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The Kenya long‐term exclosure experiment (KLEE) was established in 1995 in semi‐arid savanna rangeland to examine the separate and combined effects of livestock, wildlife and megaherbivores on their shared environment. The long‐term nature of this experiment has allowed us to measure these effects and address questions of stability and resilience in the context of multiple drought‐rainy cycles. Here we outline lessons learned over the last 29 years, and how these inform a fundamental tension in long‐term studies: how to balance the need for question‐driven research with the intangible conviction that long‐term data will yield valuable findings. We highlight the value of (1) identifying experimental effects that take many years to manifest, (2) quantifying the effects of different years (including droughts) and (3) capturing the signatures of anthropogenic change. We also highlight the potential for long‐term studies to create a collaborative community of scientists that brings new questions and motivates continued long‐term study. [ABSTRACT FROM AUTHOR]

Converting croplands to grasslands can restore ecosystem functions and services, but there is uncertainty about why some restoration treatments succeed and others do not. One likely explanation for variation in restoration outcomes is that interannual variation in the drivers of community assembly, or "year effects," is often overlooked in restoration planning. Existing restoration strategies tailor species compositions of seed mixes according to long‐term climate means and hardiness zones. However, individual years typically deviate from average climate norms such that restoration activities may be better informed by recent conditions than by climate averages. We monitored a 109‐ha field in northeastern Colorado that was converted from a winter wheat‐fallow rotation to native perennial grassland via seeding. The same seed mix was used to seed 6 of 12,120‐m strips in 2013 (drier) and 6 in 2014 (wetter). In the strips seeded in 2013, only one native grass and one shrub species from the seed mix established widely, whereas in 2014, all native grasses established. Higher soil moisture preceding seed application was positively associated with perennial grasses, while rhizomatous grasses, shrubs, and introduced annuals were associated with other variables. After seeding, high summer soil moisture was positively associated with a rhizomatous C3 grass, while the planted C4 bunchgrasses were negatively associated with high summer soil moisture and positively associated with high fall soil temperatures. We found evidence of facilitatory interactions between grasses and forbs, as well as antagonistic interactions between native perennial grasses and non‐native annuals. Our results suggest that the conditions immediately before and after planting govern community assembly and leave a lasting legacy and should be considered in planning treatments. We suggest composing seed mixes that are tailored to commonly encountered extremes of temperature and moisture availability. Land managers can also use split‐seeding or repeated seeding approaches, within or between years as bet‐hedging strategies. The development of more flexible funding mechanisms could allow for regional go/no‐go climate thresholds to avoid wasting resources. [ABSTRACT FROM AUTHOR]

Aims: Understanding the spatio‐temporal patterns of restoration outcomes is crucial to improve predictability of restoration. High beta diversity of species‐rich communities is sought because it increases overall biodiversity and improves ecosystem stability and multifunctionality. For predictive restoration, it is important to identify the significance of drivers like site characteristics but also uncontrolled factors such as spatial effects, historical factors, and year effects. Location: Dikes at river Danube, SE Germany. Methods: We studied dike grasslands 4–19 years after restoration over five years (2017–2021, 41 plots in 12 sites). We calculated beta diversity indices to describe spatial variation and temporal turnover, including their additive components 'replacement' and 'nestedness', or 'gains' and 'losses'. We analysed the main drivers of beta diversity like local site characteristics, landscape, and historical factors. Results: Spatial variation of the restored dike grasslands was dominated by the replacement component and showed no homogenisation despite a significant temporal turnover. The replacement drivers changed over time, although replacement was mainly affected by slope aspect and landscape factors. Historical factors were inconsistent over time, and no statistically clear drivers of nestedness were found. The dike grasslands exhibited a year‐to‐year turnover in species composition of 37 ± 11%. Gains and losses were balanced over time, although the ratio changed and was most pronounced on south‐facing slopes. Conclusions: The restored grasslands exhibited spatial variation by site characteristics but also by spatial factors which were not controlled by restorations. Moreover, high non‐directional temporal turnover occurred, caused most likely by weather fluctuations, slightly varying management, and stochastic biotic dynamics. Thus, flexible targets are recommended for restoration monitoring, by defining a set of desired states within a certain range. Furthermore, the dominance of the replacement component of spatial variation should move the focus from defining one precise restoration approach to defining a set of possible methods which together would foster beta diversity. [ABSTRACT FROM AUTHOR]

