| 1. |
- Antonsson, Henrik, 1976, et al.
(författare)
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Nurse plant effect of the cushion plant Silene acaulis (L.) Jacq. in an alpine environment in the subarctic Scandes, Sweden
- 2009
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 2:1, s. 17-25
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Tidskriftsartikel (refereegranskat)abstract
- Background: Facilitation plays important roles in the structuring of plant communities and several studies have found that it tends to increase with environmental severity in alpine plant communities. In addition, cushion plants have been shown to act as nurse plants, moderating extreme environmental conditions, and providing resources for other species, with substantial effects on local plant diversity. Aims: This study addresses the nurse plant effects of Silene acaulis – a common, circumpolar alpine plant species with a compact cushion-forming growth form – along an altitude transect in the mid- to high-alpine zones in northern Sweden. Methods: The numbers of species in paired S. acaulis cushions and identical-sized control plots along an altitude transect between 1150 m and 1450 m above sea level were compared, and differences in species composition were analysed. Results: At altitudes above c. 1280 m, but not at lower altitudes, more species were found inside the cushions than in their paired control plots. Species composition was similar inside cushions and in control plots. Conclusions: Our results suggest that S. acaulis acts as a nurse plant at altitudes higher than a certain threshold (c. 1280 m at the investigated site). It appears to play an important role in creating focal points for local vascular plant diversity in highalpine environments, where vegetation is open and occurs in small patches. Keywords: facilitation; plant-to-plant interactions; Silene acaulis; species richness; stress
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| 2. |
- Auffret, Alistair G., et al.
(författare)
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Ontogenetic niche shifts in three Vaccinium species on a sub-alpine mountain side
- 2010
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 3:2, s. 131-139
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Tidskriftsartikel (refereegranskat)abstract
- Background: Climate warming in arctic and alpine regions is expected to result in the altitudinal migration of plant species, but current predictions neglect differences between species' regeneration niche and established niche. Aims: To examine potential recruitment of Vaccinium myrtillus, V. uliginosum and V. vitis-idaea on a mountain slope in northern Sweden in relation to current adult occurrence. Methods: We combined a seed-sowing experiment in seven community types with adult occurrence observations and species distribution mapping. Results: Emergence of V. myrtillus and V. vitis-idaea seedlings was significantly related to community type, while V. uliginosum was indifferent, but exhibited the highest average emergence. Adult occurrence was related to community, and ontogenetic niche shifts were observed for all three study species. V. myrtillus was shown to have the highest potential recruitment in habitats at altitudes above its current populations. Conclusions: The potential for migration exists, but incongruence between regenerative and established niches presents a challenge for colonisers, as well as for plant migration modelling.
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| 3. |
- Belinchon, Rocio
(författare)
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The diversity and community dynamics of hazelwood lichens and bryophytes along a major gradient of human impact
- 2016
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 9, s. 359-370
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Tidskriftsartikel (refereegranskat)abstract
- Background: Oceanic hazelwoods in western Scotland are hypothesised to be unmanaged post-glacial relicts, representing an unusual type of old-growth forest habitat in Europe. They are characterised by an exceptionally high epiphytic diversity, including their status as hotspots' for indicators of woodland ecological continuity.Aims: The aim of this study was to evaluate the effects of climate, pollution and management on the occurrence of epiphytic lichens and bryophytes on Corylus avellana.Methods: Thirteen hazelwood study sites were systematically sampled along a climate, pollution and management gradient in Britain. Epiphyte composition and richness were examined in a strict hierarchical framework, and compared against site-, stool- and stem-scale environmental predictors.Results: The study showed that along the gradient from clean-air' relict sites to polluted' coppiced sites: (i) epiphytic local stem-scale diversity declined, (ii) there was a loss of late-successional species including foliose cyano- and tripartite lichens and bryophytes and (iii) stem sizes were reduced, providing a further limit to the accumulation of species richness within a site.Conclusions: Relict hazelwoods in western Scotland are confirmed as an example of the most intact epiphyte communities. In particular, we show that the transition to coppicing can be clearly linked to ecological processes causing species loss.
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| 4. |
- Bochenek, Grazyna, 1977, et al.
(författare)
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Annual growth of male and female individuals of the Common Ash (Fraxinus excelsior L.)
