Find research datasets worth reusing

Habitat loss shapes the structure and species roles in tropical plant-frugivore networks

Habitat loss is a global threat to biodiversity with pervasive effects on species and populations. These impacts may generate cascading effects on ecological processes propagating across ecological networks. Thus, understanding how habitat loss affects ecological networks is fundamental for conservation. We used a database of 25 plant-frugivore networks distributed across the whole Brazilian Atlantic Forest to understand how landscape-scale habitat loss shapes network structure, robustness, species role and traits related to seed dispersal. We compared whether these network properties have linear or non-linear relationships and used centrality metrics and indirect effects to evaluate if habitat loss change the role of species in plant-frugivore networks. We found linear and non-linear relationships with negative effects of habitat loss on the network structure. As a consequence of shifts in species richness and number of links, the number of interactions and the proportion of possible interactions observed (connectance) were negatively associated with habitat loss. In contrast, nestedness increased with habitat loss. Network robustness, mean bill width and mean seed size were not significantly related to habitat loss. In addition to changes in interaction patterns at network level, habitat loss also favors changes in interaction among species, shifting the species playing central roles in network organization or contributing to indirect effects in the networks. In forested landscapes, obligate frugivores are the main central species in the network, and the ones potentially contributing to indirect effects, while in deforested landscapes these roles are fulfilled by occasional frugivores. Thus, our results emphasize the widespread effect of habitat loss on plant-frugivore systems, adding evidence that its pervasive effects on biodiversity also proliferate on mutualistic interactions with negative consequences for seed dispersal that potentially go beyond the direct pairs of interacting species.

Complex urban environments provide Apis mellifera with a richer plant forage than suburban and more rural landscapes

Growth in the global development of cities, and increasing public interest in beekeeping, has led to rises in the numbers of urban apiaries. Towns and cities can provide an excellent diet for managed bees, with a diverse range of nectar and pollen available throughout a long flowering season and are often more ecologically diverse than the surrounding rural environments. Accessible urban honeybee hives are a valuable research resource to gain insights into the diet and ecology of wild pollinators in urban settings. We used DNA metabarcoding of the rbcL and ITS2 gene regions to characterise the pollen community in Apis mellifera honey, inferring the floral diet, from 14 hives across an urban gradient around Greater Manchester, UK. We found that the proportion of urban land around a hive is significantly associated with an increase in the diversity of plants foraged, and that invasive and non-native plants appear to play a critical role in the sustenance of urban bees, alongside native plant species. The proportion of improved grassland, typical of suburban lawns and livestock farms, is significantly associated with decreases in the diversity of plant pollen found in honey samples. These findings are relevant to urban landscape developers motivated to encourage biodiversity and bee persistence, in line with global bio-food security agendas.

The social network of target of rapamycin complex 1 in plants

The target of rapamycin complex 1 (TORC1) is a highly conserved serine–threonine protein kinase crucial for coordinating growth according to nutrient availability in eukaryotes. It works as a central integrator of multiple nutrient inputs such as sugar, nitrogen, and phosphate and promotes growth and biomass accumulation in response to nutrient sufficiency. Studies, especially in the past decade, have identified the central role of TORC1 in regulating growth through interaction with hormones, photoreceptors, and stress-signaling machinery in plants. In this review, we comprehensively analyse the interactome and phosphoproteome of the Arabidopsis TORC1 signaling network. Our analysis highlights the role of TORC1 as a central hub kinase communicating with the transcriptional and translational apparatus, ribosomes, chaperones, protein kinases, metabolic enzymes, and autophagy and stress response machinery to orchestrate growth in response to nutrient signals. This analysis also suggests that along with the conserved downstream components shared with other eukaryotic lineages, plant TORC1 signaling underwent several evolutionary innovations and co-opted many lineage-specific components. Based on the protein–protein interaction and phosphoproteome data, we also discuss several uncharacterized and unexplored components of the TORC1 signaling network, highlighting potential links for future studies.

