Polychaetes of the mangrove-fouling community at the Colombian Archipelago of San Andres and Old Providence,Western Caribbean

This study records the polychaetes found on the submerged roots of Rhizophora mangl on San Andres and Providence Islands, ColombianCaribbean. Sampling was done in 1998 during the rainy (July) and dry(November) seasons; each season, 17 roots were collected in threedifferent stations with different kinds of human impact, two in San Andresand one in Providence. At the same time temperature, salinity anddissolved oxygen were measured in situ. Aromatic hydrocarbons weremeasured in the laboratory. The polychaetes were removed from the rootsand identified. The available root area for the organisms was alsomeasured.Five genera and 11 species were newly recorded for the ColombianCaribbean. The most abundant families were Terebellidae in Old ProvidenceMc Bean Lagoon, Syllidae in Honda Bay and Nereididae in Hooker Bayon the San Andres Island. Thelepus `setosus' (Terebellidae) and Amblyosyllis sp. (Syllidae) were highly abundant in less polluted samplingstations such as Old Providence Mc Bean Lagoon and Honda Bay. On theother hand, Neanthes `succinea' (Nereididae) were abundant inHooker Bay which was the most polluted station. Salinity seemed to be the mostimportant parameter for the polychaete populations. The populations ofpolychaetes, as a total group, seemed to be related to the root areaavailable on both islands, independent of the season. However, during therainy season, the populations were independent of root area availability,while during the dry season, the populations were dependent on it.     

Modern surface pollen assemblages from the Middle and High Atlas,Morocco: insights into pollen representation and transport

Thirty-three modern surface samples were collected in the environmentally and climatologically contrasting regions of the Middle and High Atlas Mountains, Morocco. Samples representing forest and steppe montane environments (1935–2760 m above sea level) are clustered around study sites at Lake Tislit (High Atlas, semi-arid oro-Mediterranean bioclime) and Lake Sidi Ali and Michliffen (Middle Atlas, sub-humid montane Mediterranean bioclime). Good discrimination between regional pollen spectra is evident, with Middle Atlas samples reflecting higher arboreal cover (Cedrus and evergreen Quercus) and High Atlas samples with high abundances of non-arboreal taxa, including Artemisia and Fabaceae. These four taxa (Cedrus, evergreen Quercus, Artemisia and Fabaceae) are furthermore shown to be reliable indicators of local source vegetation within a 100 m² quadrat, taking into account threshold abundances of 7%, 20%, 4% and 10%, respectively. Deciduous Quercus, Olea and Phillyrea show long-distance pollen dispersal across both regions, contributing to non-trivial arboreal pollen (AP) values of up to 35% (typically 20–30%) in the High Atlas spectra. In the Middle Atlas, AP values of 40 to 50% occur in open sampling locations and > 60% under forest canopy cover. These insights should be taken into account when interpreting ancient pollen spectra from regional lakes and bogs for palaeoenvironmental reconstruction.     

滇南红河地区现代花粉雨特征及其与气候因子的关系

我国低纬度热带亚热带地区现代花粉雨与气候关系的研究相对缺乏。本研究以滇南红河地区43个水体(湖泊、水库和池塘)的表层沉积物为对象,探讨研究区现代花粉雨与气候因子之间的关系。花粉分析结果表明,木本植物花粉含量高,占优势的是松属、桤木属和壳斗科;次为草本植物,主要为禾本科、菊科和莎草科;花粉谱中蕨类孢子以三缝孢为主,藻类的盘星藻也常见。同时,通过红河地区13个气象观测站1961—2010年月观测数据的线性插值,获得了各水体的现代气候数据(温度包括1月均温、7月均温、春、夏、秋、冬季均温,以及雨季、旱季和年均温;降水包括春、夏、秋和冬季降水量,雨季、旱季和年降水量),并对现代花粉和气候数据进行冗余分析,以揭示影响研究区现代花粉雨的气候因子。冗余分析结果表明,春季、旱季和年降水量及7月、雨季和年均温是控制滇南红河地区现代花粉雨的主要气候因子,温度的增加导致常绿阔叶林占优势,降水减少导致松林占主导。本研究结果能够为滇南红河地区利用化石花粉记录的古气候定量重建提供重要的理论支持。     

A method to forecast the start of theBetula, Platanus andQuercus pollen seasons in North London

This paper attempts the prediction of the start of theBetula, Quercus andPlatanus pollen seasons in London, UK based on pollen sampling conducted over a 5-year period, 1987–1991. The times at which eight different thresholds of accumulated daily pollen counts (M⁻³) were passed were correlated against heat sums, chill units, accumulated sunshine hours, monthly meteorological parameters and the start dates of earlier pollen seasons to identify significant associations. Few meteorological parameters were significantly correlated with the start dates of the three pollen seasons, the exceptions being significant negative correlations between the average monthly air temperature in the months immediately preceding theBetula andPlatanus pollen season. However, significant relationships were identified between the start dates of theBetula, Quercus andPlatanus pollen seasons and the start of theCorylus, Taxus andPopulus pollen seasons with coefficients of determination as high as 98%. These indicator species were then used as predictors to forecast the start of theBetula, Quercus andPlatanus pollen seasons, both individually and in combination with one another, providing levels of explanation of up to 99%.     