- 2010
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 3:1, s. 47-57
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Tidskriftsartikel (refereegranskat)abstract
- Background: In general, females of woody dioecious plants are expected to grow more slowly than males because of the high cost associated with fruit bearing. Yet wind-pollinated species may invest relatively heavily in male reproduction, and various compensatory mechanisms can offset incurred costs, therefore the apparent growth of genders might be similar over a longer period of time. Any cost-related disparities are expected to be most pronounced in mast flowering years, when female reproductive resource demand is highest. Aims: We aimed to investigate gender-related response in relation to the cost of reproduction, and as a function of climate. Methods: Using dendrochronology techniques and analysing growth parameters at the branch level, we compared long-term and seasonal growth of male and female Fraxinus excelsior trees. Results: There was no observed decline in trunk growth of either of the genders over a 55-year period, but male and female trees had distinguishable annual growth patterns. The tree-ring widths of both genders were smaller in masting years than in other years. The difference between genders could be explained by their response to different climatic variables: females are more sensitive to spring frost and drought in early summer, while male growth depends more on late summer conditions. Conclusions: Vegetative development and flowering create a feedback system that minimises the cost of reproduction and assures that expenses are covered. Hence, growth differences between genders may be related to their phenological and physiological disparities rather than reproductive cost differences per se.
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| 5. |
- Bokhorst, Stef Frederik
(författare)
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Rapid photosynthetic recovery of a snow-covered feather moss and Peltigera lichen during sub-Arctic midwinter warming
- 2013
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 6, s. 383-392
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Tidskriftsartikel (refereegranskat)abstract
- Conclusions: The moss, and to a lesser extent the lichen, may contribute to subnivean midwinter ecosystem respiration, and both are opportunistic, and can take advantage of warmer winter phases for photosynthesis and growth. This ought to be taken into account in vegetation change projections of cryptogam-rich ecosystems.
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| 6. |
- Caseys, Celine, et al.
(författare)
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Effects of interspecific recombination on functional traits in trees revealed by metabolomics and genotyping-by-resequencing
- 2012
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 5:4, s. 457-471
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Tidskriftsartikel (refereegranskat)abstract
- Background: Understanding the potential and limits of recombination in adaptive evolution is of great interest to evolutionary biology. New (ultra-) high-throughput technologies in metabolomics and genomics hold great promise for addressing these questions, but their use in interspecific hybrids remains largely unexplored. Aims: Our goal was to test if recombination between the highly divergent genomes of Populus alba and P. tremula has the potential to contribute to the standing variation for functionally important chemical traits. Methods: We studied the metabolomes of interspecific hybrids by ultra-high-pressure liquid chromatography (UHPLC) coupled with quadrupole-time-of-flight (QTOF) mass spectrometry (MS) and initiated the characterisation of hybrid genomes by restriction site associated DNA (RAD) sequencing. Results: UHPLC-QTOF-MS indicated a complex 'mosaic' of chemical traits in recombinant hybrids and pointed to a heritable component for many of these. RAD sequencing confirmed the recombinant nature of natural hybrids previously characterised by microsatellites and suggested a complex history of recombination. Conclusions: It is likely that hybridisation has affected these species' genomes over several glacial cycles. Recombination holds great potential to create functionally relevant chemical variation in these trees. Nevertheless, correlations between chemical traits are not entirely broken up in recombinant hybrids, suggesting limits to adaptive evolution by genetic exchange.
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| 7. |
- Da Re, Daniele, et al.
(författare)
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Global analysis of ecological niche conservation and niche shift in exotic populations of monkeyflowers (Mimulus guttatus, M. luteus) and their hybrid (M. × robertsii)
- 2020
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Ingår i: Plant Ecology & Diversity. - : Taylor & Francis Group. - 1755-0874 .- 1755-1668. ; 13:2, s. 133-146
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Tidskriftsartikel (refereegranskat)abstract
- Background Hybridisation associated with biological invasions may generate new phenotypic combinations, allowing hybrids to occupy new ecological niches. To date, few studies have assessed niche shifts associated with hybridisation in recently introduced populations while simultaneously characterising the niche of parental species in both native and introduced ranges.Aims Here, we compared (1) the ecological niche of a novel hybrid monkeyflower,M. xrobertsii, with the niches of its two parental taxa (M. guttatus, M. luteus), and (2) the ecological niches of native (Americas) and introduced parental populations (Europe and New Zealand).Methods We assembled >13,000 geo-referenced occurrence records and eight environmental variables and conducted an ecological niche model analysis using maximum entropy, principal component and niche dynamics analysis.Results We found no evidence of niche shift in the hybrid, which may result in potential competition between parental and derived taxa in the introduced range.M. guttatusshowed niche conservatism in introduced populations in Europe, but a niche shift in New Zealand, whileM. luteusshowed a niche shift in Europe.Conclusions The comparison of native and non-native populations of parental taxa, suggests that whether invasions result in niche shifts or not depends on both taxon and geographic region, highlighting the idiosyncratic nature of biological invasions.
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| 8. |
- Hofgaard, Annika, et al.
