the Metaplax sheni-Cerithidae cingulata zone. The crustacean showed the highest individual density in this transect. Similar to the Deyao transect, dynamics of community biomass and the species diversity index of the Hongzhai transect were mainly influenced by mollusck. By hierarchical clustering and nonmetric multidimensional scaling, the macrobenthic fauna communities could be divided into three and four groups in the Deyao and Hongzhai transects, respectively. These groups corresponded to different types of vegetation of the mangrove swamp. Taken together, our observations indicated that the spatial zonation of the macrobenthic fauna was mainly affected by the characteristics of the mangrove community, sediment characteristics and the tidal line.     

Synchroneity of Pliocene planktonic foraminiferal datums in the North Atlantic

Leg 94 of the Deep Sea Drilling Project has provided a unique set of paleomagnetically dated cores, taken along a N-S transect in the North Atlantic. High deposition rates in the sediments, combined with the palaeomagnetic ages, have enabled existing planktonic foraminiferal zonations to be tested and a new zonation for the mid- to high latitudes to be erected. The PL zonation of Berggren (1973, 1977) is shown to be adequate as far north as 41°N, although both the LAD's ofGlobigerina nepenthes andGloborotalia margaritae occur earlier than in tropical regions. North of 41°N these two species have very diachronous LAD's, even though they are common during their range in the northern sites. The new zonation for the mid to high latitude North Atlantic is based on the FAD ofG. margaritae, FAD ofG. puncticulata, LAD ofG. cf. crassula, LAD ofN. atlantica, FAD ofG. inflata and FAD of sinistrally coiled encrustedN. pachyderma.     

Accessory respiration in the climbing perch anabas scandens

Eleven species of blackfly larvae were collected in a survey of Upper Teesdale streams, Northern England. Their distribution in these streams is given. In one stream, Moss Burn, which was studied in detail, a zonation of species occurred along its length and changes in species composition are described for one part of the stream in three summers.Part of the work included in this paper was undertaken while the author was a member of the Department of Zoology, University of Newcastle upon TynePart of the work included in this paper was undertaken while the author was a member of the Department of Zoology, University of Newcastle upon Tyne     

The evaluation of fieldwork: concept elucidation by transects

Problems associated with biology fieldwork and the teaching of ecology are outlined and it is suggested that a key to improvement in this area is the development of a more objective approach based on evaluation data indicating the effectiveness of fieldwork exercises. Lack of such data is considered to be contributing to educational inertia.

An evaluation of concept elucidation by transect exercises is reported. One concept considered important in relation to zonation is not significantly elucidated. This is considered as a limitation of the transect as an educational exercise and is taken to illustrate the potential importance of evaluation work.     

Elevational zonation of afrotropical forest bird communities along a homogeneous forest gradient

Aim This study analyses the distribution and abundance of birds from a forested tropical gradient in order to determine whether elevationally distinct communities are detectable in this habitat. Location An avifaunal census was carried out on a single transect within the tropical forest of the Udzungwa Mountains in the Eastern Arc, Tanzania, covering a range in elevation from 300 to 1850 m. Methods Two complementary data sets on forest birds were analysed, encompassing (1) data derived from standardized 20‐ha spot‐mapping censuses performed at nine elevations over 175‐m intervals from 400 to 1800 m a.s.l., and (2) all observations of birds binned into 32 data points at 50‐m intervals, from 300 to 1850 m a.s.l. The degree of zonation in the avian community along the elevational gradient was examined using the chronological clustering method, an agglomerative hierarchical clustering method that can be carried out with a range of similarity indices. Results The chronological clustering analysis of the data set based on standardized spot‐mapping revealed a clearly defined boundary at c. 1200 m a.s.l., separating lowland from montane communities. Most bird species could be categorized as belonging to one of these two communities. The data set based on all observations revealed a number of potential secondary boundaries, although these boundaries delimited the entire elevational ranges of individual species in only relatively few cases. Main conclusions In contrast to previously published studies, we find evidence of an elevational zonation of distinct communities within a seemingly homogeneous habitat. Although similar boundaries have been assumed to arise as a result of vegetational ecotones, or because of interspecific competition, these mechanisms are poorly corroborated. We suggest that the causes of patterns of zonation are not well understood, and that the interplay among species distributions, species richness, and environmental factors needs more consideration. The chronological clustering method is proposed as an appropriate tool for studying these specific patterns.     

