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  • Volume 10 Issue 4
    An endemic bird from the southern Yungas, the Yellow striped Brush finch (Atlapetes citrinellus) eating a fruit of the understory treelet Psychotria carthagenensis. Photo taken by Facundo X. Palacio.
    Research Articles
    Valentin H. Klaus, Deborah Schäfer, Till Kleinebecker, Markus Fischer, Daniel Prati, Norbert Hölzel
    2017, 10 (4): 581-591.
    Abstract ( 148 )   PDF   Save
    Aims The relationship between biodiversity and ecosystem functioning is among the most active areas of ecological research. Furthermore, enhancing the diversity of degraded ecosystems is a major goal in applied restoration ecology. In grasslands, many species may be locally absent due to dispersal or microsite limitation and may therefore profit from mechanical disturbance of the resident vegetation. We established a seed addition and disturbance experiment across several grassland sites of different land use to test whether plant diversity can be increased in these grasslands. Additionally, the experiment will allow us testing the consequences of increased plant diversity for ecosystem processes and for the diversity of other taxa in real-world ecosystems. Here, we present details of the experimental design and report results from the first vegetation survey 1 year after disturbance and seed addition. Moreover, we tested whether the effects of seed addition and disturbance varied among grassland depending on their land use or pre-disturbance plant diversity.
    Methods A full-factorial experiment was installed in 73 grasslands in three regions across Germany. Grasslands were under regular agricultural use, but varied in the type and the intensity of management, thereby representing the range of management typical for large parts of Central Europe. The disturbance treatment consisted of disturbing the top 10cm of the sward using a rotavator or rotary harrow. Seed addition consisted of sowing a high-diversity seed mixture of regional plant species. These species were all regionally present, but often locally absent, depending on the resident vegetation composition and richness of each grassland.
    Important findings Seven months after sward disturbance, respective plots had significantly increased in bare soil, seedling species richness and number of seedlings. Seed addition had increased plant species richness, but only in combination with sward disturbance. The increase in species richness, when both seed addition and disturbance was applied, was higher at high land-use intensity and low resident diversity. Thus, we show that at least the early recruitment of many species is possible also at high land-use intensity, indicating the potential to restore and enhance biodiversity of species-poor agricultural grasslands. Our newly established experiment provides a unique platform for broad-scale research on the land-use dependence of future trajectories of vegetation diversity and composition and their effects on ecosystem functioning.
    Wei Li, Jie Zhao, Howard E. Epstein, Guanghua Jing, Jimin Cheng, Guozhen Du
    2017, 10 (4): 592-600.
    Abstract ( 163 )   PDF   Save
    Aims Human activities have dramatically increased nutrient inputs to ecosystems, impacting plant community diversity, composition and functioning. Extensive research has shown that a decrease in species diversity and an increase in productivity are a common phenomenon following fertilization in grasslands ecosystem. The magnitude of the response of species diversity and above-ground net primary productivity (ANPP) to fertilization mainly depends on species traits (mean trait values) and traits variability (plasticity). Our aim of this study was to examine (i) changes of species diversity (species richness and Shannon–Wiener index) and ANPP following fertilization; (ii) which species traits or community-weighted mean (CWM) traits can determine ANPP, as expected from the 'biomass ratio hypothesis'; and (iii) the relative role of intra-specific and inter-specific trait variability in this process following fertilization.
    Methods We measured ANPP and four key plant functional traits: specific leaf area (SLA), leaf dry matter content (LDMC), mature plant height (MPH) and leaf nitrogen concentration (LNC) for 25 component species along a fertilization gradient in an alpine meadow on the Tibetan Plateau. In addition, trait variation of species was assessed using coefficients of variation (CV), and we calculated the ratio of the CV intra to the CV inter.
