Higher Plant Species Research Articles

Characteristic properties of the genesis of Alnus incana (L.) Moench. associations in the south of Western Siberia

The associations formed by Alnus incana (L.) Moench. in the south of Western Siberia are limited to the middle and lower reaches of the Irtysh river in the Tyumen region (Tobolsk district, Russia). The paper describes Alnetum pteridiosum, Alnetum urticosum, Alnetum еquisetosum, Alnetum coricosum, Alnetum coricoso – еquisetosum, Alnetum coricoso – oxalidosum, Alnetum curtico – еquisetosum, Alnetum еquisetoso – miliosum, Alnetum coricosa – stellariosum, Alnetum urtico – aegopodiosum, Alnetum urtico – stellariosum, Alnetum–cirsiosum, Alnetum cystopteriosum, Alnetum urtico – miliosum, Alnetum poо – urticosum, Alnetum chrysospleniosum, Alnetum corydaliosum, Alnetum impatieno - urticosum and Alnetum stellariosum associations. In these associations, more than a hundred of species of higher plants grow. The species composition analysis showed that they are mesothermal and hydrophilic, the shrub layer is not typical for them, and the grass cover of alder forests is not uniform in origin. During the formation of Alnetum association they interact with taiga, birch and linden forests through mutual exchange of species, and also experience anthropogenic influences, accompanied by the penetration of synanthropic species.

Distribution and Taxonomy of High Plant Species in Lake Karakir Bukhara Region

Lake Karakir (system of lakes) is located in the north west of Bukhara Oasis, it consists of 3 small lakes—a large karakir, a small karakir and an aquarium. The total area of the lake is 26.5 - 27.2 thousand hectares. As a result of the research carried out in Lake karakir, 16 families of high water plants, 34 species belonging to 24 categories were identified. The study was carried out mainly on a large spruce and an aquarium. Phragmites australis (Cav.) Trin. ex Steud. (Cav.) Trin. ex Steud. as the dominant species of high water plants, Typha angustifolia L., T. laxmannii Lepech., T. minima Funck. like species are most common.

HIGHER PLANTS AS PRODUCERS OF ORGANIC COMPOUNDS LABELED WITH STABLE DEUTERIUM ISOTOPES

The results show the seeds of some higher plant species, in particular beet (Beta vulgaris L.) and turnip rap (Brassica rapa L.), are capable of high germination ability in environments containing 99.9% deuterium oxide. These plant species can be used as producers for the biosynthetic production of deuterium-labeled organic compounds

Use of Plant Extracts in the Control of Post-Harvest Fungal Rots in Apples

Different fungi alter apples in the post-harvest period, causing considerable economic losses and risks to consumer health due to the mycotoxins that some of these fungi produce. The control of these fungal alterations in apples is mainly dependent on the use of chemical fungicides, the effectiveness of which has been well proven. However, this use is subject to restrictions due to growing concerns about risks to human health and the environment and the continued development of pathogen resistance to commonly used fungicides. A new approach to control post-harvest fungi has been implemented through the application of plant extract.It is estimated that there are more than 250,000 higher plant species on Earth that can be evaluated for their antimicrobial bioactive chemical compounds. In recent decades, researchers have evaluated plant extracts and essential oils against fungi responsible for post-harvest apple rot. Interesting results have been obtained. The purpose of this project is to summarize and discuss the results of in vitro and in situ experiments of different literatures concerning the effects of compounds derived from plants on the control of fungi responsible for rotting apples in storage.