(författare)
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Comparing warming and grazing effects on birch growth in an alpine environment : a 10-year experiment
- 2010
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 3:1, s. 19-27
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Tidskriftsartikel (refereegranskat)abstract
- Background : Tree encroachment of arctic tundra and alpine vegetation is a generally predicted response to climate warming. However, herbivory plays an important role in structuring these ecosystems and their responses to warming. Aims : To experimentally test how grazing and increased growing season temperature influence growth, physiognomy and stature of birch in the alpine zone. Methods: Trait responses of naturally regenerated birch saplings to warming (open-top chambers), and changed grazing regime (exclosures) were compared with those growing in unmanipulated conditions over a 10-year period (1999–2008). The effect of treatment over time and differences between treatments were analysed with repeated measures GLM (Generalised Linear Model) and simple contrasts in GLM. Results: Warming alone had no major effect on trait responses, however, significantly smaller leaves and an increased number of short shoots indicated warming-related growth constraints. Grazing showed a strong controlling effect on most traits, conserving low stature sapling stage characterised by fewer shoots and larger leaves, compared with non-grazed treatments. Conclusions: Although derived from one experimental site, the results point to a grazing-controlled response to environmental change, with climate (warming) as a secondary driver. This herbivore-driven masking of expected climate-driven tree expansion emphasises the necessity to consider changes in grazing regimes along with climate change, in order to avoid misleading interpretations regarding climate-driven tundra encroachment.
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| 9. |
- Huaraca Huasco, Walter, et al.
(författare)
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Seasonal production, allocation and cycling of carbon in two mid-elevation tropical montane forest plots in the Peruvian Andes
- 2014
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7:1-2, s. 125-142
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tropical montane cloud forests (TMCF) are unique ecosystems with high biodiversity and large carbon reservoirs. To date there have been limited descriptions of the carbon cycle of TMCF. Aims: We present results on the production, allocation and cycling of carbon for two mid-elevation (1500-1750 m) tropical montane cloud forest plots in San Pedro, Kosnipata Valley, Peru. Methods: We repeatedly recorded the components of net primary productivity (NPP) using biometric measurements, and autotrophic (R-a) and heterotrophic (Rh) respiration, using gas exchange measurements. From these we estimated gross primary productivity (GPP) and carbon use efficiency (CUE) at the plot level. Results: The plot at 1500 m was found very productive, with our results comparable with the most productive lowland Amazonian forests. The plot at 1750 m had significantly lower productivity, possibly because of greater cloud immersion. Both plots had similar patterns of NPP allocation, a substantial seasonality in NPP components and little seasonality in R-a. Conclusions: These two plots lie within the ecotone between lower and upper montane forests, near the level of the cloud base. Climate change is likely to increase elevation of the cloud base, resulting in shifts in forest functioning. Longer-term surveillance of the carbon cycle at these sites would yield valuable insights into the response of TMCFs to a shifting cloud base.
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| 10. |
- Lascoux, Martin, et al.
(författare)
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Past demography in forest trees : what can we learn from nuclear DNA sequences that we do not already know?
- 2008
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 1:2, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- Acquiring nuclear DNA sequences in forest tree species is becoming easier as molecular tools are developing rapidly and we now have at our disposal an array of theoretical methods to carry out statistical inferences from multilocus sequence variation. In the present article we use results from two recent studies of nuclear DNA sequence polymorphism in Norway spruce (Picea abies) and Scots pine (Pinus sylvestris) to illustrate what additional insights to each species' history can be gained compared with classical phylogeographic studies based on chloroplast or mitochondrial DNA. The sampling schemes and statistical analyses used in these two studies were similar facilitating a comparison between them. In both cases we inferred the presence of a rather severe bottleneck predating the Last Glacial Maximum (∌18,000 years ago). This result is discussed in relation to recent reassessments of the fossil pollen record and to its implication for our understanding of adaptation. Finally we briefly outline some suggestions for future research.
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| 11. |
- Marini, Lorenzo
(författare)
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Drivers of lichen species richness at multiple spatial scales in temperate forests
- 2012
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 5, s. 355-363
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Tidskriftsartikel (refereegranskat)abstract
- Background: Few studies analysing lichen diversity have simultaneously considered interactions among drivers that operate at different spatial and temporal scales. Aims: The aims of this study were to evaluate the relative importance of host tree, and local, landscape and historical factors in explaining lichen diversity in managed temperate forests, and to test the potential interactions among factors acting at different spatial scales. Methods: Thirty-five stands were selected in the Orseg region of western Hungary. Linear models and multi-model inference within an information-theory framework were used to evaluate the role of different variables on lichen species richness. Results: Drivers at multiple spatial scales contributed to shaping lichen species richness both at the tree and plot levels. Tree-level species richness was related to both tree- and plot-level factors. With increasing relative diffuse light lichen species richness increased; this effect was stronger on the higher than on the lower part of the trunks. At the plot scale, species richness was affected by local drivers. Landscape and historical factors had no, or only a marginal, effect. Conclusions: Lichen conservation in temperate managed forests could be improved if the complex interactions among host tree quality and availability, micro-climatic conditions, and management were taken into consideration.