    Important findings Our results showed that: (i) fertilization significantly reduced species richness and Shannon–Weiner diversity index, but significantly increased ANPP; (ii) there was a significant positive correlation between ANPP and CWM–SLA and CWM–MPH, yet there was no significant relationship between ANPP and CWM–LNC or CWM–LDMC; (iii) intra-specific variability in SLA and MPH was found to be much greater than inter-specific variability, especially at the higher fertilization levels. We concluded that CWM–SLA and CWM–MPH can be used to assess the impacts of species changes on ecosystem functioning, and dominant species can maximize resource use through intra-specific variability in SLA and MPH to compensate for the loss of species following fertilization, therefore maintaining high community productivity.
    Brad J. Farmilo, John W. Morgan, Dale G. Nimmo
    2017, 10 (4): 601-609.
    Abstract ( 176 )   PDF   Save
    Aims Habitat loss and fragmentation are the leading causes of global biodiversity decline. How fragmentation (leading to edge effects, increased isolation and declining habitat size) interacts with top-down processes like vertebrate herbivory, an important driver of vegetation structure and composition in many ecosystems, is poorly quantified. Interactions between fragmentation and changes in herbivory may exacerbate their individual influences on plant growth, with implications for management of native plant communities within fragmented landscapes. We examined the effects of habitat fragmentation on herbivore activity, and also how both fragmentation and mammalian herbivory influence growth of understorey plant species.
    Methods This study was conducted at the Wog Wog habitat fragmentation experiment, located in south-eastern New South Wales, Australia. We use herbivore exclusion plots across an experimentally fragmented landscape to assess the interactive effects of fragmentation and herbivory on the growth of four plant species that vary in growth form and rarity in the landscape.
    Important findings We observed species-specific responses to both herbivory and fragmentation, but no additive or interactive effects between these drivers. We show that a reduction in herbivore activity within fragments does not correspond with an increase in plant growth, even for the most palatable species. Rather, top-down processes continue to operate across the fragmented landscape. Although changes in habitat conditions within fragments appear to negatively influence both plant growth and mammalian herbivore activity, it is likely that alterations to bottom-up effects (i.e. fragmentation) may be more important than top-down effects (i.e. herbivores) for the species under investigation. The species-specific response of plants to herbivory or fragmentation may have implications for temporal and spatial population persistence in fragmented landscapes and ultimately fragment vegetation structure.
    Paula Lorenzo, Jonatan Rodríguez, Luís González, Susana Rodríguez-Echeverría
    2017, 10 (4): 610-617.
    Abstract ( 143 )   PDF   Save
    Aims The tree legume Acacia dealbata Link is an aggressive Australian invader that severely affects abiotic and biotic compartments of ecosystems worldwide. This invasive species outcompetes native plant communities through direct competition, changes in microhabitat and soil properties under the canopy and the release of allelopathic compounds. However, these effects are usually studied separately and under controlled conditions. The objective of this study was to evaluate the combined effect of these modifications exerted by A. dealbata on the establishment of native and invasive species in the field.
    Methods A full factorial experiment was performed in order to test the combined effect of microhabitat, soil type and allelopathy on the establishment of the invasive A. dealbata and three native species in the field (North–West Spain). We sowed seeds of native or invasive species in pots with different soil type (soil collected under A. dealbata or Pinus pinaster), allelopathy status (soil treated or untreated with activated carbon) and microhabitat (under the canopy of A. dealbata or P. pinaster). The number and total biomass of established plants were evaluated after 8 months. Soil abiotic properties were determined in all soils.
    Important findings The establishment of native and invasive species was significantly affected by the microhabitat, with a higher number of seedlings under the native forest (P. pinaster). The establishment of A. dealbata seedlings was also significantly promoted by its own soil. A negligible effect of allelopathy was detected on the establishment and growth of both invasive and native species. We conclude that (i) the main factor affecting seedling establishment was microhabitat rather than changes in soil properties or allelopathy, (ii) soil modifications by A. dealbata promote the establishment of its own seedlings, contributing to the progress of invasion and (iii) allelochemicals released by A. dealbata do not seem to play a key role for the establishment of native and invasive plants under field conditions in the European non-native range.
