Find research datasets worth reusing

Data from: Current and historical land use influence soil-based ecosystem services in an urban landscape

Urban landscapes are increasingly recognized as providing important ecosystem services (ES) to their occupants. Yet, urban ES assessments often ignore the complex spatial heterogeneity and land-use history of cities. Soil-based services may be particularly susceptible to land-use legacy effects. We studied indicators of three soil-based ES – carbon storage, water quality regulation, and runoff regulation – in a historically agricultural urban landscape and asked: (1) How do ES indicators vary with contemporary land cover and time since development? (2) Do ES indicators vary primarily among land-cover classes, within land-cover classes, or within sites? (3) What is the relative contribution of urban land-cover classes to potential citywide ES provision? We measured biophysical indicators (soil carbon (C), available phosphorus (P), and saturated hydraulic conductivity (Ks)) in 100 sites across 5 land-cover classes, spanning an ~125 year gradient of time since development within each land-cover class. Potential for ES provision was substantial in urban green spaces, including developed land. Runoff regulation services (high Ks) were highest in forests; water quality regulation (low P) was highest in open spaces and grasslands; and open spaces and developed land (e.g., residential yards) had the highest C storage. In developed land covers, both C and P increased with time since development, indicating effects of historical land-use on contemporary ES and tradeoffs between two important ES. Among-site differences accounted for a high proportion of variance in soil properties in forests, grasslands, and open space, while residential areas had high within-site variability – underscoring the leverage city residents have to improve urban ES provision. Developed land covers contributed most ES supply at the citywide scale, even after accounting for potential impacts of impervious surfaces. Considering the full mosaic of urban green space and its history is needed to estimate the kinds and magnitude of ES provided in cities, and to augment regional ES assessments that often ignore or underestimate urban ES supply.

opencc-zeroDec 2018View details →

Data from: Soil microbiomes underlie population persistence of an endangered plant species

Microbiomes can dramatically alter individual plant performance, yet how these effects influence higher order processes is not well resolved. In particular, little is known about how microbiome effects on individual plants alter plant population dynamics, a question critical to imperiled species conservation. Here, we integrate bioassays, multidecadal demographic data, and integral projection modeling to determine how the presence of the natural soil microbiome underlies plant population dynamics. Simulations indicated that the presence of soil microbiomes boosted population growth rates (λ) of the endangered Hypericum cumulicola by 13% on average, the difference between population growth versus decline in 76% of patches. The greatest benefit (47% increase in λ) occurred in low nutrient, high elevation habitats, suggesting that the soil microbiome may help expand H. cumulicola's distribution to include these stressful habitats. Our results demonstrate that soil microbiomes can significantly affect plant population growth and persistence, and support the incorporation of soil microbiomes into conservation planning. plant population growth and persistence, and support the incorporation of soil microbiomes into conservation planning.

Data from: Soil fungi underlie a phylogenetic pattern in plant growth responses to nitrogen enrichment

1. Under increasing anthropogenic nitrogen (N) deposition, some plant species will thrive while others will not. Previous work has shown that plant phylogeny can predict these responses, and that interactions with mycorrhizal fungi are a mechanism that drives variation in plant responses to N enrichment. Yet, much of this work has ignored the roles of other root-associated fungi and whole soil fungal communities in driving these responses. 2. We tested whether soil fungi mediate responses of plant growth and plant-soil feedbacks (between close and distant plant relatives) to N enrichment by implementing a greenhouse experiment in which we applied factorial treatments of N fertilization, host-specific soil inocula, and fungicide to 15 eucalypt tree species that co-occur on the island state of Tasmania, Australia and form two phylogenetic lineages within the subgenus Symphyomyrtus. 3. Conspecific-conditioned soil fungi enhanced growth responses to N enrichment for plants within one lineage (lineage 1) but depressed growth responses to N enrichment for plants within another lineage (lineage 2). Lineage-specific shifts in ectomycorrhizal (ECM) colonization were consistent with previous evidence that more vs. less successful strategies under N enrichment are those where carbon allocation to mycorrhizal fungi is reduced vs. maintained, respectively. The latter was also accompanied by a stronger reduction in root colonization of non-filamentous fungi (of unknown function) under N enrichment. Plant-soil feedbacks were neutral for lineage 1 but negative for lineage 2 (i.e., greater growth in soils conditioned by opposite vs. same lineage individuals), but were not altered by N enrichment or fungicide. Lineage-level differences in root colonization suggest that these feedbacks could be driven by differential plant responsiveness to dark septate endophytes and non-filamentous fungi, the colonization of which seemed to benefit plant growth. 4. Our results confirm that interactions with soil fungi (ECM fungi in particular) underlie phylogenetic patterns in tree species' growth responses to N enrichment and may thus influence which plants win or lose under future N deposition scenarios. Yet, we provide some of the first evidence (albeit from controlled rather than natural conditions) that N deposition may not play a strong role in shifting plant-soil feedbacks.