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| 12. |
- Metcalfe, Daniel
(författare)
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Assessing above-ground woody debris dynamics along a gradient of elevation in Amazonian cloud forests in Peru: balancing above-ground inputs and respiration outputs
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 143-160
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Tidskriftsartikel (refereegranskat)abstract
- Background: Dead biomass, including woody debris (WD), is an important component of the carbon cycle in tropical forests.Aims: This study analyses WD (>2 cm) and other above-ground fluxes in mature tropical forest plots along an elevational gradient (210-3025 m above sea level) in southern Peru.Methods: This work was based on inventories of fine and coarse WD (FWD and CWD, respectively), above-ground biomass, and field-based and experimental respiration measurements.Results: Total WD stocks ranged from 6.26 Mg C ha(-1) at 3025 m to 11.48 Mg C ha(-1) at 2720 m. WD respiration was significantly correlated with moisture content (P < 0.001; R-2 = 0.25), temperature (P < 0.001; R-2 = 0.12) and wood density (P < 0.001; R-2 = 0.16). Controlled experiments showed that both water content and temperature increased respiration rates of individual WD samples. The full breadth of the temperature sensitivity coefficient, or Q(10), estimates, ranging from 1.14-2.13, was low compared to other studies. In addition, temperature sensitivity of WD respiration was greater for higher elevations.Conclusions: Carbon stocks, mortality and turnover of above-ground biomass varied widely and were not significantly related with elevation or slope. This study demonstrates that some forests may be a carbon source due to legacies of disturbance and increasing temperatures, which may cause additional, short-term carbon efflux from WD. Predictions of tropical forest carbon cycles under future climate should incorporate WD dynamics and related feedback.
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| 13. |
- Metcalfe, Daniel
(författare)
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Ecosystem productivity and carbon cycling in intact and annually burnt forest at the dry southern limit of the Amazon rainforest (Mato Grosso, Brazil)
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 25-40
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Tidskriftsartikel (refereegranskat)abstract
- Background: The impact of fire on carbon cycling in tropical forests is potentially large, but remains poorly quantified, particularly in the locality of the transition forests that mark the boundaries between humid forests and savannas.Aims: To present the first comprehensive description of the impact of repeated low intensity, understorey fire on carbon cycling in a semi-deciduous, seasonally dry tropical forest on infertile soil in south-eastern Amazonia.Methods: We compared an annually burnt forest plot with a control plot over a three-year period (2009-2011). For each plot we quantified the components of net primary productivity (NPP), autotrophic (R-a) and heterotrophic respiration (R-h), and estimated total plant carbon expenditure (PCE, the sum of NPP and R-a) and carbon-use efficiency (CUE, the quotient of NPP/PCE).Results: Total NPP and R-a were 15 and 4% lower on the burnt plot than on the control, respectively. Both plots were characterised by a slightly higher CUE of 0.36-0.39, compared to evergreen lowland Amazon forests.Conclusions: These measurements provide the first evidence of a distinctive pattern of carbon cycling within this transitional forest. Overall, regular understorey fire is shown to have little impact on ecosystem-level carbon fluxes.
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| 14. |
- Metcalfe, Daniel
(författare)
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Ecosystem respiration and net primary productivity after 8-10 years of experimental through-fall reduction in an eastern Amazon forest
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 7-24
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is much interest in how the Amazon rainforest may respond to future rainfall reduction. However, there are relatively few ecosystem-scale studies to inform this debate.Aims: We described the carbon cycle in a 1 ha rainforest plot subjected to 8-10 consecutive years of ca. 50% through-fall reduction (TFR) and compare these results with those from a nearby, unmodified control plot in eastern Amazonia.Methods: We quantified the components of net primary productivity (NPP), autotrophic (R-a) and heterotrophic respiration, and estimate gross primary productivity (GPP, the sum of NPP and R-a) and carbon-use efficiency (CUE, the ratio of NPP/GPP).Results: The TFR forest exhibited slightly lower NPP but slightly higher R-a, such that forest CUE was 0.29 +/- 0.04 on the control plot but 0.25 +/- 0.03 on the TFR plot. Compared with four years earlier, TFR plot leaf area index and small tree growth recovered and soil heterotrophic respiration had risen.Conclusions: This analysis tested and extended the key findings of a similar analysis 4 years earlier in the TFR treatment. The results indicated that, while the forest recovered from extended drought in some respects, it maintained higher overall R-a relative to the undroughted control, potentially causing the droughted forest to act as a net source of CO2.
