Find research datasets worth reusing

openCC0Sep 2018View details →

Disentangling fragmentation effects on herbivory in understory plants of longleaf pine savanna

Habitat fragmentation affects species and their interactions through intertwined mechanisms that include changes to fragment area, shape, connectivity and distance to edge. Disentangling these pathways is a fundamental challenge of landscape ecology and will help identify ecological processes important for management of rare species or restoration of fragmented habitats. In a landscape experiment that manipulated connectivity, fragment shape, and distance to edge while holding fragment area constant, we examined how fragmentation impacts herbivory and growth of nine plant species in longleaf pine savanna. Probability of herbivory in open habitat was strongly dependent on proximity to forest edge for every species, increasing with distance to edge in six species (primarily grasses and annual forbs) and decreasing in three species (perennial forbs and a shrub). In the two species of perennial forbs, these edge effects were dependent on fragment shape; herbivory strongly decreased with distance to edge in fragments of two shapes, but not in a third shape. For most species, however, probability of herbivory was unrelated to connectivity or fragment shape. Growth was generally determined more strongly by leaf herbivory than by distance to edge, fragment shape, or connectivity. Taken together, these results demonstrate consistently strong edge effects on herbivory, one of the most important biotic factors determining plant growth and demography. Our results contrast with the generally inconsistent results of observational studies, likely because our experimental approach enabled us to tease apart landscape processes that are typically confounded.

openCC (other)Oct 2020View details →

Data from NUTRIENTS CAUSE GRASSLAND BIOMASS TO OUTPACE HERBIVORY 2008 - 2019

Human activities are transforming grassland biomass via changing climate, elemental nutrients, and herbivory. Theory predicts that food-limited herbivores will consume any additional biomass stimulated by nutrient inputs (‘consumer-controlled'). Alternatively, nutrient supply is predicted to increase biomass where herbivores alter community composition or are limited by factors other than food (‘resource-controlled'). Using an experiment replicated in 58 grasslands spanning six continents, we show that nutrient addition and vertebrate herbivore exclusion each caused sustained increases in aboveground live biomass over a decade, but consumer control was weak. However, at sites with high vertebrate grazing intensity or domestic livestock, herbivores consumed the additional fertilization-induced biomass, supporting the consumer-controlled prediction. Herbivores most effectively reduced the additional live biomass at sites with low precipitation or high ambient soil nitrogen. Overall, these experimental results suggest that grassland biomass will outstrip wild herbivore control as human activities increase elemental nutrient supply, with widespread consequences for grazing and fire risk.

openOpenFeb 2016View details →

Effects of vertebrate and invertebrate herbivory on plant cover in early successional habitat

This dataset contains the response of plant cover in response to experimental vertebrate exclusion and invertebrate suppression over time.

openOpenDec 2016View details →

Tree growth (height and average basal area increment) and herbivory measurements 20 years after the 1994 Hajdukovich Creek burn

This dataset contains height, diameter at breast height, and average basal area increment of aspen and black spruce from historical sites established in the Hajdukovich Creek burn. 12 pre-established sites were used, 6 from both low and high fire severity. Sites were sampled in 2014, 20 years after the fire. Furthermore, for each individual the distance from sampling point (plotless density), levels of past herbivory, health, basal age (number of tree rings visible from basal disk), age of the tree at 3 meters height, and age and height of some collected twig clusters (evidence of past herbivory) is included.

openOpenJun 2018View details →

Effects of vertebrate and invertebrate herbivory on plant cover in early successional habitat: Stem production and browsing on plants within experimental plots on the Tanana River 2012-2013

This dataset contains information on stem production and browsing on plants within experimental plots on the Tanana River. There are 6 permanent plots, each of which contains two fenced subplots and two unfenced subplots. Subplots are sprayed with either insecticide (insect-treated subplots) or water (controls) annually. This particular dataset contains the number and size of stems produced by Salix interior on unfenced study plots, and the number and size of stems browsed, during 2012-13.

openCustomJan 2020View details →

Variation in the relative effects of top-down and bottom-up forces on herbivores and herbivory along an elevational gradient in the southern Appalachian mountains in 2001