Data for: Elevational changes in insect herbivory on woody plants in six mountain ranges of temperate Eurasia: Sources of variation

Current theory predicts that the intensity of biotic interactions, and particularly herbivory, decreases with increasing latitude and elevation. However, recent studies have revealed substantial variation in both the latitudinal and elevational patterns of herbivory. This variation is often attributed to differences in study design and type of data collected by different researchers. Here, we used a standardised sampling protocol along elevational gradients in six mountain ranges, located at different latitudes within temperate Eurasia, to uncover the sources of variation in elevational patterns in insect herbivory on woody plant leaves. We discovered the considerable variation in elevational patterns among different mountain ranges; nevertheless, herbivory generally decreased with increasing elevation at both the community-wide and individual plant species levels. This decrease was mostly due to openly living defoliators, whereas no significant association was detected between herbivory and elevation among insects living within plant tissues (i.e. miners and gallers). The elevational decrease in herbivory was significant for deciduous plants but not for evergreen plants, and for low-stature plants but not for tall plants. The community-wide herbivory increased with increases in both specific leaf area and leaf size. The strength of the negative correlation between herbivory and elevation increased from lower to higher latitudes. We conclude that elevational gradients in herbivory demonstrate considerable variation, and that this variation is mostly associated with herbivore feeding habit, some plant traits and latitude of the mountain range.

Data for the article: Coupling of leaf elemental traits with root fungal community composition reveals a plant resource acquisition strategy in a desert ecosystem

Purpose: Plant-associated microbes enhance nutrient access and stress tolerance of the host species, and therefore, are crucial for plant traits and resource strategies. However, the links between aboveground plant traits and belowground microbes related to plant resource strategies under stressful conditions remain poorly understood. Methods: We tested the relationships between leaf traits linked to water (carbon isotopic composition, δ13C) and nutrient use (elemental concentrations and stoichiometry) with microbial compositions in roots and rhizospheres of two dominant species (Artemisia ordosica and Leymus secalinus) in the Mu Us Desert, northern China. Results: L. secalinus exhibited higher Mg and Mn concentrations, N:P ratios, stoichiometric flexibility, and root fungi:bacteria ratios, but lower foliar K and Ca concentrations and δ13C values than A. ordosica. The leaf N:P of L. secalinus increased with the root fungi:bacteria ratios, whereas the leaf N:P of A. ordosica decreased with the root fungi:bacteria ratios. The plant elemental levels (P, N, K, Ca, Mn, and δ13C) of L. secalinus but not A. ordosica were significantly related to their root fungal composition. Additionally, the random forest model identified four key fungal families in predicting leaf elemental traits for both plant species. Conclusion: The results suggested tight coupling and coordination between leaf elemental traits and root microbial compositions (especially fungal communities) related to plant resource acquisition strategies. By regulating aboveground and belowground feedback loops through trait flexibility and root microbial compositions, the studied plant species can sustain their resource strategies under stressful environmental conditions.

Fluctuations in resource availability shape the competitive balance among non-native plant species

Fluctuating resource availability plays a critical role in determining non-native plant invasions by mediating the competitive balance between non-native and native species. However, the impact of fluctuating resource availability on interactions among non-native species remains largely unknown. This represents a barrier to understanding invasion mechanisms, particularly in habitats that harbor multiple non-native species with different responses to fluctuating resource availability. To examine the responses of non-native plant species to nutrient fluctuations, we compared the growth of each of 12 non-native species found to be common in local natural areas to nutrients supplied at a constant rate or supplied as a single large pulse in a pot experiment. We found that seven species produced more biomass with pulsed nutrients compared to constant nutrients (hereafter 'benefitting species'), while the other five species did not differ between nutrient enrichment treatments (hereafter 'non-benefitting species'). To investigate how nutrient fluctuations influence the interactions among non-native plant species, we established experimental non-native communities in the field with two benefitting and two non-benefitting non-native species. Compared with constant nutrient supply, the single large pulse of nutrients did not influence community biomass, but strongly increased the biomass and cover of the benefitting species and decreased those of the non-benefitting species. Furthermore, the benefitting species had higher leaf N content and greater plant height when nutrients were supplied as a single large pulse than at a constant rate, whereas the non-benefitting species showed no differences in leaf N content and were shorter when nutrients were supplied as a single large pulse than at a constant rate. Our results add to the growing evidence that the individual responses of non-native species to nutrient fluctuation are species-specific. More importantly, benefitting species were favored by nutrients coming in a pulse, while non-benefitting ones were favored by nutrients coming constantly when they grew together. This suggests that nutrient fluctuations can mediate the competitive balance among non-native plants and may thus determine their invasion success in a community harbouring multiple non-native plant species.

