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  • 1.
    Barthelemy, Hélène
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Stark, Sari
    Michelsen, Anders
    Olofsson, Johan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Urine is an important nitrogen source for plants irrespective of vegetation composition in an Arctic tundra: Insights from a N-15-enriched urea tracer experiment2018In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 106, no 1, p. 367-378Article in journal (Refereed)
    Abstract [en]

    1. Mammalian herbivores can strongly influence nitrogen (N) cycling and herbivore urine could be a central component of the N cycle in grazed ecosystems. Despite its potential role for ecosystem productivity and functioning, the fate of N derived from urine has rarely been investigated in grazed ecosystems. 2. This study explored the fate of N-15-enriched urea in tundra sites that have been either lightly or intensively grazed by reindeer for more than 50years. We followed the fate of the N-15 applied to the plant canopy, at 2weeks and 1year after tracer addition, in the different ecosystem N pools. 3. N-15-urea was rapidly incorporated in cryptogams and in above-ground parts of vascular plants, while the soil microbial pool and plant roots sequestered only a marginal proportion. Furthermore, the litter layer constituted a large sink for the N-15-urea, at least in the short term, indicating a high biological activity in the litter layer and high immobilization in the first phases of organic matter decomposition. 4. Mosses and lichens still constituted the largest sink for the N-15-urea 1year after tracer addition at both levels of grazing intensity demonstrating their large ability to capture and retain N from urine. Despite large fundamental differences in their traits, deciduous and evergreen shrubs were just as efficient as graminoids in taking up the N-15-urea. The total recovery of N-15-urea was lower in the intensively grazed sites, suggesting that reindeer reduce ecosystem N retention. 5. Synthesis. The rapid incorporation of the applied N-15-urea indicates that arctic plants can take advantage of a pulse of incoming N from urine. In addition, N-15 values of all taxa in the heavily grazed sites converged towards the N-15 values for urine, bringing further evidence that urine is an important N source for plants in grazed tundra ecosystems.

  • 2. Blaser, Wilma J.
    et al.
    Sitters, Judith
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hart, Simon P.
    Edwards, Peter J.
    Venterink, Harry Olde
    Facilitative or competitive effects of woody plants on understorey vegetation depend on N-fixation, canopy shape and rainfall2013In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 101, no 6, p. 1598-1603Article in journal (Refereed)
    Abstract [en]

    A recent meta-analysis suggested that differences in rainfall are a cause of variation in tree-grass interactions in savannas, with trees facilitating growth of understorey grasses in low-rainfall areas, but competing with them under higher rainfall. We hypothesized that this effect of rainfall upon understorey productivity is modified by differences in the growth form of the woody plants (i.e. the height of the lower canopy) or by their capacity to fix nitrogen. We performed a meta-analysis of the effects of woody plants on understorey productivity, incorporating canopy height and N-fixation, and their interaction with rainfall. N-fixing woody plants enhanced understorey productivity, whereas non-fixers had a neutral or negative effect, depending on high or low canopy, respectively. We found a strong negative correlation between rainfall and the degree to which trees enhanced understorey productivity, but only for trees with a high canopy.Synthesis. The effect of woody plants on understorey productivity depends not only on rainfall, but also on their growth form and their capacity to fix N. Facilitation occurs mostly when woody plants ameliorate both water and nitrogen conditions. However, a low canopy suppresses understorey vegetation by competing for light, regardless of water and nutrient relations.

  • 3.
    Blume-Werry, Gesche
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kreyling, Juergen
    Greifswald University.
    Laudon, Hjalmar
    Sveriges Lantbruksuniversitet Umeå.
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Research Institute for Nature and Forest INBO, Kliniekstraat 25, 1070 Brussels, Belgium.
    Short-term climate change manipulation effects do not scale up to long-term legacies: effects of an absent snow cover on boreal forest plants2016In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 104, no 6, p. 1638-1648Article in journal (Refereed)
    Abstract [en]

    1. Despite time-lags and nonlinearity in ecological processes, the majority of our knowledge about ecosystem responses to long-term changes in climate originates from relatively short-term experiments.

    2. We utilized the longest ongoing snow removal experiment in the world and an additional set of new plots at the same location in northern Sweden to simultaneously measure the effects of longterm (11 winters) and short-term (1 winter) absence of snow cover on boreal forest understorey plants, including the effects on root growth and phenology.

    3. Short-term absence of snow reduced vascular plant cover in the understorey by 42%, reduced fine root biomass by 16%, reduced shoot growth by up to 53% and induced tissue damage on two common dwarf shrubs. In the long-term manipulation, more substantial effects on understorey plant cover (92% reduced) and standing fine root biomass (39% reduced) were observed, whereas other response parameters, such as tissue damage, were observed less. Fine root growth was generally reduced, and its initiation delayed by c. 3 (short-term) to 6 weeks (long-term manipulation).

    4. Synthesis. We show that one extreme winter with a reduced snow cover can already induce ecologically significant alterations. We also show that long-term changes were smaller than suggested by an extrapolation of short-term manipulation results (using a constant proportional decline). In addition, some of those negative responses, such as frost damage and shoot growth, were even absolutely stronger in the short-term compared to the long-term manipulation. This suggests adaptation or survival of only those individuals that are able to cope with these extreme winter conditions, and that the short-term manipulation alone would overpredict long-term impacts. These results highlight both the ecological importance of snow cover in this boreal forest, and the value of combining short- and long-term experiments side by side in climate change research.

