Pasture Populations Research Articles

Fecundity and survival of flumetsulam-resistant and -susceptible Ranunculus acris plants with and without exposure to the herbicide

ABSTRACT Variable efficacy of the acetohydroxyacid synthase (AHAS) inhibitor herbicide, flumetsulam, against dairy pasture populations of Ranunculus acris, has been attributed to resistance. We compared, over two years, the fitness of two resistant (R) clones and nine susceptible (S) clones treated or not with flumetsulam by measuring seed yields and survival of plants. Without the herbicide, all plants grew and survived. The seed yields of the R and S plants without the herbicide were similar (327 and 217 seeds/plant, respectively in Year 1, and 257 and 323 seeds/plant in Year 2) indicating no fitness penalty to the resistance. With the herbicide, growth and survival of the R plants was unaffected, whereas all S plants were defoliated before seedhead formation but 96% regrew from their rhizomes in Year 2. Seed yields of the treated R and S plants in Year 1 were 347 and 0 seeds/plant, respectively and 243 and 205 seeds/plant in Year 2. Survival of flumetsulam-susceptible R. acris plants following spraying would maintain susceptible AHAS alleles in the population, while without a fitness penalty, resistant plants would persist in non-spraying years facilitating further selection when the herbicide is used again.

Long‐term trends in the genotypic integrity, phenotype and reproductive development of perennial ryegrass (Lolium perenne L.) populations in New Zealand dairy pastures: Implications for pasture persistence

AbstractFailure of perennial ryegrass‐based pastures to persist beyond 3 years post‐sowing is an increasing threat to the sustainability of livestock industries in the north of New Zealand. Little is known of the long‐term responses of plants and populations to the environmental stresses responsible for persistence failure, or the effects of ryegrass genetics on those responses. Plants were collected from 10‐year‐old pastures sown in two environments (Waikato, North Island: warm‐temperate, summer/autumn dry; Canterbury, South Island: cool temperate, irrigated) to four ryegrass functional types and grazed by dairy cattle. Surviving plants in Canterbury pastures were almost all true‐to‐type for the original genotype, whereas there was substantial ingress of volunteer plants in the diploid cultivars in Waikato. Plants confirmed as true‐to‐type were compared to reference plants grown from the original seed lines. Leaf mass was lower in survivor plants than in reference plants for all functional types. This effect was reversed by recruitment of new plants from seed in a grazing deferment treatment applied at the Waikato site 18 months before plant collection, in a manner consistent with epigenetic control. Reproductive development was delayed by 4–6 days in survivors of mid‐ and late flowering diploid cultivars: this effect appeared to be the result of true genetic differentiation. There was less aftermath heading in the Canterbury survivors, but not Waikato survivors, compared with the reference plants. The relevance of these findings for ryegrass survival strategies and targeted selection of traits for improved persistence is discussed.

Evaluation of the Relationship between Cultivar, Endophyte and Environment on the Expression of Persistence in Perennial Ryegrass Populations Using High-Throughput Phenotyping

Perennial ryegrass (Lolium perenne L.) is a commonly grown pasture species in temperate agriculture, mainly serving as a primary energy source for dairy cows. However, its limited persistence often leads to missed production potential and early resowing, especially in countries that experience summer drought, e.g., Australia and New Zealand. Therefore, understanding the factors influencing perennial ryegrass pasture persistence is crucial for sustainable land management and climate resilience in pasture-based animal production systems. Significant gaps in knowledge exist regarding the factors influencing pasture persistence, as the number of conducted studies in this area remains limited. This study aimed to investigate the factors influencing the expression of persistence in perennial ryegrass populations using airborne and ground-based sensors. A field experiment was conducted in the southwest region of Victoria, Australia, involving ten commercial perennial ryegrass cultivar–endophyte combinations in two different populations. Persistence was evaluated using sensor-based and conventional pasture measurements over two consecutive autumns. The results revealed significant fixed effects of cultivar, endophyte, and environment and their interactions on persistence traits of perennial ryegrass. Cultivars Alto, Samson, and One50 exhibited high levels of persistence when infected with novel endophyte strains. Furthermore, prolonged environmental stresses were found to drive directional selection within pasture populations. The findings emphasise the importance of selecting appropriate cultivar–endophyte combinations and early detection of signs of poor persistence to optimise sward longevity and financial returns from pasture-based animal production systems. This study fills a knowledge gap regarding the factors influencing pasture persistence and provides valuable insights for sustainable pasture management strategies.

