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Photodegradation of plant litter cuticles enhances microbial decomposition by increasing uptake of non-rainfall moisture

Litter decomposition plays a central role in carbon cycling in terrestrial ecosystems worldwide. In drylands, which cover 40% of the Earth's land surface, photodegradation and biotic decomposition driven by non-rainfall moisture are important mechanisms of litter decay, though studies have only recently begun examining interactions between these two processes. We describe a novel priming mechanism in which photodegradation and biotic decay of the cuticle of plant litter increases litter absorption of non-rainfall moisture (fog, dew, and water vapor), supporting greater microbial decomposition. We used several field experiments in a coastal fog desert and a series of in situ observations to demonstrate a relationship between solar radiation, cuticle integrity, water absorption rates, and mass loss. Experimentally attenuating solar radiation for 36 months slowed mass loss, reduced cuticle degradation, and decreased litter moisture uptake relative to litter under ambient sunlight controls. In a separate field experiment, removing the cuticle of recently senesced grass tillers increased mass loss four-fold over 6 months relative to controls. Tillers with degraded cuticles also absorbed 3.8 times more water following an overnight dew event than did those with intact cuticles. Finally, fungal growth was consistently greater on the sun-facing side of in situ tillers than on the shaded side, coincident with greater cuticle degradation. We present a conceptual model where the cuticle of plant litter acts as a water-resistant barrier that is first degraded by solar radiation and surficial microbes, increasing litter's ability to absorb enough water during non-rainfall moisture events to support substantial biotic decomposition inside the tissue. Considering how photodegradation and non-rainfall moisture are both substantial drivers of litter decomposition in drylands, understanding how they interact under realistic field conditions will help us better predict how these systems are responding to changing climate regimes.

Mycorrhizal colonization and root diameter of native and invasive plants of eastern North America

Arbuscular mycorrhizal colonization (total and arbuscules) were measured in roots of 10 species of eastern North American woody plants. Five were non-native invasive and 5 were native species. Roots were collected from ingrowth cores over three harvests during a single season, from a common garden. Diameter was estimated from published root density and specific root length values for each species.

Plant collections for conservation and restoration: can they be adapted and adaptable?

Plant collections are important for the conservation of threatened species, and as a source of material for ecological restoration. Typically we want collections to have high genetic diversity so populations founded from it are adaptable to future challenges. Sometimes, we have additional objectives for collections, such as enrichment for desirable traits controlled by adaptive alleles. We used landscape genomic datasets for two plants, Westringia fruticosa and Wilkiea huegeliana, to design collections that are genetically diverse, and that are adapted to warming climates. We characterized temperature adaptation by: (i) using the mean annual temperature of the sites of origin of the plants, and (ii) using the representation of alleles that are associated with warm temperatures. In Westringia fruticosa, there was a negative correlation, or tradeoff between designing a collection that was both genetically diverse and adapted to warm temperatures. This tradeoff was weaker in Wilkiea huegeliana. We hypothesized this was because neutral genetic variation was strongly correlated with temperature in Westringia fruticosa, and not in Wilkiea huegeliana. Accordingly, when we shuffled the temperature data, breaking up the covariance between Westringia fruticosa genetic variation and temperature, there was a relaxation of the observed tradeoff. In sum, we explore tradeoffs between genetic diversity and environmental adaptation in plant collections, and highlight factors that influence the strength of these tradeoffs. This represents a useful step towards understanding when selection will have a large cost in genetic diversity, and when it will be possible to design a collection that is both adapted and adaptable.