  • 4. Cromsigt, Joris PGM
    et al.
    te Beest, Mariska
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Restoration of a megaherbivore: landscape-level impacts of white rhinoceros in Kruger National Park, South Africa2014In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 102, no 3, p. 566-575Article in journal (Refereed)
    Abstract [en]

    Megaherbivores have been lost from most ecosystems world-wide, and current increases in poaching of rhino and elephant spp. threaten their status in the systems where they still occur. Although megaherbivores are said to be key drivers of ecosystem structure and functioning, empirical evidence is strongly biased to studies on African elephant. We urgently need a better understanding of the impact of other megaherbivore species to predict the consequences of megaherbivore loss. We used a unique 'recolonization experiment' to test how a megagrazer, white rhinoceros, is affecting the structure of savanna grasslands in Kruger National Park (KNP). With a 30-year record of rhinoceros distribution, we quantified how they recolonized KNP following their re-introduction. This allowed us to identify landscapes with high rhino densities and long time since recolonization versus landscapes with low rhino densities that were recolonized more recently but were otherwise biophysically similar. We recorded grassland heterogeneity on 40transects covering a total of 30km distributed across both landscapes. We used two proxies of grassland heterogeneity: % short grass cover and number of grazing lawn patches. Grazing lawns are patches with specific communities of prostrate-growing stoloniferous short grass species. Short grass cover was clearly higher in the high rhino impact (17.5%) than low rhino impact landscape (10.7%). Moreover, we encountered ~20 times more grazing lawns in the high rhino impact landscape. The effect of rhino on number of lawns and on short grass cover was similar to the two dominant geologies in KNP, basalt-derived versus granite-derived soils. Synthesis. We provide empirical evidence that white rhinoceros may have started to change the structure and composition of KNP's savanna grasslands. It remains to be tested if these changes lead to other ecological cascading effects. However, our results highlight that the current rhino poaching crisis may not only affect the species, but also threaten the potential key role of this megaherbivore as a driver of savanna functioning.

  • 5.
    Ericson, Lars
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Burdon, J J
    Muller, W J
    Spatial and temporal dynamics of epidemics of the rust fungus Uromyces valerianae on populations of its host Valeriana salina1999In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 87, no 4, p. 649-658Article in journal (Refereed)
  • 6.
    Ericson, Lars
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Burdon, J J
    Muller, W J
    The rust pathogen Triphragmium ulmariae as a selective force affecting its host, Filipendula ulmaria2002In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 90, no 1, p. 167-178Article in journal (Refereed)
  • 7.
    Ericson, Lars
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mueller, Warren J.
    Burdon, Jeremy J.
    28-year temporal sequence of epidemic dynamics in a natural rust-host plant metapopulation2017In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 105, no 3, p. 701-713Article in journal (Refereed)
    Abstract [en]

    1. A long-term study of disease dynamics caused by the rust Uromyces valerianae in 31 discrete populations of Valeriana salina provides a rare opportunity to explore extended temporal patterns in the epidemiology of a natural host-pathogen metapopulation. 2. Over a 28-year period, pathogen population dynamics varied across the metapopulation with disease incidence (presence/absence), prevalence (% plants infected) and severity (% leaf area covered by lesions) all showing strong population and year effects, indicative of heterogeneity among years and host populations in the suitability of conditions for the pathogen. 3. Disease incidence within individual host populations was significantly affected by host population size, disease prevalence the previous year and the proximity of neighbouring populations infected in the current year. After accounting for these variables there was still a marked temporal component with winter sea level having a significant effect; as did summer rainfall in the second part of the study period (1997-2011). 4. Disease prevalence was also effected by host population size and disease prevalence in the previous year. However, it was less affected by spatial aspects of disease spread than was disease incidence. Winter sea level and June rainfall significantly affected disease prevalence. 5. Assessment of disease impact on plant performance found strong variation in disease severity associated with the aspect and positioning of host populations. Plants growing in lower disease environments produced significantly more seeds than those growing in high disease sites. 6. Significant variation in reaction to infection by U. valerianae was detected among plants within four populations and between these different populations. 7. Synthesis. The epidemiology of Uromyces valerianae was highly influenced by host population size, previous disease and distance. After accounting for these factors, there was a clear temporal signal of change in disease incidence linked to winter sea level and summer rainfall. These patterns reinforce the importance of considering interactions in multiple populations over long periods of time in order to obtain a clear picture of the variability in disease-induced selection pressures across time and space. The behaviour of the pathogen fitted that predicted for a metapopulation with considerable asynchrony in epidemiological patterns among demes.

  • 8.
    Falster, Daniel
    et al.
    Department of Biological Sciences, Macquarie University, NSW 2109, Sydney, Australia.
    Brännström, Åke
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Dieckmann, Ulf
    Evolution and Ecology Program, International Institute for Applied Systems Analysis, Schlossplatz 1, 2361 Laxenburg, Austria.
    Westoby, Mark
    Department of Biological Sciences, Macquarie University, NSW 2109, Sydney, Australia.
    The influence of four major plant traits on average height, leaf area cover, net primary productivity, and standing biomass in single-species forests: a theoretical investigation2011In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 99, no 1, p. 148-164Article in journal (Refereed)
    Abstract [en]

    Numerous plant traits are known to influence aspects of individual performance, including rates of carbon uptake, tissue turnover, mortality and fecundity. These traits are bound to influence emergent properties of vegetation because quantities such as leaf-area cover, average height, primary productivity and density of standing biomass result from the collective behaviour of individuals. Yet, little is known about the influence of individual traits on these emergent properties, despite the widespread use in current vegetation models of plant functional types, each of which is defined by a constellation of traits.