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| 15. |
- Metcalfe, Daniel
(författare)
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Productivity and carbon allocation in a tropical montane cloud forest in the Peruvian Andes
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 107-123
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Tidskriftsartikel (refereegranskat)abstract
- Background: The slopes of the eastern Andes harbour some of the highest biodiversity on Earth and a high proportion of endemic species. However, there have been only a few and limited descriptions of carbon budgets in tropical montane forest regions.Aims: We present the first comprehensive data on the production, allocation and cycling of carbon for two high elevation (ca. 3000 m) tropical montane cloud forest plots in the Kosnipata Valley, Peruvian Andes.Methods: We measured the main components and seasonal variation of net primary productivity (NPP), autotrophic (R-a) and heterotrophic (R-h) respiration to estimate gross primary productivity (GPP) and carbon use efficiency (CUE) in two 1-ha plots.Results: NPP for the two plots was estimated to be 7.05 +/- 0.39 and 8.04 +/- 0.47 Mg C ha(-1) year(-1), GPP to be 22.33 +/- 2.23 and 26.82 +/- 2.97 Mg C ha(-1) year(-1) and CUE was 0.32 +/- 0.04 and 0.30 +/- 0.04.Conclusions: We found strong seasonality in NPP and moderate seasonality of R-a, suggesting that forest NPP is driven by changes in photosynthesis and highlighting the importance of variation in solar radiation. Our findings imply that trees invest more in biomass production in the cooler season with lower solar radiation and more in maintenance during the warmer and high solar radiation period.
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| 16. |
- Metcalfe, Daniel
(författare)
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The production, allocation and cycling of carbon in a forest on fertile terra preta soil in eastern Amazonia compared with a forest on adjacent infertile soil
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 41-53
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Tidskriftsartikel (refereegranskat)abstract
- Background: Terra preta do indio or 'dark earth' soils formed as a result of a long-term addition of organic matter by indigenous peoples in Amazonia.Aims: Here we report on the first study of productivity, allocation and carbon cycling from a terra preta plot in eastern Amazonia (Caxiuana, Para, Brazil), and contrast its dynamics with a nearby plot on infertile soil (ferralsols).Methods: We determined total net primary production (NPP) for fine roots, wood, and canopy and total autotrophic respiration (rhizosphere, wood, and canopy respiration) from two 1-ha plots on contrasting soils.Results: Both gross primary productivity (GPP) (35.68 +/- 3.65 vs. 32.08 +/- 3.46 Mg C ha(-1) year(-1)) and carbon use efficiency (CUE) (0.44 +/- 0.06 vs. 0.42 +/- 0.05) were slightly higher at the terra preta plot. Total NPP (15.77 +/- 1.13 Mg C ha(-1) year(-1) vs. 13.57 +/- 0.60 Mg C ha(-1) year(-1)) and rates of fine root production (6.41 +/- 1.08 vs. 3.68 +/- 0.52 Mg C ha(-1) year(-1)) were also greater at the terra preta plot vs. the tower plot.Conclusions: Forests on terra preta soil fix slightly more carbon and allocate slightly more of that carbon towards growth than forests on the infertile plot, which leads to greater total NPP, which was disproportionately allocated to fine roots. However, since increased fine root NPP was partially offset by increased heterotrophic soil respiration, the increased root growth was unlikely to greatly enhance soil carbon stocks in terra preta soils.
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| 17. |
- Metcalfe, Daniel
(författare)
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The productivity, allocation and cycling of carbon in forests at the dry margin of the Amazon forest in Bolivia
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 55-69
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Tidskriftsartikel (refereegranskat)abstract
- Background: The dry transitional forests of the southern Amazonia have received little attention from a carbon cycling and ecosystem function perspective, yet they represent ecosystems that may be impacted by global climate change in the future.Aims: To compare the full carbon cycle for two 1-ha forest plots that straddle the ecotone between humid forest and dry forest in Amazonia, ca. 100 km from Santa Cruz, Bolivia.Methods: 2.5 years of measurements of the components of net primary production (NPP) and autotrophic respiration were collected.Results: Total NPP was 15.5 +/- 0.89 Mg C ha(-1) year(-1) at the humid site and 11.27 +/- 0.68 Mg C ha(-1) year(-1) at the dry site; a total Gross Primary Production (GPP) of 34.14 +/- 2.92 Mg C ha(-1) year(-1) and 26.88 +/- 2.70 Mg C ha(-1) year(-1) at the two sites. Carbon use efficiency for both sites was higher than reported for other Amazonian forests (0.45 +/- 0.05 and 0.42 +/- 0.05).Conclusions: Drier soil conditions selected for the dry deciduous tree species which had higher leaf photosynthesis and total GPP. NPP allocation patterns were similar at the two sites, suggesting that in terms of carbon allocation, the dry forests of the southern Amazonia behave as a scaled-down version of wetter humid forests.