Genet dynamics and its variation among genets of a clonal plant Convallaria keiskei

In clonal plant populations, a number of genetically identical ramets form a genet. While coexisting ramets potentially perform independently, their behaviours not only depend on ages and sizes but are also constrained by genetic background. In this study, genet dynamics and its variability among neighbouring genets were investigated based on the ramet demography of each genet in Convallaria keiskei. Genet dynamics were first formulated as a matrix model with the two components of clonal growth (clonal reproduction) and survival-transitions between ramet size classes. Then, a statistical estimation of the matrix elements was established using three datasets: aboveground demographic censuses, belowground directional rhizomatous connections and genetic identification of ramets. Finally, genet growth rates reflecting both the changes of clonal growth and ramet size growth were estimated and compared for fundamental demographic elements among genets. Over three years of aboveground annual censuses of a 28 × 2 m plot, 2,021 ramets were identified as belonging to 28 genotypes. Belowground excavation detected 515 clonal fragments. Genet growth rate of three dominant genets varied with medians of 1.13, 1.02 and 1.05; 95% credible intervals of the posterior distributions did not overlap between the genet with the largest median and the others. The variation was caused primarily by differences in clonal growth rather than survival-transitions between size classes. Clonal growth by branching was rarer than at the tips but contributed to the maintenance of the genet. Therefore, both clonal growth frequencies and connecting patterns of ramets caused the variation of genet dynamics and established genets persist for a long time through the positive growth rates, which would contribute to maintaining a population. We also conclude that fundamental demographic elements relating to clonal growth traits (the features of individual genets) strongly impact genet dynamics.

opencc-by-4.0Nov 2022View details →

zenodo36/100

Data from: Mixed Signals from the Stable Isotope Composition of Precipitation and Plant Waxes in the Northern Tropical Andes

These files are the supplementary information for Pérez‐Angel, L. C., Sepúlveda, J., Montes, C., Smith, J. J., Molnar, P., González-Arango, C., Snell, K., Dildar, N., Mixed Signals from the Stable Isotope Composition of Precipitation and Plant Waxes in the Northern Tropical Andes. Journal of Geophysical Research: Biogeosciences (In Revision).    This work was funded by the National Science Foundation NSF | GEO | Division of Earth Sciences (EAR): 1929199

Dataset for: Designing a surveillance program for early detection of alien plants and insects in Norway

Naturalized species of alien plants and animals comprise < 3% of biodiversity recorded in Norway but have had major impacts on natural ecosystems through displacement of native species. Encroachment of alien species has been especially problematic for coastal sites close to transport facilities and urban areas with high-density housing. The goal of our field project was to design and test a surveillance program for early detection of alien species of vascular plants and terrestrial insects at the first phase of establishment in natural areas. In our 3-year project (2018–2020), we sampled 60 study plots in three counties in the Oslofjord region of southern Norway. Study plots (6.25 ha) were selected by two criteria: manual selection based on expert opinion (27 plots) or by random selection based on weights from a hotspot analysis of occurrence of alien species (33 plots). Vascular plants were surveyed by two experienced botanists who found a total of 239 alien species of vascular plants in 95 rounds of surveys. Insects and other invertebrates were captured with a single Malaise trap per site, with 3-4 rounds of repeated sampling. We used DNA-metabarcoding to identify invertebrates based on DNA extractions from crushed insects or from the preservative media. Over 3,500 invertebrate taxa were detected in 255 rounds of sampling. We recorded 20 alien species of known risk and 115 species that were new to Norway, including several 'doorknocker' species identified by previous risk assessments. We modeled the probabilities of occupancy (y) and detection (p) with occupancy models with repeated visits by multiple observers (vascular plants) or multiple rounds of sampling (insects). The two probabilities covaried with risk category for alien organisms and both were low for species categorized as no known or low risk (range = 0.052 to 0.326) but were higher for species categorized as severe risk (range = 0.318 to 0.651). Selecting sites at random or manually did not improve the probability of finding novel alien species, but occupancy had a weak positive relationship with housing density for some categories of alien plants and insects. We used our empirical estimates to test alternative sampling designs that would minimize the combined variance of occupancy and detection (A-optimality criterion). Sampling designs with 8–10 visits per site were best for surveillance of new alien species if the probabilities of occupancy and detection were both low, and provided low conditional probabilities of site occupancy (psi-hat(cond) £ 0.032) and a high probabilities of cumulative detection (p-hat(star) ³ 0.943). Our field results demonstrate that early detection is feasible as a key component of a national surveillance program based on early detection and rapid response (EDRR).