It is a well established fact that top-down (predation), bottom-up (resource availability) and lateral (interference) interactions are the dominant biotic forces in terrestrial ecosystems in addition to a host of other interactions like mutualism and symbiosis. The primary emphasis has always been to look for a singular mechanistic explanation in determining community dynamics. The ecological literature is replete with controversy on the subject of whether top-down or bottom-up forces predominate in ecosystems and their role in dynamics of ecological communities. The emerging consensus is that both top-down and bottom-up forces act in concert and the impetus is shifting towards the elucidation of the context, biotic and abiotic, under which these forces come into play. There are very few studies that have addressed this question and looked at the simultaneous interaction of these forces. I propose to study the effects of spatial heterogeneity in biotic and abiotic factors along an elevation gradient on the relative impacts of top-down and bottom-up forces and the result of their interactive effects on folivory. Specifically, I shall address the effects of spatial variation in plant quality and predation pressure and their interactive impacts on insect herbivore biomass and consumption. I shall also address the effects of complexity within/among trophic levels on the impact of these forces. The study aims to bring about a greater understanding of the role played by abiotic factors and complexity in community dynamics.

openCC (other)Jan 2020View details →

PIE LTER predation and herbivory rates associated with marsh sites used in space for time sea level rise study, Rowley, MA.

This dataset contains aggregated observations of predation and herbivory rates on tethered bait in each quadrat of the space for time substitution observations in salt marsh sites in Rowley and Newbury, MA.

openOpenJan 2020View details →

SGS-LTER Disturbance intensity and above- and belowground herbivory effects on long-term recovery of shortgrass steppe on the Central Plains Experimental Range, Nunn, Colorado, USA 1977-1990

This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection. Additional information and referenced materials can be found: http://hdl.handle.net/10217/83444 The importance of disturbance intensity and herbivory by cattle and white grubs, or the larvae of June beetles to recovery of shortgrass steppe ecosystems in Colorado, USA were evaluated over a 14 year time period. Disturbance intensity was defined by survival of the dominant grass species (Bouteloua gracilis) after an outbreak of root feeding activity by white grubs. 16 patches of vegetation consisting of four pairs of adjacent ungrazed-grazed by cattle locations with 2 replicates that were recently affected by white grubs were selected in 1977. Disturbance intensity was determined in 1977 by the area in each patch that contained live tillers of B. gracilis. Permanent plots were lcoated both within and outside of each patch. Plant basal cover and density by species were estimated at time of peak aboveground biomass in 6 different years on each plot. Successional dynamics on patches was similar to areas affected by other types of disturbances, however, rate of recovery was faster for patches affected by grubs. Grazing by cattle was infrequently important to plant recovery, a result similar to effects of grazing on other aspects of shortgrass steppe. Disturbance intensity wa

opencc-zeroJun 2020View details →

Latitudinal pattern in community-wide herbivory does not match the pattern in herbivory averaged across common plant species

1. The latitudinal herbivory hypothesis (LHH) predicts that plant losses to herbivores decrease from low to high latitudes. Although the LHH is a community-level hypothesis, it has been rarely tested with data on community-wide herbivory, i.e. the percentage of annual production of foliar biomass consumed by insects from all plant species at a given site. Therefore, we asked whether community-wide leaf herbivory follows the same latitudinal pattern as observed for an unweighted average of herbivory across common plant species. 2. We selected ten study sites in boreal forests from 60°N to 69°N along 1000 km long latitudinal gradient in NW Russia. We measured relative foliar losses to insect herbivores in seven woody plant species (jointly comprising over 95% of the community-wide aboveground biomass) and estimated their current-year foliar biomass. We averaged leaf herbivory for all seven species and calculated community-wide leaf herbivory by weighting the relative foliar losses of each plant species against the contribution of that species to the annual foliar biomass production. 3. Leaf herbivory was five-fold higher in deciduous species than in conifers. Latitudinal patterns in herbivory varied from a significant poleward decrease in all deciduous species to a significant poleward increase in Norway spruce. Herbivory values, averaged across seven plant species, decreased with latitude and followed the pattern observed in deciduous plants due to their higher foliar losses compared with conifers. By contrast, community-wide herbivory did not change with latitude. This discrepancy emerged because the proportion of deciduous plant foliage in the community increased with increasing latitude, and this increase counterbalanced the simultaneous poleward decrease in losses of these species to insects. 4. Synthesis The herbivory measured by averaging relative losses of individual plant species and the community-wide herbivory are likely to show different latitudinal patterns in various plant communities. The contributions of plant species to the total foliar biomass production should be taken into account in studies of spatial patterns of herbivory which test community-level hypotheses. This approach may provide new insight into macroecological research on biotic interactions and improve our understanding of the role of insect herbivores in ecosystem-level processes.