    We examine the influence of four key traits (leaf economic strategy, height at maturation, wood density, and seed size) on four emergent vegetation properties (average height of leaf area, leaf-area index, net primary productivity and biomass density). We employ a trait-, size- and patch-structured model of vegetation dynamics that allows scaling up from individual-level growth processes and probabilistic disturbances to landscape-level predictions. A physiological growth model incorporating relevant trade-offs was designed and calibrated based on known empirical patterns. The resulting vegetation model naturally exhibits a range of phenomena commonly observed in vegetation dynamics.

    We modelled single-species stands, varying each trait over its known empirical range. Seed size had only a small effect on vegetation properties, primarily because our metapopulations were not seed-limited. The remaining traits all had larger effects on vegetation properties, especially on biomass density. Leaf economic strategy influenced minimum light requirement, and thus total leaf area and basal area. Wood density and height at maturation influenced vegetation mainly by modifying individual stem mass. These effects of traits were maintained, and sometimes amplified, across stands differing in productivity and mean disturbance interval.

    Synthesis: Natural trait variation can cause large differences in emergent properties of vegetation, the magnitudes of which approach those arising through changes to site productivity and disturbance frequency. Our results therefore underscore the need for next-generation vegetation models that incorporate functional traits together with their effects on the patch and size structure of vegetation.

  • 9. Harper, Karen A.
    et al.
    Macdonald, S. Ellen
    Mayerhofer, Michael S.
    Biswas, Shekhar R.
    Esseen, Per-Anders
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hylander, Kristoffer
    Stewart, Katherine J.
    Mallik, Azim U.
    Drapeau, Pierre
    Jonsson, Bengt-Gunnar
    Lesieur, Daniel
    Kouki, Jari
    Bergeron, Yves
    Edge influence on vegetation at natural and anthropogenic edges of boreal forests in Canada and Fennoscandia2015In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 103, no 3, p. 550-562Article in journal (Refereed)
    Abstract [en]

    Although anthropogenic edges are an important consequence of timber harvesting, edges due to natural disturbances or landscape heterogeneity are also common. Forest edges have been well studied in temperate and tropical forests, but less so in less productive, disturbance-adapted boreal forests. We synthesized data on forest vegetation at edges of boreal forests and compared edge influence among edge types (fire, cut, lake/wetland; old vs. young), forest types (broadleaf vs. coniferous) and geographic regions. Our objectives were to quantify vegetation responses at edges of all types and to compare the strength and extent of edge influence among different types of edges and forests. Research was conducted using the same general sampling design in Alberta, Ontario and Quebec in Canada, and in Sweden and Finland. We conducted a meta-analysis for a variety of response variables including forest structure, deadwood abundance, regeneration, understorey abundance and diversity, and non-vascular plant cover. We also determined the magnitude and distance of edge influence (DEI) using randomization tests. Some edge responses (lower tree basal area, tree canopy and bryophyte cover; more logs; higher regeneration) were significant overall across studies. Edge influence on ground vegetation in boreal forests was generally weak, not very extensive (DEI usually <20m) and decreased with time. We found more extensive edge influence at natural edges, at younger edges and in broadleaf forests. The comparison among regions revealed weaker edge influence in Fennoscandian forests.Synthesis. Edges created by forest harvesting do not appear to have as strong, extensive or persistent influence on vegetation in boreal as in tropical or temperate forested ecosystems. We attribute this apparent resistance to shorter canopy heights, inherent heterogeneity in boreal forests and their adaptation to frequent natural disturbance. Nevertheless, notable differences between forest structure responses to natural (fire) and anthropogenic (cut) edges raise concerns about biodiversity implications of extensive creation of anthropogenic edges. By highlighting universal responses to edge influence in boreal forests that are significant irrespective of edge or forest type, and those which vary by edge type, we provide a context for the conservation of boreal forests.

  • 10.
    Ingvarsson, P K
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ericson, Lars
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Spatial and temporal variation in disease levels of a floral smut (Anthracoidea heterospora) on Carex nigra1998In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 86, no 1, p. 53-61Article in journal (Refereed)
  • 11.
    Jansson, R
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Zinko, U
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Merritt, D M
    Nilsson, C
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Hydrochory increases riparian plant species richness: a comparison between a free-flowing and a regulated river2005In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 93, p. 1094-1103Article in journal (Refereed)
    Abstract [en]
    • 1The importance of dispersal for plant community structure is poorly understood. Previous studies have hypothesized that patterns in the distribution and genetic structure of riparian plant communities were caused by hydrochory, i.e. plant dispersal by water. We separated the relative contributions of propagules from hydrochory and other dispersal vectors by comparing colonization in pairs of plots, one subject to flooding and deposition of hydrochores and the other unflooded.
    • 2The number of colonizing individuals and the mortality rate of individuals per year did not differ significantly with flooding, but hydrochory increased the number of colonizing species per year and plot by 40–200%. The pool of colonizing species was 36–58% larger per year for flooded than for unflooded plots, indicating that hydrochory increased the diversity by facilitating long-distance dispersal. Hydrochory resulted in more diverse plant communities after 3 years of succession at both plot and reach scales, despite the fact that flooding caused plant mortality.
    • 3We found no evidence that dams reduce the abundance and diversity of water-dispersed propagules by acting as barriers for plant dispersal. The role of hydrochory for plant colonization was similar between a free-flowing and a regulated river, although in fragmented rivers propagule sources are likely to be more local (within-impoundment).
    • 4We conclude that plant dispersal by water, as well as fluvial disturbance, is important for enhancing species richness in riparian plant communities. As flowing water may carry buoyant seeds long distances, riparian plant communities may receive a comparatively large proportion of their seeds by long-distance dispersal.
  • 12.
    Krab, Eveline J.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Soil and Environment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Roennefarth, Jonas
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, Greifswald, Germany.
    Becher, Marina
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Blume-Werry, Gesche
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Experimental Plant Ecology, Institute of Botany and Landscape Ecology, Greifswald University, Greifswald, Germany.
    Keuper, Frida
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. INRA, AgroImpact UR1158, Barenton Bugny, France.
    Klaminder, Jonatan
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Kreyling, Juergen
    Makoto, Kobayashi
    Milbau, Ann
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Biodiversity and Natural Environment, Research Institute for Nature and Forest - INBO, Brussels, Belgium.
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Winter warming effects on tundra shrub performance are species-specific and dependent on spring conditions2018In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 106, no 2, p. 599-612Article in journal (Refereed)
    Abstract [en]