Wild Bee Conservation within Urban Gardens and Nurseries: Effects of Local and Landscape Management

Across urban environments, vegetated habitats provide refuge for biodiversity. Gardens (designed for food crop production) and nurseries (designed for ornamental plant production) are both urban agricultural habitats characterized by high plant species richness but may vary in their ability to support wild pollinators, particularly bees. In gardens, pollinators are valued for crop production. In nurseries, ornamental plants rarely require pollination; thus, the potential of nurseries to support pollinators has not been examined. We asked how these habitats vary in their ability to support wild bees, and what habitat features relate to this variability. In 19 gardens and 11 nurseries in California, USA, we compared how local habitat and landscape features affected wild bee species abundance and richness. To assess local features, we estimated floral richness and measured ground cover as proxies for food and nesting resources, respectively. To assess landscape features, we measured impervious land cover surrounding each site. Our analyses showed that differences in floral richness, local habitat size, and the amount of urban land cover impacted garden wild bee species richness. In nurseries, floral richness and the proportion of native plant species impacted wild bee abundance and richness. We suggest management guidelines for supporting wild pollinators in both habitats.

An explicit test of Pleistocene survival in peripheral versus nunatak refugia in two high mountain plant species.

Pleistocene climate fluctuations had profound influence on the biogeographical history of many biota. As large areas in high mountain ranges were covered by glaciers, biota were forced either to peripheral refugia (and possibly beyond to lowland refugia) or to interior refugia (nunataks). However, nunatak survival remains controversial as it relies solely on correlative genetic evidence. Here, we test hypotheses of glacial survival using two high alpine plant species (the insect‐pollinated Pedicularis asplenifolia and wind‐pollinated Carex fuliginosa) in the European Alps. Employing the iDDC (integrative Distributional, Demographic and Coalescent) approach, which couples species distribution modelling, spatial and temporal demographic simulation and Approximate Bayesian Computation, we explicitly test three hypotheses of glacial survival: (a) peripheral survival only, (b) nunatak survival only and (c) peripheral plus nunatak survival. In P. asplenifolia the peripheral plus nunatak survival hypothesis was supported by Bayes factors (BF> 100), whereas in C. fuliginosa the peripheral survival only hypothesis, although best supported, could not be unambiguously distinguished from the peripheral plus nunatak survival hypothesis (BF = 5.58). These results are consistent with current habitat preferences (P. asplenifolia extends to higher elevations) and the potential for genetic swamping (i.e., replacement of local genotypes via hybridization with immigrating genotypes [expected to be higher in the wind‐pollinated C. fuliginosa]). Although the persistence of plants on nunataks during glacial periods has been debated and studied over decades, this is one of the first studies to explicitly test the hypothesis instead of solely using correlative evidence.

Ecologyсal-taxonomic structure of wood and shower plants of industrial pads of PJSC «Central Iron Ore Enrichment Works»

The article is devoted to shrubs and plant groups in the territory of the industrial sites of PJSC «Central Mining and Processing Plant». The material of this work was collected in the growing season 2017-2018 years on the territory of the central industrial site and industrial sites №2 Gleuvatsky Quarry, the Giant mine, Artemivsky Quarry, Petrovsky Quarry, mine them. Ordzhonikidze, sludge workshops, which are separated in space and placed at a certain distance from each other separated in kind. The studied tree and shrub communities were formed with the participation and maintained by the person in a satisfactory condition. In the course of itinerant field investigations the species belonging to trees and shrubs were determined. In the future, on the basis of the ecomorphic characteristics of the species, comparative ecological-taxonomic spectra of tree-shrub plant communities of industrial sites were constructed. As a result of researches it was found out that the tree-shrub groupings of the industrial sites of PJSC «TSGZK» consist of 96 species of higher plants belonging to 28 families. Gymnosperms account for a small fraction of taxonomic spectra. Within the sites there is considerable variability in the number of species and families. The most numerous are the families Rosaceae, Salicaceae, Aceraceae. Families of Aceraceae, Rosaceae, Fabaceae, Hippocastanaceae, Oleaceae, Salicaceae, Ulmaceae, Pinaceae are represented by species at all industrial sites of PJSC «CMPP». Only within the Ordzhonikidze mine site are species of the Berberidaceae, Paeoniaceae family occurring, and within the Gleevatsky Quarry site, there are Cannabaceae families. In the taxonomic spectra of plant communities of all sites, the dominant position is occupied by the family Rosaceae. Monovid families occupy half or more of the taxonomic spectra. By reducing the number of species, families, share of species participation in shrubs and shrubs, the corresponding declines can be constructed. The same series can characterize tree-shrub plant groups by the density of species of trees, shrubs, individuals per unit area. According to the ecological and biomorphic characteristics of the species, the corresponding spectra of bio- and ecomorphs are constructed. Ecological spectra are individual in proportion to the participation of certain ecomorphs for each shrub community of the site. Rows of decreasing species numbers are constructed for each ecomorph. It is established that in tree and shrub plant groups of all industrial sites of PJSC «CMPP» wood life forms with root-root system dominate, vegetatively motionless. In the spectra of ecomorphs, the most numerous are solvants, phanerophytes, mesotrophs, entomophiles. In the spectra of hygro-, heliomorph and diasporax, the composition of dominant ecomorphs changes at the industrial sites.

