Stable isotope ratios of carbon and nitrogen in pollen grains in order to characterize plant functional groups and photosynthetic pathway types

Measurements of delta(13)C, delta(15)N and C : N ratios on modern pollen grains from temperate plants, including whole grains as well as extracted sporopollenin, were analysed in order to characterize physiological plant types at the pollen level and to determine the variation of these parameters in modern pollen grains of the same climatic area. Measurements are presented for 95 batches of whole modern pollen from 58 temperate species and on the stable fraction of modern pollen grains, chemically extracted sporopollenin, for two modern species. Fourier transform infrared (FTIR) and cross-polarization and magic-angle spinning (CP/MAS) sporopollenin spectra were conducted in parallel. C(3) and C(4) plants can be separated by delta(13)C measurements based on pollen. Probabilistic assignments to plant functional groups (herbaceous, deciduous woody, evergreen woody) of C(3) plants by the means of a discriminant analysis can be made for C : N ratios and for delta(13)C. The results are related to other studies on sporopollenin in order to use this method in future work on fossil samples. Stable isotope measurements on pollen allow improved pollen diagrams, including forms that cannot be differentiated at species level, increasing the accuracy and resolution of plant physiological type distribution in quaternary and older fossil sediments.     

FT-IR microspectroscopy: a promising method for the rapid identification of Listeria species

This work presents a pilot study to investigate the potential of fourier transform infrared (FT-IR) microspectroscopy for rapid identification of Listeria at the species level. Using this technique, FT-IR spectra were acquired from 30 strains from five Listeria species. The FT-IR spectra were analysed using stepwise canonical discriminant analysis and partial least-squares regression in a stepwise identification scheme. The results showed that 93% of all the samples were assigned to the correct species, and that 80% of the Listeria monocytogenes strains were correctly identified. In comparison, 100% of the samples, including the L. monocytogenes samples, were correctly identified using spectra acquired by FT-IR macrospectroscopy. The results show that FT-IR microspectroscopy has potential as a rapid screening method for Listeria, which is especially valuable for the food industry.     

傅立叶变换红外光谱技术对5种沙门氏菌的快速分类鉴定

[目的]建立沙门氏菌属内鼠伤寒沙门氏菌、肠炎沙门氏菌、猪霍乱沙门氏菌、亚利桑那沙门氏菌、波斯坦沙门氏菌5种菌的傅立叶变换红外(Fourier transform infrared,FT-IR)光谱数据库及FT-IR分类鉴定方法.[方法]应用FT-IR技术对5种沙门氏菌进行指纹图谱数据采集,应用化学计量学分析方法对光谱进行分析.[结果]建立了5种沙门氏菌的标准FT-IR光谱数据库,用于FT-IR技术对5种可疑目标沙门氏菌进行鉴定;建立了基于主成分分析(Principal component analysis,PCA)和分级聚类分析(Hierarchical cluster analysis,HCA)两种聚类分析模型,均可成功将5种沙门氏菌进行区分.[结论]傅立叶变换红外光谱分析方法简便、快速、易操作,结果重现性好,是一种区分5种沙门氏菌的有效方法.     

The plant vigour hypothesis revisited – how is browsing by ungulates and elephant related to woody species growth rate?

The way herbivores select what to eat is of considerable practical and theoretical interest, and has given rise to different theories and hypotheses. The plant vigour hypothesis predicts that herbivores feed preferentially on vigorous, i.e., large and/or fast-growing plants or plant parts. These predictions have previously primarily been tested on variation within plant species. Here we test whether differences in vigour among plant species in the same environment can explain differences in herbivore attack. We studied variation in browsing pressure by a guild of large herbivores on different woody species in an African savanna ecosystem. Shoot growth rate, annual shoot length, basal shoot diameter and annual shoot volume of 14 woody plant species were measured in the field. Plant species’ shoot vigour represented by the first PCA axis scores generated from the four shoot variables were then related to browsing pressure (% utilisation) on each of the species by native ungulates and elephant. Nutrient and fibre concentrations and tannin activity were also determined for the 14 woody plant species. We found ungulate browsing pressure to show a unimodal relationship with plant species’ shoot vigour. The heaviest browsing pressure was on plant species with shoots of intermediate vigour. We suggest that species with less vigorous shoots had low nutrient and high fibre concentrations and offered small bite sizes, whereas species with vigorous shoots had high nutrient concentrations but larger shoot diameters than the bite diameters of browsing ungulates. Elephant browsing pressure was not related to plant species’ shoot vigour.     