    Hong Qian
    2017, 10 (4): 618-625.
    Abstract ( 141 )   PDF   Save
    Aims The tropical conservatism hypothesis (TCH) links environmental tolerance, diversification, dispersal and evolutionary history in explaining why warm, wet tropical regions harbor more species than colder, drier regions. The TCH is considered as a dominant explanation for broad-scale patterns of species richness across the globe, such as the latitudinal diversity gradient. At its core, the TCH predicts a positive relationship between clade age and temperature. Here, I test this prediction using a data set of angiosperm tree assemblages from Malesia.
    Methods I assembled an altitudinal gradient of 15 communities of angiosperm trees. I calculated the mean family age (MFA) of tree species for each community. I used ordinary regression analysis and spatial autoregression analysis to determine the relationships of species richness and MFA with elevation, temperature and precipitation. I used correlation analysis to assess relationships between paired variables.
    Important findings MFA is negatively correlated with tree species richness, and increases with elevation and decreases with temperature for the altitudinal gradient. MFA remains significantly increasing with decreasing temperature along the altitudinal gradient after accounting for spatial autocorrelation in a species-ordination space. The negative relationship between clade age and temperature along the altitudinal gradient in Malesia is contrary to the TCH.
    Mohammad Farzam, Hamid Ejtehadi
    2017, 10 (4): 626-633.
    Abstract ( 167 )   PDF   Save
    Aims Species composition and diversity of the mountainous rangelands are results of interactions between environmental severities, heterogeneous topography and facilitative effects by nurse plants. This research was aimed to compare relative effects of these three environmental variables on the natural vegetation of a mountainous rangeland. For a more detailed understanding, effects of four different nurse species were separately compared on the various plant growth forms and on two community plant responses (diversity and abundance).
    Methods A mountainous semiarid rangeland was selected in Baharkish, Quchan, Northeast of Iran. Density and canopy cover of all plant species were recorded under the canopy of four different shrubs and in open areas, in north and south-facing aspects, and in a normal and a drought year. Shannon diversity, total abundance (% cover) and the abundance of different growth forms were used as criteria for assessing effects of the environmental variables. Data were arranged in a factorial combination and analyzed by three-way analysis of variance using a GLM analysis.
    Important findings (i) Drought, aspect and canopy created niche differentiation: annual forbs and shrubs were more affected by drought, whereas geophytes and grasses were more responsive to slope aspects. Effects of drought and slope aspect were more profound on species diversity, whereas that of canopy facilitation was stronger on plant abundance. (ii) Canopy facilitation was dependent on severity of the abiotic factors and life history of interacting species. Canopy facilitation allowed for the persistence of only annual forbs, but it was disadvantaged during the drought year. Plant community responses to abiotic factors (slope and drought) were more dependent on the plant growth form, while responses to canopy facilitation were more dependent on the morphology and/or ecology of nurse shrubs. (iii) Effect of shrubs was dependent on their morphology and ecology: shrubs with larger canopy area and nitrogen fixation capability increased, but those with allelopathic effects or a dense canopy structure decreased the diversity of the understory species.
    Roderick W. Bouman, Sandy-Lynn Steenhuisen, Timotheüs van der Niet
    2017, 10 (4): 634-648.
    Abstract ( 156 )   PDF   Save
    Aims Closely related species frequently co-occur in plant communities. The role of niche partitioning for allowing their coexistence has been called into question, but most studies on community ecology neglect pollination as a niche component, and thus potentially underestimate niche partitioning. Here, we investigate the importance of the pollination niche for determining coexistence in a biodiversity hotspot. We specifically test whether co-flowering insect-pollinated species of Erica, the most species-rich plant genus of the South African Cape Floristic Region, are characterized by different functional floral traits and different specialized pollination systems.
