Explore the vast range of titles available.

Successional dynamics in plant community assembly may result from both deterministic and stochastic ecological processes. The relative importance of different ecological processes is expected to vary over the successional sequence, between different plant functional groups, and with the disturbance levels and land-use management regimes of the successional systems. We evaluate the relative importance of stochastic and deterministic processes in bryophyte and vascular plant community assembly after fire in grazed and ungrazed anthropogenic coastal heathlands in Northern Europe. A replicated series of post-fire successions (n = 12) were initiated under grazed and ungrazed conditions, and vegetation data were recorded in permanent plots over 13 years. We used redundancy analysis (RDA) to test for deterministic successional patterns in species composition repeated across the replicate successional series and analyses of co-occurrence to evaluate to what extent species respond synchronously along the successional gradient. Change in species co-occurrences over succession indicates stochastic successional dynamics at the species level (i.e., species equivalence), whereas constancy in co-occurrence indicates deterministic dynamics (successional niche differentiation). The RDA shows high and deterministic vascular plant community compositional change, especially early in succession. Co-occurrence analyses indicate stochastic species-level dynamics the first two years, which then give way to more deterministic replacements. Grazed and ungrazed successions are similar, but the early stage stochasticity is higher in ungrazed areas. Bryophyte communities in ungrazed successions resemble vascular plant communities. In contrast, bryophytes in grazed successions showed consistently high stochasticity and low determinism in both community composition and species co-occurrence. In conclusion, stochastic and individualistic species responses early in succession give way to more niche-driven dynamics in later successional stages. Grazing reduces predictability in both successional trends and species-level dynamics, especially in plant functional groups that are not well adapted to disturbance.

Landbirds are especially vulnerable during migration as they move through novel habitats and encounter enhanced predation risk, unpredictable food resources, enhanced competition, and inclement weather. Further, numerous studies suggest exotic vegetation species have the potential to alter habitat quality, in turn affecting the fitness of migratory birds. The purpose of this study was to evaluate fitness correlates associated with fall migrant use of shrubland habitat dominated by nonnative honeysuckle (Lonicera spp.) in northeastern Pennsylvania. Additionally, we looked for differences in stopover ecology between demographic cohorts (age, and in the case of Common Yellowthroat [Geothlypis trichas], both age and sex). We used estimates of mass change as our primary fitness indicator, assuming that evidence of positive mass change reflects fat deposition and hence indicates quality habitat. Our results suggest that of 7 species, 1 gained mass, 5 neither gained nor lost mass, and 1 lost mass. Further, while we found little evidence of age or sex differences in migratory timing, we did find evidence that older birds gained mass at a higher rate than younger in 2 species and that, while male Common Yellowthroats maintained mass while using our site, females lost mass. We conclude that our exotic-dominated shrubland habitat does not provide high-quality stopover habitat for most species. Received 4 July 2020. Accepted 22 October 2020.

The response of soil microbial communities to a changing climate will impact global biogeochemical cycles, potentially leading to positive and negative feedbacks. However, our understanding of how soil microbial communities respond to climate change and the implications of these changes for future soil function is limited. Here, we assess the response of soil bacterial and fungal communities to long-term experimental climate change in a heathland organo-mineral soil. We analysed microbial communities using Illumina sequencing of the 16S rRNA gene and ITS2 region at two depths, from plots undergoing 4 and 18 years of in situ summer drought or warming. We also assessed the colonisation of Calluna vulgaris roots by ericoid and dark septate endophytic (DSE) fungi using microscopy after 16 years of climate treatment. We found significant changes in both the bacterial and fungal communities in response to drought and warming, likely mediated by changes in soil pH and electrical conductivity. Changes in the microbial communities were more pronounced after a longer period of climate manipulation. Additionally, the subsoil communities of the long-term warmed plots became similar to the topsoil. Ericoid mycorrhizal colonisation decreased with depth while DSEs increased; however, these trends with depth were removed by warming. We largely ascribe the observed changes in microbial communities to shifts in plant cover and subsequent feedback on soil physicochemical properties, especially pH. Our results demonstrate the importance of considering changes in soil microbial responses to climate change across different soil depths and after extended periods of time.