A preliminary assessment of changes in plant-dwelling insects when threatened plants are translocated

Translocation of threatened species is a tool used increasingly to conserve biodiversity, but the suite of co-dependent species that use the threatened taxa as hosts can be overlooked. We investigate the preliminary impact of translocating three threatened plant species on insect species and the integrity of insect assemblages that depend on these plants as their hosts. We compare the insect assemblages between natural populations of the threatened species, related non-threatened plant species growing wild near the threatened plants, and threatened plants translocated to another site approximately 40?km away. We used host breadth models and a coextinction risk protocol to determine which insect species are potentially host-specific on the threatened plants, and then assessed these insects?? potential presence at the translocation site. We found that insect assemblages on naturally-occurring threatened plants had more individuals, higher species density and higher species richness than assemblages on translocated plants. For one plant species, Leucopogon gnaphalioides, species composition differed significantly between wild and translocated populations (P?<?0.001). Furthermore, four insect species that were host-specific to Banksia brownii and B. montana were not detected on the translocated plants. Instead, translocated plants supported insect assemblages more similar to those of related plant species from the surrounding area. We conclude that threatened plant translocations that involve seed collection and propagation may have limited benefit for individual dependent species or the supported insect assemblage. Additional conservation actions will be required to maintain the diversity of insect assemblages and host-dependent relationships.     

Production of organic acids by probiotic lactobacilli can be used to reduce pathogen load in poultry

Probiotic Lactobacillus can be used to reduce the colonization of pathogenic bacteria in food animals, and therefore reduce the risk of foodborne illness to consumers. As a model system, we examined the mechanism of protection conferred by Lactobacillus species to inhibit C. jejuni growth in vitro and reduce colonization in broiler chickens. Possible mechanisms for the reduction of pathogens by lactobacilli include: 1) stimulation of adaptive immunity; 2) alteration of the cecal microbiome; and, 3) production of inhibitory metabolites, such as organic acids. The Lactobacillus species produced lactic acid at concentrations sufficient to kill C. jejuni in vitro. We determined that lactic acid produced by Lactobacillus disrupted the membrane of C. jejuni, as judged by biophotonics. The spectral features obtained using Fourier-transform infrared (FT-IR) and Raman spectroscopy techniques were used to accurately predict bacterial viability and differentiate C. jejuni samples according to lactic acid treatment. FT-IR spectral features of C. jejuni and Lactobacillus grown in co-culture revealed that the metabolism was dominated by Lactobacillus prior to the killing of C. jejuni. Based on our results, the development of future competitive exclusion strategies should include the evaluation of organic acid production.     

Feeding Ecology of Sympatric Mouse Lemur Species in Northwestern Madagascar

We performed a comparative pilot study on vertical space use and feeding ecology of 2 closely related sympatric mouse lemur species in northwestern Madagascar. We recorded feeding behavior and the use of vertical forest strata for 6 gray and 4 golden-brown mouse lemur females that we followed for 120 h. We carried out feeding experiments and analyzed fecal samples for food remains. Both species showed no significant difference in use of forest strata. They had a similar overall diet, with insect secretions and gum as main plant food resources; arthropod remains occurred in about half of all fecal samples. Both lemurs used in common >50% of the plant species that each consumed, which accounts for ≥70% of all individual plants used. However, both species used >40% of their feeding plant species exclusively and seemed to differ in their degree of specialization on certain plant species.     