Juvenile survival is critical to population persistence and evolutionary change. However, the survival of juvenile plants from emergence to reproductive maturity is rarely quantified. This is especially true for long‐lived perennials with extended pre‐reproductive periods. Furthermore, studies rarely have the replication necessary to account for variation among populations and cohorts. We estimated juvenile survival and its relationship to population size, density of conspecifics, distance to the maternal plant, age, year, and cohort for Echinacea angustifolia, a long‐lived herbaceous perennial. In 14 remnant prairie populations over seven sampling years, 2007–2013, we identified 886 seedlings. We then monitored these individuals annually until 2021 (8–15 years). Overall, juvenile mortality was very high; for almost all cohorts fewer than 10% of seedlings survived to age 8 or to year 2021. Only two of the seedlings reached reproductive maturity within the study period. Juvenile survival increased with distance from the maternal plant and varied more among the study years than it did by age or cohort. Juvenile survival did not vary with population size or local density of conspecific neighbors. Our results suggest that low juvenile survival could contribute to projected population declines. [ABSTRACT FROM AUTHOR]

Coating seeds with amendments to increase germination, emergence, and establishment is a promising strategy for dryland restoration. Seed coatings containing fungicides offer a potential solution in regions where fungal pathogens cause seed mortality during the winter stratification period between late fall seeding and spring germination. The effectiveness of the fungicide treatment, however, may be dictated by weather and within‐site microenvironment. We tested how fungicide coating influenced seedling emergence of native grasses within sagebrush stands by planting untreated seeds and seeds coated (encrusted) with and without active fungicide ingredients in furrows that extended from the canopy edge of sagebrush plants (Artemisia tridentata ssp. wyomingensis) into the interspace. This was replicated at four sites across the Intermountain West in two successive years. We planted two native grasses, bottlebrush squirreltail (Elymus elymoides) and bluebunch wheatgrass (Pseudoroegneria spicata). Emergence was extremely low in both years, with a complete seeding failure (i.e. zero emergence) at two sites in the first year and three sites in the second year. At one site where emergence was sufficient for statistical analysis: (1) the coating on the fungicide and blank treatments inhibited emergence under anomalously dry conditions and (2) across seed treatments, proximity to a sagebrush canopy slightly increased seedling emergence. The variable emergence patterns across sites and years (i.e. the highest emergence was for the site–year combination with the lowest precipitation) highlight the sensitivity of seeding outcomes to, and dependence of fungicide seed coatings on, site conditions, and the necessity of repeating experiments across different weather years. [ABSTRACT FROM AUTHOR]

Year of establishment can be a critical driver of plant communities with the establishment stage of community development particularly susceptible to factors including ambient rain, temperature, and other temporally variable drivers (e.g., seed and seedling predators). However, while year effects have been shown to drive community structure at local (patch) scales, it is yet unexplored how these within‐patch effects scale up to drive landscape‐level patterns of biodiversity. These dynamics are likely to be critical but are overlooked in many systems including those with high‐frequency disturbance regimes or active management. Here we leveraged a series of field‐based grassland mesocosms established identically at three sites across 5 years, and each monitored for 4–8 years. We compared the strength of these temporal and spatial drivers (year effects and site effects) on consequent patterns of spatial and temporal variability (beta diversity and turnover) between plots seeded with native perennial species versus those seeded with nonnative annual species. The composition of plots seeded with perennial species showed strong effects of planting year and consequently exhibited higher beta diversity within sites (across mesocosms established in five different years within sites), while plots seeded with annual species had higher between‐site variation but low beta diversity within sites. Plots with annual species were also more temporally variable than plots with perennial species. These findings have important implications for our understanding of key drivers of biodiversity across landscapes. Specifically, we showed that variable trajectories in community composition generated by site and year effects during establishment can promote beta diversity across landscapes dominated by perennial species, but are considerably less impactful in annual‐dominated systems. These findings further our understanding of the importance of assembly dynamics on landscape‐scale patterns of diversity, and have important management implications for restoration efforts. [ABSTRACT FROM AUTHOR]