opencc-zeroDec 2015View details →

Data from: Disruption of plant-soil-microbial relationships influences plant growth

Differential dispersal of plant and microbial propagules may result in the geographical disassociation of plant populations from their local abiotic conditions and microbial communities, especially in the face of species introductions and changing climates. To assess the potential consequences of disrupting historical relationships between plant populations, microbial communities, and soil conditions, we grew Carpinus caroliniana seedlings from populations across the species range in combinations of sterilized soils and soil microbial communities, in soils collected from sites with or without conspecific trees. This controlled environment study simulated the consequences for seedling growth of independently or jointly disrupting the historical plant population-soil match, plant population-microbial community match, and microbial community-soil match. Seedlings grown in soils from areas without conspecifics had lower biomass, but benefited from inoculation with their historical microbial communities. For conspecific-cultured soils, growth was optimized when seedlings grew with novel microbial communities, but only when microbial communities were local with respect to abiotic soil conditions. Correlative evidence suggests that this may stem from alignment of ectomycorrhizal fungal communities to abiotic soil conditions. Synthesis: Maintaining historical plant-microbial community relationships may benefit plant species spreading into new areas; however, for movement within current ranges, maintaining the historical relationship between microbial communities and the abiotic aspects of soils may have more important consequences for early growth.

Data from: Decoupled responses of soil bacteria and their invertebrate consumer to warming, but not freeze-thaw cycles, in the Antarctic Dry Valleys

Altered temperature profiles resulting in increased warming and freeze–thaw cycle (FTC) frequency pose great ecological challenges to organisms in alpine and polar ecosystems. We performed a laboratory microcosm experiment to investigate how temperature variability affects soil bacterial cell numbers, and abundance and traits of soil microfauna (the microbivorous nematode Scottnema lindsayae) from McMurdo Dry Valleys, Antarctica. FTCs and constant freezing shifted nematode body size distribution towards large individuals, driven by higher mortality among smaller individuals. FTCs reduced both bacterial and nematode abundance, but bacterial cell numbers also declined under warming, demonstrating decoupled consumer–prey responses. We predict that higher occurrence of FTCs in cold ecosystems will select for large body size within soil microinvertebrates and overall reduce their abundance. In contrast, warm temperatures without FTCs could lead to divergent responses in soil bacteria and their microinvertebrate consumers, potentially affecting energy and nutrient transfer rates in soil food webs of cold ecosystems.

opencc-zeroMay 2020View details →

Data from: Plant-soil feedback contributes to predicting plant invasiveness of 68 alien plant species differing in invasive status

Understanding what species characteristics allow some alien plants to become invasive while others fail is critical to our understanding of community assembly processes. While many characteristics have been shown to predict plant invasiveness, the importance of plant-soil feedback (PSF) in invasions has been difficult to assess since individual studies include only a few species and use disparate methodology. We studied PSF of 68 invasive and non-invasive alien species in a single two-phase common garden experiment, and compared the relative importance of PSF, residence time, phylogenetic novelty and plant traits for plant invasiveness. Additionally, we explored relationships between PSF, residence time and phylogenetic novelty. PSF for seedling establishment, but not for biomass, was a significant predictor of invasive status, with invasive species having more positive PSF than non-invasive species. Its explanatory power was, however, much lower than that of specific leaf area, height, and residence time. Phylogenetically novel species experienced less negative PSF than species with native congeners, suggesting they benefit more from enemy release. PSF of non-invasive species, contrary to that of invasive species, was becoming more negative with increasing residence time. We demonstrated that PSF for seedling establishment plays a role in predicting plant invasiveness and is a better predictor than more commonly studied PSF for plant biomass. Other species traits, such as specific leaf area, however, predict plant invasiveness much better than the PSF.