Differentiating aquatic plant communities in a eutrophic river using hyperspectral and multispectral remote sensing

1. This study evaluates the efficacy of remote sensing technology to monitor species composition, areal extent and density of aquatic plants (macrophytes and filamentous algae) in impoundments where their presence may violate water‐quality standards. 2. Multispectral satellite (IKONOS) images and more than 500 in situ hyperspectral samples were acquired to map aquatic plant distributions. By analyzing field measurements, we created a library of hyperspectral signatures for a variety of aquatic plant species, associations and densities. We also used three vegetation indices. Normalized Difference Vegetation Index (NDVI), near‐infrared (NIR)‐Green Angle Index (NGAI) and normalized water absorption depth (D_H)_, at wavelengths 554, 680, 820 and 977 nm to differentiate among aquatic plant species composition, areal density and thickness in cases where hyperspectral analysis yielded potentially ambiguous interpretations. 3. We compared the NDVI derived from IKONOS imagery with the in situ, hyperspectral‐derived NDVI. The IKONOS‐based images were also compared to data obtained through routine visual observations. Our results confirmed that aquatic species composition alters spectral signatures and affects the accuracy of remote sensing of aquatic plant density. The results also demonstrated that the NGAI has apparent advantages in estimating density over the NDVI and the D_H. 4. In the feature space of the three indices, 3D scatter plot analysis revealed that hyperspectral data can differentiate several aquatic plant associations. High‐resolution multispectral imagery provided useful information to distinguish among biophysical aquatic plant characteristics. Classification analysis indicated that using satellite imagery to assess Lemna coverage yielded an overall agreement of 79% with visual observations and >90% agreement for the densest aquatic plant coverages. 5. Interpretation of biophysical parameters derived from high‐resolution satellite or airborne imagery should prove to be a valuable approach for assessing the effectiveness of management practices for controlling aquatic plant growth in inland waters, as well as for routine monitoring of aquatic plants in lakes and suitable lentic environments.     

Metabolomic analysis of the interaction between plants and herbivores

Insect herbivores by necessity have to deal with a large arsenal of plant defence metabolites. The levels of defence compounds may be increased by insect damage. These induced plant responses may also affect the metabolism and performance of successive insect herbivores. As the chemical nature of induced responses is largely unknown, global metabolomic analyses are a valuable tool to gain more insight into the metabolites possibly involved in such interactions. This study analyzed the interaction between feral cabbage (Brassica oleracea) and small cabbage white caterpillars (Pieris rapae) and how previous attacks to the plant affect the caterpillar metabolism. Because plants may be induced by shoot and root herbivory, we compared shoot and root induction by treating the plants on either plant part with jasmonic acid. Extracts of the plants and the caterpillars were chemically analysed using Ultra Performance Liquid Chromatography/Time of Flight Mass Spectrometry (UPLCT/MS). The study revealed that the levels of three structurally related coumaroylquinic acids were elevated in plants treated on the shoot. The levels of these compounds in plants and caterpillars were highly correlated: these compounds were defined as the ‘metabolic interface’. The role of these metabolites could only be discovered using simultaneous analysis of the plant and caterpillar metabolomes. We conclude that a metabolomics approach is useful in discovering unexpected bioactive compounds involved in ecological interactions between plants and their herbivores and higher trophic levels.     

A methodology for screening haemolymph of intertidal mussels, Mytilus edulis, using FT-IR spectroscopy as a tool for environmental assesment

Developing effective, rapid and inexpensive methods for monitoring and conserving aquatic resources is an important issue for environmental managers. This study focuses on Mytilus edulis, a keystone species of many coastal marine communities, which is frequently used as a biomonitor for a range of pollutants. Recent advances in post-genomic technologies have provided new methods of biochemical screening, and Fourier transform-infrared spectroscopy (FT-IR) is one such method that could enable bioindicator species to be used for environmental assessment. This paper develops a methodology to apply the FT-IR approach to marine intertidal M. edulis and addresses three methodological issues: First, the optimum physical location for biofluid sampling is examined (i.e. laboratory versus field). Secondly, the effects of transportation of frozen biofluid sampling from either the field-site or laboratory to the analytical facility are considered. Finally, the effect of repeated FT-IR measurements on collected M. edulis haemolymph samples is examined. From these results we suggest sampling haemolymph from M. edulis at the top of the shore prior to immediate snap-freezing in liquid nitrogen. Sample transportation can occur on ice for up to eight hours before storage at −80 °C. FT-IR measurements should occur within three months of collection and samples should not be used or thawed more than twice. We show how this method can be used to differentiate successfully between four different estuarine environments. Ultimately, through addressing these methodological questions, we provide a protocol to allow efficient sampling and FT-IR measurement of M. edulis as collected from the intertidal areas of rocky and muddy shores. We conclude that due to current monitoring needs presented by the European Water Framework Directive such an approach could prove to be an invaluable future tool for assessing coastal water quality.     