    Climate change-driven increases in winter temperatures positively affect conditions for shrub growth in arctic tundra by decreasing plant frost damage and stimulation of nutrient availability. However, the extent to which shrubs may benefit from these conditions may be strongly dependent on the following spring climate. Species-specific differences in phenology and spring frost sensitivity likely affect shrub growth responses to warming. Additionally, effects of changes in winter and spring climate may differ over small spatial scales, as shrub growth may be dependent on natural variation in snow cover, shrub density and cryoturbation. We investigated the effects of winter warming and altered spring climate on growing-season performance of three common and widespread shrub species in cryoturbated non-sorted circle arctic tundra. By insulating sparsely vegetated non-sorted circles and parts of the surrounding heath with additional snow or gardening fleeces, we created two climate change scenarios: snow addition increased soil temperatures in autumn and winter and delayed snowmelt timing without increasing spring temperatures, whereas fleeces increased soil temperature similarly in autumn and winter, but created warmer spring conditions without altering snowmelt timing. Winter warming affected shrub performance, but the direction and magnitude were species-specific and dependent on spring conditions. Spring warming advanced, and later snowmelt delayed canopy green-up. The fleece treatment did not affect shoot growth and biomass in any shrub species despite decreasing leaf frost damage in Empetrum nigrum. Snow addition decreased frost damage and stimulated growth of Vaccinium vitis-idaea by c. 50%, while decreasing Betula nana growth (p < .1). All of these effects were consistent the mostly barren circles and surrounding heath. Synthesis. In cryoturbated arctic tundra, growth of Vaccinium vitis-idaea may substantially increase when a thicker snow cover delays snowmelt, whereas in longer term, warmer winters and springs may favour E. nigrum instead. This may affect shrub community composition and cover, with potentially far-reaching effects on arctic ecosystem functioning via its effects on cryoturbation, carbon cycling and trophic cascading. Our results highlight the importance of disentangling effects of winter and spring climate change timing and nature, as spring conditions are a crucial factor in determining the impact of winter warming on plant performance.

  • 13.
    Kullman , Leif
    et al.
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Öberg , L
    Post-Little Ice Age tree line rise and climate warming in the Swedish Scandes: a landscape ecological perspective2009In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 97, no 3, p. 415-429Article in journal (Refereed)
    Abstract [en]

    Elevational tree line change in the southern Swedish Scandes was quantified for the period 1915-2007 and for two sub-periods 1915-1975 and 1975-2007. The study focused on Betula pubescens ssp. czerepanovii, Picea abies and Pinus sylvestris at a large number of sites distributed over an 8000-km(2) area. The basic approach included revisitations of fixed sites (elevational belt transects) and measurements of tree line positions (m a.s.l.) during these three periods.

    Over the past century, tree lines of all species rose at 95% of the studied localities, with means of 70-90 m. All three species displayed maximum upshifts by about 200 m, which manifests a near-perfect equilibrium with instrumentally recorded air temperature change. This magnitude of response was realized only in particular topographic situations, foremost wind-sheltered and steep concave slopes. Other sites, with more wind-exposed topoclimatic conditions, experienced lesser magnitudes of upshifts. Thus, spatial elevational tree line responses to climate change are markedly heterogeneous and site-dependent. Modelling of the future evolution of the forest-alpine tundra transition has to consider this fact. Even in a hypothetical case of substantial climate warming, tree lines are unlikely to advance on a broad front and a large proportion of the alpine tundra will remain treeless.

    During the period 1975-2007, the tree lines of Picea and Pinus (in particular) advanced more rapidly than that of Betula towards the alpine region. These species-specific responses could signal a potential trajectory for the evolution of the ecotone in a warmer future. Thereby a situation with some resemblance with the relatively warm and dry early Holocene would emerge.

    Substantial tree line upshifts over the past two to three decades coincide with air and soil warming during all seasons. This implies that both summer and winter temperatures have to be included in models of climate-driven tree line performance.

    Synthesis. Maximum tree line rise by 200 m represents a unique trend break in the long-term Holocene tree line regression, which has been driven by average climate cooling for nearly 10 000 years. Tree line positions are well-restored to their pre-Little Ice Age positions. Recent tree line ascent is a truly anomalous event in Holocene vegetation history and possibly unprecedented for seven millennia.

  • 14.
    Lett, Signe
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Marie-Charlotte
    Wardle, David
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bryophyte traits explain climate-warming effects on tree seedling establishment2017In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 105, no 2, p. 496-506Article in journal (Refereed)
    Abstract [en]

    Above the alpine tree line, bryophytes cover much of the tundra soil surface in dense, often monospecific carpets. Therefore, when climate warming enables tree seedling establishment above the tree line, interaction with the bryophyte layer is inevitable. Bryophytes are known to modify their environment in various ways. However, little is known about to which extent and by which mechanisms bryophytes affect the response of tree seedlings to climate warming.