Global warming may have profound effects on terrestrial ecosystems. However, a comprehensive evaluation of the effects of warming on ecosystem nitrogen (N) pools and dynamics is not available. Here, we compiled data of 528 observations from 51 papers and carried out a meta-analysis of experimental warming effects on 13 variables related to terrestrial N pools and dynamics. We found that, on average, net N mineralization and net nitrification rate were increased by 52.2 and 32.2%, respectively, under experimental warming treatment. N pools were also increased by warming, although the magnitude of this increase was less than that of N fluxes. Soil microbial N and N immobilization were not changed by warming, probably because microbes are limited by carbon sources. Grassland and shrubland/heathland were less responsive to warming than forest, probably because the reduction of soil moisture by warming offset the temperature effect in these areas. Soil heating cable and all-day treatment appeared to be the most effective method on N cycling among all treatment methods. Results of this meta-analysis are useful for better understanding the response of N cycling to global warming and the underlying mechanism of warming effects on plants and ecosystem functions.

Conservation management is increasingly being required to support both the provision of ecosystem services and maintenance of biodiversity. However, trade‐offs can occur between biodiversity and ecosystems services. We examine whether such trade‐offs can be resolved through landscape‐scale approaches to management. We analysed the biodiversity value and provision of selected ecosystem services (carbon storage, recreation, aesthetic and timber value) on patches of lowland heathland in the southern English county of Dorset. We used transition matrices of vegetation dynamics across 112 heathland patches to forecast biodiversity and ecosystem service provision on patches of different sizes over a 27‐year timeline. Management scenarios simulated the removal of scrub and woodland and compared (i) no management (NM); (ii) all heaths managed equally (AM); and management focused on (iii) small heaths (SM) and (iv) large heaths (LM). Results highlighted a number of trade‐offs. Whereas biodiversity values were significantly lower in woodland than in dry and humid heath, timber, carbon storage and aesthetic values were highest in woodland. While recreation value was positively related to dry heath area, it was negatively related to woodland area. Multicriteria analysis ranked NM highest for aesthetic value, carbon storage and timber value. In contrast, SM ranked highest for recreation and LM highest for biodiversity value. In no scenario did the current site‐based approach to management (AM) rank highest. Synthesis and applications. Biodiversity–ecosystem service trade‐offs are reported in lowland heathland, an ecosystem type of high conservation value. Trade‐offs can be addressed through a landscape‐scale approach to management, by varying interventions according to heathland patch size. Specifically, if management for biodiversity conservation is focused on larger patches, the aesthetic, carbon storage and timber value of smaller patches would increase, as a result of woody succession. In this way, individual heathland patches of either relatively high biodiversity value or high value for provision of ecosystem services could both potentially be delivered at the landscape scale.

The relationship between competition and productivity in plant communities is unclear, and this is likely to be due to (1) a confusion in the literature between productivity and biomass, (2) the lack of studies assessing variation in competition in all combinations of biomass and productivity. We assessed the outcome of plant–plant interactions by removing the neighbors around five focal species in 14 herbaceous communities with contrasting biomasses and productivities: meadows with high biomass and productivity, heathlands with high biomass and low productivity, understory communities of deciduous forests with low biomass and high productivity and calcareous grasslands with low biomass and low productivity. Competition intensity was quantified with the relative interaction index (RII) calculated for both survival and growth of the transplanted targets assessed with the increase in leaf number. To examine which traits better explain variation in competition and what drives variation in diversity, we also quantified litter decomposition rate, species composition and diversity and six morphological traits related to plant size and growth rate for eight dominant species of each community. Our main questions were: (1) Is competition mostly related to biomass or productivity? (2) Which traits of the community dominants better explain variation in competition? (3) Is variation in competition and related traits correlated with variation in diversity? Competition for survival significantly increased with increasing community biomass (but not productivity). In addition, competition for survival increased with the size traits and competitive effects of the dominant species of the communities, whereas diversity decreased. Competition for growth also increased with increasing productivity, but only for high-biomass communities. Additionally, the increase in competition for growth with increasing soil fertility, as measured with litter decomposition rate, was only due to an increase in target growth in plots without neighbors and was unrelated to community competitive effects and species diversity. The results of our study illustrate how the confusion between productivity and biomass could have contributed to the long-standing debate on variation in competition along productivity gradients and its consequence for diversity.