Native and exotic plants of fragments of sagebrush steppe produced by geomorphic processes versus land use

Habitat fragmentation and invasion by exotic species are regarded as major threats to the biodiversity of many ecosystems. We surveyed the plant communities of two types of remnant sagebrush-steppe fragments from nearby areas on the Snake River Plain of southeastern Idaho, USA. One type resulted from land use (conversion to dryland agriculture; hereafter AG Islands) and the other from geomorphic processes (Holocene volcanism; hereafter kipukas). We assessed two predictions for the variation in native plant species richness of these fragments, using structural equation models (SEM). First, we predicted that the species richness of native plants would follow the MacArthur–Wilson (M–W) hypothesis of island biogeography, as often is expected for the communities of habitat fragments. Second, we predicted a negative relationship between native and exotic plants, as would be expected if exotic plants are decreasing the diversity of native plants. Finally, we assessed whether exotic species were more strongly associated with the fragments embedded in the agricultural landscape, as would be expected if agriculture had facilitated the introduction and naturalization of non-native species, and whether the communities of the two types of fragments were distinct. Species richness of native plants was not strongly correlated with M–W characteristics for either the AG Islands or the **kipukas. The AG Islands had more species and higher cover of exotics than the kipukas, and exotic plants were good predictors of native plant species richness. Our results support the hypothesis that proximity to agriculture can increase the diversity and abundance of exotic plants in native habitat. In combination with other information, the results also suggest that agriculture and exotic species have caused loss of native diversity and reorganization of the sagebrush-steppe plant community.     

Associations Between Weevils (Coleoptera: Curculionidea) and Plants, and Conservation Values in Two Tussock Grasslands, Otago, New Zealand

Ecosystem level processes and species interactions have become important concepts in conservation and land management. Despite being New Zealand’s greatest contributors to global diversity, native invertebrates have been largely overlooked in the assessment of land values, and their diversity has often been assumed to reflect native plant diversity without justification. Invertebrates can in fact affect plant species composition, and in ecosystems such as New Zealand’s remaining indigenous and semi-modified tussock grasslands can do so in excess of more conspicuous vertebrate grazers. An understanding of the interactions between invertebrates and their plant hosts may be informative in assessing land conservation values, increase the efficiency of rapid inventory analyses and would be applicable across the production-conservation spectrum. This study considers the Curculionoidea, vascular plant, bryophyte and lichen communities of two semi-modified tussock grasslands in the Otago region of southern New Zealand. Quantitative plant and invertebrate sampling were carried out in January 2001. Data were analysed using ANalysis Of SIMilarity (ANOSIM) and Multi-Dimensional Scaling (MDS) ordination techniques. Vascular plant, bryophyte and lichen species richness was highest in the same site and plots as native weevil species richness, however the proportion of native vegetation in these locations was lower. Associations identified between Curculionoidea and vascular plants were dismissed due to the confounding effect of species frequency across samples. This appeared to have little influence on associations with bryophytes and/or lichens and these were given more weighting. The ecological implications of associations are considered and variability in weevil composition is discussed in reference to the tussock grassland environment. The importance of plant–invertebrate relationships to conservation and the uses and limitations of the PRIMER MDS ordination technique for determining associations are discussed.     

Competition hierarchy and plant defense in a guild of ants on tropical Passiflora

In facultative ant–plant interactions, ants may compete with each other for food provided by extrafloral nectar (EFN) plants. We studied resource competition and plant defense in a guild of ants that use the same EFN resource provided by two species of Passiflora in a seasonal rain forest in tropical China. At least 22 ant species were recorded using the EFN resource, although some of those species were rare. Among these ants, Paratrechina sp.1 and Dolichoderus thoracicus were more aggressive than other species. Ant aggressiveness measured as ant behavioral dominance index (BDI) was positively correlated with ant abundance on the Passiflora species studied. Ant BDI was also positively correlated to the protection that ants provided against herbivory. In Passiflora siamica, the number of workers patrolling on the plants did negatively correlate with average leaf loss per plant. We conclude that in this facultative Passiflora–ant system, plant defense upon herbivore was indeed influenced by the total number of ants present on plant and the aggressiveness of these ants.     