    Methods Communities of co-flowering Erica species were studied at three sites in the fynbos biome in the Western Cape of South Africa. We focused on five species with flowers that conform to an insect pollination syndrome. We assessed whether floral traits important for pollinator attraction and mechanical fit overlap by comparison of scent (gas chromatography coupled with mass spectrometry), colour (spectrophotometry and models of bee vision), nectar volume and concentration and corolla morphology. Pollinator partitioning was quantified by comparison of floral visitor profiles and pollinator importance, calculated as the product of visitation rate, number of flowers probed per visit and pollen load for each functional visitor group among species within communities. Potential effects of competition were assessed by comparing visitation rates both directly and using anther ring disturbance as a proxy for lifetime visitation.
    Important findings Floral phenotypes differed among species within communities in all functional traits. Visitor assemblages were diverse, including ants, beetles, flies, honeybees, moths and solitary bees. However, the Cape honeybee, Apis mellifera capensis, was the main pollinator of all but one Erica species. Insect visitation rates were significantly lower for E. imbricata and E. calycina relative to congeners, but high rates of anther ring disturbance, which differed significantly in only two out of seven comparisons, suggest that long-term visitation rates are mostly similar among species that share pollinators. This study shows that coexistence of co-flowering insect-pollinated Erica species is not determined by specialization for different pollination systems. Pollinator sharing might rather lead to facilitation among co-flowering species, and floral constancy mediated by extensive interspecific floral trait variation might mitigate its potentially negative effects.
    Laurent De Vriendt, Marc-André Lemay, Martine Jean, Sébastien Renaut, Stéphanie Pellerin, Simon Joly, François Belzile, Monique Poulin
    2017, 10 (4): 649-659.
    Abstract ( 155 )   PDF   Save
    Aims Habitat connectivity is important in conservation since isolation can diminish the potential of a population for adaptation and increase its risk of extinction. However, conservation of naturally patchy ecosystems such as peatlands has mainly focused on preserving specific sites with exceptional characteristics, neglecting the potential interconnectivity between patches. In order to better understand plant dynamics within a peatland network, we assessed the effect of population isolation on genetic distinctiveness, phenotypic variations and germination rates using the peatland-obligate white-fringed orchid (Platanthera blephariglottis).
    Methods Fifteen phenotypic traits were measured for 24 individuals per population (20 distinct populations, Quebec, Canada) and germination rates of nearly 20000 seeds were assessed. Genetic distinctiveness was quantified for 26 populations using single nucleotide polymorphism markers obtained via a pooled genotyping-by-sequencing approach. Geographic isolation was measured as the distance to the nearest population and as the number of populations occurring in concentric buffer zones (within a radius of 2, 5 and 10 km) around the studied populations.
    Important findings All phenotypic traits showed significant differences among populations. Genetic results also indicated a pattern of isolation-by-distance, which suggests that seed and/or pollen exchange is restricted geographically. Finally, all phenotypic traits, as well as a reduced germination rate, were correlated with either geographic isolation or genetic distance. We conclude that geographic isolation likely restricts gene flow, which in turn may affect germination. Consequently, it is imperative that conservation programs take into account the patchy nature of such ecosystems, rather than targeting a few specific sites with exceptional character for preservation.
    Jie Chen, Qing Xu, Deqiang Gao, Aiyun Song, Yuguang Hao, Yingbin Ma
    2017, 10 (4): 660-669.
    Abstract ( 153 )   PDF   Save
    Aims West Ordos Desert (WOD) in Inner Mongolia of China is characterized by unique geographical and ecological features to avoid the direct invasion of Quaternary Continental Glaciation, so it hosts many endangered relic species such as Tetraena mongolica, Ammopiptanthus mongolicus and Potaninia mongolica from Tertiary. However, how these plants utilize available water sources remains unknown. The objective of this study was to investigate the water utilization strategies of selected rare and endangered plant species in WOD by comparing hydrogen isotope ratios between their xylem water and possible water sources following four rainfall events of varying-intensities.