Simulating the population dynamics of barley grass (Hordeum spp.) and impacts of weed management strategies in a southern Australian lucerne (Medicago sativa) pasture

Context Barley grass (Hordeum spp. L.) is an annual, invasive grass weed of southern Australian crops and pastures, frequently associated with weight loss and carcass damage in sheep due to its sharp seeds. Knowledge gaps exist regarding optimal density thresholds for effective control to reduce impacts on animal production. The value of integrated weed management (IWM) over individual control options for reducing barley grass populations in pasture is also unknown. Aims We aimed to develop a model for simulating the population dynamics of barley grass within lucerne (Medicago sativa L.) pastures of southern Australia and to test the hypothesis that combining herbicides with mowing will be more effective for removing barley grass seedbanks over time than individual control measures. Methods The model was developed within Microsoft Excel and adapted from other annual grass models. The model takes a Monte Carlo approach to simulate control impacts on weed seedbanks over 10 years using five weed-control density thresholds. It was parameterised using data from recent experiments and available literature. Key results The most effective long-term control strategy for barley grass occurred with a density threshold of 5 seedlings m−2 by combining early and late herbicide applications, and by combining early and late herbicides with mowing, reducing the seedbank by 86% and 89%, respectively. Conclusions Simulation results showed that IWM programs were more effective than individual control options in reducing the barley grass seedbanks over 10 years, particularly at low weed densities (≤50 seedlings m−2). Implications Incorporation of this model into a bioeconomic grazing systems model will be valuable for determining the economic impacts and optimal weed-control strategies for minimising the effects of barley grass seed contamination in lamb production systems.

Optimizing long-acting acaricide use for integrated tick management of Rhipicephalus australis-infesting cattle in New Caledonia.

The tick Rhipicephalus australis, formerly known as Rhipicephalus microplus, is the most economically important ectoparasite of livestock in New Caledonia, affecting cattle health and production. Decades of control attempts based on the application of chemical acaricides have exerted a strong selective pressure on R. australis populations, some of which have evolved resistance to these treatments. Research to develop integrated tick control programs is now focused on decreasing applications of chemicals. This study reports the implementation of a method of pasture and herd management involving minimal strategic use of long-acting acaricides, here defined as those having substantial efficacy against larvae for several weeks. Diverse parameters concerning the utilization of long-acting acaricides in association with pasture and herd management on 21 New Caledonian farms over a 5-year period were analyzed to optimize their strategic use. Longer larval acaricidal effect was achieved with a commercial pour-on formulation of fluazuron than with a commercial injectable (subcutaneous) formulation containing 3.15% ivermectin. Pasture and herd management allowed an increase in the delay between a long-lasting acaricide application and the subsequent acaricide treatment from 11.0weeks to 17.7weeks. However, if ticks were detected and reported by producers on the day of a long-acting acaricide application, the delay to the following treatment was reduced from 18.5weeks to 11.2weeks. The impact of a long-acting acaricide treatment on larval populations in pastures was greatest with a stocking rate of 5 animals per hectare grazing during 1week. These results provide science-based evidence to cattle producers for adaptive integrated tick management in order to delay the development of acaricide resistance.

Spill-over attack by the gall fly, Urophora stylata, on congeners of its target weed, Cirsium vulgare

The gall fly, Urophora stylata, was released in New Zealand in 1998 as a biocontrol agent for the thistle weed, Cirsium vulgare (Scotch thistle). In the summer of 2018, a survey was conducted to assess the field host range of the biocontrol agent in New Zealand. A random selection of 18 pasture populations under sheep and/or beef production, where C. vulgare was present, was surveyed to quantify the attack intensity (gall size relative to seedhead size) on C. vulgare, and the presence of attack on other thistle weeds within the same population. At each location, seedheads were collected from C. vulgare and all other thistle species (Cardueae) present, which included Cirsium arvense (Californian thistle), Cirsium palustre (marsh thistle), Carduus nutans (nodding thistle), and an Arctium species (burdock). In addition to attack on C. vulgare, the gall fly was recorded on C. arvense (at six locations) and C. palustre (at one location). The probability of the presence of attack on C. arvense was positively correlated with the attack intensity on C. vulgare, suggesting that attack on C. arvense is a ‘spill-over effect’ occurring where seedheads of C. vulgare are in limited supply.