Transcriptome analysis reveals plasticity in gene regulation due to environmental cues in Primula sikkimensis, a high altitude plant species

BackgroundStudying plasticity in gene expression in natural systems is crucial, for predicting and managing the effects of climate change on plant species. To understand the contribution of gene expression level variations to abiotic stress compensation in a Himalaya plant (Primula sikkimensis), we carried out a transplant experiment within (Ambient), and beyond (Below Ambient and Above Ambient) the altitudinal range limit of species. We sequenced nine transcriptomes (three each from each altitudinal range condition) using Illumina sequencing technology. We compared the fitness variation of transplants among three transplant conditions.ResultsA large number of significantly differentially expressed genes (DEGs) between below ambient versus ambient (109) and above ambient versus ambient (85) were identified. Transcripts involved in plant growth and development were mostly up-regulated in below ambient conditions. Transcripts involved in signalling, defence, and membrane transport were mostly up-regulated in above ambient condition. Pathway analysis revealed that most of the genes involved in metabolic processes, secondary metabolism, and flavonoid biosynthesis were differentially expressed in below ambient conditions, whereas most of the genes involved in photosynthesis and plant hormone signalling were differentially expressed in above ambient conditions. In addition, we observed higher reproductive fitness in transplant individuals at below ambient condition compared to above ambient conditions; contrary to what we expect from the cold adaptive P. sikkimensis plants.ConclusionsWe reveal P. sikkimensis’s capacity for rapid adaptation to climate change through transcriptome variation, which may facilitate the phenotypic plasticity observed in morphological and life history traits. The genes and pathways identified provide a genetic resource for understanding the temperature stress (both the hot and cold stress) tolerance mechanism of P. sikkimensis in their natural environment.

On the relationships between plant species richness and the environment: a case study in Eastern Ghats, India.

Many places of the earth support high plant species richness, but emphasis is given to biodiversity hotspots with rich endemic species under threats of destruction by anthropogenic interventions. This definitely underplays species conservation at several places significant for optimisation of preserving natural ecosystems. Here we explore influences of climate, physiography and disturbance on plant species richness of the Eastern Ghats. We focus on the implications of water-energy dynamics and climatic heterogeneity on community distribution. Initially, 26-environmental variables were considered for the study, but eight least correlated variables viz., aspect, human appropriation of net primary productivity, global human footprint, mean annual temperature, mean annual precipitation, precipitation of driest quarter, terrain ruggedness index and temperature seasonality were utilised for further analysis. A total of 1670 species from 2274 sampling locations of 22564 records were examined using canonical correspondence analysis (CCA) and decision trees. Water-energy dynamics broadly regulates plant richness, with significant influence of mean annual precipitation and temperature. Precipitation of the driest quarter is the most significant factor in describing plant richness, indicating the availability of water during the dry period is crucial. The rise in temperature is likely to deteriorate further, where temperature seasonality is significant. Temperature seasonality determines thermal variability and assesses the intensity of climate change impacts on plant richness. The study offers ecological insights for successful conservation and management planning for the sustenance of the Eastern Ghats' rich biodiversity.