Ecological restoration outcomes are highly variable, undermining efforts to recover biodiversity and ecosystem functions. One poorly understood source of variability is 'year effects'—interannual variation in environmental conditions during the first year of restoration that alter successional trajectories of plant communities.There have been few experimental tests disentangling planting years from other differences among restoration projects (e.g. edaphic conditions, restoration approach), particularly those resolving mechanisms for year effects such as planting‐year rainfall. Moreover, past year effect studies focused almost exclusively on species‐level consequences. Therefore, the extent to which year effects influence the traits of communities is unknown.To address these gaps and provide a mechanistic test of how precipitation contributes to year effects, we conducted an experiment where we manipulated rainfall (drought, average and high levels) during the first growing season, replicated across three establishment year treatments to disentangle the effects of precipitation from other drivers of year effects. In each establishment year, we seeded the same species mix to initiate grassland restoration. We then surveyed plant community compositions annually for 5 years to quantify trait responses of restored communities to planting year rainfall.We found that variation in planting‐year precipitation altered community assembly trajectories by influencing community‐weighted mean (CWM) trait composition, and these effects persisted for at least 5 years. Over time, CWM specific leaf area and CWM seed mass decreased and CWM plant height increased. The effect of age on CWM plant height was stronger in plots that received mean and high watering treatments compared to drought treatments. This effect was also observed for CWM seed mass, albeit weaker.We also found some evidence for planting year effects unrelated to planting‐year rainfall for the three CWM traits, illustrating how interannually varying environmental conditions besides rainfall can generate persistent year effect on plant communities through their traits.Synthesis and applications. Our results provide evidence for planting year rainfall interacting with community assembly to alter the functional trait composition of restored grasslands. This suggests that interannual variation in rainfall during establishment is an important source of divergent biodiversity and functional outcomes in restored grasslands. [ABSTRACT FROM AUTHOR]

An increasing number of studies is investigating insect population trends based on time series data. However, the available data is often subject to temporal pseudoreplication. Inter‐annual variability of environmental conditions and strong fluctuations in insect abundances can impede reliable trend estimation. Temporal random effect structures in regression models have been proposed as solution for this issue, but remain controversial.We investigated trends in ground beetle abundance across 24 years using generalised linear mixed models. We fitted four models: A base model, a model featuring a random year intercept, a model featuring basic weather parameters, and a model featuring both random year intercept and weather parameters. We then performed a simple sensitivity analysis to assess the robustness of the four models with respect to influential years, also testing for possible spurious baseline and snapshot effects.The model structure had a significant impact on the overall magnitude of the estimated trends. However, we found almost no difference among the models in how the removal of single years (sensitivity analysis) relatively affected trend coefficients. The two models with a random year intercept yielded significantly larger confidence intervals and their p‐values were more sensitive during sensitivity analysis. Significant differences of the model with random year intercept and weather parameters to all other models suggest that the random year effects and specific weather effects are rather additive than interchangeable.We conclude that random year intercepts help to produce more reliable and cautious uncertainty measures for insect population trends. Moreover, they might help to identify influential years in sensitivity analyses more easily. We recommend random year intercepts in addition to any variables representing temporally variable environmental conditions, such as weather variables. [ABSTRACT FROM AUTHOR]