Population genetics and diversity structure of an invasive earthworm in tropical and temperate pastures from Veracruz, Mexico.

Pontoscolex corethrurus (Müller, 1857) is an invasive tropical earthworm, globally distributed. It reproduces through parthenogenesis, which theoretically results in low genetic diversity. The analysis of the population structure of P. corethrurus using molecular markers may significantly contribute to understanding the ecology and reproductive system of this earthworm species. This work assessed the genetic diversity and population structure of P. corethrurus with 34 polymorphic inter simple sequence repeat markers, covering four populations in tropical and temperate pastures from Veracruz State. Nuclear markers distinguished two genetic clusters, probably corresponding to two distinct genetic lineages. The number of clones detected in the AC population was lower than expected for a parthenogenetic species. Also, the apparent lack of differences in population structures related to the geographic region among the populations studied may indicate that human-mediated transference is prevalent in these areas. Still, most individuals apparently belong to lineage A, and only a few individuals seem to belong to the lineage B. Thus, the admixture signatures found among the four populations of P. corethrurus may have facilitated a successful invasion by directly increasing fitness. In summary, addressing the genetic variation of P. corethrurus with ISSR markers was a suitable approach, as it evidenced the genetic diversity and relationships in the populations evaluated.

Distribution of the Red Imported Fire Ant Solenopsis invicta (Hymenoptera: Formicidae) in Central Florida Pastures.

Habitat disturbance has been found to facilitate the introduction of a wide range of species, including the red imported fire ant Solenopsis invicta Buren (Hymenoptera: Formicidae: Myrmicinae). Despite the link between S. invicta colonization and disturbance, little is known about how different intensities or types of disturbance might impact S. invicta populations. In this study, we used S. invicta populations in cattle pastures to understand how variation in disturbance type and frequency correlates with the density of S. invicta mounds. In total, 56 plots were surveyed for mound abundance during both the wet and dry seasons on a subtropical south Florida ranch. Explanatory variables were grouped into five categories based on disturbance type: 1) historic pasture conversion; 2) modern pasture management (mowing, dragging, chopping, or aerating); 3) grazing intensity (a measure vegetation height and dung pat abundance); 4) distance to human-made and natural localized disturbance (roads, ditches, and wetlands); and 5) abiotic conditions (soil temperature, soil moisture). Overall, the average number of mounds per plot was not significantly different between seasons, but was significantly higher in intensive pastures, which are converted to nonnative forage grasses than in seminative pastures during the dry season. Time since soil disturbance (aeration and chopping of pasture) was a significant predictor of S. invicta densities in both dry and wet seasons, with an increase in time since disturbance being associated with higher mound densities. Other forms of pasture management that did not disturb the soil, such as dragging and mowing, as well as distance to localized disturbances (wetlands, roads, and ditches) were not found to have a significant correlation in either season.

A colourimetric microplate assay for simple, high throughput assessment of synthetic and biological nitrification inhibitors

A simple, rapid, colourimetric method for screening biological nitrification inhibitors in plants is presented. Our approach combines the use of the Griess assay to track the rate of nitrite (NO2 −) production by pure cultures of ammonia oxidising bacteria in the presence and absence of nitrification inhibitors with a simple method for collecting root exudates from plants. NO2 − formation was tracked colourimetically on a microplate reader over 9 h of incubation. The advantage of this method is that it provides a simple, high throughput means of measuring biological nitrification inhibition in root exudates, using wild-type bacterial cultures. NO2 − formation rates and inhibition levels measured using the high through-put method were highly correlated with those measured by tracking NO2 − formation using a segmented flow analyser. The method was able to quantify inhibition of Nitrosomonas europaea by the synthetic nitrification inhibitors allythiourea (AT), dicyandiamide (DCD) and 3,4,-dimethylpyrazole phosphate (DMPP) with IC50 values similar to those reported in the literature. The method detected biological nitrification inhibition (BNI) in root exudates from Brachiaria humidicola and the lack of BNI in root exudates from wheat cv. Janz with minimal alteration of the exudates prior to testing. The results also showed that the more common soil ammonia oxidising bacterium (AOB), Nitrosospira multiformis, was much less sensitive to AT and DCD than N. europaea but had similar sensitivity to DMPP. This method provides a potentially useful way of screening large numbers of root exudate samples allowing for phenotyping of the BNI trait in crop and pasture populations which will be required for the trait to be introduced into commercial varieties.