    We aimed to assess and understand the importance of bryophyte species identity and traits for tree seedling performance at tree line temperatures and their response to warmer conditions. Seedlings of two common, tree line-forming tree species (Betula pubescens and Pinus sylvestris) were planted into intact cushions of eight common tundra bryophyte species and bryophyte-free soil and grown for 18 weeks at current (7·0 °C) and near-future (30–50 years; 9·2 °C) tree line average growing-season temperatures. Seedling performance (biomass increase and N-uptake) was measured and related to bryophyte species identity and traits indicative of their impact on the environment.

    Tree seedlings performed equally well or better in the presence of bryophytes than in bryophyte-free soil, which contrasts to their usually negative effects in milder climates. In addition, seedling performance and their response to higher temperatures depended on bryophyte species and seedlings of both species grew largest in the pan-boreal and subarctic bryophyte Hylocomium splendens. However, B. pubescens seedlings showed much stronger responses to higher temperatures when grown in bryophytes than in bryophyte-free soil, while the opposite was true for P. sylvestris seedlings. For B. pubescens, but not for P. sylvestris, available organic nitrogen of the bryophyte species was the trait that best predicted seedling responses to higher temperatures, likely because these seedlings had increased N-demands.

    Synthesis. Climatically driven changes in bryophyte species distribution may not only have knock-on effects on vascular plant establishment, but temperature effects on seedling performance are themselves moderated by bryophytes in a species-specific way. Bryophyte traits can serve as a useful tool for understanding and predicting these complex interactions.

  • 15.
    Lett, Signe
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wardle, David A.
    Nilsson, Marie-Charlotte
    Teuber, Laurenz M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Dorrepaal, Ellen
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    The role of bryophytes for tree seedling responses to winter climate change: Implications for the stress gradient hypothesis2018In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 106, no 3, p. 1142-1155Article in journal (Refereed)
    Abstract [en]

    When tree seedlings establish beyond the current tree line due to climate warming, they encounter existing vegetation, such as bryophytes that often dominate in arctic and alpine tundra. The stress gradient hypothesis (SGH) predicts that plant interactions in tundra become increasingly negative as climate warms and conditions become less harsh. However, for seedlings, climate warming might not result in lower winter stress, if insulating snow cover is reduced. We aimed to understand if bryophytes facilitate seedling survival in a changing winter climate and if these effects of bryophytes on tree seedlings comply with the SGH along elevational gradients under contrasting snow conditions. In the Swedish subarctic, we transplanted intact bryophyte cores covered by each of three bryophyte species and bryophyte-free control soil from above the tree line to two field common garden sites, representing current and future tree line air temperature conditions (i.e. current tree line elevation and a lower, warmer, elevation below the tree line). We planted seedlings of Betula pubescens and Pinus sylvestris into these cores and subjected them to experimental manipulation of snow cover during one winter. In agreement with the SGH, milder conditions caused by increased snow cover enhanced the generally negative or neutral effects of bryophytes on seedlings immediately after winter. Furthermore, survival of P. sylvestris seedlings after one full year was higher at lower elevation, especially when snow cover was thinner. However, in contrast with the SGH, impacts of bryophytes on over-winter survival of seedlings did not differ between elevations, and impacts on survival of B. pubescens seedlings after 1year was more negative at lower elevation. Bryophyte species differed in their effect on seedling survival after winter, but these differences were not related to their insulating capacity.Synthesis. Our study demonstrates that interactions from bryophytes can modify the impacts of winter climate change on tree seedlings, and vice versa. These responses do not always comply with SGH, but could ultimately have consequences for large-scale ecological processes such as tree line shifts. These new insights need to be taken into account in predictions of plant species responses to climate change.

  • 16.
    Lind, Lovisa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Nilsson, Christer
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Vegetation patterns in small boreal streams relate to ice and winter floods2015In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 103, no 2, p. 431-440Article in journal (Refereed)
    Abstract [en]

    In-stream and riparian vegetation are species rich, productive and dynamic. Their patterns insmall boreal streams are largely driven by seasonal flow regimes. Traditionally, flow-related processes during the growing season, particularly the spring flood, have been seen as the most important, whereas vegetation has been viewed as being dormant and ‘less affected’ during winter.

    Riparian and in-stream vegetation were inventoried during the summers 2011–2013 in eight reaches of northern Swedish streams. Along each reach, the ice formation was surveyed during winter by visual inspections and with permanently placed cameras. We then evaluated the potential effects of ice regimes and winter flooding on riparian and in-stream vegetation during 3 years by relating the abundance of winter floods caused by anchor ice to the cover, composition and biomass of vegetation.

    We found that the numbers of winter floods were higher along reaches with anchor-ice formation than in reaches without. We also found that species diversity of riparian vegetation was higher inthe reaches with anchor ice. This resulted from a lower cover of riparian dwarf shrubs and a higher cover of graminoids and forbs along reaches with anchor ice. We also found a lower cover of instream algae but a higher cover of bryophytes in anchor-ice reaches. These patterns were consistent throughout the study period although there were interannual differences in temperature, water levels and ice cover.

    During our study period, we encountered an average of 20 shifts per winter between freezing and thawing, while there was an average of 10 shifts per winter during 1960–1990. This indicates a warming climate in high latitudes. Higher temperatures and more shifts between freezing and thawing may initially increase ice dynamics. However, with further increases in mean temperature, ice production should eventually decrease.