Data from: Testing genotypic variation of an invasive plant species in response to soil disturbance and herbivory

Herbivores, competitors, and predators can inhibit biological invasions ("biotic resistance" sensu Elton 1959), while disturbance typically promotes biological invasions. Although biotic resistance and disturbance are often considered separately in the invasion literature, these two forces may be linked. One mechanism by which disturbance may facilitate biological invasions is by decreasing the effectiveness of biotic resistance. The effects of both disturbance and biotic resistance may vary across invading genotypes, and genetic variation in the invasive propagule pool may increase the likelihood that some genotypes can overcome biotic resistance or take greater advantage of disturbance. We conducted an experimental field trial in which we manipulated soil disturbance (thatch removal and loosening soil) and the presence of insect herbivores and examined their effects on the invasion success of 44 Medicago polymorpha genotypes. As expected, insecticide reduced leaf damage and increased Medicago fecundity, suggesting that insect herbivores in this system provide some biotic resistance. Soil disturbance increased Medicago fecundity, but did not alter the effectiveness of biotic resistance by insect herbivores. We found significant genetic variation in Medicago in response to disturbance, but not in response to insect herbivores. These results suggest that the ability of Medicago to invade particular habitats depends on the amount of insect herbivory, the history of disturbance in the habitat, and how the specific genotypes in the invader pool respond to these factors.

opencc-zeroMay 2020View details →

Data from: Contrasting per-gram competitive and soil resource effects in grasses and woody plants

1. Plant species differ in their competitive effects by decreasing resource availability via uptake, but in some cases may increase resource availability via non-uptake pathways. Here we explore differences between grasses and woody plants in their competitive effects, and relate these to differences in resource effects. 2. We grew five species each of grasses and woody plants in monocultures for eight years. In the final two growing seasons, competitive effects were measured by growing transplants in all monocultures and in plots without neighbours. 3. Total competitive effects were significantly greater for woody plants than grasses. In contrast, the competitive effect per gram of grasses was about 17 times greater than that of woody plants. 4. For grasses, soil water and soil available N decreased significantly with increasing biomass. In contrast, for woody plants, soil water and soil available N increased significantly with increasing biomass. The results suggest that the intense per-gram competitive effects in grasses is related to the uptake of soil resources, and that the significantly lower per-gram competitive effects of woody plants may be related to their positive effects on soil resources. 5. Synthesis. The results link differences in competitive effects between grasses and woody plants to differences in the direction of their effects on soil resources. These differences may contribute to the entrainment of negative feedback in grasslands, excluding trees by means of strong competition, and the entrainment of positive feedback beneath woody plants establishing in grasslands, resulting in a state change from grassland to woody vegetation.

opencc-zeroDec 2018View details →

Data from: Cross-biome patterns in soil microbial respiration predictable from evolutionary theory on thermal adaptation

Climate warming may stimulate microbial metabolism of soil carbon, causing a carbon cycle-climate feedback whereby carbon is redistributed from soil to atmospheric CO2. The magnitude of this feedback is uncertain, in part because warming-induced shifts in microbial physiology and/or community composition could retard or accelerate soil carbon losses. Here, we measure microbial respiration rates for soils collected from 22 sites in each of three years, at locations spanning boreal to tropical climates. Respiration was measured in the laboratory with standard temperatures, moisture and excess carbon substrate, to allow physiological and community effects to be detected independent from the influence of these abiotic controls. Patterns in respiration for soils collected across the climate gradient are consistent with evolutionary theory on physiological responses that compensate for positive effects of temperature on metabolism. Respiration rates per unit microbial biomass were as much as 2.6-times higher for soils sampled from sites with a mean annual temperature (MAT) of -2.0 versus 21.7ºC. Subsequent 100-day incubations suggested differences in the plasticity of the thermal response among microbial communities, with communities sampled from sites with higher MAT having a more plastic response. Our findings are consistent with adaptive metabolic responses to contrasting thermal regimes that are also observed in plants and animals. These results may help build confidence in soil carbon-climate feedback projections by improving understanding of microbial processes represented in biogeochemical models.