    Methods We measured the hydrogen isotope ratios of xylem water from T. mongolica, A. mongolicus and P. mongolica and an accompanying species Sarcozygium xanthoxylum and potential water sources (including precipitation and soil water in different soil layers from 0 to 150cm) over 9 days following each of four varying-intensity rainfall events during the summer of 2012. And then calculated the percentage utilization of potential water sources by each species after each rainfall events using the linear mixing model. We also made the measurements of soil moisture and root biomass in favor of interpretation of plant water use strategies.
    Important findings Tetraena mongolica, A. mongolicus and S. xanthoxylum primarily relied on deep soil water, whereas P. mongolica depended predominantly on rainwater. These rare and endangered desert plants had differential utilizations of available water sources, so some competition for limited water existed among some species. Tetraena mongolica had a competitive relationship in absorption of soil moisture with the same family species S. xanthoxylum, suggesting that T. mongolica and S. xanthoxylum should be restored separately at different areas in the WOD. Overall, this study provides a better understanding of water use strategies of these four plants and scientific evidence for protecting rare and endangered plants, maintaining regional species diversity, and developing effective vegetation restoration plans in the WOD.
    Madhav P. Thakur, Peter B. Reich, Cameron Wagg, Nicholas A. Fisichelli, Marcel Ciobanu, Sarah E. Hobbie, Roy L. Rich, Artur Stefanski, Nico Eisenhauer
    2017, 10 (4): 670-680.
    Abstract ( 163 )   PDF   Save
    Aims Climate warming raises the probability of range expansions of warm-adapted temperate species into areas currently dominated by cold-adapted boreal species. Warming-induced plant range expansions could partly depend on how warming modifies relationships with soil biota that promote plant growth, such as by mineralizing nutrients. Here, we grew two pairs of congeneric herbaceous plants species together in soil with a 5-year warming history (ambient, +1.7°C, +3.4°C) and related their performances to plant-beneficial soil biota.
    Methods Each plant pair belonged to either the mid-latitude temperate climate or the higher latitude southern boreal climate. Warmed soils were extracted from a chamberless heating experiment at two field sites in the temperate-boreal ecotone of North America. To isolate potential effects of different soil warming histories, air temperature for the greenhouse experiment was identical across soils. We hypothesized that soil with a 5-year warming history in the field would enhance the performance of temperate plant species more than boreal plant species and expected improved plant performances to have positive associations with plant growth-promoting soil biota (microbial-feeding nematodes and arbuscular mycorrhizal fungi).
    Important findings Our main hypothesis was partly confirmed as only one temperate species performed better in soil with warming history than in soil with history of ambient temperature. Further, this effect was restricted to the site with higher soil water content in the growing season of the sampling year (prior to soil collection). One of the boreal species performed consistently worse in previously warmed soil, whereas the other species showed neutral responses to soil warming history. We found a positive correlation between the density of microbial-feeding nematodes and the performance of one of the temperate species in previously wetter soils, but this correlation was negative at the site with previously drier soil. We found no significant correlations between the performance of the other temperate species as well as the two boreal species and any of the studied soil biota. Our results indicate that soil warming can modify the relation between certain plant species and microbial-feeding nematodes in given soil edaphic conditions, which might be important for plant performance in the temperate-boreal ecotone.
    Josefina G. Campoy, Rubén Retuerto, Sergio R. Roiloa
    2017, 10 (4): 681-691.
    Abstract ( 165 )   PDF   Save
    Aims Carpobrotus edulis (L.) N.E.Br. is known to invade many coastal ecosystems around the world, and it has been considered as one of the most severe threats to numerous terrestrial plant communities. Therefore, the study of the relationships between life-history traits that may favour its invasiveness and the invasibility of the environments is necessary to improve our knowledge about invasion success. In this research, we specifically tested the effects of physiological integration in genotypes from contrasting habitats, where the importance of integration is expected to differ. Thus, the main objective of this work was to detect the presence of adaptive plasticity in the capacity for clonal integration in this aggressive invader.