opencc-zeroDec 2019View details →

Data from: Lythrum salicaria common garden under Neogalerucella herbivory

We transplanted1088 seedlings of the invasive perennial plant Lythrum salicaria (purple loosestrife), from 136 maternal families sourced from 17 populations in the region around Ottawa, Canada, into a common garden containing 4 plots. The 17 populations differed in their prior exposure to the biocontrol agent Neogalerucella spp. leaf beetles (naïve = no prior exposure; recent = secondary colonization, ~5-15 years; release = sites of biocontrol release, ~20 years ago). Plants were planted in a wetland containing other Lythrum plants and experienced ambient (but significant) herbivory by Neogalerucella spp. leaf beetles. We measured herbivory, plant size and biomass over a period of 3.5 years; see the publication for more details. This experiment used the same seed material as a previously published greenhouse study by Stastny & Sargent 2017 (see below). Additional datasets, such as the proportion and phenology of flowering individuals, leaf size, stem and meristem numbers, etc., are available upon request.

Additive and non-additive responses of seedlings to simulated herbivory and drought data

Drought is a global threat, increasing in severity and frequency throughout tropical ecosystems. Although plants often face drought in conjunction with biotic stressors, such as herbivory or disease, experimental studies infrequently test the simultaneous effects of drought and biotic stress. Because multiple simultaneous stressors may have non-additive and complex effects on plant performance, it is difficult to predict plant responses to multiple threats from research examining one stress at a time. Using an experimental approach in the greenhouse, we investigated potential non-additivity in seedling growth and survival to simulated drought and herbivory across a phylogenetically diverse pool of ten Hawaiian plant species. Overall, seedlings showed limited tolerance, defined as similar growth and survival in stressed compared to control (non-stressed) plants, to simulated herbivory and drought, with the combined effects of both stressors to be generally additive and negative across species. Significant variation in stress tolerance was detected among species, and species variation was explained, at least in part, by functional traits such that species with larger root/shoot ratios and smaller seeds, tended to demonstrate greater herbivory and drought tolerance. Future research incorporating additional trait analysis and different stressors could shed light on mechanisms underlying seedling stress tolerance and clarify whether additivity, as detected in this study, extends across other combinations of stressors. Such work will provide needed insights into the regeneration of seedlings in tropical forests under threats of herbivory and climate change.

Forest cover and proximity decrease herbivory and increase crop yield via enhanced natural enemies in soybean fields

Non-crop habitats are essential for sustaining biodiversity of beneficial arthropods in agricultural landscapes, which can increase ecosystem services provision and crop yield. However, their effects on specific crop systems are less clear, such as soybean in South America, where the responses of pests and natural enemies to landscape structure have only recently been studied. Here, we analyzed how native forest fragments at local and landscape scales influenced arthropod communities, herbivory, and yield in soybean fields in central Argentina. To do this, we selected soybean fields located in agricultural landscapes with varying proportions of forest cover. At two distances (10 and 100m) from a focal forest fragment, we sampled natural enemy and herbivore arthropods, and measured soybean herbivory and yield. We focused on herbivore diversity, abundance of key soybean pests in the region (caterpillars and stink bugs), and their generalist and specialist natural enemies. Higher abundance of predators, lower herbivory rates, and increased yield were found near forests, while overall forest cover in the landscape was positively related with parasitoid and stink bug abundance, soybean yield, and negatively with herbivory. Moreover, yield was positively linked to richness and abundance of generalist and specialist enemies and independent of herbivory according to piecewise Structural Equation Models. Synthesis and applications. Our results show positive effects of native forests on biodiversity and yield in soybean crops, highlighting the need for conservation of forest fragments in agricultural landscapes. Moreover, the relation between natural enemies and crop yield suggests that Chaco forests support a diverse and abundant community of natural enemies that can provide sustained levels of ecosystem services and result in positive effects for farmers.