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| 18. |
- Metcalfe, Daniel
(författare)
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The productivity, metabolism and carbon cycle of two lowland tropical forest plots in south-western Amazonia, Peru
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 85-105
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Tidskriftsartikel (refereegranskat)abstract
- Background: The forests of western Amazonia are known to be more dynamic that the better-studied forests of eastern Amazonia, but there has been no comprehensive description of the carbon cycle of a western Amazonian forest.Aims: We present the carbon budget of two forest plots in Tambopata in south-eastern Peru, western Amazonia. In particular, we present, for the first time, the seasonal variation in the detailed carbon budget of a tropical forest.Methods: We measured the major components of net primary production (NPP) and total autotrophic respiration over 3-6 years.Results: The NPP for the two plots was 15.1 +/- 0.8 and 14.2 +/- 1.0 Mg C ha(-1) year(-1), the gross primary productivity (GPP) was 35.5 +/- 3.6 and 34.5 +/- 3.5 Mg C ha(-1) year(-1), and the carbon use efficiency (CUE) was 0.42 +/- 0.05 and 0.41 +/- 0.05. NPP and CUE showed a large degree of seasonality.Conclusions: The two plots were similar in carbon cycling characteristics despite the different soils, the most notable difference being high allocation of NPP to canopy and low allocation to fine roots in the Holocene floodplain plot. The timing of the minima in the wet-dry transition suggests they are driven by phenological rhythms rather than being driven directly by water stress. When compared with results from forests on infertile forests in humid lowland eastern Amazonia, the plots have slightly higher GPP, but similar patterns of CUE and carbon allocation.
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| 19. |
- Metcalfe, Daniel
(författare)
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The seasonal cycle of productivity, metabolism and carbon dynamics in a wet aseasonal forest in north-west Amazonia (Iquitos, Peru)
- 2014
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 7, s. 71-83
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Tidskriftsartikel (refereegranskat)abstract
- Background: The forests of north-west Amazonia are characterised by the highest levels of tree diversity in the world, high rainfall and relatively fertile soils.Aims: Here we present a comprehensive description of the carbon cycle of two 1 ha forests plots in Allpahuayo, near Iquitos, Peru, one on an occasionally inundated alisol/gleysol landscape, the other on an arenosol (sandy soil).Methods: Data on the components of net primary productivity (NPP) and autotrophic respiration were collected over the period 2009-2011, and summed to estimate gross primary productivity (GPP) and carbon use efficiency (CUE).Results: Overall, these forests showed high values of GPP (39.05 +/- 4.59 and 41.88 +/- 4.60 Mg C ha(-1) year(-1)). Despite the lack of a dry season, the forests showed distinct seasonality in tree growth, litterfall, flowering and fine root productivity. This showed that tropical forests with little seasonality in water supply can still exhibit distinct seasonality in NPP and carbon use, apparently synchronised to the solar radiation cycle. We found remarkably little difference in productivity between the alisol/gleysol plot and the arenosol plot.Conclusions: The GPP was higher than those reported for forests in Brazilian Amazonia on more infertile soils. The CUE was also higher, which may be related to the high forest dynamism and natural disturbance rate. These two factors combined to result in amongst the highest NPP values reported for Amazonia.
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| 20. |
- Moen, Jon, et al.
(författare)
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Factors structuring the treeline ecotone in Fennoscandia
- 2008
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Ingår i: Plant Ecology & Diversity. - : Taylor & Francis. - 1755-0874 .- 1755-1668. ; 1:1, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- Many hypotheses have been put forward to explain the structure and position of alpine treelines. The spatial complexity of the ecotone, ranging from sharp boundaries to networks of tree patches within a heath matrix, may explain why no consensus has been reached. In this paper, we discuss factors from abiotic disturbances to herbivory that may help understand the spatial structure of the alpine treeline ecotone in Fennoscandia. The ecotone is dominated by mountain birch (Betula pubescens ssp. tortuosa), and may show a wide range of spatial structures. We discuss the influence of topography, seed limitations, seedling establishment, growth limitations, abiotic disturbances and herbivory as structuring factors. All of these factors may operate, but their relative importance in space and time is unknown. There is a basic difference between factors that prevent the establishment of trees, and thus act on early life history stages, and factors that thin out a previously dense forest, and thus act on adult trees. Mortality caused directly or indirectly by geometrid moths may belong to the latter category. We suggest that seedling and sapling mortality is more important than seed limitation for the establishment of new individuals in the treeline ecotone. Important mortality factors may be abiotic disturbances, competition (or allelopathy) from field layer plants and herbivory. The relative role of these factors needs to be examined further.
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| 21. |
- Priyadi Rusantoyo, Hari
(författare)
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The lowland forest tree community in Malinau, Kalimantan (Indonesian Borneo): results from a one-hectare plot
- 2010
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 3, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- Conclusions: This is one of the richest hectares of forest trees reported from Indonesia. Species possess broad edaphic preferences and diverse biogeographic affinities. Tree species density likely reflects disturbance history and climatic stability as well as a combination of site factors reflecting the complex local geology, rugged landscape context, and associated edaphic variation. Further botanical explorations in Malinau and other poorly known regions of Borneo are required.