Data from: Do temperate tree species diversity and identity influence soil microbial community function and composition?

Studies of biodiversity-ecosystem function in treed ecosystems have generally focused on aboveground functions. The present study investigates inter-trophic links between tree diversity and soil microbial community function and composition.We examined how microbial communities in surface mineral soil responded to experimental gradients of tree species richness (SR), functional diversity (FD), community-weighted mean trait value (CWM) and tree identity. The site was a 4-yr-old common garden experiment near Montreal, Canada, consisting of deciduous and evergreen tree species mixtures. Microbial community composition, community-level physiological profiles (CLPP) and respiration were evaluated using phospholipid fatty acid (PLFA) analysis and the MicroRespTM system, respectively. The relationship between tree species richness and glucose induced respiration (GIR), basal respiration (BR), metabolic quotient (qCO2) followed a positive but saturating shape. Microbial communities associated with species mixtures were more active (basal respiration (BR)), with higher biomass (glucose induced respiration (GIR)), and used a greater number of carbon sources than monocultures. Communities associated with deciduous tree species used a greater number of carbon sources than those associated with evergreen species, suggesting a greater soil carbon storage capacity. There were no differences in microbial composition (PLFA) between monocultures and SR mixtures. The FD and the CWM of several functional traits affected both BR and GIR. In general, the CWM of traits had stronger effects than did FD, suggesting that certain traits of dominant species have more effect on ecosystem processes than does FD. Both the functions of GIR and BR were positively related to aboveground tree community productivity. Both tree diversity (SR) and identity (species and functional identity – leaf habit) affected soil microbial community respiration, biomass and composition. For the first time, we identified functional traits related to life history strategy, as well as root traits that influence another trophic level, soil microbial community function, via effects on BR and GIR.

opencc-zeroAug 2019View details →

Data from: Effects of soil type and light on height growth, biomass partitioning, and nitrogen dynamics on 22 species of tropical dry forest tree seedlings: comparisons between legumes and nonlegumes

PREMISE OF THE STUDY: The seedling stage is particularly vulnerable to resource limitation, with potential consequences for community composition. We investigated how light and soil variation affected early growth, biomass partitioning, morphology, and physiology of 22 tree species common in tropical dry forest, including eight legumes. Our hypothesis was that legume seedlings are better at taking advantage of increased resource availability, which contributes to their successful regeneration in tropical dry forests. METHODS: We grew seedlings in a full-factorial design under two light levels in two soil types that differed in nutrient concentrations and soil moisture. We measured height biweekly and, at final harvest, biomass partitioning, internode segments, leaf carbon, nitrogen, δ 13 C, and δ 15 N. KEY RESULTS: Legumes initially grew taller and maintained that height advantage over time under all experimental conditions. Legumes also had the highest final total biomass and water-use efficiency in the high-light and high-resource soil. For nitrogen-fixing legumes, the amount of nitrogen derived from fixation was highest in the richer soil. Although seed mass tended to be larger in legumes, seed size alone did not account for all the differences between legumes and nonlegumes. Both belowground and aboveground resources were limiting to early seedling growth and function. CONCLUSIONS: Legumes may have a different regeneration niche, in that they germinate rapidly and grow taller than other species immediately after germination, maximizing their performance when light and belowground resources are readily available, and potentially permitting them to take advantage of high light, nutrient, and water availability at the beginning of the wet season.

opencc-zeroApr 2020View details →

Data from: Livestock overgrazing disrupts the positive associations between soil biodiversity and nitrogen availability