Herbivory Improves the Fitness of Predatory Beetles

While many predatory arthropods consume non-prey foods from lower trophic levels, little is known about what drives the shift from predator to omnivore. Predatory lady beetles often consume non-prey foods like plant foliage and pollen. One species, Coccinella septempunctata, eats foliage to redress sterol deficits caused by eating sterol-deficient prey. Here we explore how omnivory benefits lady beetle fitness. We reared seven species of lady beetles – from five genera distributed across the tribe Coccinellini – on pea aphids in the presence or absence of fava bean foliage; pea aphids have very low sterol content. Foliage supplements lengthened the development times of four species and decreased survival to adulthood of two species; it had no effect on adult mass. We mated beetles in a 2x2 factorial design (males with or without foliage paired with females with or without foliage). For each species, we observed a profound paternal effect of foliage supplements on fitness. Females mated to foliage-supplemented males laid more eggs and more viable eggs compared to females mated to non-supplemented males. Foliage-supplemented males produced 2.9–4.6 times more sperm compared to non-supplemented males for the three species examined. We analyzed the sterol profile of four beetle species reared on pea aphids – with or without foliage – and compared their sterol profile to field-collected adults. For two lab-reared species, sterols were not detected in adult male beetles, and overall levels were generally low (total ng of sterol/beetle range: 3-33 ng); the exception being P. quatuordecimpunctata females (total ng of sterol/beetle range: 50-157 ng). Laboratory-reared lady beetle sterol content was not significantly affected by the presence of foliage. Field-collected beetles had higher levels of sterols compared to lab-reared beetles (2,452–145,348 ng per beetle); cholesterol and sitosterol were the dominant sterols in field-collected and lab-reared beetles. Our findings indicate that herbivory benefits lady beetle fitness across the Coccinellini, and that this was entirely a paternal effect. Our data provides a rare example of a nutritional constraint impacting fitness in a sex-specific manner. It also shows, more broadly, how a nutritional constraint can drive predators toward omnivory. 17-Jul-2020

Range-extending tropical herbivores increase diversity, intensity and extent of herbivory functions in temperate marine ecosystems

1. Climate change is modifying species distributions around the world, forcing some species poleward, where they can alter trophic interactions. Many tropical herbivorous fishes have successfully expanded their ranges into temperate ecosystems, and while it is clear they drive increases in herbivory rates in specific localities, little is known about how they might affect the diversity of herbivory functions across large spatial scales, considering their interaction with assemblages of native herbivores in temperate habitats. 2. We assessed the spatial overlap and habitat associations of native temperate and range-expanding tropical herbivorous fishes in six sub-regions of south-western Australia to determine how incursions of tropical species may have affected the diversity, redundancy (index of uniqueness) and the 'spatial extent' (addition of functions in new areas) and 'intensity' (increasing density of functional groups) of specific herbivory functions in recipient ecosystems. 3. Tropical herbivores were more abundant in temperate ecosystems, forming schools from 40 (parrotfish) to 200 (rabbitfish) individuals strongly associated with seagrass meadows and reefs with high cover of turf algae. Overlap with temperate herbivores was highest in the northern sub-regions, forming unique assemblages, with no apparent species displacements. The addition of tropical species increased functional diversity and uniqueness (the complement of redundancy), introducing novel herbivory functions to many locations. Seagrass browsing increased in spatial extent (27%) and intensity (15 x), while seaweed browsing and grazing increased in intensity by up to 2.5 x in regions with high abundances of tropical herbivores. 4. Our results suggest that the diversity, intensity and spatial extent of different herbivory functions can change as tropical species with different habitat affinities, behaviors and diets shift their distributions poleward. Changes in functional redundancy are likely to be heterogeneous in space and might not increase initially because the diversity of herbivory functions is relatively low in some temperate marine ecosystems. However, there is the potential for greater redundancy as further tropical species arrive, their abundances increase and the spatial and functional overlap of communities rises.