Vascular plant 15N natural abundance in heath and forest tundra ecosystems is closely correlated with presence and type of mycorrhizal fungi in roots

In this study we show that the natural abundance of the nitrogen isotope 15, δ¹⁵N, of plants in heath tundra and at the tundra-forest ecocline is closely correlated with the presence and type of mycorrhizal association in the plant roots. A total of 56 vascular plant species, 7 moss species, 2 lichens and 6 species of fungi from four heath and forest tundra sites in Greenland, Siberia and Sweden were analysed for δ¹⁵N and N concentration. Roots of vascular plants were examined for mycorrhizal colonization, and the soil organic matter was analysed for δ¹⁵N, N concentration and soil inorganic, dissolved organic and microbial N. No arbuscular mycorrhizal (AM) colonizations were found although potential host plants were present in all sites. The dominant species were either ectomycorrhizal (ECM) or ericoid mycorrhizal (ERI). The δ¹⁵N of ECM or ERI plants was 3.5–7.7‰ lower than that of non-mycorrhizal (NON) species in three of the four sites. This corresponds to the results in our earlier study of mycorrhiza and plant δ¹⁵N which was limited to one heath and one fellfield in N Sweden. Hence, our data suggest that the δ¹⁵N pattern: NON/AM plants > ECM plants ≥ ERI plants is a general phenomenon in ecosystems with nutrient-deficient organogenic soils. In the fourth site, a␣birch forest with a lush herb/shrub understorey, the differences between functional groups were considerably smaller, and only the ERI species differed (by 1.1‰) from the NON species. Plants of all functional groups from this site had nearly twice the leaf N concentration as that found in the same species at the other three sites. It is likely that low inorganic N availability is a prerequisite for strong δ¹⁵N separation among functional groups. Both ECM roots and fruitbodies were ¹⁵N enriched compared to leaves which suggests that the difference in δ¹⁵N between plants with different kinds of mycorrhiza could be due to isotopic fractionation at the␣fungal-plant interface. However, differences in δ¹⁵N between soil N forms absorbed by the plants could also contribute to the wide differences in plant δ¹⁵N found in most heath and forest tundra ecosystems. We hypothesize that during microbial immobilization of soil ammonium the microbial N pool could become ¹⁵N-depleted and the remaining, plant-available soil ammonium ¹⁵N-enriched. The latter could be a main source of N for NON/AM plants which usually have high δ¹⁵N. In contrast, amino acids and other soil organic N compounds presumably are ¹⁵N-depleted, similar to plant litter, and ECM and ERI plants with high uptake of these N forms hence have low leaf δ¹⁵N. Further indications come from the δ¹⁵N of mosses and lichens which was similar to that of ECM plants. Tundra cryptogams (and ECM and ERI plants) have previously been shown to have higher uptake of amino acid than ammonium N; their low δ¹⁵N might therefore reflect the δ¹⁵N of free amino acids in the soil. The concentration of dissolved organic N was 3–16 times higher than that of inorganic N in the sites. Organic nitrogen could be an important N source for ECM and, in particular, ERI plants in heath and forest tundra ecosystems with low release rate of inorganic N from the soil organic matter. Received: 8 June 1997 / Accepted: 28 February 1998     

Relationships between root characteristics and seed size in two contrasting floras