    Synthesis. Ice and winter floods caused by anchor ice appear to be important disturbance agents that allow less competitive species to establish along small boreal streams. If ice dynamics is reduced, the composition and production of riparian and in-stream vegetation may be changed, with possible consequences for the entire stream ecosystem.

  • 17.
    Makoto, Kobayashi
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Teshio Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Horonobe, Japan.
    Wilson, Scott D.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences. Department of Biology, University of Regina, Regina, SK, Canada.
    When and where does dispersal limitation matter in primary succession?2019In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 107, no 2, p. 559-565Article in journal (Refereed)
    Abstract [en]

    Primary succession encompasses the earliest and most fundamental stages of community assembly. The relative contributions of plant dispersal and ecosystem development, the main drivers that control the rate of primary succession, remain largely unknown, in spite of their central roles in community organization in general. Understanding the contribution of dispersal is especially critical because it casts light on our ability to manage succession resulting from climate change or anthropogenic disturbance.

    Here, we review the literature in order to understand when and where dispersal limits primary succession. Studies from many systems (tropical, temperate, boreal, arctic, alpine, floodplain forest, desert, mines, volcanic eruption and glacier forelands) show that dispersal limitation occurs consistently in the early stages of primary succession, suggesting that this is a general pattern. On the other hand, we found strong biases in study sites towards the Northern Hemisphere, temperate regions, volcanic eruptions and glacier forelands, which suggests that there are risks in drawing general conclusions about the importance of dispersal for primary succession for other biomes.

    Little is known about the contribution of dispersal to the later stages of primary succession. We present a recently developed method, multiscale chronosequence comparison that compares rates of succession in similar systems at relatively small and large spatial scales. Rapid succession at small scales compared to large scales suggests that seed dispersal influences succession over time periods of centuries and also limits the development of ecosystem functions such as vegetation cover and soil carbon accumulation.

    Synthesis: Dispersal limitation likely matters not only in the early stages but also in the late stages of primary succession by controlling the rate at which new species arrive. Both the accumulation of comparable case studies and novel approaches, such as multiscale chronosequence comparisons and factorial experiments, in contrasting biomes, are necessary to clarify the generality or context dependency of the role of dispersal in future primary successions undergoing changing climate.

  • 18.
    Niemi, Lena
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Wennström, Anders
    Hjältén, Joakim
    Waldmann, Patrik
    Ericson, Lars
    Spatial variation in resistance and virulence in the host-pathogen system Salix triandra-Melampsora amygdalinae2006In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 94, no 5, p. 915-921Article in journal (Refereed)
  • 19. Saona, Nora M
    et al.
    Albrectsen, Benedicte R.
    Umeå University, Faculty of Science and Technology, Department of Plant Physiology. Umeå University, Faculty of Science and Technology, Umeå Plant Science Centre (UPSC).
    Ericson, Lars E
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bazely, Dawn R
    Environmental stresses mediate endophyte-grass interactions in a boreal archipelago2010In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 98, no 2, p. 470-479Article in journal (Refereed)
    Abstract [en]

    1. Both evolutionary theory and empirical evidence from agricultural research support the view that asexual, vertically transmitted fungal endophytes are typically plant mutualists that develop high infection frequencies within host grass populations. In contrast, endophyte–grass interactions in natural ecosystems are more variable, spanning the range from mutualism to antagonism and comparatively little is known about their range of response to environmental stress.

    2. We examined patterns in endophyte prevalence and endophyte–grass interactions across nutrient and grazing (from Greylag and Canada geese) gradients in 15 sites with different soil moisture levels in 13 island populations of the widespread grass Festuca rubra in a boreal archipelago in Sweden.

    3. In the field, endophyte prevalence levels were generally low (range = 10–53%) compared with those reported from agricultural systems. Under mesic-moist conditions endophyte prevalence was constantly low (mean prevalence = 15%) and was not affected by grazing pressure or nutrient availability. In contrast, under conditions of drought, endophyte prevalence increased from 10% to 53% with increasing nutrient availability and increasing grazing pressure.

    4. In the field, we measured the production of flowering culms, as a proxy for host fitness, to determine how endophyte-infected plants differed from uninfected plants. At dry sites, endophyte infection did not affect flowering culm production. In contrast, at mesic-moist sites production of flowering culms in endophyte-infected plants increased with the covarying effects of increasing nutrient availability and grazing pressure, indicating that the interaction switched from antagonistic to mutualistic.

    5. A concurrent glasshouse experiment showed that in most situations, the host appears to incur some costs for harbouring endophytes. Uninfected grasses generally outperformed infected grasses (antagonistic interaction), while infected grasses outperformed uninfected grasses (mutualistic interaction) only in dry, nutrient-rich conditions. Nutrient and water addition affected tiller production, leaf number and leaf length differently, suggesting that tillers responded with different strategies. This emphasizes that several response variables are needed to evaluate the interaction.

    6. Synthesis. This study found complex patterns in endophyte prevalence that were not always correlated with culm production. These contrasting patterns suggest that the direction and strength of selection on infected plants is highly variable and depends upon a suite of interacting environmental variables that may fluctuate in the intensity of their impact, during the course of the host life cycle.