opencc-by-4.0Nov 2020View details →

zenodo36/100

Dataset of 'Search for top-down and bottom-up drivers of latitudinal trends in insect herbivory in oak trees in Europe'

This file correspond to the dataset that has being used in the article ‘Search for top-down and bottom-up drivers of latitudinal trends in insect herbivory in oak trees in Europe’ by Elena Valdés-Correcher et al. in Global Ecology and Biogeography.

opencc-zeroMar 2020View details →

Strategies in herbivory by mammals revisited: The role of liver metabolism in a juniper specialist ( Neotoma stephensi ) and a generalist ( Neotoma albigula )

Although herbivory is widespread among mammals, few species have adopted a strategy of dietary specialization. Feeding on a single plant species often exposes herbivores to high doses of similar plant secondary metabolites (PSMs), which may exceed the animal's detoxification capacities. Therefore, theory predicts that specialists will have unique detoxification mechanisms to process high levels of dietary toxins. To evaluate this hypothesis, we compared liver metabolism of a juniper specialist, Neotoma stephensi (diet >85% juniper), to that of a sympatric generalist, N. albigula (diet ≤30% juniper). Specifically, we quantified the content of a key detoxification enzyme, cytochrome P450 2B (CYP2B) in liver microsomes, as well as the microsomal turnover of α-pinene, the most abundant terpene in the juniper species consumed by the specialist woodrat. In both Neotoma species, a 30% juniper diet increased CYP2B content (2-3x) and α-pinene turnover rates (4-fold). In N. stephensi, higher levels of dietary juniper (60% and 100%) further induced CYP2B content and increased turnover rates of α-pinene. Although no species-specific differences in α-pinene turnover rates were observed at 30% dietary juniper, CYP2B content was 1.7x higher in N. stephensi than in N. albigula (p<0.01). In N. stephensi, the rates of α-pinene turnover increased with dietary juniper and were positively correlated with CYP2B content. The ability of N. stephensi to elevate CYP2B content and rate of α-pinene turnover with increasing levels of juniper in the diet (from 30-100%) may facilitate juniper specialization in this species.

Data from: Herbivory and eutrophication mediate grassland plant nutrient responses across a global climatic gradient

Plant stoichiometry, the relative concentration of elements, is a key regulator of ecosystem functioning and is also being altered by human activities. In this paper we sought to understand the global drivers of plant stoichiometry and compare the relative contribution of climatic vs. anthropogenic effects. We addressed this goal by measuring plant elemental (C, N, P and K) responses to eutrophication and vertebrate herbivore exclusion at eighteen sites on six continents. Across sites, climate and atmospheric N deposition emerged as strong predictors of plot‐level tissue nutrients, mediated by biomass and plant chemistry. Within sites, fertilization increased total plant nutrient pools, but results were contingent on soil fertility and the proportion of grass biomass relative to other functional types. Total plant nutrient pools diverged strongly in response to herbivore exclusion when fertilized; responses were largest in ungrazed plots at low rainfall, whereas herbivore grazing dampened the plant community nutrient responses to fertilization. Our study highlights (1) the importance of climate in determining plant nutrient concentrations mediated through effects on plant biomass, (2) that eutrophication affects grassland nutrient pools via both soil and atmospheric pathways and (3) that interactions among soils, herbivores and eutrophication drive plant nutrient responses at small scales, especially at water‐limited sites.

Data from: Herbarium specimens reveal increasing herbivory over the past century

Predicting how ecological interactions will respond to global change is a major challenge. Plants and their associated insect herbivores compose much of macroscopic diversity, yet how their interactions have been altered by recent environmental change remains underexplored. To address this gap, we quantified herbivory on herbarium specimens of four plant species with records extending back 112 years. Our study focused on the northeastern US, where temperatures have increased rapidly over the last few decades. This region also represents a range of urban development, a form of global change that has shown variable effects on herbivores in the past studies. Herbarium specimens collected in the early 2000s were 23% more likely to be damaged by herbivores than those collected in the early 1900s. Herbivory was greater following warmer winters and at low latitudes, suggesting that climate warming may drive increasing insect damage over time. In contrast, human population densities were negatively associated with herbivore damage. To explore whether changes in insect occurrence or abundance might explain shifts in herbivory, we used insect observational records to build climate occupancy models for lepidopteran herbivores (butterflies and moths) of our focal plant species. These models show that higher winter temperatures were associated with higher probability of insect herbivore presence, while urbanization was associated with reduced probability of herbivore presence, supporting a link between insect herbivore occurrence and herbivory mediated through environment. Synthesis. Using a temporal record of plant herbivory that spans over a century, we show that both temperature and urbanization influence insect damage to plants, but in very different ways. Our results indicate that damage to plants by insect herbivores will likely continue to increase through time in the northeastern US as global temperatures rise, but that urbanization may disrupt local effects of winter warming on herbivory by excluding certain herbivores. These changes may scale to shape ecosystem processes that are driven by herbivory, including plant productivity.