opencc-zeroDec 2021View details →

Resprouting ability differs among plant functional groups along a soil acidification gradient in a meadow: A rhizosphere perspective

Soil acidification as a global change factor can devastatingly affect plant growth and productivity. In frequently disturbed ecosystems, plant resprouting ability strongly determines biomass reconstruction and resilience after aboveground damage. However, how plant regrowth responds to soil acidification remains largely unknown, especially regarding the role of the rhizosphere in mediating this response. We manipulated a soil-acidification gradient via adding purified elemental sulfur powder at various rates (0-50 g S m−2 year−1) in a frequently mown meadow. Shoot regrowth of functional groups were measured after clipping and supporting roles of rhizosphere versus bulk soils were disentangled using isotope labelling along the acidification gradient. Regrowth of grasses and sedges increased while forbs decreased along the acidification gradient. The results suggest that grasses were competitors capable of taking up nutrients from both rhizosphere and bulk soils, while sedges were acid-tolerators with lower sensitivity to decreased nitrogen-mineralization rates. Forbs, as typical ruderals, were vulnerable to N competition with microbes, particularly in the rhizosphere soil. Therefore, biomass regrowth of forbs was explained more by physicochemical and biological parameters from the rhizosphere than bulk soil Synthesis. Divergent interplay between plant functional groups and rhizosphere soils was the prominent driver for biomass regrowth responding to soil acidification.

opencc-zeroDec 2021View details →

Data for: Plant and herbivorous insect communities respond in complex ways to rainfall manipulation in an oak savanna grassland

Changes in precipitation due to climate change will have consequences for plant and herbivorous insect communities alike. Multiple hypotheses explain how changes in plant diversity and productivity can lead to changes in herbivore community composition. Yet as rainfall patterns change, the bottom-up effects on the relationships between plant and herbivore communities are less well understood. Using a long-term rainfall manipulation experiment in a remnant patch of Garry oak (Quercus garryana) savanna, we examined how plant diversity and productivity have responded to variation in soil moisture over six years. This highly endangered ecosystem is predicted to experience significantly wetter springs and drier summers by 2080. We also investigated plant-mediated, indirect effects of manipulated rainfall on herbivore diversity and abundance, drawing on multiple hypotheses describing the relationships between plant and herbivore communities. For example, the more individuals hypothesis predicts that increased plant productivity results in increased herbivore abundance which in turn results in increased herbivore diversity. We found that plant productivity was influenced by soil moisture, but the direction and magnitude of the response varied across years, and no support for plant diversity influencing productivity. We also found that the cover and productivity of grasses increased significantly with increasing precipitation. In addition to a significant direct effect on herbivore diversity, soil moisture had a significant indirect negative effect on herbivore abundance, via the negative effect of plant productivity on abundance, contradicting the more individuals hypothesis. Synthesis: Our results highlight that not only can drought result in significant reductions in plant productivity in this threatened ecosystem, but that these changes will also result in increases in herbivore abundance. In contrast, where soil moisture is higher, grasses will become more dominant resulting in decreased abundance. Ultimately, predicting how this system responds to changes in precipitation will depend on the ability to predict whether growing season soil moisture will be consistently drier or wetter in the future, a significant challenge. Going forward, investigating how variation in precipitation due to climate change affects the links between trophic levels, including how herbivores affect plant communities, remains critical for understanding ecosystem processes and stability.

Eco-evolutionary contributions to community trait change in floating aquatic plants

An entire community of organisms may become modified when its environment changes. These modifications can happen through physiological process (plasticity), evolutionary processes (adaptation) or shifts in species composition (sorting). The outcome of these three sources of change constitutes the community's phenotypic response, but how they combine to drive community trait dynamics is not currently well understood. We have conducted a community selection experiment in which communities of short-lived floating aquatic plants were grown in a range of stressful conditions, and measured changes in their body size. Determinants of phenotypic change were assessed with a full community reciprocal transplant which led to estimates of the contributions of plasticity, adaptation, and sorting. Species were modified during the experiment by both plasticity and adaptation, but in either case the magnitude and direction of change differed among species. Sorting and adaptation were of equal magnitude, but tended to act in opposite directions: in conditions where species with large fronds prevailed, each species evolved smaller fronds, and vice versa. We conclude that community trait dynamics cannot be understood simply by extrapolating the adaptive response of any single species to the whole community.

opencc-by-4.0Dec 2021View details →

zenodo36/100

Measurements of natural radioactivity levels and associated radiation hazard indices in Moringa plant leaf samples from selected areas in southern Ethiopia.