Use of iron oxide nanoparticles for immobilizing phosphorus in-situ: Increase in soil reactive surface area and effect on soluble phosphorus

Phosphorus (P) immobilization has potential for reducing diffuse P losses from legacy P soils to surface waters and for regenerating low-nutrient ecosystems with a high plant species richness. Here, P immobilization with iron oxide sludge application was investigated in a field trial on a noncalcareous sandy soil. The sludge applied is a water treatment residual produced from raw groundwater by Fe(II) oxidation. Siliceous ferrihydrite (Fh) is the major Fe oxide type in the sludge. The reactive surface area assessed with an adapted probe ion method is 211–304 m2 g−1 for the Fe oxides in the sludge, equivalent to a spherical particle diameter of ~6–8 nm. This size is much larger than the primary Fh particle size (~2 nm) observed with transmission electron microscopy. This can be attributed to aggregation initiated by silicate adsorption. The surface area of the indigenous metal oxide particles in the field trial soils is much higher (~1100 m2 g−1), pointing to the presence of ultra-small oxide particles (2.3 ± 0.4 nm). The initial soil surface area was 5.4 m2 g−1 and increased linearly with sludge application up to a maximum of 12.9 m2 g−1 when 27 g Fe oxides per kg soil was added. In case of a lower addition (~10–15 g Fe oxides per kg soil), a 10-fold reduction in the phosphate (P-PO4) concentration in 0.01 M CaCl2 soil extracts to 0.3 µM was possible. The adapted probe ion method is a valuable tool for quantifying changes in the soil surface area when amending soil with Fe oxide-containing materials. This information is important for mechanistically predicting the reduction in the P-PO4 solubility when such materials are used for immobilizing P in legacy P soils with a low P-PO4 adsorption capacity but with a high surface loading.

Thermal niche traits of high alpine plant species and communities across the tropical Andes and their vulnerability to global warming

AbstractAimThe climate variability hypothesis (CVH) predicts that locations with reduced seasonal temperature variation select for species with narrower thermal ranges. Here we (a) test the CVH by assessing the effect of latitude and elevation on the thermal ranges of Andean vascular plant species and communities, and (b) assess tropical alpine plants vulnerability to warming based on their thermal traits.LocationHigh tropical Andes.TaxonVascular plants.MethodsTemperature data for 505 vascular plant species from alpine communities on 49 summits, were extracted from 29,627 georeferenced occurrences. Species thermal niche traits (TNTs) were estimated using bootstrapping for: minimum temperature, optimum (mean) temperature and breadth (maximum‐minimum). Plant community‐weighted scores were estimated using the TNTs of their constituent species. CVH was tested for species, biogeographical species groups and communities. Vulnerability to global warming was assessed for species, biogeographical species groups and communities.ResultsSpecies restricted to the equator showed narrower thermal niche breadth than species whose ranges stretch far from the equator, however, no difference in niche breadth was found across summits’ elevation. Biogeographical species groups distributed close to the equator and restricted to alpine regions showed narrower niche breadth than those with broader ranges. Community‐weighted scores of thermal niche breadth were positively related to distance from equator but not to elevation. Based on their TNTs, species restricted to equatorial latitudes and plant communities dominated by these species were identified as the most vulnerable to the projected 1.5°C warming, due to a potentially higher risk of losing thermal niche space.Main conclusionsOur study confirms that the CVH applies to high tropical Andean plant species and communities, where latitude has a strong effect on the thermal niche breadth. TNTs are identified as suitable indicators of species’ vulnerability to warming and are suggested to be included in long‐term biodiversity monitoring in the Andes.