Plants vary greatly in root system characteristics, but the causes of this variation are poorly understood. We hypothesised that root system size is closely linked to the plant’s ecological strategy, and that seed size is correlated with root diameter, as a result of anatomical constraints. We analysed the relationships between root characteristics – root depth, basal root diameter and root type – and other plant attributes in more than 300 plant species from two ecologically and geographically contrasted areas: Britain and NE Spain. We used statistical tests that took into account phylogenetic patterns in the data. Apart from plant life span, only plant height and seed size were related to root size in the adult plants. Plant species with shallow or thin main roots had smaller seeds than species with deep or thick main roots, and species with taproots had bigger seeds than plants with fibrous or especially with adventitious roots. These relationships were consistent in the two floras. Seed size was related to plant height, but this association was weaker than that between seed size and root depth. Root depth explained a significant proportion of the variation in seed weight, independently from life form or dispersal mode and, in some cases, more than either of them. These results suggest that traditional ecological explanations do not adequately explain the relationship between seed and plant adult size, and that there will be other, complementary explanations. In particular, we propose that the relationship between seed size and plant height is secondary. The putative causal sequence is that deep-rooted plants (which are generally taller) have large seeds because of allometric and developmental constraints that mean that only large seeds can produce the thick roots that can grow rapidly to depth.     

Taxonomic discrimination of flowering plants by multivariate analysis of Fourier transform infrared spectroscopy data

Fourier transform infrared spectroscopy (FTIR) provides biochemical profiles containing overlapping signals from a majority of the compounds that are present when whole cells are analyzed. Leaf samples of seven higher plant species and varieties were subjected to FTIR to determine whether plants can be discriminated phylogenetically on the basis of biochemical profiles. A hierarchical dendrogram based on principal component analysis (PCA) of FTIR data showed relationships between plants that were in agreement with known plant taxonomy. Genetic programming (GP) analysis determined the top three to five biomarkers from FTIR data that discriminated plants at each hierarchical level of the dendrogram. Most biomarkers determined by GP analysis at each hierarchical level were specific to the carbohydrate fingerprint region (1,200–800 cm^–1) of the FTIR spectrum. Our results indicate that differences in cell-wall composition and structure can provide the basis for chemotaxonomy of flowering plants.Abbreviations FTIR Fourier transform infrared spectroscopy - GP Genetic programming - PCA Principal component analysis - PyMS Pyrolysis mass spectrometry     

Plant characters related to slug feeding: a re‐analysis of feeding studies using trait data from botanical databases and literature

Slugs feed on some plant species but not on others for reasons that are not yet fully understood. We re‐examined the two largest studies on the preference of Arion lusitanicus for different plant species. Briner & Frank (1998) measured the consumption index of slugs (CI_B) based on the dry leaf mass eaten per day per gram of slug mass. Kozlowski & Kozlowska (2009) also measured a consumption index of slugs (CI_K) but on the basis of the area eaten per day per gram of slug mass. The two indices showed a moderate positive rank correlation. Briner & Frank (1998) found that slugs preferred annual to perennial plants and crops rather than wild species. On the other hand, Kozlowski & Kozlowska (2009) found no statistically significant difference in slug preference for annuals, biennials or perennials. Using botanical databases we selected plant traits related to slug herbivory and analysed 141 species. We first analysed the two data sets separately and found that CI_B was higher for seedlings with a higher relative growth rate although this result was only marginally statistically significant. In addition, we found that annuals were consumed more than perennials and that cultivated plants were consumed more than wild plants. This is in agreement with the conclusions of Briner & Frank (1998). For CI_K slugs consumed less from plants with high dry matter content (DMC). The use of classification and regression tree models solves the problem of analysing datasets with missing values. Regarding CI_B, the tree models indicated that life cycle was the major branch. Within perennials, cultivated/wild origin of plants was the most important predictor of slug feeding. Within wild perennials slugs ate more from plants with low specific leaf area (SLA), i.e. relatively thick leaves. Within annuals we found the unexpected result that slugs ate more from plant species with either alkaloids or glucosinolates than from species without one of these compounds. For CI_K, the results of tree models showed that slugs preferred shade‐intolerant plants to shade‐tolerant plant species. Within the shade‐tolerant group slugs fed more on leaves with low DMC. We only partially understand which factors make plants acceptable to slugs. We discuss this issue along with the pros and cons of the two methods used to calculate CI.     