Plant community assembly outcomes can be contingent upon establishment year (year effects) due to variations in the environment. Stochastic events such as interannual variability in climate, particularly in the first year of community assembly, contribute to unpredictable community outcomes over the short term, but less is known about whether year effects produce transient or persistent states on a decadal timescale. To test for short‐term (5‐year) and persistent (decadal) effects of establishment year climate on community assembly outcomes, we restored prairie in an agricultural field using the same methods in four different years (2010, 2012, 2014, and 2016) that captured a wide range of initial (planting) year climate conditions. Species composition was measured for 5 years in all four restored prairies and for 9 and 11 years in the two oldest restored prairies established under average precipitation and extreme drought conditions. The composition of the four assembled communities showed large and significant differences in the first year of restoration, followed by dynamic change over time along a similar trajectory due to a temporary flush of annual volunteer species. Sown perennial species eventually came to dominate all communities, but communities remained distinct from each other in year five. Precipitation in June and July of the establishment year explained short‐term coarse community metrics (i.e., species richness and grass/forb cover), with wet establishment years resulting in a higher cover of grasses and dry establishment years resulting in a higher cover of forbs in restored communities. Short‐term differences in community composition, species richness, and grass/forb cover in restorations established under average precipitation and drought conditions persisted for 9–11 years, with low interannual variability in the composition of each prairie over the long term, indicating persistently different states on a decadal timescale. Thus, year effects resulting from stochastic variation in climate can have decadal effects on community assembly outcomes. [ABSTRACT FROM AUTHOR]

Relationships between biodiversity and ecosystem functioning depend on the processes structuring community assembly. However, predicting biodiversity‐ecosystem functioning (BEF) relationships based on community assembly remains challenging because assembly outcomes are often contingent on history and the consequences of history for ecosystem functions are poorly understood. In a grassland restoration experiment, we isolated the role of history for the relationships between plant biodiversity and multiple ecosystem functions by initiating assembly in three different years, while controlling for all other aspects of community assembly. We found that two aspects of assembly history—establishment year and succession—altered species and trait community trajectories, which in turn altered net primary productivity, decomposition rates, and floral resources. Moreover, history altered BEF relationships (which ranged from positive to negative), both within and across functions, by modifying the causal pathways linking species identity, traits, diversity, and ecosystem functions. Our results show that the interplay of deterministic succession and environmental stochasticity during establishment mediate historical contingencies that cause variation in biodiversity and ecosystem functions, even under otherwise identical assembly conditions. An explicit attention to history is needed to understand why biodiversity‐ecosystem function relationships vary in natural ecosystems: a critical question at the intersection of fundamental theory and applications to environmental change biology and ecosystem restoration. [ABSTRACT FROM AUTHOR]

Interannual variation, especially weather, is an often‐cited reason for restoration "failures"; yet its importance is difficult to experimentally isolate across broad spatiotemporal extents, due to correlations between weather and site characteristics. We examined post‐fire treatments within sagebrush‐steppe ecosystems to ask: (1) Is weather following seeding efforts a primary reason why restoration outcomes depart from predictions? and (2) Does the management‐relevance of weather differ across space and with time since treatment? Our analysis quantified range‐wide patterns of sagebrush (Artemisia spp.) recovery, by integrating long‐term records of restoration and annual vegetation cover estimates from satellite imagery following thousands of post‐fire seeding treatments from 1984 to 2005. Across the Great Basin, sagebrush growth increased in wetter, cooler springs; however, the importance of spring weather varied with sites' long‐term climates, suggesting differing ecophysiological limitations across sagebrush's range. Incorporation of spring weather, including from the "planting year," improved predictions of sagebrush recovery, but these advances were small compared to contributions of time‐invariant site characteristics. Given extreme weather conditions threatening this ecosystem, explicit consideration of weather could improve the allocation of management resources, such as by identifying areas requiring repeated treatments; but improved forecasts of shifting mean conditions with climate change may more significantly aid the prediction of sagebrush recovery. [ABSTRACT FROM AUTHOR]