Local Communities' Knowledge, Attitude and Perception Toward Cebu Black Shama (Copsychus cebuensis Steere) and its Habitat Characteristics in Cebu Island, Philippines

A knowledge, attitude & perception (KAP) survey was conducted in four important bird areas (IBAs) in Cebu island, Philippines towards the protection and conservation of the Cebu black shama (Copsychus cebuensis) and its habitat. Similarly, the habitat quality of the black shama in the island was also assessed in terms of vegetation composition and diversity. A total of 193 households were interviewed from July 2013 to December 2013. Most of the respondents only finished elementary and high school levels. However, their mean knowledge score was above 6.50 while their attitude mean score was above 9.40. Their perception scores, on the other hand, were highly positive. Regardless of their educational attainment, people living near the identified black shama territories were highly knowledgeable, aware and positive towards the protection and conservation of the endangered bird and its habitat. Forty-five black shama territories were sampled employing 20 m x 20 m quadrats from September 2013 – February 2014. The black shama habitat is characterized with high plant species diversity (H’>3.50), even plant distribution (e >0.75), and low dominance index (D >0.01). In terms of vegetation composition, the black shama habitats were not similar. Integrating the social and ecological knowledge to conservation will likely promote a wider perspective of effective conservation program implementation than social or ecological knowledge alone.

A single point mutation in the C-terminal extension of wheat Rubisco activase dramatically reduces ADP inhibition via enhanced ATP binding affinity

Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) activase (Rca) is a AAA+ enzyme that uses ATP to remove inhibitors from the active site of Rubisco, the central carboxylation enzyme of photosynthesis. Rca α and β isoforms exist in most higher plant species, with the α isoform being identical to the β form but having an additional 25-45 amino acids at the Rca C terminus, known as the C-terminal extension (CTE). Rca is inhibited by ADP, and the extent of ADP sensitivity of the Rca complex can be modulated by the CTE of the α isoform, particularly in relation to a disulfide bond structure that is specifically reduced by the redox-regulatory enzyme thioredoxin-f. Here, we introduced single point mutations of Lys-428 in the CTE of Rca-α from wheat (Triticum aestivum) (TaRca2-α). Substitution of Lys-428 with Arg dramatically altered ADP inhibition, independently of thioredoxin-f regulation. We determined that the reduction in ADP inhibition in the K428R variant is not due to a change in ADP affinity, as the apparent constant for ADP binding was not altered by the K428R substitution. Rather, we observed that the K428R substitution strongly increased ATP substrate affinity and ATP-dependent catalytic velocity. These results suggest that the Lys-428 residue is involved in interacting with the γ-phosphate of ATP. Considering that nucleotide-dependent Rca activity regulates Rubisco and thus photosynthesis during fluctuating irradiance, the K428R substitution could potentially provide a mechanism for boosting the performance of wheat grown in the dynamic light environments of the field.

Reduce health damage cost of greenhouse gas and ammonia emissions by assembling plant diversity in floating constructed wetlands treating wastewater

Abstract In wastewater treatment, to find a clean approach with low damage cost to human and ecosystem health has received increasing concerns. Constructed wetlands are regarded as a green treatment technology, but they are also important sources of greenhouse gas and ammonia emissions. However, the effects of optimizing plant community on the human and ecosystem health damage costs of multiple gas emissions are poorly understood. In this study, an experiment with 90 hydroponic microcosms that simulated floating constructed wetlands treating wastewater with a high concentration of ammonium was set to manipulate plant diversity to reduce health damage costs, which integrated the emissions of nitrous oxide, methane, and ammonia. Results showed that: (1) increasing plant species richness reduced the human and ecosystem health damage costs of the three gases; (2) the systems with Arundo donax had lower greenhouse gas emissions and ecosystem health damage costs, while the systems with Lythrum salicaria had lower ammonia emissions and human health damage costs than systems without the species; (3) the structural equation model indicated that the plant combinations with high biomass or high nitrate removal ability contributed to reducing health damage costs. This study suggests that manipulating high plant species richness and proper species is a clean approach in floating constructed wetlands for high ammonium wastewater treatment with low environmental costs.

Iodine biofortification through expression of HMT, SAMT and S3H genes in Solanum lycopersicum L.