Nutrient cycling in a tropical seasonal rain forest of Xishuangbanna, Southwest China. Part 1: tree species: nutrient distribution and uptake

Tropical rain forests are characterized by large numbers of the species with diverse growth habits. The objective of the present study was to determine the distribution of nutrient content in the major trees of the tropical rain forests in Xishuangbanna. This will improve the understanding of the nutrient losses from such sites that result from harvesting and flow of nutrients within the ecosystem and lead to the development of effective and rational forest management strategies. Based on the results in this study, the distribution of nutrients among biomass components of trees varied: The ordering of major elements concentrations was K>N>Mg>Ca>P in branch, stem and root tissues but was N>K>Mg>Ca>P in leaves. The maximum amount of all nutrients per ha occurred in the stems followed by branches, roots and leaves. Of the total uptake of 6167.7 kg ha⁻¹ of all nutrients, the contribution of various nutrients was found to be N (2010.6 t ha⁻¹), P (196.3 t ha⁻¹), K (2123.8 kg ha⁻¹), Ca (832 kg ha⁻¹) and Mg (1005 kg ha⁻¹). However, comparing the nutrient uptake of other tropical and sub tropical forests, the results indicated that rates for the Xishuangbanna forests were 20–35% lower than previously reported values.     

Composition Patterns of Caribbean Limestone Forests: Are Parsimony,Classification, and Ordination Analyses Congruent?1

This study presents an analysis of floristic composition patterns for limestone vegetation from three Caribbean islands: Hispaniola, Mona, and Puerto Rico. The physical setting of these communities varies from very dry to wet climates, and from ridgetops, slopes, to plateaus. Consequently, vegetation communities have variable species composition. The questions addressed were: (1) What are the patterns of species composition among limestone vegetation types based on a parsimony analysis of species assemblages (PASA) and how congruent are they widi geography, climate, topography, and vegetation physiognomy? and (2) How do PASA patterns compare to floristic patterns obtained with a classification (UPGMA) and an ordination (NMS)? The main distinction of floristic categories was between communities of humid and dry climates, followed by a finer separation of communities congruent with topography; vegetation physiognomy corresponded with both. PASA, UPGMA, and NMS produced highly coincident floristic groups; however, affinities among groups were different. Advantages of PASA over UPGMA and NMS are that PASA produces groupings strictly based on the shared species and provides different measures of support for floristic groups. The three techniques indicated that the humid and dry limestone areas of Puerto Rico had floristically divergent dry‐type vegetation, even when they were structurally and physiognomically convergent. Also, floristic affinities of dry communities in Puerto Rico were stronger with dry communities on other islands than to more humid communities on the same island; thus, humidity regime is stronger than geography in promoting floristic links among limestone vegetation communities of die Caribbean. Almost every conclusion obtained from UPGMA and NMS was also taken from PASA, and so all diree techniques are compatible. The methodological, theoretical, and interpretive simplicity of PASA is what makes it an attractive procedure for studies that examine composition patterns.     

Reconstruction of local vegetation in ad 915 at an oligotrophic mire in northern Japan from pollen, present-day vegetation and tephra data

The use of data for present-day vegetation, modern and pretephra pollen have, together, allowed reconstruction of the spatial pattern of the vegetation of an oligotrophic mire, Shimo-kenashi Mire, in ad 915. The modern pollen data were compared with the surrounding vegetation, showing that pollen of Ericaceae, Rosaceae (excluding Sanguisorba), Sphagnum and Liliaceae, together with trees and shrubs, which form scrub or thicket, indicate the limits of the mires. Shimo-kenashi Mire was narrower in ad 915 and had more islands and peninsulas of scrub. Subsequently, the mire margin has advanced and the scrub islands and peninsulas have disappeared at some sites. The fact that the mire is spreading implies that conditions are wetter since ad 915, caused by changes in local hydrology. This history of vegetation at the site will contribute to the conservation and management of the mire as trends in vegetational change provide the basic information for conservation strategy.     