Livestock overgrazing influences both microbial communities and nutrient cycling in terrestrial ecosystems. However, the role of overgrazing in regulating the relationship between soil biodiversity and nitrogen availability remains largely unexplored. We performed long-term grazing exclusion experiments across eight sites along precipitation gradient covering three major types of grassland in northern China to compare the linkage between soil microbial diversity and N availability in overgrazed versus non-grazed conditions. We found a positive association between fungal diversity and soil available N in non-grazed grasslands. However, the positive association was absent in overgrazed environments. Bacterial diversity is not related to soil available N in either non-grazed or overgrazed grasslands. Moreover, in bacterial community, we found a positive link between the relative abundance of Actinobacteria with soil available N in non-grazed, but not overgrazed, grasslands. Instead we found the links between relative abundance of Bacteroidetes and Acidobacteria with soil available N in overgrazed grasslands, but not non-grazed, grasslands. Our work provides evidence that the relationships between microbial diversity and ecosystem functions are context-dependent, and so microbial community diversity is likely not the major driver of soil N mineralization in overgrazed grasslands. Our study suggests that high intensity anthropogenic activities in grasslands restrains the capacity of diverse soil microbial communities to sustain ecosystem function, and more broadly the capacity of entire ecosystems to maintain important ecosystem processes such as plant production. Our study also indicates that the fundamental microbial communities associated with N availability change with differing land management strategies (e.g. livestock grazing).

Data from: Plant-soil feedbacks mediate shrub expansion in declining forests, but only in the right light

1. Contemporary global change, including the widespread mortality of foundation tree species, is altering ecosystems and plant communities at unprecedented rates. Plant-soil interactions drive myriad community dynamics, and we hypothesized such interactions may be an important driver of succession following the loss of foundation tree species. 2. We examined whether plant-soil biota interactions, in the context of a putatively important light gradient associated with foundation tree decline, mediate the expansion of Rhododendron maximum in southeastern US forests where Tsuga canadensis (eastern hemlock), a dominant foundation tree species, is in decline. Using an 11-month, controlled inoculation experiment paired with Illumina sequencing, we tested the following hypotheses: (1) Relative to conspecific (R. maximum-conditioned) soils, R. maximum seedlings have higher performance in soils conditioned by T. canadensis and lower performance in interspace soils (conditioned by neither T. canadensis nor R. maximum) due to variation in soil fungal biota, and (2) seedling performance is greater in high light versus low light environments (matching environments under infested versus uninfested T. canadensis crowns, respectively). 3. In partial support of the first hypothesis, we found that R. maximum seedling performance was highest in T. canadensis-conditioned and R. maximum-conditioned soils and lowest in interspace soils. Mechanistically, soils conditioned by T. canadensis and R. maximum had more ericoid and ectomycorrhizal fungi, less saprotrophic fungi, and were less species-rich than interspace soils, and variation in these community traits predicted substantial variation in R. maximum seedling biomass. However, in support of our second hypothesis, soil effects on plant performance were evident in high light only; in low light, soil inoculation did not affect plant performance and plants performed worse. 4. Synthesis. Our findings suggest interactions with soil biota act synergistically with altered abiotic environments to mediate species responses to widespread foundation tree mortality, providing evidence for a novel mechanism of plant response to large-scale disturbance. Examining plant-soil interactions in the context of relevant abiotic gradients can therefore enhance our understanding, predictions, and management of community development processes following forest disturbance.

Data from: Legacy effects of land use on soil nitrous oxide emissions in annual crop and perennial grassland ecosystems

Land use conversions into and out of agriculture may influence soil-atmosphere greenhouse gas fluxes for many years. We tested the legacy effects of land use on cumulative soil nitrous oxide (N2O) fluxes for five years following conversion of 22 year-old Conservation Reserve Program (CRP) grasslands and conventionally tilled agricultural fields (AGR) to continuous no-till corn, switchgrass, and restored prairie. An unconverted CRP field served as a reference. We assessed the labile soil C pool of the upper 10 cm in 2009 (the conversion year) and in 2014 using short-term soil incubations. We also measured in situ soil N2O fluxes biweekly from 2009 through 2014 using static chambers except when soils were frozen. The labile C pool was ~2-fold higher in soils previously in CRP than in those formerly in tilled cropland. Five-year cumulative soil N2O emissions were ~3-fold higher in the corn system on former CRP than on former cropland despite similar fertilization rates (~184 kg N ha-1 yr-1). The lower cumulative emissions from corn on former cropland were similar to emissions from switchgrass that was fertilized less (~57 kg N ha-1 yr-1), regardless of former land use, and lowest emissions were observed from the unfertilized restored prairie and reference systems. Findings support the hypothesis that soil labile carbon levels modulate the response of soil N2O emissions to nitrogen inputs, with soils higher in labile carbon but otherwise similar – in this case reflecting land use history – responding more strongly to added nitrogen.