Predation risk can modify the foraging behaviour of frugivorous carnivores: implications of rewilding apex predators for plant-animal mutualisms

Apex predators play key roles in food webs and their recovery can trigger trophic cascades in some ecosystems. Intra-guild competition can reduce the abundances of smaller predators and perceived predation risk can alter their foraging behaviour thereby limiting seed dispersal by frugivorous carnivores. However, little is known about how plant-frugivore mutualism could be disturbed in the presence of larger predators. We evaluated the top-down effect of the regional superpredator, the Iberian lynx (Lynx pardinus), on the number of visits and fruits consumed by medium-sized frugivorous carnivores, as well as the foraging behaviour of identified individuals, by examining the consumption likelihood and the foraging time. We carried out a field experiment in which we placed Iberian pear (Pyrus bourgaeana) fruits beneath fruiting trees and monitored pear removal by frugivorous carnivores, both inside and outside of lynx ranges. Using camera traps, we recorded the presence of the red fox (Vulpes vulpes), the Eurasian badger (Meles meles) and the stone marten (Martes foina), as well as the number of fruits they consumed and their time spent foraging. Red fox was the most frequent fruit consumer carnivore. We found there were fewer visits and less fruit consumed by foxes inside of lynx ranges, but lynx presence did not seem to affect badgers. We did not observe any stone marten visits inside of lynx territories. The foraging behaviour of red foxes was also altered when inside of lynx ranges whereby foxes were less efficient, consuming less fruit per unit of time and having shorter visits. Local availability of fruit resources, forest coverage and individual personality also were important variables to understand visitation and foraging in a landscape of fear. 5. Our results show a potential trophic cascade from apex predators to primary producers. The presence of lynx can reduce frugivorous carnivore numbers and induce shifts in their feeding behaviour that may modify the seed dispersal patterns with likely consequences for the demography of many fleshy-fruited plant species. We conclude that knowledge of the ecological interactions making up trophic webs is anasset to design effective conservation strategies, particularly in rewilding programs.

opencc-by-4.0Mar 2022View details →

Contigs scaffolding with Hi-C for plant genomes

Example contigs fasta file use in the protocol: Contigs scaffolding with Hi-C for plant genomes

Human impact, climate and dispersal strategies determine plant invasion on islands

Aim: Biological invasions are likely determined by species dispersal strategies as well as environmental characteristics of a recipient region, especially climate and human impact. However, the contribution of climatic factors, human impact and dispersal strategies in driving invasion processes is still controversial and not well embedded in the existing theoretical considerations. Here, we study how climate, species dispersal strategies and human impact determine plant invasion processes on islands distributed in all major oceans in the context of directional ecological filtering. Location: Six mountainous, tropical and subtropical islands in three major oceans: Island of Hawai'i and Maui (Pacific), Tenerife and La Palma (Atlantic), La Réunion and Socotra (Indian Ocean). Taxon: Vascular Plants. Methods: We recorded 360 non-native species in 218 plots along roadside elevational transects covering the major temperature, precipitation and human impact (i.e. road density) gradients of the islands. We collected dispersal strategies for a majority of the recorded species and calculated the environmental niche per species using a hypervolume approach. Results: Non-native species' generalism (i.e., mean community niche width) increased with precipitation, elevation and human impact but showed no relationship with temperature. Increasing precipitation led to environmental filtering of non-native species resulting in more generalist species under high precipitation conditions. We found no directional filtering for temperature but an optimum range of most species between 10 and 20°C. Niche widths of non-native species increased with the prevalence of certain dispersal strategies, particularly anemochory and anthropochory. Main conclusions: Plant invasion on tropical and subtropical islands seems to be mainly driven by precipitation and human impact, while temperature seems to be of little importance. Furthermore, anemochory and anthropochory are dispersal strategies associated with large niche widths of non-native species. Our study allows a more detailed look at the mechanisms behind directional ecological filtering of non-native plant species in non-temperature limited ecosystems.