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| 22. |
- Roth, Nina, 1984-, et al.
(författare)
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Experimental warming outside the growing season and exclusion of grazing has a mild effect on upland grassland plant communities in the short term
- 2023
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Ingår i: Plant Ecology & Diversity. - 1755-0874 .- 1755-1668. ; 16:5-6, s. 189-201
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Tidskriftsartikel (refereegranskat)abstract
- Background: Winters are expected to warm more than summers in central and northern Europe, with largely unknown effects on grassland plant communities.Aims: By studying the interactions between winter warming and summer grazing, we aimed to disentangle their effects and give recommendations for future grassland management.Methods: Our study area Upper Teesdale, England has winter temperatures close to 0°C and a well-studied vegetation, known for its arctic-alpine species growing at their climatic warm range limits. We set up a winter warming experiment using open top chambers (ca. +0.5°C) from mid-September until mid-May 2019 to 2022 and excluded sheep grazing during summer in a fully factorial design.Results: Graminoid biomass increased, and bryophyte biomass decreased with winter warming. There was little to no evidence that winter warming affected any of the other plant response variables we measured, neither did grazing nor the interaction between winter warming and grazing.Conclusions: Our experiment was relatively short in duration and treatments were realistic in magnitude, therefore the plant communities responded only slightly. Nevertheless, our data suggest a change towards more dominant vascular species and less bryophytes with winter warming, which might lead to lasting changes in the plant communities in the longer-term if not buffered by suitable grazing management.
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| 23. |
- Stöckli, Veronika, et al.
(författare)
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Using historical plant surveys to track biodiversity on mountain summits
- 2011
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Ingår i: Plant Ecology & Diversity. - : Taylor & Francis. - 1755-0874 .- 1755-1668. ; 4:4, Special Issue, s. 415-425
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Tidskriftsartikel (refereegranskat)abstract
- Background: Botanical records have been collected from mountain summits worldwide since the sixteenth century. Such records are of particular interest following the end of the Little Ice Age, when alpine climate changed. Aims: To review the evolution of alpine summit flora research and define appropriate re-surveys for documenting floristic changes since the mid-nineteenth century. Methods: The history of botanical observations of mountain summits worldwide conducted between the mid-sixteenth and mid-twentieth century is outlined. Secondly, we review evidence for floristic change on mountain summits from studies made between 1980 and 2010. Thirdly, we examine the methods used in earlier summit surveys and suggest appropriate approaches for reconducting such surveys. Results: We found ca. 300 summit flora studies up to 200 years old that are potentially suitable for re-surveying; most of them are in the Alps. Recent studies showed an increase in species numbers and an upward range extension of some species from lower elevations. For re-surveying it is judged best to carry out data collection by individual surveyors for sound comparisons with earlier studies. Conclusions: Data collected in historical summit flora studies allow their exploitation for long-term observation provided contemporary methods are replicated and the detection rate is estimated in the re-surveys.
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| 24. |
- Sundqvist, Maja K., et al.
(författare)
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Establishment of boreal forest species in alpine dwarf-shrub heath in subarctic Sweden
- 2008
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Ingår i: Plant Ecology & Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 1:1, s. 67-75
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Tidskriftsartikel (refereegranskat)abstract
- Background: Saplings of mountain birch ( Betula pubescens ssp. czerepanovii) have established in pockets of dwarf-shrub heath approximately 250 m above the treeline in the Latnjavagge Valley, northern Sweden. Aim: We examined if the establishment of these mountain birch outposts was related to favourable local microclimate, and if birch establishment has affected the surrounding vegetation, changing it from dwarf-shrub heath to more akin to birch forest floor. Methods: Daily mean and mean maximum temperatures were compared for two sites in the dwarf-shrub heath ( 990 m a. s. l., few birch saplings; 1060 m a. s. l., numerous birch saplings) between January 2005 and June 2006. The cover-abundance of vascular plants was estimated in sample plots in dwarf-shrub heath with mountain birch, dwarf-shrub heath without mountain birch, in heath between the upper limit of closed mountain birch forest and the treeline, and in closed mountain birch forest. Species composition and diversity were statistically compared. The presence in the dwarf-shrub heath of boreal montane species other than birch was also noted. Results: The higher elevation site, containing a higher density of birch, had a significantly higher growing season temperature than the lower elevation site. There was a significant difference in plant community composition between the alpine heath plots containing mountain birch saplings and plots without mountain birch, alpine heath with birch being more similar to the plots of the treeline ecotone and the birch forest than to alpine heath without birch. No significant difference in species diversity among plots in dwarf-shrub heath was found and species diversity increased with altitude. A number of montane species were observed in the dwarf-shrub heath, however, their distribution was not associated with that of the mountain birch. Conclusions: This study provides evidence for favourable microclimate being a key driver for the establishment of mountain birch above the treeline. In addition, the results imply that the composition of the dwarf-shrub heath changes after the establishment of mountain birch to a plant community whose composition points towards a birch forest.