Data from: Population variation, environmental gradients, and the evolutionary ecology of plant defense against herbivory

A central tenet of plant defense theory is that adaptation to the abiotic environment sets the template for defense strategies, imposing a tradeoff between plant growth and defense. Yet, this tradeoff, commonly found among species occupying divergent resource environments, may not occur across populations of single species. We hypothesized that more favorable climates and higher levels of herbivory would lead to increases in growth and defense across plant populations. We evaluated whether plant growth and defense traits co-varied across 18 populations of showy milkweed (Asclepias speciosa) inhabiting an east-west climate gradient, spanning 25° of longitude. A suite of traits impacting defense (e.g., latex, cardenolides), growth (e.g., size), or both (e.g., SLA, trichomes) were measured in natural populations and in a common garden, allowing us to evaluate plastic and genetically based variation in these traits. In natural populations, herbivore pressure increased towards warmer sites with longer growing seasons. Growth and defense traits showed strong clinal patterns and were positively correlated. In a common garden, clines with climatic origin were only recapitulated for defense traits. Correlations between growth and defense traits were also weaker and more negative in the common garden compared to the natural populations. Thus, our data suggest that climatically favorable sites likely facilitate the evolution of greater defense at minimal costs to growth, likely because of increased resource acquisition.

Data from: Acceleration or deceleration of litter decomposition by herbivory depends on nutrient availability through intraspecific differences in induced plant resistance traits

1. Herbivores often induce changes in plant defensive chemistry or nutrient content that may respectively inhibit or promote microbial decomposition of senesced litter. Often the directional impact of herbivores on decomposition is considered to be a property of a species or ecosystem. While rarely explored, intraspecific plasticity in the induction of defensive strategies across environmental gradients may also result in divergent impacts of herbivores on decomposition (deceleration vs. acceleration). 2. Here, we examined how soil nutrient conditions determine after-life effects of herbivory, using nine goldenrod (Solidago altissima) genotypes grown across four levels of nutrient supply and with or without grasshopper herbivory. In this species, herbivory induces defensive traits in genotypes grown in high soil nutrient conditions but induces tolerance (compensatory growth) in low nutrient conditions. We combined senesced litter from each treatment with a common soil inoculum in experimental microcosms and measured soil respiration and litter mass loss over 100 days as estimates of decomposition. 3. Plant genotype, nutrient environment, and herbivory all had significant effects on decomposition. The legacy effect of herbivory overwhelmed the positive effects of high soil nutrient supply on decomposition. This significant herbivory nutrient environment interaction meant that herbivore-induced plants grown in high nutrient environments produced litter that was more resistant to microbial breakdown than litter from the same genotype not exposed to herbivory. But the opposite occurred at low nutrient levels where litter from herbivore-induced plants was most readily decomposed. Further we mechanistically tie nutrient and herbivory legacy treatments to decomposition rates through predictable changes in leaf trait expression. Lastly, we demonstrate a significant correlation among herbivore growth rates on the living tissue and decomposition efficiencies by the microbial community of the senesced tissue, suggesting that herbivores and microbes perceive the "quality" of the induced substrate similarly. 4. Synthesis: Herbivore-induced changes in leaf palatability and trait expression due to defense induction or compensatory growth can cascade through to either promote or inhibit the decomposability of leaf litter within a single species. These findings offer mechanistic understanding of how spatial heterogeneity in ecosystem process rates can be generated by spatial variation in herbivory and nutrient availability.