  • 20. Smith, D L
    et al.
    Ericson, L
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Burdon, J J
    Epidemiological patterns at multiple spatial scales: an 11-year study of a Triphragmium ulmariae-Filipendula ulmaria metapopulation2003In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 91, no 5, p. 890-903Article in journal (Refereed)
  • 21. Smith, DL
    et al.
    Ericson, Lars
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Burdon, JJ
    Co-evolutionary hot and cold spots of selective pressure move in space and time2011In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 99, p. 634-641Article in journal (Refereed)
    Abstract [en]

    1. A long-term study (19 years) of a host–pathogen metapopulation involving 133–220 separate populations of the wild plant Filipendula ulmaria and its rust pathogen Triphragmium ulmariae shows marked changes in the occurrence (32–55% demes) and severity of disease and rates of extinction and re-establishment of individual populations (0.006–0.174 and 0.030–0.195 per annum, respectively) over time.

    2. Modelling of the spatio-temporal dynamics of disease demonstrated year-to-year changes associated with a range of different environmental features, but also more consistent, longer-term patterns influenced by a complex suite of factors.

    3. Both the level of disease and its spatial location varied through time and generated a changing pattern of selective pressure across the metapopulation.

    4. Synthesis. Our results suggest that co-evolutionary hot spots and cold spots can be highly dynamic within metapopulations, thereby fuelling the co-evolutionary process even more than previously suspected.

  • 22. Strengbom, J
    et al.
    Nordin, A
    Nasholm, T
    Ericson, Lars
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Parasitic fungus mediates change in nitrogen-exposed boreal forest vegetation2002In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 90, no 1, p. 61-67Article in journal (Refereed)
  • 23. van Leeuwen, Casper H. A.
    et al.
    Sarneel, Judith M.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    van Paassen, Jose
    Rip, Winnie J.
    Bakker, Elisabeth S.
    Hydrology, shore morphology and species traits affect seed dispersal, germination and community assembly in shoreline plant communities2014In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 102, no 4, p. 998-1007Article in journal (Refereed)
    Abstract [en]

    1. Seed dispersal and germination are two primary processes influencing plant community assembly. On freshwater shores, water levels regulate both processes. However, it is still unclear how water levels, shore morphology and species traits interactively affect seed dispersal and germination, and how these interactions determine plant community assembly. We hypothesize that a drawdown water regime enhances seed establishment compared to a year-round stable water level, that this increases species richness and diversity, and that this is modulated by species traits and shore morphology. 2. Germination of 20 wetland plant species with different dispersal capacities (floating capacity expressed as seed floatation half-time) and soil moisture preferences for germination (Ellenberg F) was tested on artificial shores in 24 outdoor ponds in two complementary experiments over 8 weeks. The 'dispersal experiment' tested the effect of water regime on recruitment of hydrochorously dispersing seeds. The 'seed bank experiment' tested the effect of water regime on germination from a sown seed bank, on steep and gradual shores. 3. In the dispersal experiment, the drawdown regime increased recruitment and species richness. Longer floating species colonized a larger shoreline section. Soil moisture preference for germination did not determine colonization patterns. 4. In the seed bank experiment, the drawdown regime increased the number of seedlings on gradual sloping shores, but not on steep shores. The number of germinating seedlings corresponded to the area subjected to the drawdown regime in both shore types. Species richness was not affected by water regime or shore morphology, and species traits did not determine shoreline colonization. Most seeds germinated in moist soil conditions for all species. 5. Synthesis. A spring drawdown instead of stable water regime stimulates establishment of hydrochorously dispersing seeds in temperate wetlands, leading to higher species richness and diversity. Germination from the seed bank is more affected by water regime and shore surface than by the tested species traits. Species traits, water levels and shore morphology together determine wetland plant community assembly, with dispersal as the main driver of seedling community diversity. Water-level regulations and shore morphology can be used to influence plant communities in wetland restoration.

  • 24.
    Waites, Anna R.
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Ågren, Jon
    Department of Plant Ecology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden.
    Pollinator visitation, stigmatic pollen loads, and among-population variation in seed set in Lythrum salicaria2004In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 92, no 3, p. 512-526Article in journal (Refereed)
    Abstract [en]
    1. Small populations of reward-producing plants are likely to be less attractive to animal pollinators than large populations. As a result, both the quantity and the proportion of compatible pollen deposited on receptive stigmas, and seed output per plant, may be lower in small than in large populations.
    2. We examined whether pollinator visitation, pollen deposition and seed set varied with population size in the self-incompatible, tristylous herb Lythrum salicaria, in the Skeppsvik archipelago, northern Sweden. We documented both the number of compatible and incompatible conspecific and heterospecific pollen grains received per flower, seed set and degree of pollen limitation of long-styled plants in 14 populations of different size in two consecutive years, and recorded the visitation rate to individual plants and the number of flowers visited per plant in eight of the populations.
    3. As predicted, the visitation rate tended to increase, while the number of flowers visited per plant tended to decrease with increasing population size. However, visitation rates were low overall and temporally highly variable, and these relationships only approached statistical significance. The proportion and absolute number of compatible pollen grains received increased with population size, while the total amounts of conspecific and heterospecific pollen grains received did not vary significantly with population size. The results of supplemental hand-pollinations indicated that the among-population variation in seed set was due to insufficient transfer of compatible pollen in small populations.
    4. Seed output increased with the receipt of compatible pollen grains up to about 200 compatible pollen grains received per flower. Between 73% and 98% of the L. salicaria pollen grains received were incompatible, and between 9% and 81% of the pollen grains deposited were heterospecific (population means). However, there was no evidence that the deposition of high numbers of incompatible conspecific and heterospecific pollen grains reduced seed set.
    5. In the study populations of L. salicaria, variation in seed output and pollen limitation are apparently governed primarily by factors influencing the transfer of compatible pollen. The results are consistent with the hypothesis that a reduction in the efficiency of pollen transfer among compatible mating types may markedly reduce the reproductive output in small populations of self-incompatible plants. In light of the current rapid transformation and fragmentation of habitats, there is a pressing need both to clarify how the pollination success of plants with different pollination systems is affected by large-scale changes in population size, density and isolation, and to determine the demographic consequences of differences in pollination intensity.
  • 25. Wardle, David A.
    et al.
    Jonsson, Micael
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Bansal, Sheel
    Bardgett, Richard D.
    Gundale, Michael J.
    Metcalfe, Daniel B.
    Linking vegetation change, carbon sequestration and biodiversity: insights from island ecosystems in a long-term natural experiment2012In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 100, no 1, p. 16-30Article in journal (Refereed)
    Abstract [en]