Phosphorus reserves increase grass regrowth after defoliation

Accumulation of P above levels that promote growth, a common plant response called “luxury consumption”, can be considered as a form of reserve to support future growth when the nutrient can subsequently be mobilized. However, the effect of P reserves on regrowth following defoliation has not been demonstrated. We tested the hypothesis that P luxury consumption increases plant tolerance to defoliation. We performed two experiments with four grass species from a continuously grazed temperate grassland in the Flooding Pampa (Argentina). The first experiment, aimed at generating P luxury consumption by fertilization, resulted in one species (Sporobolus indicus) showing luxury consumption. In this way, we were able to obtain plants of S. indicus with similar biomass but contrasting amounts of P reserves. The second experiment evaluated the subsequent regrowth following defoliation on a P-free medium of these plants differing in P reserves. Regrowth was larger for plants that had shown P luxury consumption during a previous period than for plants with lower levels of P reserves. During regrowth these plants showed a clear pattern of P remobilization from the stubble, crown, and root compartments to the regrowing tissue, in addition to a likely reutilization of P present in leaf-growth zones. This work is the first showing that high levels of P reserves can confer tolerance to defoliation by promoting compensatory growth under P deficiency.     

Response of floodplain grassland plant communities to altered water regimes

Floodplain grasslands are often composed of a mosaic of plant communities controlled by hydrological regime. This article examines the sensitivity of floodplain grassland plant communities to water regime using reciprocal transplantation of an inundation grassland and a flood-meadow within an English floodplain. Experimental treatments comprised control, transplanted and lifted plots; the last treatment, in order to elucidate any disturbance effects of transplantation. Plant community response was analysed using species abundance and their ecological traits. Results from both communities showed substantial annual variations related to hydrology, including significant species changes, but generally, vegetation seemed to be responding to drier conditions following a major flood event. This ‘drying’ trend was characterised by increased species diversity, a greater abundance of competitive species and fewer typical wetland plants. Transplanted community composition increasingly resembled receptor sites and transplant effects were most pronounced the first year after treatment for both vegetation types. Differential responses to water regime were detected for the two plant communities. The inundation grassland community was particularly dynamic with a composition that rapidly reflected drying conditions following the major flood, but transplantation into a drier flood-meadow site prompted little additional change. The flood-meadow community appeared more resistant to post-inundation drying, but was sensitive to increased wetness caused by transplantation into inundation grassland, which significantly reduced six species while none were significantly favoured. The effects of disturbance caused by lifting the transplants were limited in both communities, although five species showed significant annual fluctuations. The study shows that small alterations in water regime can prompt rapid vegetation changes and significant plant species responses in floodplain grasslands, with effects probably magnified through competitive interactions. The dynamic properties of floodplain vegetation demonstrated by this study suggest that its classification, management and monitoring are challenging and ideally should be based on long-term studies.     

Valuation of Forests and Plant Species in Indigenous Territory and National Park Isiboro-Sécure,Bolivia

Valuation of Forests and Plant Species in Indigenous Territory and National Park Isiboro-Sécure, Bolivia. A quantitative ethnobotanical study was conducted in Indigenous Territory and National Park Isiboro-Sécure (TIPNIS), Bolivia, to assess the usefulness assigned by local Yuracaré and Trinitario ethnic groups to different terra firme and floodplain forests. Furthermore, we investigated which variables are good predictors for the use value attributed to plant species in the research area. Plants were collected during transect, walk-in-the-woods and homegarden sampling. Ethnobotanical and ethnoecological data of the inventoried plants were obtained from 12 Yuracaré and 14 Trinitario participants through semistructured interviews. On average, 84% of species in transects were claimed to be useful to people. The understorey (2.5 cm ≤ dbh < 10 cm) of the sampled forest types contained more useful species than the overstorey (dbh ≥ 10 cm), particularly for species with a medicinal and/or social use function. The local use value of plant species can be predicted, in part, from their botanical family, growth form, density, frequency, mean and maximum dbh, and ecological importance value. Our data confirm the hypothesis that density and frequency of plants in the landscape are both related to perceived plant accessibility. Accessibility of plants partly seems to guide their usefulness in TIPNIS. Indigenous assessment of accessibility and abundance of plants also covaried with their perceived usefulness and therefore has a potential for uncovering patterns in the perceived utility of plants.