An accumulating number of studies are reporting severe insect declines. These studies aim to quantify temporal changes in invertebrate populations and community composition and attribute them to anthropogenic drivers.Seibold et al. 2019 (Nature, 574, 671–674) analysed arthropod biomass, abundance and species richness from forest and grassland plots in a region of Germany and reported declines of up to 78% between 2008 and 2018. However, their analysis did not account for the confounding effects of temporal pseudoreplication.We show that simply by including a year random effect in the statistical models and thereby accounting for the common conditions experienced by proximal sites in the same years, four of the five reported declines become non‐significant out of six tests overall.To place recent estimates of insect trends in a broader context, we analysed invertebrate biomass, abundance and richness from 640 time series from 1167 sites around the world. We found that the average trends across the terrestrial and freshwater realms were not significantly distinguishable from no net change. Shorter time series that are likely most affected by sampling error variance – such as those in Seibold et al. 2019 (Nature, 574, 671–674) – yielded the most extreme decline and increase estimates.We suggest that the media uptake of negative trends from short time series may be serving to exaggerate the 'insect Armageddon' and could undermine public confidence in research. We advocate that future research uses appropriate model structures to build a more robust understanding of biodiversity change. [ABSTRACT FROM AUTHOR]

Environmental conditions that vary from year to year can be strong drivers of ecological dynamics, including the composition of newly assembled communities. However, ecologists often chalk such dynamics up to "noise" in ecological experiments. Our lack of attention to such "year effects" hampers our understanding of contingencies in ecological assembly mechanisms and limits the generalizability of research findings. Here, we provide examples from published research demonstrating the importance of year effects during community assembly across study systems. We further quantify these year effects with two case studies—a grassland restoration experiment and a study of postfire conifer recruitment—finding that the effects of initiation year on community composition can dictate community as much, if not more, than the effects of experimental treatments or site. The evidence strongly suggests that year effects are pervasive and profound, and that year effects early in community assembly can drive strong and enduring divergence in community structure and function. Explicit attention to year effects in ecological research serves to illuminate basic ecological principles, allowing for better understanding of contingencies in ecology. These dynamics also have strong implications for applied ecological research, offering new insights into ecological restoration as well as future climate change. [ABSTRACT FROM AUTHOR]

The persistence and distribution of species under changing climates can be affected by both direct effects of the environment and indirect effects via biotic interactions. However, the relative importance of direct and indirect climate effects on recruitment stages is poorly understood. We conducted a manipulative experiment to test the multiway interaction of direct and competition-mediated effects of climate change on vegetation dynamics. Following stand-replacing fire in California mixed-conifer forest, we seeded two conifer species, Pinus ponderosa and Abies concolor, in two consecutive years, one relatively normal and the other with an unusually wet and snowy winter followed by a hot summer. We additionally manipulated snow amount and competitive environment for both years. We found the effects of the snowpack treatment were contingent upon other abiotic factors (year of seeding) and biotic factors (shrub competition). Under ambient snowpack, shrubs reduced recruitment of P. ponderosa seedlings, but this negative effect disappeared with reduced snowpack. Additionally, the effects of shrubs on seedlings differed between cohorts and by life stage. In a warmer future, decreased snowpack may increase seedling emergence, but hotter and drier summers will decrease seedling survival; the effects of shrubs on conifers may become less negative as temperatures increase. [ABSTRACT FROM AUTHOR]

Ecological restoration can reverse biodiversity loss worldwide, yet restoration goals and outcomes vary widely, which limits this potential. Divergent restoration outcomes may stem from variation in conditions at the outset of restoration, but empirical evidence is lacking and typically confounded with site differences. Additionally, precipitation is usually cited as the source of this variation, although a wide range of conditions can vary annually. We tested for effects of planting year on seedling establishment by installing identical restorations in three different years. Within those years, we manipulated rainfall with rain‐out shelters to disentangle the effects of precipitation from other annually variable conditions. Additionally, we tested whether increasing seed mix richness buffers against adverse planting conditions. For the first growing season after planting, we followed emergence and survival of sown prairie species and nonsown weed species to determine how planting year conditions influence an establishing plant community, if at all. We found that seedling establishment differed across planting years and precipitation treatments, and that varying emergence patterns by species led to differences in the composition of the first‐year community. We also found significant variation in sown species establishment across years when precipitation was held constant, illustrating the previously overlooked role of nonprecipitation drivers on planting year effects. Higher seed mix richness did not consistently improve establishment of sown species under different planting conditions. This research provides important experimental evidence for effects of interannual variation in planting conditions on first‐year establishment. Future work will examine how these initial changes affect longer‐term assembly dynamics. [ABSTRACT FROM AUTHOR]