Recovering mountain Mediterranean grasslands for breeding birds: ecology and population status shape species responses to management

The Mediterranean basin is considered one of the most important biodiversity hotspots. This extraordinary richness originates mainly from thousands of years of human activities that deeply modified the landscape. Safeguarding the so-called cultural landscapes plays a key role in biodiversity conservation. In this paper we present the results of our monitoring of the effects of the life project “Preservation of mountain grasslands of the Tuscan Apennines”, mainly characterized by shrub-cutting actions, on bird populations in the Pratomagno pasture, one of the two areas where the project was implemented, a SPA in eastern Tuscany. The monitoring plan covers a period of 5 years. We tested the effects of shrub clearing on a series of bird community parameters, such as abundance and richness of common species and of some ecological guilds. We also tested the timing of the response to the interventions (immediate or drawn out over time). Our results show a dramatic decrease of birds associated with shrubland, while there were no important increases in grassland species, with the sole exception of Woodlark. Regardless of their positive or negative effects, our results show different response times for individual species or groups of species. Moreover, species with a bad regional conservation status increased less than those with a good one. Broadly speaking, these results suggest that the efficacy of such projects depends on a careful preliminary assessment of a number of aspects, encompassing the nature of the interventions themselves and the characteristics of the target sites, but also the type of response of target species and the conservation status of target populations.

Mating system variation among populations, individuals and within and among fruits in Bertholletia excelsa

Abstract The aim of this study was to investigate variation in mating system among three Brazilian Amazon populations of the tree Bertholletia excelsa with different levels of anthropogenic interventions. We collected open-pollinated seeds from one natural population, remnant trees dispersed in a pasture, and trees from a plantation. Outcrossing rate not varied among the populations and indicates that all seeds were originated from outcrossing (tm=1.0). Mating among relatives was significant higher in the plantation than forest and pasture populations, probably due the fact that many trees are related in the plantation. Correlated mating was significantly higher in pasture (rp=0.47) and plantation (rp=0.51) than in the natural population (rp=0.22), suggesting that trees in natural population are pollinated by a higher number of pollen donors. The paternity correlation was significantly higher within (rp(w)=0.41) than among fruits (rp(a)=0.18), showing a higher probability to find full-sibs within than among fruits. The fixation index was generally lower in seed trees than in their seedlings, suggesting selection for heterozygous individuals from seedling to adult stages. Progeny arrays collected from the natural population had a lower proportion of pairwise full-sibs than in pasture and plantation and higher variance effective size (2.75) than trees in pasture (2.15) and plantations (2.22). Results highlight that seed collections for conservation, breeding and reforestation programs preferentially should be carried out in natural populations due low proportion highest variance effective size within progeny.

Genetic inference of epiphytic orchid colonization; it may only take one

Colonization of vacant habitat is a fundamental ecological process that affects the ability of species to persist and undergo range modifications in continually shifting landscapes. Thus, understanding factors that affect and limit colonization has important ecological and conservation implications. Epiphytic orchids are increasingly threatened by various factors, including anthropogenic habitat disturbance. As cleared areas (e.g. pastures) are recolonized by suitable host trees, the establishment and genetic composition of epiphytic orchid populations are likely a function of their colonization patterns. We used genetic analyses to infer the prevailing colonization pattern of the epiphytic orchid, Brassavola nodosa. Samples from three populations (i.e. individuals within a tree) from each of five pastures in the dry forest of Costa Rica were genotyped with neutral nuclear and chloroplast markers. Spatial autocorrelation and hierarchical genetic structure analyses were used to assess the relatedness of individuals within populations, among populations within pastures and among populations in different pastures. The results showed significant relatedness within populations (mean r=0.166) and significant but lower relatedness among populations within a pasture (mean r=0.058). Our data suggest that colonization of available habitats is by few individuals with subsequent population expansion resulting from in situ reproduction, and that individuals within a tree are not a random sample of the regional seed pool. Furthermore, populations within a pasture were likely colonized by seeds produced by founders of a neighbouring population within that pasture. These results have important ramifications for understanding conservation measures needed for this species and other epiphytic orchids.