    1. Despite recent interest in linkages between above- and below-ground communities and their consequences for ecosystem processes, much remains unknown about their responses to long-term ecosystem change. We synthesize multiple lines of evidence from a long-term natural experiment to illustrate how ecosystem retrogression (the decline in ecosystem process rates due to long-term absence of major disturbance) drives vegetation change, and thus above-ground and below-ground carbon (C) sequestration, and communities of consumer biota.

  • 26. Wardle, David A.
    et al.
    Jonsson, Micael
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mayor, Jordan R.
    Metcalfe, Daniel B.
    Above-ground and below-ground responses to long-term nutrient addition across a retrogressive chronosequence2016In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 104, no 2, p. 545-560Article in journal (Refereed)
    Abstract [en]
    1. There is much interest in understanding ecosystem responses to local-scale soil fertility variation, which has often been studied using retrogressive chronosequences that span thousands of years and show declining fertility and plant productivity over time. There have been few attempts to experimentally test how plant nutrient limitation changes during retrogression.
    2. We studied a well-characterized system of 30 forested lake islands in northern Sweden that collectively represent a 5350-year post-fire retrogressive chronosequence, with fertility and productivity decreasing as time since fire increases. For each island, we set up four plots on understorey vegetation, each subjected to a different fertilizer treatment over 6 years: no additions, nitrogen (N) only, phosphorus (P) only and N + P.
    3. We found that both N and P additions reduced feather moss and thus total plant biomass. Meanwhile, the three dominant vascular plant species showed contrasting biomass responses, but similar responses of foliar nutrient concentrations to nutrient additions. Fertilization reduced most microbial groups and altered CO2 fluxes, most likely through feather moss reduction. Against expectations, the majority of interactive effects of N and P were antagonistic.
    4. Changes in effects of nutrient additions during retrogression were usually modest.Empetrum hermaphroditum biomass was increasingly promoted by P and N + P addition, while vascular plant N-to-P ratios were increasingly reduced by P addition, indicating increasing plant limitation by nutrients (notably P) during retrogression. Below-ground, positive effects of N addition on soil mineral N increased, while negative effects of N addition on soil fungi decreased during retrogression; no other below-ground effects of fertilization changed along the gradient.
    5. Synthesis. Our results show that forest understorey communities on islands of different fire history and thus stages of retrogression show relatively modest differences in how they respond to nutrient addition despite large changes in ecosystem productivity and soil fertility, probably because of high species turnover and adaptation of communities to infertile conditions. While increased nutrient availability (as expected through global change) may have important ecological consequences, these effects are likely, especially below-ground, to be rather similar across ecosystems that differ greatly in nutrient availability and productivity.
  • 27. Wenk, Elizabeth Hedi
    et al.
    Abramowicz, Konrad
    Umeå University, Faculty of Science and Technology, Department of Mathematics and Mathematical Statistics.
    Westoby, Mark
    Falster, Daniel S.
    Investment in reproduction for 14 iteroparous perennials is large and associated with other life-history and functional traits2018In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 106, no 4, p. 1338-1348Article in journal (Refereed)
    Abstract [en]

    1. While theoretical models predict reproductive allocation (RA) should approach 100% of available energy as a plant ages, available empirical data suggest much lower RA values in perennial plants. In this study, we have two aims. First, we assess whether the discrepancy between theory and data arises from methodological differences in how growth and RA are calculated. Specifically, we hypothesize RA in older plants is large when compared to growth in leaf area, that is, after excluding turnover of stem and leaf tissues. Second, we hypothesize that species with cheap tissues or those that are shorter reach RA = 0.5 at a younger age.

    2. We measured investment in leaf, stem and reproduction on individuals from 14 co-occurring woody perennial iteroparous species. A fire chronosequence allowed us to use a space-for-time substitution to estimate RA schedules for each species, simultaneously measuring reproductive and vegetative production on individuals differing in age.

    3. For most (11 of 14) species, we found RA eventually reached 100% of available energy, with another two species reaching at least 80%. Increases in RA were associated with a decline in growth of leaf area. Comparing species, we found that species with cheap leaves reached RA = 0.5 sooner (they could be called fast-living), whereas delayed maturation and slower increases in RA were associated with greater maximum height.

    4. Synthesis. Explicitly accounting for the cost of leaf replacement leads to the high estimates of reproductive allocation in perennial plants predicted by theoretical models, limiting or even halting leaf area expansion. For some species, so much energy is allocated to reproduction that leaf area declines year-upon-year for multiple growing seasons preceding death. Connecting lifetime reproductive allocation schedules with leaf area expansion, leaf life span, and plant maximum height demonstrates how reproductive allocation schedules synthesize a plant's life-history strategy, making them a valuable tool for connecting plant traits and demography.

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