The outcomes of restoration efforts are contingent on the specifics of the restoration practices utilized, but also on uncontrolled contingencies such as site effects and year effects. Although restoration practitioners have long been aware that the successes of their projects vary from site to site and from year to year, there have been few direct experimental tests of these contingencies., We established grassland restoration plots identically across three sites in northern California, in each of four establishment years (for 12 site-year combinations)., The resulting plant communities differed significantly across sites and across establishment years. As a consequence of these community differences, there were 'forb years' and 'grass years', although these sometimes differed among sites. Multivariate analysis identified mean annual temperature and total precipitation as likely drivers of some of these differences., Synthesis and applications. Our results not only confirm the idiosyncratic nature of the results of restoration efforts (and ecological experiments in general) but also demonstrate that some of this variation can potentially be related to measurable environmental conditions. Understanding the drivers of this variability can ultimately aid restoration practitioners by allowing them to focus restoration efforts on years and sites most likely to yield desired outcomes. [ABSTRACT FROM AUTHOR]

The order in which species arrive during community assembly can be an important driver of community composition and function. However, the strength of these priority effects can be variable, in part because of strong site and year effects. To understand how priority effects vary in importance with abiotic conditions, we initiated identical community assembly experiments in which we varied the timing of arrival of native and exotic grass species in each of 4 yr across three grassland sites in northern California. This uniquely replicated experiment tested the power of priority to determine initial community structure in a restoration context across a natural range of conditions. There were large and significant differences in both total seeded cover and the strength of priority across sites and years of initiation, confirming the suspicion that most ecological experiments may lack spatial and temporal generality. On the other hand, much of the variation in strength of priority could be related to climate. Strikingly, however, the model fit across the three sites and the first 3 yr of the study (the first nine experiments) was radically altered when we included the fourth year, which was characterized by an unusual weather pattern with higher temporal variability in rainfall (a rainfall pattern predicted to increase with climate change). This year produced relatively low strength of priority, supporting the suggestion that highly variable climates may be associated with lower strength of priority effects. Experiments that examine community assembly over a range of naturally occurring abiotic conditions enhance our ability to predict when priority effects will be important, allowing us to explore shifting patterns of community assembly in the face of climate change and optimize restoration strategies based on environmental conditions. [ABSTRACT FROM AUTHOR]

Abstract: Covariation between vital rates is recognized as an important pattern to be accounted for in demographic modeling. We recently introduced a model for estimating vital rates and their covariation as a function of known and unknown effects, using generalized linear mixed models (GLMM’s) implemented in a hierarchical Bayesian framework (Evans et al., 2010) In particular, this model included a model-wide year effect (YEAR) influencing all vital rates, which we used to estimate covariation between vital rates due to exogenous factors not directly included in the model. This YEAR effect connected the GLMMs of vital rates into one large model; we refer to this as the “connected GLMMs” approach. Here we used a simulation study to evaluate the performance of a simplified version of this model, compared to separate GLMMs of vital rates, in terms of their ability to estimate correlations between vital rates. We simulated data from known relationships between vital rates and a covariate, inducing correlations among the vital rates. We then estimated those correlations from the simulated data using connected vs. separate GLMMs with year random effects. We compared precision and accuracy of estimated vital rates and their correlations under three scenarios of the pervasiveness of the exogenous effect (and thus true correlations). The two approaches provide equally good point estimates of vital rate parameters, but connected GLMMs provide better estimates of covariation between vital rates than separate GLMMs, both in terms of accuracy and precision, when the common influence on vital rates is pervasive. We discuss the situations where connected GLMMs might be best used, as well as further areas of investigation for this approach. [Copyright &y& Elsevier]