Verticillium dahliae and other pathogenic fungi in Cirsium arvense from New Zealand pastures: occurrence, pathogenicity and biological control potential

Cirsium arvense (Californian thistle) populations in pastures throughout New Zealand were surveyed in November–December 2005 (30 sites) and January–March 2006 (94 sites) to identify potential biological control agents for this weed. Fungi were isolated from healthy shoots and shoots showing leaf yellowing/browning, stunting or localized lesions. Verticillium dahliae was isolated most frequently, being detected at 30% of the sites in 2005 and at 51% in 2006. Other pathogenic/saprophytic fungi isolated included Sclerotinia sclerotiorum, Plectosphaerella cucumerina and species of Cylindrocarpon, Rhizoctonia and Phoma. Inoculating cut shoots of C. arvense with conidia of V. dahliae, or cutting shoots with a wetted blade previously used to cut infected shoots resulted in yellowing of leaves and shoot death. Spread of V. dahliae infection among plants facilitated by cutting when wet may explain the reported demise of C. arvense populations mown during rainfall and the fungus may have potential as a bioherbicide.

Varying atmospheric methane concentrations affect soil methane oxidation rates and methanotroph populations in pasture, an adjacent pine forest, and a landfill

We describe experiments to better understand how CH4 oxidation rates by different methanotroph communities respond to changing CH4 concentrations. We used a novel system of automatically monitored chambers to investigate the response of CH4 oxidation rates in a New Zealand pasture and adjacent pine forest soil exposed to varying atmospheric CH4 concentrations.Type II methanotrophs that dominate CH4 oxidation in the forest soil became progressively saturated as CH4 concentrations rose from ambient (1.8ppmv) to 570ppmv, as shown by a decrease in uptake efficiency from 20% to 2% removal. By contrast, CH4 oxidation in the pasture soil where Type I methanotrophs dominate increased in proportion to the increase in CH4 inlet concentration, oxidising about 2% of the inlet CH4 flux throughout. Modelling based on Michaelis-Menten kinetics revealed that low-affinity (Type I) methanotrophs were solely responsible for CH4 oxidation in pasture soils, whereas high affinity (Type II) methanotrophs only contributed about 10% of the CH4 oxidation in the forest soil. Increased aeration status using a soil–perlite (1:1) mixture doubled CH4 oxidation rates at both ambient (1.8ppmv) and 40ppmv atmospheric CH4. A similar volcanic soil previously exposed for 8 y to high CH4 fluxes from a landfill had removal efficiencies consistently above 95% for atmospheric CH4 concentrations up to 7500ppmv when the CH4 oxidation rate was7000μg CH4 kg−1soil h−1.

Land use and hydroclimatic influences on Faecal Indicator Organisms in two large Scottish catchments: Towards land use-based models as screening tools

Faecal Coliform (FC) bacteria were used as Faecal Indicator Organisms (FIOs) for assessment of microbiological pollution risk in two large, mixed land use catchments in Scotland. FC counts varied spatially in relation to land use and human population and resulting trophic status. These were highest in catchments with a high cover of improved pasture (which was assumed to be a proxy for cattle and sheep grazing densities) and significant human populations. FC counts were lowest in oligotrophic upland areas, where domesticated animal populations were low. In both lowland and upland catchments, peak FC counts occurred under periods of elevated flows during summer. However, in lowland agricultural catchments of higher trophic status, contamination appears to be chronic and occurs all year round. In contrast, upland headwater catchments exhibit more episodic peaks in relation to high flow events. Larger scale catchments integrate the inputs from contrasting head water streams. Spatial variations in stream FC concentrations can be predicted to a first approximation using multiple regression based on catchment characteristics. Land cover was the most important factor, with percentage improved pasture being the primary control and human population being of secondary importance. These two factors could explain 78% of the variation in mean annual FC concentrations and 65% of the 95th percentile. This simple linear model provides a screening tool for rapid assessment of pollution risk in unmonitored catchments. However, improved prediction of short-term dynamics and peak values requires higher resolution sampling and process-based models of FC production, survival and transport. A particularly important need is an improved characterisation of the hydrological connectivity which controls the flux from pollutant reservoirs on the landscape into river channel networks.