Data from: Large herbivores trigger spatiotemporal changes in forest plant diversity

Large herbivores can exert top-down control on terrestrial plant communities, but the magnitude, direction, and scale-dependency of their impacts remain equivocal, especially in temperate and boreal forests, where multiple disturbances often interact. Using a unique, long-term and replicated landscape experiment, we assessed the influence of a high density of white-tailed deer (Odocoileus virginianus) on the spatiotemporal dynamics of diversity, composition, and successional trajectories of understorey plant assemblages in recently logged boreal forests. This experiment provided a rare opportunity to test whether deer herbivory represents a direct filter on plant communities or if it mainly acts to suppress dominant plants which, in turn, release other plant species from strong negative plant-plant interactions. These two hypotheses make different predictions about changes in community composition, alpha and beta diversity in different vegetation layers and at different spatial scales. Our results showed that deer had strong effects on plant community composition and successional trajectories, but the resulting impacts on plant alpha and beta diversity patterns were markedly scale-dependent in both time and space. Responses of tree and non-tree vegetation layers were strongly asymmetric. Deer acted both as a direct filter and as a suppressor of dominant plant species during early forest succession, but the magnitude of both processes was specific to tree and non-tree vegetation layers. Although our data supported the ungulate-driven homogenization hypothesis, compositional shifts and changes of alpha diversity were poor predictors of beta diversity loss. Our findings underscore the importance of long-term studies in revealing non-linear temporal community trends, and they challenge managers to prioritize particular community properties and scales of interest, given contrasting trends of composition, alpha, and beta diversity across spatial scales.

Data from: Woody plant secondary chemicals increase in response to abundant deer and arrival of invasive plants in suburban forests

Plants in suburban forests of eastern North America face the dual stressors of high white-tailed deer density and invasion by nonindigenous plants. The combination of chronic deer herbivory and strong competition from invasive plants could alter a plant's stress- and defense-related secondary chemistry, especially for long-lived juvenile trees in the understory, but this has not been studied. We measured foliar total antioxidants, phenolics, and flavonoids in juveniles of two native trees, Fraxinus pennsylvanica (green ash) and Fagus grandifolia (American beech), growing in six forests in the suburban landscape of central New Jersey, USA. The trees grew in experimental plots that had been subject for 2.5 years to factorial treatments of deer access/exclosure X addition/no addition of the nonindigenous invasive grass Microstegium vimineum (Japanese stiltgrass). As other hypothesized drivers of plant secondary chemistry, we also measured non-stiltgrass herb layer cover, light levels, and water availability. Univariate mixed model analysis of the deer and stiltgrass effects and multivariate structural equation modeling (SEM) of all variables showed that both greater stiltgrass cover and greater deer pressure induced antioxidants, phenolics, and flavonoids, with some variation between species. Deer were generally the stronger factor, and stiltgrass effects were most apparent at high stiltgrass density. SEM also revealed that soil dryness directly increased the chemicals; deer had additional positive, but indirect, effects via influence on the soil; in beech PAR positively affected flavonoids; and herb layer cover had no effect. Juvenile trees' chemical defense/stress responses to deer and invasive plants can be protective, but also could have a physiological cost, with negative consequences for recruitment to the canopy. Ecological implications for species and their communities will depend on costs and benefits of stress/defense chemistry in the specific environmental context, particularly with respect to invasive plant competitiveness, extent of invasion, local deer density, and deer browse preferences.

opencc-by-4.0Mar 2022View details →

Data from: Net plant interactions are highly variable and weakly dependent on climate at the global scale

Data were collected from the literature. The dataset is a compilation of published studies. An ISI Web of Science search covering the time period from 1900 onwards was conducted to identify the publications on plant interactions. Each publication was individually reviewed, and the reference list was inspected to identify additional relevant publications. We collected a total 1,220 publications for data compilation. We built a global dataset of 10,502 pairs of plant interaction data.

Soil property, microbial abundance, and plant and invertebrate biomass data across a natural soil temperature gradient in Iceland from August 2018

This is a dataset of soil physiochemical properties, bacterial and fungal abundance, and above and belowground plant and invertebrate biomass, sampled at 40 plots in the Hengill geothermal valley, Iceland, from 15th to 22nd August 2018. The plots span a temperature gradient of 10-35 °C over the sampling period, and this temperature gradient is consistent over time. The dataset also includes data on the decomposition rate of soil organic matter, which was sampled at 60 plots in the Hengill valley from May to July 2015.