Moringa stenopetala (MS) is a multipurpose tree whose leaf is consumed by people of all ages in southern Ethiopia. In this study, natural radioactivity levels of 226Ra, 232Th, and 40K, as well as the related dangerous radiological characteristics, were measured on different sites of moringa samples using high-purity germanium (HPGe) gamma-ray spectrometry. Average activity concentrations of 226Ra, 232Th, and 40K in moringa leaves are found to be 0.49 ± 0.12, 3.84 ± 1.12, and 573.29 ± 26.79 Bq.kg-1, respectively. Moreover, the average values of the corresponding radiological parameters, Raeq, Hint, and annual effective dose (Eave) (sum), were also found to be 50.13 ± 3.79 Bq.kg-1, 0.136 ± 0.010, and 0.238 ± 0.089 mSvy-1, respectively. When the obtained results for all of the samples were compared to globally accepted criteria, they were discovered to be lower than the allowable world average levels. Furthermore, the lifetime cancer risk was revealed to be far lower than the allowable limit. According to the study, the risk of absorbing natural radionuclides from moringa leaf ingestion is insignificant. The findings can be utilized to create radiation safety norms and regulations for the use of moringa leaves as food and medication.

Long-term spatially-replicated data show no physical cost to a benefactor species in a facilitative plant-plant interaction

Facilitation is an interaction where one species (the benefactor) positively impacts another (the beneficiary). However, the reciprocal effects of beneficiaries on their benefactors are typically only documented using short-term datasets. We use Azorella selago, a cushion plant species and benefactor, and a co-occurring grass species, Agrostis magellanica, on sub-Antarctic Marion Island, comparing cushion plants and the grasses growing on them over a 13-year period using a correlative approach. We additionally compare the feedback effect of A. magellanica on A. selago identified using our long-term dataset with data collected from a single time period. We hypothesized that A. selago size and vitality would be negatively affected by A. magellanica cover and that the effect of A. magellanica on A. selago would become more negative with increasing beneficiary cover and abiotic-severity, due to, e.g., more intense competition for resources. We additionally hypothesized that A. magellanica cover would increase more on cushion plants with greater dead stem cover, since dead stems do not inhibit grass colonization or growth. The relationship between A. magellanica cover and A. selago size and vitality was not significant in the long-term dataset, and the feedback effect of A. magellanica on A. selago did not vary significantly with altitude or aspect; however, data from a single time period did not consistently identify this same lack of correlation. Moreover, A. selago dead stem cover was not significantly related to an increase in A. magellanica cover over the long term; however, we observed contrasting results from short-term datasets. Long-term datasets may, therefore, be more robust (and practical) for assessing beneficiary feedback effects than conventional approaches, particularly when benefactors are slow-growing. For the first time using a long-term dataset, we show a lack of physical cost to a benefactor species in a facilitative interaction, in contrast to the majority of short-term studies.

Population bottleneck associated with but likely preceded the recent evolution of self-fertilization in a coastal dune plant

Evolution of self-fertilization may be initiated by a historical population bottleneck, which should diagnostically reduce lineage-wide genetic variation. However, selfing can also strongly reduce genetic variation after it evolves. Distinguishing process from pattern is less problematic if mating system divergence is recent and geographically simple. Dramatically reduced diversity is associated with the transition from outcrossing to selfing in the Pacific coastal endemic Abronia umbellata that includes large-flowered, self-incompatible populations (var. umbellata) south of San Francisco Bay and small-flowered, autogamous populations (var. breviflora) to the north. Compared to umbellata, synonymous nucleotide diversity across 10 single-copy nuclear genes was reduced by 94% within individual populations and 90% across the whole selfing breviflora lineage, which contained no unique polymorphisms. The geographic pattern of genetic variation is consistent with a single origin of selfing that occurred recently (7–28 kya). These results are best explained by a historical bottleneck, but the two most northerly umbellata populations also contained little variation and clustered with selfing populations, suggesting that substantial diversity loss preceded the origin of selfing. A bottleneck may have set the stage for the eventual evolution of selfing by purging genetic load that prevents the spread of selfing.