Earthworm abundance and species composition in organic forage production systems of northern Colorado receiving different soil amendments

We evaluated the effects of soil amendments on earthworm communities in organic annual forage and perennial pasture systems in northern Colorado. In the annual forage study (1) an annual warm season grass teff (Eragrostis tef) and (2) bare fallow were main plot treatments and received one of three soil amendments: (1) composted dairy manure (CDM), (2) raw dairy manure (RDM), and (3) no amendment as control. For the perennial pasture study, CDM was topdressed onto a grass mixture consisting of orchardgrass, smooth and meadow bromegrass at rates ranging from 0 to 44.8Mgha−1. At both sites, earthworm and soil samples were collected in July 2009. The earthworms identified from both systems were composed of endogeic species Aporrectodea rosea (Savigny), A. tuberculata (Eisen), and A. turgida (Eisen), the first being found only in the perennial pasture. In the annual forage study, earthworm total abundance did not differ between teff and bare fallow treatments. However, within bare fallow treatment, earthworm total abundance was significantly affected by soil amendment, with CDM averaging approximately 1.4 and 5.4 times greater earthworm total abundance than RDM and the control, respectively. Earthworm total abundance was found to be positively correlated with soil Cu (R=0.51, P=0.03) and K (R=0.58, P=0.01). In the perennial pasture, earthworm total abundance tended to increase with an increase in the CDM rate to 33.6Mgha−1. However, no further increase was observed when the CDM rate was increased to 44.8Mgha−1. At this site, earthworm total abundance was negatively correlated with EC (R=−0.37, P=0.02). Our results suggest that high quality (low C/N ratio) dairy manure is important for maintaining a high earthworm population. Larger CDM application rates appear to discourage earthworm populations probably due to salinity stress. Further study is necessary to elucidate the exact effects of manure quality and quantity on earthworm populations in annual forages and perennial pastures.

Resolving the urban nest predator paradox: The role of alternative foods for nest predators

Urbanization is a leading cause of species endangerment in the United States; however, certain species thrive in urban habitats. The loss of key predators or the addition of new predators in urban areas could alter the structure of urban communities. A reduction in nest predation is hypothesized to explain the high density of urban birds, yet urban areas typically have increased populations of avian nest predators. The loss of important nest predators in urban habitats, prey switching of urban predators, or successful nest defense against avian nest predators could explain this urban nest predator paradox. To assess these hypotheses I compared nest predation rates of Northern mockingbirds ( Mimus polyglottos) in parking lots and residential neighborhoods to populations in pastures and wildlife preserves during 2007–2009 in Florida, USA and placed video cameras on a subset of nests in 2008–2009. Data do not support the hypothesis that urban nest predation rates are consistently lower than non-urban nest predation rates. Of the 56 nest predation events recorded, cats were the dominant urban predator and Cooper’s hawks ( Accipiter cooperii) were the dominant non-urban predator. There was no evidence for a loss of important nest predators in urban habitats; however, prey switching by Cooper’s hawks likely occurred. There was also indirect evidence for the importance of nest defense. Furthermore, some of the cats recorded as nest predators in residential neighborhoods were owned cats and all but one cat predation event occurred at night. To reduce nest predation rates, cat owners should keep their cats indoors at night.