    Methods In a greenhouse experiment, we compared the performance, in terms of growth and photochemical efficiency, of two C. edulis ecotypes. Connected and severed ramet pairs from coastal sand dunes and rocky coast habitats were grown in substrates of different quality and heterogeneity.
    Important findings Our study clearly indicates that clonal integration improves growth and photosynthetic efficiency in the aggressive invader C. edulis. Two different aspects of clonal integration determine site-specific strategies in this species in order to optimize its successful propagation in a particular habitat. We demonstrated that the adaptation of C. edulis to local environments has led to a differential selection of two complex clonal traits associated with the capacity for clonal integration. In patchy sand dunes, C. edulis has evolved ecotypes with ramets highly plastic in patterns of biomass allocation, which allows ramets to specialize in the acquisition of the resource that is locally most abundant, i.e., a spatial division of labour among ramets. However, in the harsher rocky coast habitats, local adaptation produced highly integrated ecotypes, where resource sharing is not combined with a specialization of resource acquisition.
    Phyllis H. Pischl, Nicholas A. Barber
    2017, 10 (4): 692-701.
    Abstract ( 168 )   PDF   Save
    Aims Climate change is predicted to cause both increased temperatures and changes in precipitation, leading to more severe droughts in some areas. How these changes will affect plant growth may depend in part on biotic context. Most vascular plants form symbiotic relationships with arbuscular mycorrhizal fungi (AMF), root symbionts that provide soil nutrients to plants in exchange for carbohydrates, which may reduce the effects of environmental stresses on plants. We investigated if AMF modified temperature and drought effects on plant growth, fitness and defenses against herbivory.
    Methods We manipulated AMF presence, temperature and water availability on bell pepper plants (Capsicum annuum L.) in a field setting to measure plant growth and fitness responses. In a growth chamber experiment, we also investigated if AMF influenced insect herbivores feeding on plants at elevated temperatures.
    Important findings Drought consistently reduced plant growth, and AMF did not change drought impacts. However, with sufficient water, AMF tended to benefit plant growth and flower production (but not fruit production) compared to non-mycorrhizal plants. In the growth chamber, temperature and AMF influenced plant protein and phosphorus contents, but not defensive chemistry or herbivore performance. Thus, AMF may ameliorate the effects of temperature stress due to climate change on plants by increasing growth and nutrient content, but these effects do not extend to the constitutive herbivory defenses examined here.
    Julia Sánchez Vilas, Rubén Retuerto
    2017, 10 (4): 702-712.
    Abstract ( 134 )   PDF   Save
    Aims Sexes of dimorphic species often differ in ecophysiological traits and display spatial segregation. These differences have been interpreted as an evolved response of the sexes to meet the specific resource demands associated with reproduction. Sexes may differ not only in the amount of resources allocated to reproduction but also in the timing of allocation to reproduction. In this study, we hypothesize that as a consequence of their specific resource demands for reproduction, the sexes of the dune plant Honckenya peploides differ in terms of temporal patterns of water use efficiency and nitrogen use and acquisition.
    Methods Water use efficiency, as inferred from leaf carbon isotope discrimination (Δ 13 C), nitrogen use, estimated by leaf nitrogen isotope composition (δ 15 N), and the foliar carbon and nitrogen contents were measured in males and females at three different points in time.
    Important findings Females had greater water use efficiency than males, regardless of time. The ratio of N 15 to N 14 did not change with time in males, but significantly decreased in August for females. The total N content in the leaf tissues of females decreased as the season progressed, while in males a decrease was only found from April to June and then it remained constant from June to August. A similar pattern, but reversed, was followed by the foliar C/N ratio. Additionally, negative relationships between leaf Δ 13 C and N content were found at all times for males and only at the end of the season for females. Thus, our hypothesis that sex-specific patterns of nitrogen and water use efficiency will depend on time was supported. Overall, our results highlight the importance of including time in studies of sexual dimorphism, and also the role that physiological specialization plays in meeting the specific demands associated with reproduction.