Dataset from: Warming effects on grassland productivity depend on plant diversity

Aim: Climate warming and biodiversity loss both alter plant productivity, yet we lack an understanding of how biodiversity regulates the responses of ecosystems to warming. In this study, we examine how plant diversity regulates the responses of grassland productivity to experimental warming using meta-analytic techniques. Location: Global Major taxa studied: Grassland ecosystems Methods: Our meta-analysis is based on warming responses of 40 different plant communities obtained from 20 independent studies on grasslands across five continents. Results: Our results show that plant diversity and its responses to warming were the most important factors regulating the warming effects on plant productivity, among all the factors considered (plant diversity, climate and experimental settings). Specifically, warming increased plant productivity when plant diversity (indicated by effective number of species) in grasslands was lesser than 10, whereas warming decreased plant productivity when plant diversity was greater than 10. Moreover, the structural equation modelling showed that the magnitude of warming enhanced plant productivity by increasing the performance of dominant plant species in grasslands of diversity lesser than 10. The negative effects of warming on productivity in grasslands with plant diversity greater than 10 were partly explained by diversity-induced decline in plant dominance. Main Conclusions: Our findings suggest that the positive or negative effect of warming on grassland productivity depends on how biodiverse a grassland is. This could mainly owe to differences in how warming may affect plant dominance and subsequent shifts in interspecific interactions in grasslands of different plant diversity levels.

Data for: Invasion by an exotic grass species homogenises native freshwater plant communities

A growing body of evidence has shown that biological invasions cause shifts in species composition of communities in space and time. Although biological invasions are considered a major driver of biotic homogenisation worldwide, most previous studies are conducted at small spatial scales and over short time periods, which may have underestimated the impacts of exotic species on native communities. Using a unique dataset of aquatic plants sampled in 235 sites over 12 years (2007–2010 and 2015–2019) in a large reservoir (Itaipu Reservoir; 1,350 km²), we analyzed how the invasion of a non-native grass (Urochloa arrecta) affects the species richness, ecological uniqueness (i.e., local contribution to beta diversity – LCBD) and temporal β–diversity of native plant communities. From 3,934 surveyed plant communities, U. arrecta was recorded in 2,888 samples and it was absent from 1,046 samples. Overall, species richness and ecological uniqueness of native plant communities were markedly lower in sites invaded than non-invaded by U. arrecta. From 2007 to 2019, the ecological uniqueness of native plants was 60% lower in the invaded than non-invaded sites. Whereas in invaded sites the species loss was the dominant mechanism driving native communities over time, in non–invaded sites the gain of new native species was the primary mechanism underlying community trajectories. Moreover, comparing native plant communities before and after the invasion of U. arrecta, species richness, ecological uniqueness and species gains of native plant communities decreased, whereas species losses increased after the invasion of U. arrecta. Finally, the positive relationship between native biodiversity and precipitation was stronger in sites non-invaded than invaded by U. arrecta. Synthesis: Our findings provide comprehensive evidence that an invasive plant is decreasing the spatial and temporal β–diversity of native plant communities through declining species richness, rather than simply correlating with them. This suggests that U. arrecta is driving native plants to become less diverse and homogeneous after the invasion, both spatially and temporally. Our findings illustrate that at broad scales, aquatic plant communities may become increasingly homogeneous with the increasing number of biological invasion events taking place worldwide.

Experimental extensification of mountain grasslands restores plant species richness but not species composition in the mid-term

<ol> <li>The traditional grasslands that characterize the cultural landscapes of the palaeartic mountain massifs represent biodiversity hotspots. Yet, they are currently threatened by the intensification of farming practices, notably excesses in fertilization and irrigation.</li> <li>We experimentally investigated the passive restoration of montane and subalpine hay meadows after six years of management intensification, with different levels of fertilization and irrigation, followed by five years of release of intensive management, i.e. extensification. More specifically, relying on a full randomized block-design replicated at 11 Swiss study sites constituted of extensively-managed meadows, we exposed during six years (2010-2015) four 20 m diameter plots to three levels of intensification (low, medium and high inputs), while a fourth plot served as a control (no inputs). In the second phase of the experiment (2016-2020), all study meadows underwent farming extensification.</li> <li>We monitored total species richness and plant diversity (Simpson diversity), indicator plant species as well as the composition and variability of the plant communities based on Bray-Curtis dissimilarity distances.</li> <li>We found that total species richness decreased in the most intensified plots after six years of intensification, but all plots retrieved their baseline species richness after five years of re-extensification. Additionally, we found no difference between the years in plant diversity (Simpson diversity) among the treatments. Yet, intensification led to different plants communities' compositions in all three levels of intensification in 2015 compared to the extensive plots, and this structural difference remained after five years of re-extensification.</li> <li>Synthesis and applications. Land-use intensification induces a rapid impoverishment of the flora of mountain meadows. Our results demonstrate the potential of mountain hay meadows to passively restore plant species richness after re-extensification, however plants communities did not fully recover. We recommend maintaining fertilization inputs as low as possible and operating active restoration on grasslands formerly intensified.</li> </ol>