•Dispersal limitation, biotic interactions and environmental filters interact to drive plant and fungal community assembly, but their combined effects are rarely investigated. •This study examines how different heathland plant and fungal colonization scenarios realized via three biotic treatments ‐ addition of mature heathland derived sod, addition of hay and no additions ‐ affect soil fungal community development over six years along a manipulated pH gradient in a large‐scale experiment starting from an agricultural, topsoil removed state. •Our results show that both biotic and abiotic (pH) treatments had a persistent influence on the development of fungal communities, but that sod additions diminished the effect of abiotic treatments through time. Analysis of correlation networks between soil fungi and plants suggests that the reduced effect of pH in the sod treatment, where both soil and plant propagules were added, might be due to plant‐fungal interactions since the sod additions caused stronger, more specific, and more consistent connections compared to no addition treatment. •Based on these results, we suggest that the initial availability of heathland fungal and plant taxa, that reinforce each other, can significantly steer further fungal community development to an alternative configuration, overriding otherwise prominent effect of abiotic (pH) conditions.

Heather, Calluna vulgaris , is a key species of European dry heath and central determinant of its conservation status. The established Calluna life cycle concept describes four phases—pioneer, building, mature, and degeneration—distinguishable by growth and vitality characteristics of undisturbed plants grown from seeds. However, little is known about the life cycle and ageing of plants subjected to severe disturbance, although measures to this effect (burning, mowing) are common in heathland management. We studied the vitality of over 400 heather plants by examining multiple morphological (plant height, long shoot and inflorescence lengths, flowering activity), anatomical (growth rings) and environmental (management, nitrogen deposition, climate) attributes. We found Calluna vitality to be mainly determined by the aboveground stem age, and that severe disturbances promote vigorous vegetative regeneration. Ageing-related shifts in the habit and vitality of plants resprouting from stem-base buds is similar to that of seed-based plants, but the former revealed higher vitality when young, at the cost of a shorter life span. In contrast, plants originating from decumbent stems resemble building-stage plants but apparently lack the capacity to re-enter a cycle including stages other than degeneration-type. As a consequence, we supplemented the established heather life cycle concept with a post-disturbance regeneration cycle of plants derived from resprouting. We conclude that management of dry lowland heathlands should include rotational small-scale severe disturbance to support both seed germination and seedling establishment as well as vegetative regeneration chiefly of young heather plants capable of resprouting from buds near rootstock.

Temperature and nutrients are major limiting factors in subarctic tundra. Experimental manipulation of nutrient availability along elevational gradients (and thus temperature) can improve our understanding of ecological responses to climate change. However, no study to date has explored impacts of nutrient addition along a tundra elevational gradient, or across contrasting vegetation types along any elevational gradient. We set up a full factorial nitrogen (N) and phosphorus (P) fertilization experiment in each of two vegetation types (heath and meadow) at 500 m, 800 m, and 1000 m elevation in northern Swedish tundra. We predicted that plant and microbial communities in heath or at lower elevations would be more responsive to N addition while communities in meadow or at higher elevations would be more responsive to P addition, and that fertilizer effects would vary more with elevation for the heath than for the meadow. Although our results provided little support for these predictions, the relationship between nutrient limitation and elevation differed between vegetation types. Most plant and microbial properties were responsive to N and/or P fertilization, but responses often varied with elevation and/or vegetation type. For instance, vegetation density significantly increased with N + P fertilization relative to the other fertilizer treatments, and this increase was greatest at the lowest elevation for the heath but at the highest elevation for the meadow. Arbuscular mycorrhizae decreased with P fertilization at 500 m for the meadow, but with all fertilizer treatments in both vegetation types at 800 m. Fungal to bacterial ratios were enhanced by N + P fertilization for the two highest elevations in the meadow only. Additionally, microbial responses to fertilization were primarily direct rather than indirect via plant responses, pointing to a decoupled response of plant and microbial communities to nutrient addition and elevation. Because our study shows how two community types differ in their responses to fertilization and elevation, and because the temperature range across this gradient is ∼3°C, our study is informative about how nutrient limitation in tundra may be influenced by temperature shifts that are comparable to those expected under climate change during this century.