The uptake process and physiological reaction of plants to aromatic iodine compounds have not yet been documented. The aim of this research was to compare uptake by tomato plants of KI and KIO3, as well as of organic iodine compounds – 5-ISA (5-iodosalicylic acid), 3,5-diISA (3,5-diiodosalicylic acid), 2-IBeA (2-iodobenzoic acid), 4-IBeA (4-iodobenzoic acid) and 2,3,5-triIBeA (2,3,5-triiodobenzoic acid). Only 2,3,5-triIBeA had a negative influence on plant development. All organic iodine compounds were taken up by roots and transported to leaves and fruits. Among all the compounds applied, the most efficiently transferred iodine was 2-IBeA – to fruits, and 4-IBeA – to leaves. The order of iodine accumulation in fruit cell compartments was as follows: organelles > cell walls > soluble portions of cells; for leaf and root cells, it was: organelles > cell walls or soluble portions, depending on the compound applied. The compounds studied influence iodine metabolism through expression of the HMT gene which encodes halide ion methyltransferase in leaves and roots. Also, their influence on modification of the activity of the SAMT and S3H genes that encode salicylic acid carboxyl methyltransferase and salicylic acid 3-hydroxylase was established. It was discovered that exogenously applied 5-ISA, 3,5-diISA, 2-IBeA and 4-IBeA are genuinely (endogenously) synthesised in tomato plants; to date, this has not been described for the tomato, nor for any other species of higher plant.

Under filed conditions, mycorrhizal inoculum effectiveness depends on plant species and phosphorus nutrition

The cultivation of horticultural crops, such as green peppers, tomatoes, eggplants and bell peppers is very common in semi-arid Mediterranean climate conditions. Two field experiments were performed to determine the effect of mycorrhizal species, plant species and phosphorus levels on mycorrhizal effectiveness and phosphorus (P) and zinc (Zn) nutrient uptake. In the first experiment, under field conditions, four plants species were inoculated with five arbuscular mycorrhizae (AM) species. In the second field experiment, under the same soil conditions, the same plant species were treated with three levels of phosphorus (P), i.e., control; 50 kg and 100 kg P2O5 ha−1. The most effective mycorrhiza species Claroideoglomus etunicatum selected in the first experiment was used in the second field first experiment. In the first experiment, fruit yield enhancement, yield increase, inoculation effectiveness and nutrient concentration in the plant leaves were analyzed. Under field conditions, plant species growth is strongly dependent on the species of AM fungi. Tomato and green pepper plants were inoculated with Cl. etunicatum, eggplants were inoculated with Funneliformis mosseae and bell peppers were inoculated with Rhizophagus clarus, which are high fruit-yielding plant species. In general, Fu. mosseae and Cl. etunicatum increased the yield of the tomatoes, green peppers and eggplants. It seems mycorrhiza species specific to plant species. In the second experiment, mycorrhizal inoculation with P fertilizer application, in particular a moderate amount of P (50 kg ha−1 P2O5) fertilizer increased the green pepper, bell pepper and tomato fruit yield compared with non-inoculated plants and non-P fertilizer application treatments. Increasing the application of P level reduced the mycorrhizal inoculation effectiveness (MIE). The results indicate that for all four solanaceae family plants 50 kg ha−1 P2O5 is a P level threshold for mycorrhizal development, which enhanced plant growth and addition of fertilizer over 50 kg ha−1 P2O5 reduced MIE. P and Zn uptake were significantly increased with mycorrhizal inoculation. These findings are supported by our hypothesis that mycorrhiza inoculation can reduce mycorrhizal dependent horticultural plants P fertilizer requirement.