Cruoriella rhodoliths from shallow-water back reef environments in La Parguera, Puerto Rico (Caribbean Sea)

The occurrence of shallow-water (0.9 to 1.3 m) rhodoliths in back reef environments in southwest Puerto Rico is reported. The rhodoliths were generally cylindrical, discoidal or irregular in shape with an average longest dimension of 7.2 cm. They occurred at a maximum density of 524 m⁻². The rhodoliths were composed of mostly coral nuclei with concentric laminations of aragonite-producing Cruoriella armorica (Peyssonneliaceae, Rhodophyta). Maximum Cruoriella accretion around coral nuclei was 30 mm although accretions of 1 to 20 mm were more common. Based on measurements of Cruoriella accretion, these shallow water rhodoliths are estimated to have minimum ages of 12 to 24 years. It is further estimated that approximately 2% of the rhodoliths are turned over daily. Accepted: 1 October 1999     

Bird species richness in vegetation fences and in strips of residual rain forest vegetation at Los Tuxtlas, Mexico

Fragmentation of the lowland tropical rain forest has resulted in loss of animal and plant species and isolation of remaining populations that puts them at risk. At Los Tuxtlas, Mexico, lowland rain forests are particularly diverse in the avian fauna they contain and while most of the forests have been fragmented by human activity, many of the fragments still harbor diverse assemblages of bird species. In these landscapes, linear strips of residual rain forest vegetation along streams as well as linear strips of vegetation fences (live fences) crossing the pastures might provide some connectivity to bird populations existed in forest fragments. We investigated bird species richness and relative abundance in one 6-km long section of live fences (LF) bordering a dirt road and in two 6-km long sections of residual forest vegetation along a river (MR) and one permanent stream (BS). We used point count procedures which resulted in the count of 2984 birds representing 133 species. At the LF site we detected 74% of the species, 72% at the BS site and 57% at the MR site. Only 38% of the species were common among sites. Neotropical migratory birds accounted for 34–41% of the species counted at all sites. While edge and open habitat birds accounted for 6–10% of the species and for 50% of the records at the three vegetation strips, about 90% of the species were forest birds. Distance to forest fragments and degree of disturbance of the vegetation seemed to negatively influence bird species presence at the BS and MR strips. Rarefaction analysis indicated that the LF strip was richer in species than the other two sites, but the occurrence of the three vegetation strips in the landscape seem to favor the presence of many more species. We discuss the value of these vegetation strips to birds as stepping stones in the fragmented landscape.     

Variation in seed and seedling traits in Pithecellobium pedicellare,a tropical rain forest tree

Summary Pithecellobium pedicellare, a mimosoid legume, is a large canopy tree in the tropical rain forests of Costa Rica. We examined the pattern of variation in seed weight, germination date, hypocotyl length (stem), and rachis length (the first leaf) of the seedlings in this species. Seeds collected from widely dispersed individual trees at the La Selva Biological Station, Costa Rica, were randomly planted in blocks, and grown under controlled, indoor conditions for about 2 weeks. There-fore, we were able to quantify the effects of maternal family on mean seed weight and the effects of maternal family and microenvironment on the remaining traits examined. A significant effect of maternal family was detected for all traits. In particular, the maternal effects on germination date and seedling size traits which were consistently significant even after controlling the initial seed weight may indicate that the maternal effects reflect, at least to some extent, maternal genetic control over these traits. Despite overall strong maternal effects, the performance of maternal siblings, such as the rachis length, differed among blocks. The sensitivity of maternal siblings to the local environments may contribute to the maintenance of genetic variability in this highly outcrossing tropical species.     

Modern pollen/vegetation/land-use relationships in mountain environments: an example from the Champsaur valley (French Alps)

This study aims at elucidating modern pollen spectra/environmental data relationships from both natural and human-induced vegetation types as an aid for palaeo-ecological reconstructions. A set of 51 surface moss polsters was sampled from different vegetation and land-use types in the Champsaur area (French Alps) and analysed to obtain modern pollen analogues of ancient cultural landscapes in mountain ecosystems. Samples were selected from grazed areas, mown meadows, cultivated fields, fallow land and deciduous and coniferous forests. Vegetation composition around the sampling points and seventeen types of environmental variables (e.g., management type, soil and topography) were collected all for these 51 sites. Patterns of modern local pollen variation in relation to the environmental variables were explored by means of canonical correspondence analysis (CCA) and associated statistical tests. This correlative model allows us to determine the major explanatory variables and to identify taxa indicative of particular anthropogenic activities, and thus may help to calibrate fossil pollen assemblages.The indicator pollen types are evaluated in the light of comparable material from lowland and mid-elevation areas of western Europe. The results of the French data-set confirm some of the conclusions drawn from the North European data-sets, but also show some site specific features. Pollen markers with a broader global significance common to other regions include Rhinanthus type, Apiaceae and Dipsacaceae for mown meadows, Urtica type, Plantago media/major, Trifolium type and Potentilla type for grazed areas, and Cerealia type, Centaurea cyanus, and Polygonum aviculare for cultivated fields. New pollen anthropogenic indicators typical of our study area are Sanguisorba officinalis, Vicia type (mowing), Lotus type, Onobrychis type, Centaurea nigra type, Serratula type (grazing), Sinapis type and Papaver rhoeas (cultivation). This study provides potentially valuable analogues for human-induced vegetation types, and it may then become possible to interpret more objectively local pollen diagrams from Alpine mountain environments in terms of past cultural landscape development.     