Interannual variation in experimental field conditions produce variability in the results of experiments monitored over multiple years, termed here “year effects.” When experimental treatments are replicated in separate years, interannual variation may influence treatment effects and produce significant treatment by initiation-year interactions. Understanding the frequency and strength of these effects requires initiating identical experiments across years. We conducted a review of literature covering more than 500 experimental articles published in 7 journals between 1966 and 2008. Only 5% of the 276 general ecological field studies initiated experiments in multiple years. This rarity was even more evident in the journal Restoration Ecology, in which none of the 173 surveyed experimental studies initiated experiments in multiple years. In contrast, 48% of the 58 field experiments published in an agronomy journal were replicated across years. We found only 17 studies that tested treatment by initiation-year interactions. Despite their rarity, 76% of these studies found significant interactions between treatment and initiation year. We conclude that the results of many ecological field experiments are likely to be contingent on the year in which they are implemented. We discuss the importance of treatment by initiation-year interactions in ecology and restoration, factors that have hindered the inclusion of temporal replication in the past, and some suggestions for the appropriate design and analysis of temporally replicated experiments. We argue for more deliberate investigation of temporal contingency in ecological experimentation, especially in the field of restoration ecology, which may be particularly sensitive to treatment by initiation-year interactions. [ABSTRACT FROM AUTHOR]

Understanding the degree to which species assemblages naturally vary over time will be critically important when assessing whether direct management effects or contingency is responsible for species gain or loss. In this study, we tested three predictions related to short-term variation in prairie moth communities: (1) communities would only exhibit significant temporal variation in newly restored sites (1–3 years old); (2) prairie size and age would positively influence community reassembly, with larger, older restorations sampling a greater proportion of the regional species pool; and (3) older restorations (7–10 years old) would have yet to converge on the community composition of prairie remnants. Moths were sampled from 13 Tallgrass prairie restorations and remnants in central Iowa in 2004–2005. Repeated measures analysis of variance revealed significant effects of sampling year on moth species richness and abundance as well as on the richness of two functional groups, but difference among prairie types was only observed in 2005. Rarefaction analysis revealed that older restorations and prairie remnants supported higher species richness compared to recently planted sites, and nonmetric, multidimensional scaling ordination indicated that restorations older than 7 years were clearly converging on the species composition of remnants. These results suggest that moth communities in restorations and remnants are highly variable in time but that as restorations age, they appear to reaccumulate moth species found in prairie remnants. The long-term persistence of a particular species assemblage within a given site, however, might be a difficult endpoint to attain in central Iowa prairies because of significant annual variation in species occurrence. [ABSTRACT FROM AUTHOR]

Correlations between catch rates in bottom-trawl surveys and indices of environmental conditions or fish distribution have been attributed to effects of the environmental conditions or fish distribution on catchability to the survey. We tested this hypothesis using data on cod in the southern Gulf of St Lawrence. Survey catch rates of cod were significantly correlated with indices of bottom temperature and of cod temperature and depth distributions. Correlations were in the directions expected on the basis of predicted effects on catchability or availability to the survey. However, tests involving calibrations of sequential population analysis (SPA) or residuals from multiplicative analyses of the survey catch rates (with terms for yearclass, age and cumulative mortality) did not support the hypothesis that these correlations resulted from effects on catchability to the survey. These tests provided no support for an effect of cod temperature or depth distribution on catchability. They provided some support for an effect of bottom temperature conditions on availability to the survey, but this effect on availability was not reflected by the correlations observed between bottom temperature indices and survey catch rates. We conclude that adjustments for effects on catchability should be based on relationships with inconsistencies in survey catch rates instead of relationships with the catch rates themselves. These adjustments could be incorporated in calibration of the SPA or calculated based on relationships with residuals from models relating survey catch rate to yearclass, age and fishing mortality. However, such adjustments were negligible in the case of southern Gulf of St Lawrence cod. [ABSTRACT FROM PUBLISHER]