opencc-zeroNov 2019View details →

Data from: Spatial transitions in tree cover are associated with soil hydrology, but not with grass biomass, fire frequency, or herbivore biomass in Serengeti savannahs

1. Although there is a well-known association between tree cover and soil texture in savannahs, the hydrological drivers of tree cover variation have not been systematically explored, particularly in parallel with factors such as fire, herbivory, and tree-grass interactions. The relationship between hydrological factors and tree cover is important for resolving the relative contribution of bottom-up vs. top-down factors in structuring savannah vegetation. 2. We quantified soil moisture dynamics across eight 1-km transects spanning tree cover gradients from open to woody savannah in Serengeti National Park in Tanzania using soil moisture sensors coupled with dataloggers. We mapped tree cover at two spatial scales through supervised classification of high-resolution satellite imagery. We simultaneously produced water retention curves in open and woody habitats within each transect to compare soil hydrological properties and to convert volumetric water content (θ) from dataloggers to plant-available water over the course of an annual cycle. We also quantified grass biomass at 100 locations per transect, estimated fire frequency from MODIS satellite data, and quantified herbivore occupancy with paired camera traps situated in open and woody habitats within each transect. 3. We found a positive relationship between tree cover and soil moisture drainage rate, and found that open habitats had more negative water potentials than woody habitats for a given value of θ. In contrast, we found no evidence for a consistent relationship between grass biomass or fire frequency and tree cover. We found evidence for higher browser occupancy in woody than open habitats, but no habitat effects on herbivores as a group (browsers plus grazers), suggesting that herbivory is unlikely to be the dominant factor explaining variation in tree cover. 4. Our results suggest that variation in tree cover is partly driven by hydrological (edaphic) factors unrelated to fire, herbivory, tree-grass interactions or mean annual precipitation at these spatial scales in Serengeti. We contrast our findings with previous work attributing tree cover shifts in Serengeti to precipitation gradients.

opencc-zeroJan 2020View details →

Data from: Agricultural land-use history and restoration impact soil microbial biodiversity

<ol> <li>Human land uses, such as agriculture, can leave long-lasting legacies as ecosystems recover. As a consequence, active restoration may be necessary to overcome land-use legacies; however, few studies have evaluated the joint effects of agricultural history and restoration on ecological communities. Those that have studied this joint effect have largely focused on plants and ignored other communities, such as soil microbes.</li> <li>We conducted a large-scale experiment to understand how agricultural history and restoration tree thinning affect soil bacterial and fungal communities within longleaf pine savannas of the southern United States. This experiment contained 64 pairs of remnant (no history of tillage agriculture) and post-agricultural (reforested following abandonment from tillage agriculture >60 years prior) longleaf pine savanna plots. Plots were each 1-ha and arranged into 27 blocks to minimize land-use decision making biases. We experimentally restored half of the remnant and post-agricultural plots by thinning trees to reinstate open-canopy savanna conditions and collected soils from all plots five growing seasons after tree thinning. We then evaluated soil bacterial and fungal communities using metabarcoding.</li> <li>Agricultural history increased bacterial diversity but decreased fungal diversity, while restoration increased both bacterial and fungal diversity. Both bacterial and fungal richness were correlated with a range of environmental variables including aboveground variables like leaf litter and plant diversity, and belowground variables such as soil nutrients, pH, and organic matter, many of which were also impacted by agricultural history and restoration.</li> <li>Fungal and bacterial community compositions were shaped by restoration and agricultural history resulting in four distinct communities across the four treatment combinations.</li> <li>Past agricultural land use left persistent legacies on soil microbial biodiversity, even over half a century after agricultural abandonment and after intensive restoration activities. The impacts of these changes on soil microbe biodiversity could play important roles in the functioning of ecosystems following agricultural abandonment and during restoration.</li> </ol>

opencc-zeroApr 2020View details →

Data from: Fate of the soil seed bank of giant ragweed and its significance in preventing and controlling its invasion in grasslands