Pimpinella saxifraga is maintained in road verges by mosaic management

Road verges have been proposed as refuges for vulnerable grassland species in the modern, changing landscape, but little comparative knowledge exists on how management regimes affect population dynamics of such species. We compared the effects of various management regimes on the population dynamics of Pimpinella saxifraga in road verges and pastures, using elasticities and LTRE analyses with underlying vital rates as model components in three road verges and three pastures in an agricultural landscape in W Norway. Under present management regimes, we observed slightly higher population growth rates in pastures than in road verges. The pasture populations had comparatively lower survival but higher reproduction than the road verge populations, thus demonstrating a management-induced negative correlation. Such negative correlations may reflect species’ adaptability to environment changes, thereby reducing the extinction risk. We generally observed small changes in P. saxifraga demography to management but considerable variation along environmental gradients, underlining the importance of studying multiple populations. The linear form of the road verges enabled a fine-scale mosaic application of different management regimes. Individuals growing in zones receiving survival-lowering management produced seeds that compensated the lack of seeds in zones receiving fertility-lowering management. The observation of ‘mosaic’ management that allows road verge metapopulations to complement each others life-history characteristics exemplifies the unique potential of road verge ecosystems to maintain semi-natural grassland species like P. saxifraga, as well as providing habitats for different species exhibiting various life histories.

A history of facial eczema (pithomycotoxicosis) research

Facial eczema (pithomycotoxicosis), a photosensitisation of ruminants grazing pasture, has been known in New Zealand for over 100 years, but its cause, a toxin produced by a largely saprophytic fungus, Pithomyces chartarum, growing on litter at the base of pasture and sporing profusely under warm moist conditions in late summer and autumn, was found only 50 years ago. As the fungus spores it produces the toxin sporidesmin which, when eaten by sheep, cattle, goats or deer, causes liver injury with inflammation and blockage of bile ducts. Phylloerythrin, a photodynamic breakdown product of chlorophyll, is no longer excreted but circulates in the blood, causing lesions of unpigmented skin when the affected animal is exposed to sunlight. Lesions do not appear until at least a week after sporidesmin has been ingested, and this lag period delayed discovery of the causative agent, first thought to have been an abnormal metabolite of rapidly growing ryegrass. However, before the role of P. chartarum was discovered, the pathology of the disease had been described, toxic extracts had been made from herbage mown from pastures associated with facial eczema outbreaks, and the weather conditions preceding outbreaks had been defined. When the causative agent was identified, cultures of P. chartarum on artificial media produced sporidesmin for chemical characterisation and animal dosing trials. Control of facial eczema in the field was first by avoiding toxic pasture, detected by P. chartarum spore counts on herbage, later by reducing P. chartarum pasture populations by spray application of substituted thiabendazole fungicides, and later still by protecting animals with oral doses of zinc at close to toxic levels. Sheep vary widely in their sensitivity to sporidesmin, either under field conditions in facial eczema outbreaks or when dosed orally with sporidesmin, and breeding resistant animals by selection after sporidesmin challenge is the best long‐term control method at present. Whilst facial eczema outbreaks have been most severe in New Zealand, the disease has been reported from an increasing number of countries with warm temperate climates in which ruminants are intensively grazed on pasture. The great majority of New Zealand isolates of P. chartarum produce sporidesmin, but varying proportions of those in other countries do not.

Pollination context effects in the high‐mountain dimorphic Armeria caespitosa (Plumbaginaceae): Neighborhood is something more than density

Frequency-dependent processes are relevant for flowering plant reproduction, especially for species with disassortative mating. In an individual-based study, we tested not only the effects of local density on reproductive success at small spatial scales, but also those of neighborhood quality. To test the neighborhood effects on the reproduction of Armeria caespitosa, a dimorphic Mediterranean high-mountain endemic, we introduce a novel pollination context (PC) index that considered the distance, floral display, and floral morph of neighbors at small scales (within 2 m from the focal plant), studying rock and pasture populations at both edges of the species altitudinal distribution. Reproductive success depended significantly on PC only at the low populations, suggesting that the PC effects are population-dependent and supporting the hypothesis that the neighborhood quality influences the reproductive success of A. caespitosa at least in stressful conditions. Moreover, fruit set was morph-dependent in the high-pasture population. The specific role of the spatial structure of compatible vs. incompatible morphs at small scales of the dimorphic self-incompatibility system in Armeria deserves further attention. Parameters other than plant density are useful for the study of small-scale density-dependent processes that affect pollination and other reproductive components, especially if they integrate neighborhood quality information at adequate spatial scales.