How do alien plants distribute along roads on oceanic islands? A case study in Tenerife, Canary Islands

Islands are paradigms of the pervasive spread of alien plants, but little work has been done assessing pattern and cause of the distribution of such plants in relation to roads on oceanic islands. We studied richness, composition, and distribution of alien plants and compared them with native species along roads on Tenerife (Canary Islands). We studied a single road transect that sampled two contrasting wind-facing aspects (leeward versus windward) and ran from coastal Euphorbia scrubland through thermophilous scrubland to Makaronesian laurel forest at the top of a mountainous massif. We evaluated the effects of elevation, aspect, distance to urban nuclei, and several road-edge features (including road-edge width and management—implying disturbance intensity), using regression models, analysis of variance, and multivariate ordination methods. Richness of both endemics and native nonendemics was explained by elevation (related to well-defined vegetation belts), steepness of the edge slope, and cover of rocky ground. Despite a short elevational gradient (0–650 m), we found clear altitudinal zonation by biogeographic origin of both nonendemic natives and aliens, and altitudinal distribution of aliens followed the same zonation as that of natives. Alien species’ richness was related to management intensity determining edge disturbance, road-edge width, and distance to the nearest urban nuclei (propagule sources). Different variables explained distribution patterns of natives, endemics, and aliens along roadsides on leeward and windward aspects. Altitude and aspect also had a strong influence on the frequency of life strategies (woody species, annuals and biennial/perennial herbs) of roadside plant communities. Due to harsher environmental filters operating on the leeward aspect, alien species were distributed along the altitudinal gradient in apparent consistency with general biogeographical affinities. Tropical/subtropical taxa showed exponential decrease with increasing elevation, Mediterranean taxa showed a unimodal response (i.e., maximum richness at mid elevation, minimum at the extremes of the gradient), and temperate taxa showed linear increase with elevation. Native but nonendemic species followed analogous trends to those of aliens. This suggests climatic matching as a prerequisite for successful invasion of this topographically complex island. Other road traits, such as edge width, slope steepness, soil cover, and road-edge disturbance intensity may play a complementary role, at a more local scale, to shape the distribution of alien plants on these island roads.     

The distribution of vascular plant species and guilds in space and time along a desert gradient

Abstract. We studied distribution patterns of vascular plant species and environmental variables for three years along a permanent transect traversing a closed-drainage watershed in the northern Chihuahuan Desert of south-central New Mexico, USA. The transect extended for 2.7 km from a basin floor playa (1310 m elevation, fine-textured soil), across a piedmont slope, and onto the base of a granitic mountain (1410 m elevation, coarse-textured soil). The gradients in elevation and soils across our transect, along with variable seasonal rainfall, downslope redistribution of water and organic matter, and soil texture-related variation in infiltration, water holding capacity, and moisture release characteristics, interact to generate a complex spatial and temporal gradient of available soil water and nitrogen. We grouped plant species into guilds according to growth form and photo synthetic pathway type. These guilds are spatially and temporally differentiated along the transect such that particular groups utilize particular seasonal phases or spatial regions of the gradient. We identified six distinct plant communities along the transect. C₄ perennial grasses dominated the mesic/high nitrogen portion of the gradient, which occurred at the highest (upper piedmont grassland, dominated by Bouteloua eriopoda) and lowest (playa, dominated by Panicum obtusum) elevations along the transect. C₃ shrubs were dominant in the xeric/low nitrogen portion of the gradient located near the middle of the transect (bajada shrubland, dominated by Larrea tridentata). C₃ shrubs also dominated a narrow zone of vegetation located adjacent to the playa (playa fringe, dominated by Prosopisglandulosa). C₄ perennial grasses, C₃ subshrubs, and C₃ and C₄ perennial forbs and annuals were co-dominant in the intermediate locations along the gradient, which occurred below (mixed basin slopes) and above (lower piedmont grassland) the bajada shrubland. Life-form distribution patterns at the small scale of our study reflect some of the patterning that occurs at larger scales in response to climate gradients. The distributions of some species and guilds along the transect are apparently modified by competitive interactions.     