干旱区石羊河流域河水孢粉组合特征

石羊河流域初春和仲夏两季不同地点 ,洪水期、平水期 30个河水样孢粉分析显示 ,没有人类影响的情况下 ,河水样孢粉组合是由河流上游径流区的植物孢粉和采样点附近植被孢粉组成的 ,前者在孢粉组合中至少占30 %～ 6 0 %。河水搬运孢粉的能力非常强 ,可长距离、大量地搬运孢粉。孢粉组合中河水贡献孢粉的含量较高 ,如 :云杉属 (PiceaDietr.)花粉河水的贡献率在中下游可达 16 .5 %和 7.7%。采样时间、地点影响河水的孢粉组合和浓度 ,洪水期是孢粉搬运的主要时期。河水经过水库后 ,其中孢粉绝大多数沉积在水库中。     

Patterns of natural 15N abundance in the leaf-to-soil continuum of tropical rain forests differing in N availability on Mount Kinabalu,Borneo

We investigated the natural abundance of ¹⁵N in sun leaves and other components of tropical rain forests on altitudinal sequences of eight sites that form a gradient of soil N availability with varying ectomycorrhizal abundances on Mt. Kinabalu, Borneo. We investigated how soil N availability and ectomycorrhizal abundance related to the ¹⁵N abundance of ecosystem components. ¹⁵N values (¹⁵N abundance relative to ¹⁴N) increased consistently in the following order at each site: sun leaves, leaf litter, fine roots and from shallower organic to deeper mineral soil horizons. Enrichment (3–6 ¹⁵N) of ¹⁵N occurred at the litter–topsoil interface at all sites, and the magnitude of the enrichment correlated negatively with ¹⁵N depletion in the foliage, irrespective of ectomycorrhizal abundance. Foliar ¹⁵N values significantly positively correlated with their N concentrations. Foliar (and litter and root) ¹⁵N values correlated positively with NO₃ availability, and negatively with NH₄ availability. The two positive correlations of foliar ¹⁵N with foliar N and NO₃ availability were inconsistent with the assumption that stronger nitrification (hence a greater nitrate availability) produced a more ¹⁵N-depleted active inorganic N pool. The isotopic fractionation during the passage of N through ectomycorrhizas to plants might explain the positive correlation of foliar ¹⁵N and N concentration; however, this mechanism could not fully explain the correlation in our case because strong foliar ¹⁵N depletions occurred at the sites that lacked ectomycorrhizas. Alternatively, the positive correlation across sites reflected the tightness of N cycling. Strong nitrification and associated isotopic fractionation might have occurred at N-richer sites and the subsequent removal of NO₃ from the system could decrease isotopically `lighter' N at these sites.     

Oxalis debilis in China: distribution of flower morphs, sterile pollen and polyploidy

BACKGROUND AND AIMS: Oxalis debilis is a South American tristylous species that is currently naturalizing in China. Based on field observations and herbarium data a report is made on its pollination, morph frequencies, pollen viability, seed set and chromosome number. In addition, a new chromosome count for the species in Africa is provided. METHODS: Field observations were conducted in six provinces in south-east China. Flower visitors were recorded and nectar sugar was measured with a refractometer. The species' compatibility system was determined by carrying out experimental self- and cross-pollinations on bagged inflorescences. Stigma receptivity and pollen viability was determined using the MTT test. KEY RESULTS AND CONCLUSIONS: Populations of O. debilis in China contain either the mid-style-length morph or the short morph, but not both. Pollination is by nectar- and pollen-foraging bees; pollen viability is low; and seed set in natural and experimentally self- or cross-pollinated flowers is extremely low. Chromosome counts indicate that O. debilis contains diploid and tetraploid forms in its native as well as introduced range, which does not support a previous hypothesis that the predominant vegetative reproduction in this species is an escape from pentaploidy.     

Botanical affinity of pollen harvested by Apis mellifera L. in a semi-arid area from Bahia,Brazil

We analysed the botanical composition of pollen harvested by Apis mellifera L. in the Canudos Biological Station, Bahia, Brazil, and the influence of climatic factors on pollen sample composition was assessed. Forty-six pollen types were identified belonging to species occurring in the study area. The family Leguminosae was of significant importance amongst the samples, represented by ten pollen types. Diodia radula, Rhaphiodon echinus, and Mimosa misera pollen types occurred most constantly among the samples. We observed that isolated pollen class characterises samples analysed. It was also observed that pollen type richness is directly linked to rainfall, reflecting the strong influence of this climatic parameter on flowering intensity, and thus on the ability of the bees to obtain food resources.