Space resource utilization of dominant species integrates abundance- and functional-based processes for better predictions of plant diversity dynamics

Sustainable ecosystem management relies on our ability to predict changes in plant diversity and to understand the underlying mechanisms. Empirical evidence demonstrates that abundance- and functional-based processes simultaneously explain the loss of plant diversity in response to human activities. Recently, a novel indicator based on percent cover (CoverD) and maximum height (HeightD) of the dominant plant species – Space Resource Utilization (SRUD) – has proven to give robust and better predictions of plant diversity dynamics than community biomass. Whether the superior predictive ability of SRUD is due to its capacity to simultaneously capture abundance- and functional-based processes remains unknown. Here, we tested this hypothesis by quantifying mechanistic links between changes in SRUD and biodiversity in response to nutrients and herbivores. Furthermore, we assessed the relative contribution of dominant, intermediate, and rare species to reduced density of individuals by combining null model analysis with field experiments. We found that SRUD successfully captured changes in ground-level light availability and changes in the number of individuals to predict plant diversity dynamics, and each of CoverD and HeightD partly and independently contributed to both processes. Comparative results from null model analysis and field experiments confirmed that individual losses of dominant, intermediate, and rare species followed non-random processes. Specifically, compared with random loss process, rare species lost proportionally more individuals and thus disproportionately contributed to species loss, while dominant and intermediate species lost less. Our results demonstrate that SRUD captures both abundance- and functional-based processes thus explaining why SRUD provides more accurate predictions of changes in species diversity. Given that rare species can play an important role in shaping community structure, resisting against invasion, impacting higher trophic levels, and providing multiple ecosystem functions, reducing the SRU of dominant species could alleviate the risk of exclusion of rare species by mitigating abundance- and functional-based competition processes.

Plant species with higher chemical defenses enhance herbivore cellular immunity with differential effectiveness against two parasitoid species

Insect herbivores simultaneously experience bottom-up effects of plant defensive chemistry and the top-down effects of natural enemies. At the intersection of these effects are herbivore immune systems, herbivore traits that have largely been overlooked in studies of plant-insect interactions. Most previous studies have demonstrated compromised immunity of herbivores that feed on plants with higher defensive chemistry. Many studies have used embedded microfilaments or silica beads as proxies for parasitoid eggs. Yet, parasitoids may evade or suppress host immune responses by injecting venom, calyx fluid, or through modifications of their egg surface structure, necessitating studies that include all three trophic levels to obtain a complete picture of how plant traits may modulate herbivore immunity.Here we examined the effect of host plant species that differ in glucosinolate (anti-herbivore compounds produced by plants in the Brassicaceae) concentrations on the immune status of an herbivore and its consequences for two species of parasitoids with different life history traits.We found that larvae of the butterfly Pieris rapae that fed on field mustard Brassica rapa, which contain 52-fold higher glucosinolate concentrations than collards B. oleracea, attained lower body weights and experienced prolonged development to adulthood.Yet, caterpillars that fed on B. rapa had enhanced cellular immunity, as measured by total and differential hemocyte counts, as well as melanization capacity compared to larvae that fed on B. oleracea.In turn, the likelihood that at least some eggs in clutches of the gregarious endoparasitoid Cotesia glomerata would be encapsulated, leading to a reduction in brood size, were three times greater when their host caterpillars fed on B. rapa compared to B. oleracea. Interestingly, eggs of the solitary endoparasitoid Cotesia rubecula were rarely encapsulated irrespective of the host plant on which their host caterpillar fed. Therefore, our results suggest that plant defense metabolites can influence the expression of herbivore immunity, but the effectiveness of this response strongly depends on the identity of the parasitoid and its ability to evade the caterpillar immune response, and possibly the evolution of these trophic interactions in non-native systems.