Zonation of mangrove flora and fauna in a subtropical estuarine wetland based on surface elevation

In the context of sea‐level rise (SLR), an understanding of the spatial distributions of mangrove flora and fauna is required for effective ecosystem management and conservation. These distributions are greatly affected by tidal inundation, and surface elevation is a reliable quantitative indicator of the effects of tidal inundation. Most recent studies have focused exclusively on the quantitative relationships between mangrove‐plant zonation and surface elevation, neglecting mangrove fauna. Here, we measured surface elevation along six transects through the mangrove forests of a subtropical estuarine wetland in Zhenzhu Bay (Guangxi, China), using a real‐time kinematic global positioning system. We identified the mangrove plants along each transect and investigated the spatial distributions of arboreal, epifaunal, and infaunal molluscs, as well as infaunal crabs, using traditional quadrats. Our results indicated that almost all mangrove forests in the bay were distributed within the 400–750 m intertidal zone, between the local mean sea level and mean high water (119 cm above mean sea level). Mangrove plants exhibited obvious zonation patterns, and different species tended to inhabit different niches along the elevation gradient: Aegiceras corniculatum dominated in seaward locations while Lumnitzera racemosa dominated in landward areas. Mangrove molluscs also showed distinct patterns of spatial zonation related to surface elevation, independent of life‐form and season. The spatial distributions of some molluscs were correlated to the relative abundances of certain mangrove plants. In contrast, the spatial distributions of crabs were not related to surface elevation. To the best of our knowledge, this is the first study to explicitly quantify the influences of surface elevation on the spatial distributions of mangrove fauna. This characterization of the vertical ranges of various flora and fauna in mangrove forests provides a basic framework for future studies aimed at predicting changes in the structure and functions of mangrove forests in response to SLR.     

Population dynamics ofGlaux maritima (L.) along a distributional cline

Population fluctuations ofGlaux maritima, along a transect on a Baltle sea shore meadow, were recorded between 1979 and 1983. A bimodal distribution in numbers along the transect reflects the variation in factors regulating numbers: The two maintenance systems of the species, vegetative propagation and sexual reproduction play different roles. Vegetative propagation is fast and responds quickly to variations in the environment. The seeds germinate in strongly fluctuating temperatures which are triggered by disturbances such as flooding, damaging the vegetation.     

Distribution of Clostridium perfringens and Fecal Sterols in a Benthic Coastal Marine Environment Influenced by the Sewage Outfall from McMurdo Station, Antarctica

The spatial distribution, movement, and impact of the untreated wastewater outfall from McMurdo Station, Antarctica, were investigated under early austral summer conditions. The benthic environment was examined to determine the distribution of Clostridium perfringens in sediment cores and the intestinal contents of native invertebrates and fish along a transect of stations. These stations extended ca. 411 m south of the outfall. The findings revealed that the concentration of C. perfringens decreased with depth in the sediment and distance from the outfall. High percentages of tunicates and sea urchins were colonized with this bacterium along the transect. Coprostanol concentrations were also measured in sediment samples taken from each of the transect stations, and a similar trend was observed. These results are in agreement with the findings of previous studies performed with the water column and collectively provide evidence that the disposal of domestic wastes deserves special consideration in polar marine environments.     

Non-pollen palynomorphs from surface sediments along an altitudinal transect of the Venezuelan Andes

Palynological studies including records of non-pollen palynomorphs (NPP) are uncommon in the Neotropics, in spite of their demonstrated usefulness in other regions. Modern analog studies to improve palaeoecological interpretations of NPP are even more scarce. Here, we report the NPP assemblages recorded in modern surface samples from an altitudinal transect of the Venezuelan Andes, ranging from about 2300 and 4600 m. We compared the assemblages with the results of previous pollen analyses of the same samples. The variables considered to explain NPP patterns along the transect are altitude and the local habitat of the sampling site (“sample type”). A total of 65 NPP taxa - classified into algal and zoological remains, and fungal spores - have been found. Unidentified taxa (23) have been named with a code, depicted and described for further reference. Fungal spores are well represented along the whole transect, whereas algal and zoological remains are absent or very scarce in the lower and the uppermost ranges. The altitudinal zonation of fungal spores matches with that of pollen and the corresponding vegetation belts, suggesting a close relationship. The known environmental requirements of some of the fungi identified allowed inferences on particular ecological features, in agreement with previous palynological interpretations. Both elevation and sample type are needed to explain the observed differences in the assemblages of the three groups, the elevation being more decissive for fungal spores and the local habitat of the sampling site for algal and zoological remains. The sample type effect is minimised when the NPP studied are considered altogether, thus increasing their usefulness as palaeoecological proxies. This study reinforces the utility of modern analog surveys of NPP with palaeoecological purposes and encourages further research, particularly in poorly known areas, as for example tropical regions.