Pollen of giant ragweed (GR), an annual non-native invasive weed, causes serious respiratory allergies in some humans and animals. Chemical control of GR in grassland can produce toxic side effects in herbs and livestock. This paper discusses methods used to prevent infestation and to control this species by analyzing the soil seed bank (SSB) and limiting the invasiveness of GR. By studying GR distributed in grassland of the Yili Valley, Xinjiang, China, this paper compares the spatial and temporal changes of seed density along with seed germination, dormancy, and death at different times after invasion and in different soil layers. The study analyzed population characteristics over time, seed fate, and control methods for this species with the goal of reducing the of SSB density of GR. The SSB of GR in grassland occurs mainly in the 0–5 cm soil layer but also to depths of 15 cm. Seed density in the SSB decreased by 68.1% to 82.01% from the seed maturity period to the early non-fertile period. >98.7% of the seeds rotten, eaten, germinated, dispersed or died within one year after being produced. The seed germination rate of the SBB decreased with an increasing number of years after invasion. When stored for 1 or 4 years, seed germination rates fell by 40%, during which time seed mortality increased by almost 40%. When GR was completely eradicated for 2 consecutive years, the SSB and population densities decreased by >99%. The vast majority of GR seeds germinated or died within one year; long term dry storage also significantly decreased the germination rate. Newly produced seeds are the main source of seeds in the SSB; seeds have a strong ability to germinate. Therefore, thoroughly eradicating GR plants for several years before the seeds can mature provides an effective control method in grasslands.

Data from: Spatial heterogeneity of plant-soil feedbacks increases per capita reproductive biomass of species at an establishment disadvantage

Plant–soil feedbacks have been widely implicated as a driver of plant community diversity, and the coexistence prediction generated by a negative plant–soil feedback can be tested using the mutual invasibility criterion: if two populations are able to invade one another, this result is consistent with stable coexistence. We previously showed that two co-occurring Rumex species exhibit negative pairwise plant–soil feedbacks, predicting that plant–soil feedbacks could lead to their coexistence. However, whether plants are able to reproduce when at an establishment disadvantage ("invasibility"), or what drivers in the soil might correlate with this pattern, are unknown. To address these questions, we created experimental plots with heterogeneous and homogeneous soils using field-collected conditioned soils from each of these Rumex species. We then allowed resident plants of each species to establish and added invader seeds of the congener to evaluate invasibility. Rumex congeners were mutually invasible, in that both species were able to establish and reproduce in the other's resident population. Invaders of both species had twice as much reproduction in heterogeneous compared to homogeneous soils; thus the spatial arrangement of plant–soil feedbacks may influence coexistence. Soil mixing had a non-additive effect on the soil bacterial and fungal communities, soil moisture, and phosphorous availability, suggesting that disturbance could dramatically alter soil legacy effects. Because the spatial arrangement of soil patches has coexistence implications, plant–soil feedback studies should move beyond studies of mean effects of single patch types, to consider how the spatial arrangement of patches in the field influences plant communities.

Data from: Flooding and soil composition determine beta-diversity of lowland forests in Northern South America

Beta diversity may be determined by dispersal limitation, environment and phylogeographic history. Our objective was to advance the understanding of plant species turnover in rainforests in Northern South America and determine which factors are affecting species beta-diversity. We evaluated the relative effect of environmental variables (i.e. soil, climate, fragmentation and flooding frequency) and dispersal limitation (i.e. geographical distance and resistance distance due mountain barriers) on tree beta diversity in 32 1-ha lowland forest plots. We found that tree species turnover was better explained by environmental distance than by geographic distance. Although, soil conditions and flooding regime were good predictors of tree species composition, almost half of the variance remained unexplained. In our study system, the Eastern Andean ridge had no significant effect on plant beta diversity, probably because of its young age in relation to the phylogeny. Our results provide support for the importance of environmental factors and suggests a more restricted role of dispersal limitation. Therefore, we advise that conservation strategies of lowland trees should consider specific forest types (e.g. seasonally flooded vs. terra firme, as well as piedmont vs. central Amazonian forests).