Using contact networks and next-generation sequencing for wildlife epidemiology

Horizontal transmission of infectious diseases is strongly determined by the contact network between hosts [1] . Environmental and ecological variables that define the probability of contacts between individuals, such as food resource quality and quantity, have been largely neglected in models studying the dynamics and epidemiology of wildlife diseases. In this work, we used pollinators and their pathogens to study the role of contact networks in a natural multi-host pathogen community. In agricultural landscapes, wild flowers are the most important food resources of insect pollinators such as bees and flies. To boost yields of agricultural crops and ensure pollinator conservation, the UK Environmental Stewardship scheme prompted farmers to grow pollinator-friendly wild flower margins along their fields ( Fig. 1 ). Wild flower margins ( Fig. 1 ) have proven to be efficient to increase both density and diversity of bees in agricultural areas, and to increase pollination success of surrounding crops. As the rate of disease transmission should increase with host density, we hypothesize that the success of wild flower margins may generate hubs for pathogen exchange within the bee community. Several recent studies have illustrated the frequent transmission of infectious diseases between managed and wild bees, potentially via the shared use of flowers [2] . However, the environmental and ecological drivers of disease dynamics between pollinators remain uncharacterised [3] . To understand the role of flower density and diversity for bee disease transmission, we reconstructed high-resolution plant–insect visitor networks from flower visitation data collected in ten farms in Southern England (five farms participating in the scheme vs. five control farms), as well as a record of bee pollen collection to describe the resource bees were exploiting (pollen vs. nectar). When analysing the plant–pollinator networks, we found that flower density and diversity strongly define pollinator density and foraging behaviour, and influence the structure of indirect ‘contact networks’ among pollinators (via the use of flower species). Particularly, we found flower diversity to be positively correlated with the reduction of niche overlap between insect species. This response of insect pollinators suggest that wild flower margins with high plant species richness may reduce insect competition for resources, and potentially reduce the risk of inter-specific disease transmission by supporting diverse diet for insects exploiting different flowers. To test the effect of plant diversity on pathogen dynamics in bees, we sampled pollinators on these farms and characterized their virome by deep transcriptome sequencing. We are now combining these environmental data to virus discovery in order to reveal the impact of the agri-environmental scheme on viral dynamics. Ultimately, we aim to identify environmental (flower density, agricultural practices) and ecological factors (plant taxa, insect community assemblage) that significantly enhance the transmission of plant and pollinator viral diseases within our model to eventually improve agricultural practises and wildlife management.

Patterns in a species‐rich tropical understory plant community

AbstractUnderstory plants are an important component of the high plant species diversity characteristic of neotropical rain forests. Herbs, shrubs, understory trees, and saplings of canopy trees occupy a broadly uniform environment of abundant rainfall, low light levels, and high humidity. We asked whether this community at the La Selva Biological Station in the Caribbean lowlands of Costa Rica was structured by environmental filters such as soil origin, topographic position, and understory light availability. We used nested quadrats to assess effects of soil origin (recent alluvium, weathered alluvium, residual volcanic soil) and topographic position (ridges, mid‐slopes and flats) on species composition, density, and diversity and measured six edaphic and understory light parameters. Non‐metric multidimensional scaling ordinations were based on frequency of occurrence in 20 quadrats for 272 species in the shrub size class and 136 species in the small‐tree size class for 17 sites. Three axes were correlated with composite environmental variables produced by principal component analysis representing slope, extractable phosphorus, and light. NMS site positions also reflected soil origin, topographic position, and geographic location. The analyses illustrated a complex community structured by species responses to environmental filters at multiple, interdigitated spatial scales. We suggest that light availability affected by canopy dynamics and dispersal limitation provides additional sources of variation in species distributions, which interact with edaphic patterns in complex ways.Abstract in Spanish is available with online material.

Editorial

Editorial

Donald Henry Northcote. 27 December 1921—7 January 2004

Don Northcote became eminent in the field of plant biochemistry following his identification of the processes involved in the synthesis and deposition of polysaccharides that constitute the cell wall of plants. His researches spanned lower and higher plant species and he showed by the application of a variety of experimental techniques, including radioautography, electrophoresis, freeze etching and the novel use of electron microscopy, that much of the material of the cell wall is synthesized in cytoplasmic organelles before being transported to the developing wall in vesicles assembled from the membranes of the Golgi body. His findings inspired many colleagues to build on the foundation he laid for understanding the biochemistry of cell morphogenesis. Nearly his entire career was spent in fundamental research and teaching in the Department of Biochemistry, University of Cambridge, from 1948 until his retirement in 1992. In addition, he was a fellow of St John's College, Cambridge, from 1960 to 1976, and he served Sidney Sussex College, Cambridge, as master from 1976 to 1992.