Mutualism has its limits: consequences of asymmetric interactions between a well-defended plant and its herbivorous pollinator

Concern for pollinator health has focused on social bees and their agricultural services, but not all pollinators are bees, and their ecosystem services also promote biodiversity and conservation. Pollinating herbivores generate ecological conflicts when they utilize the same plant as a nectar source and larval host. We tracked individual-level metrics of pollinator health – growth, survivorship, fecundity – across the life cycle of a pollinating herbivore, the hawkmoth Hyles lineata, through its interactions with Oenothera harringtonii, a rare plant polymorphic for the floral volatile (R)-(-)-linalool. Linalool had no impact on moth attraction to O. harringtonii flowers but suppressed oviposition on experimentally supplemented plants. Leaves of O. harringtonii showed robust resistance against herbivory by H. lineata from leaf-disc to wholeplant scales, through poor larval growth and survivorship. Higher larval performance on other Oenothera species indicates that constitutive herbivore resistance by O. harringtonii is not generic. Leaf volatiles differed among populations of O. harringtonii but were not induced by larval herbivory. Elagitannins and other phenolics varied among leaf, bud and seed tissues but showed no evidence of herbivore induction. Our findings highlight asymmetric plant-pollinator interactions and the importance of third parties, such as alternative host plants, in maintaining pollinator health.

opencc-by-4.0Mar 2022View details →

Virtual Storage Plant (VSP) final demonstration of congestion management

This the dataset of final demostration of using distributed control with consensus algorithm for congestion management using a virtual storage plant. The dataset contains raw data from 1 experiment for 1 HLU5-UC4 scenarios: TC_5.04. The experiments were conducted at the University of Zagreb's Smart Grid Laboratory (SGLab).

Odor of achlorophyllous plants' seeds

<div class="page"> <div class="section"> <div class="layoutArea"> <div class="column"> Seed dispersal by ants is an important means of migration for plants. Many myrmecochorous plants have specialized appendages in their seeds called elaiosome, which provide nutritional rewards for ants, and enable effective seed dispersal. However, some non-myrmecochorous seeds without elaiosomes are also dispersed by ant species suggesting that additional mechanisms other than elaiosomes for seed dispersal by ants. The seeds of the achlorophyllous and myco-heterotrophic herbaceous plant Monotropastrum humile are very small without elaiosomes, we investigated whether odor of the seeds could mediate seed dispersal by ants. We performed a bioassay using seeds of M. humile and the ant Nylanderia flavipes to demonstrate ant-mediated seed dispersal. We also analyzed the volatile odors emitted from M. humile seeds and conducted bioassays using dummy seeds coated with seed volatiles. Although elaiosomes were absent from the M. humile seeds, the ants carried the seeds to their nests. They also carried the dummy seeds coated with the seed volatile mixture to the nest, and left some dummy seeds inside the nest and discarded the rest of the dummy seeds outside the nest with a bias toward specific locations, which might be conducive to germination. We concluded that, in M. humile seeds, volatile odor mixtures were sufficient to induce seed carrying behavior by the ants even without elaiosomes. </div> </div> </div> </div>

opencc-by-4.0Apr 2022View details →

Dataset for Gianinetti 2022 - plants-1652229

These are the longitudinal germination data for my paper "In Dormant Red Rice Seeds, the Inhibition of Early Seedling Growth, but Not of Germination, Requires Extracellular ABA" published on Plants (MDPI). The first five columns (treatment, trt; experiment start date, exp; day of observation, day; replicate number, rep; number of seeds in each replicate, n) are the factor variables and the last three columns (pericarp splitting, ps; first growth stage S1, fgs; difference between ps and fgs, diff) are the response variables. The response variables are cumulative counts of binomial events (for example, cumulative number of germinated seeds).

opencc-zeroDec 2022View details →

Directed endozoochorous dispersal by scavengers facilitate sexual reproduction in otherwise clonal plants at cadaver sites