    Facundo X. Palacio, Juan Manuel Girini, Mariano Ordano
    2017, 10 (4): 713-720.
    Abstract ( 139 )   PDF   Save
    Aims Animals in search of fleshy fruits forage mostly according to the number of available fruits and then select individual fruits based on reward quality or advertised subtle traits. This hierarchical pattern of fruit choice would be translated into patterns of selection strength mediated by frugivores on fruit display traits. Thus, frugivores would exert higher selection pressures on fruit crop size and lower selection pressures on within-plant variation of phenotypic traits (infructescence, fruit and seed size). However, no attempt to link this behavioral mechanism of hierarchical trait selection to natural selection patterns has been made. Therefore, we sought to determine the relationship between the hierarchical decision-making process of fruit choice and patterns of natural selection on fruit traits.
    Methods We recorded bird visits and measured fruit-related traits (fruit crop size, fruit diameter and seed weight) in a natural population of Psychotria carthagenensis, a bird-dispersed treelet, in a Yungas forest from Argentina. To assess phenotypic selection patterns on fruit display traits, we performed multivariate selection analysis, and to explicitly identify a hierarchy of fruit trait choice we used a classification tree as a predictive model.
    Important findings Selection patterns on fruit display traits were in agreement with a hierarchical process of fruit choice made by birds. The strength of directional selection on the total number of fruits in a plant (i.e. fruit crop size) was nearly two times higher than on fruit size, and the classification tree analysis supported this hierarchical pattern. Our results support previous evidence that seed dispersers shape fruit crop size with higher intensity than subindividual fruit traits. Also, high levels of subindividual phenotypic variation of fruit display traits may be explained by relaxed selection pressures exerted by frugivores. Empirical studies also show that this pattern may constitute a general phenomenon among other plant–animal interactions.
    Amy-Marie Gilpin, Justin C. Collette, Andrew J. Denham, Mark K. J. Ooi, David J. Ayre
    2017, 10 (4): 721-729.
    Abstract ( 134 )   PDF   Save
    Aims Worldwide, evidence suggests that exotic pollinators can disrupt plant mating patterns. However, few studies have determined if pollination by the honeybee Apis mellifera (the world's most widely introduced pollinator) reduces offspring quality when compared with pollination by native birds. The Australian Proteaceae provides an excellent opportunity to test the impact of honeybees in pollination systems that are adapted to birds and non-flying mammals.
    Methods We compared the frequency of flower visitation and foraging behaviour of birds and insects within seven populations of Banksia ericifolia. Banksia ericifolia is hermaphroditic and has large nectar-rich, orange inflorescences typical of bird and mammal pollinated species. For a subset of the study populations, we compared the quality of seed produced via an exclusion treatment (that only allowed invertebrates to access flowers) with an open-pollination treatment (potentially visited by mammals, birds and invertebrates), by measuring seed weight, germination rates (T 50), percent germination, seedling height after 14 days since the emergence of the cotyledon and time to emergence of the cotyledon.
    Important findings Apis mellifera was the only apparent insect pollinator and the most frequent flower visitor, while the open treatment inflorescences were also frequently visited by avian pollinators, primarily honeyeater species. The foraging behaviour of honeybees and honeyeaters showed striking differences that potentially affect patterns of pollen transfer. Honeybees made significantly greater proportions of within cf. among plant movements and only 30% (n = 48) of honeybees foraged for pollen (nectar foragers carried no pollen) whilst all birds were observed to contact both stigmas and anthers when foraging for nectar. Despite these fundamental differences in behaviour, there was little effect of treatment on seed set or quality. Our data show that while honeybees appear to alter patterns of pollen transfer within B. ericifolia populations, they do not impact reproductive rates or performance of early life-stages.
IF: 1.780
5-year IF: 2.674
Wen-Hao Zhang
Bernhard Schmid
CN 10-1172/Q
ISSN 1752-9921(print)
ISSN 1752-993X(online)