<ol> <li>The regeneration niche of many plant species involves spatially and temporally unpredictable disturbances, called recruitment windows of opportunity. However, even species with clear dispersal adaptations such as fleshy berries may not successfully reach such elusive regeneration microsites. Ericaceous, berry-producing species in the northern hemisphere demonstrate this dispersal limitation. They are said to display a reproductive paradox owing to their lack of regeneration in apparently suitable microsites despite considerable investment in producing large quantities of berries.</li> <li>Cadavers generate vegetation-denuded and nutrient-rich disturbances termed cadaver decomposition islands. Cadavers attract facultative scavengers with considerable capacity for endozoochorous seed dispersal. We hypothesize that cadaver decomposition islands facilitate recruitment in berry-producing ericaceous species due to endozoochorous dispersal directed towards favorable microsites with low competition.</li> <li>We examined seedling establishment within a permanent, semi-regular 10 × 10 m grid across an ungulate mass die-off on the Hardangervidda plateau in southeastern Norway. Competing models regarding the relative importance of factors governing recruitment were evaluated, specifically cadaver location (elevated seed rain) and microsite conditions (competition).</li> <li>We found that cadaver decomposition islands did facilitate seedling establishment, as cadaver density was the best predictor of seedling distribution. Other important factors governing seedling establishment such as percentage cover of soil and vascular plants alone were inadequate to explain seedling establishment.</li> <li> Synthesis: This study provides a novel understanding of sexual reproduction in species with cryptic generative reproduction. The directed nature of endozoochorous dispersal combined with long-distance dispersal abilities of medium to large vertebrate scavengers towards cadavers allows plants to exploit the advantageous but ephemeral resource provided by cadaver decomposition islands.</li> </ol>

opencc-by-4.0Sep 2021View details →

Dataset on the Chemistry of Australian Plant Exudates from Historical Collection

FT-IR.zip: FT-IR dataset GC-MS.zip: GC-MS dataset ICP-MS.zip: ICP-MS dataset Py-GC-MS.zip: Py-GC-MS dataset XRS C K-edge.zip: X-ray Raman spectroscopy dataset at the carbon K edge XRS O K-edge.zip: X-ray Raman spectroscopy dataset at the carbon O edge

Flexible diets enable pollinators to cope with changes in plant community composition

Switching plant species visited by pollinators (partner flexibility), has been proposed as a behavioural mechanism able to attenuate the negative impacts of shifts in plant communities on pollination. However, it is unclear if the magnitude of such response is generalizable or depends on the environmental context. Moreover, the ability of pollinators to exploit plants with dissimilar traits (trait flexibility) has been overlooked, even though it can affect the spectrum of new partners available. To shed some light on this problem, we quantified partner and trait flexibility in five communities from four different environments, from Alpine to semi-arid. We evaluated if the rate at which pollinators incorporated new plant species throughout the flowering season was similar across communities or context-dependent. Then, we assessed if pollinators changed the type of flowers visited and if such trait flexibility was related to their capacity to visit new plant species. Finally, we developed an agent-based model to explore if diet flexibility can protect pollination when the plant community changes. To this end, we used scenarios of phenological decoupling. In general, pollinators switched interaction partners to cope with the temporal replacement of plant species. Yet, the magnitude of such behaviour varied across communities, probably in response to differences in the number of floral resources available. Also, pollinators were able to visit plant species with dissimilar traits, though both components of diet flexibility (partner identity and traits) did not necessarily covary. Thus, to have a full picture of pollinators' diet flexibility we need to consider the floral traits of partners. Finally, our theoretical model shows that diet flexibility can protect pollination after shifts in plant communities; but that such positive effects are limited by trait-matching between co-occurring species. Overall, our study highlights the importance of incorporating plant traits when evaluating the ability of pollinators to find new interaction partners. Besides, our simulation results suggest that diet flexibility may not unequivocally protect pollination against changes in plant communities, especially if they entail shifts in the characteristics of the floral assemblage, and hence, the ability of pollinators to find new interaction partners can be compromised.

Return of forest structure and diversity in tropical restoration plantings

Stepping-stone restoration plantings can reconcile conservation goals and local land use needs in highly fragmented ecosystems. We explored how initial planting composition influences recruiting plant species density, diversity, abundance, and forest structure in a 13-year-old restoration experiment in Los Tuxtlas, Veracruz, Mexico. Treatments included 8 fenced plantings with animal-dispersed species, 8 plantings with wind-dispersed species, 8 unplanted plots to favor natural succession, and 8 plots in the primary forest as reference sites. We predicted that that by attracting more seed dispersers, animal-dispersed plantings would most closely resemble the primary forest. A census of trees taller than 2 m showed that while wind-dispersed plantings had more recruits, the animal-dispersed plantings most closely resembled the primary forest in pioneer abundance, species density and abundance of biotically-dispersed and abiotically-dispersed plants, individual tree basal area (m2/ha), and vertical structure. The wind-dispersed plantings more closely approximated the forest in non-pioneer abundance and community composition. However, restoration treatments were more similar to each other than to the primary forest and did not differ in plant diversity. Animal-dispersed and wind-dispersed plantings did not differ in non-pioneer species density and matched the primary forest in total plot basal area. Higher abundance of trees in wind-plantings is explained by lower establishment limitations, seed legacy effects, and rapid reproduction of a few planted species. As the experiment continues, we expect treatment effects on seed dispersers will more strongly influence the recruiting plant community, leading the animal-dispersed plantings to more closely resemble the primary forest in diversity and forest structure.

Phenotypic and genotypic divergence of plant-herbivore interactions along an urbanization gradient

Urban environments provide challenging conditions for species survival, including increased temperatures, drought, and pollution. Species can deal with these conditions through evolution across generations or the immediate expression of phenotypic plasticity. The resulting phenotypic changes are key to the performance of species and their interactions with other species in the community. We here document patterns of herbivory in Arabidopsis thaliana along a rural-urban gradient, and tested the genetic background and ecological consequences of traits related to herbivore resistance. Aphid densities increased with urbanization levels along the gradient while plant size did not change. Offspring of urban mothers, raised under common garden conditions, were larger and had a decreased trichome density and seed set but a higher caterpillar (Pieris brassicae) tolerance. In contrast, no urban evolution was detected for defenses against aphids (Myzus persicae). Aphids reduced seed set more strongly in urban offspring, but this effect disappeared in second-generation plants. In general, urban adaptations as expressed in size and caterpillar tolerance were found, but these adaptations were associated with smaller inflorescences. The maternal effect on the response of seed set to aphid feeding demonstrates the relevance of intergenerational plasticity as a direct ecological consequence of herbivory. Our study demonstrates that the urban environment interacts with the plant's genotype and the extended phenotype as determined by ecological interactions.

Skua and plant dispersal: Lessons from the Argentine Islands - Kyiv Peninsula region in the maritime Antarctic

Birds are one of the most likely dispersal vectors for plants in Antarctica. We studied the nesting behavior of south polar skua (Catharacta maccormicki) and brown skua (Catharacta antarctica lonnbergi) to assess their potential role in ornithochory in the Argentine Islands - Kyiv Peninsula region. Nest samples were collected during 2009-2020 years in the Argentine Islands - Kyiv Peninsula region including all islands and coasts of the Graham Land from the Lemaire Channel to the islands of Berthelot Islands from north to south and extending from west to east from the Roca Islands, Cruls Islands, Rasmussen Point to the coast. We found that skuas utilize different nest building materials, including bryophytes, vascular plants (hairgrass Deschampsia antarctica), and lichens. In south polar skua nests, mosses and lichens dominate in the nest material; in brown skuas Deschampsia antarctica and mosses dominate. Both bird species likely collect nest components from nearby vegetation formations (<1 m distant). We conclude that C. maccormicki and C. antarctica lonnbergi are not selective in their choice of plant species, simply using the materials that dominate near the nest. Therefore, both species carry these materials from nearby sites, and only occasionally bring them from distant places. In conclusion, for both species we did not find any evidence to support their involvement in long-distance ornithochory (stomatochory) in the region.