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| 25. |
- Van Bogaert, Rik, et al.
(författare)
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Competitive interaction between aspen and birch moderated by invertebrate and vertebrate herbivores and climate warming
- 2009
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 2:3, s. 221-U4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Considerable changes in vegetation structure and distribution are predicted in high latitude ecosystems as a result of amplified climate change. However, some documented plant community changes do not follow model predictions. Aim: We compared the growth of and the responses to climate variation by the thermophilic aspen (Populus tremula) and its sub-Arctic competitor mountain birch (Betula pubescens ssp. czerepanovii) over the past 100 years. Methods: Repeat photography, high-resolution vegetation transects, dendro-ecological analysis, and local climate record archives were used to study changes in vitality and distributional range of the two tree species in response to climate variability. Results: Aspen grew 45% faster and had seven times higher recruitment numbers than birch. However, no aspen stand expansion was observed, most likely because of browsing by moose (Alces alces). Birch, on the other hand, suffered from cyclic outbreaks of the autumnal moth (Epirrita autumnata). One-hundred-year-old birch trees experienced on average 9.0 years of reduced growth due to moth herbivory compared to 1.4 years for aspen. Moreover, these moth outbreaks on birch stimulated recruitment of aspen in birch stands. Conclusions: As the sub-Arctic continues to become warmer, the dynamics between aspen and birch in forest ecosystems will likely depend on the number of vertebrate browsers relative to the number of aspen recruits, while major moth outbreaks on birch may facilitate the spread of aspen by reducing competition. Our results suggest that alternating episodes of apparent species range stabilities (homeostasis) and abrupt non-linear shifts may characterise species migration patterns in this ecosystem.
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| 26. |
- Vowles, Tage, et al.
(författare)
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The impact of shrub browsing by mountain hare and reindeer in subarctic Sweden
- 2016
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Ingår i: Plant Ecology and Diversity. - : Informa UK Limited. - 1755-0874 .- 1755-1668. ; 9:4, s. 421-428
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Tidskriftsartikel (refereegranskat)abstract
- Background: Climate warming has been causing an increase in tall shrub cover around the Arctic, however, mammalian herbivory has been shown to inhibit shrub expansion. Though the effect of reindeer (Rangifer tarandus) and many other mammals has been widely studied in this context, the role of the mountain hare (Lepus timidus) in subarctic Scandinavia remains unknown. Aims: To quantify browsing from mountain hare and reindeer on tall shrubs in different vegetation types and to investigate differences in shrub preference between the two. Methods: In the summers of 2013 and 2014, we counted signs of browsing by hare and reindeer on tall shrub species in 31 study plots at three alpine locations in the Scandes range, Sweden. Results: Hare browsing was significantly more frequent than that by reindeer in two (dry-mesic heath and dry meadow) out of seven vegetation types studied. Reindeer browsing was significantly higher in the low herb meadow and Långfjället shrub heath. Two shrub species, Betula nana and Salix hastata, were significantly more browsed by hare, while reindeer browsing was significantly higher on S. phylicifolia and S. lapponum. Conclusions: Our results show that mountain hares can cause extensive damage to tall shrubs in the subarctic and may have a stronger impact on shrub communities than previously recognised.
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| 27. |
- Molau, Ulf, 1951
(författare)
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Long-term impacts of observed and induced climate change on tussock tundra near its southern limit in northern Sweden
- 2010
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Ingår i: PLANT ECOLOGY & DIVERSITY. - 1755-0874. ; 3:1, s. 29-34
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Tidskriftsartikel (refereegranskat)abstract
- Background: Tussock tundra is a main component of the Low Arctic vegetation cover. As it is adapted to underlying permafrost, its marginal sites at its southern distribution limit could be excellent indicators of climate change. There are still some scattered outpost stands of tussock tundra in the subarctic-alpine area of northern Fennoscandia, now showing signs of decline. Aims: The objective was to document changes in community structure of the tussock tundra over a 12-year period in experimentally warmed plots and in non-manipulated controls. In addition, the study included a survey of the present cover of tussock tundra in northern Swedish Lapland and a long-term monitoring of annual flowering intensity in the dominant species, the arctic hare's-tail cottongrass, Eriophorum vaginatum. Methods: The extent of tussock tundra in the region was assessed in a helicopter survey in 2005, followed by ground truthing in 2006. Climate and permafrost have been monitored at Latnjajaure, northern Swedish Lapland, since 1992. An experimental warming study employing open-top chambers (OTCs) was initiated at Latnjajaure for a number of habitats in 1993–1995, and all tussock tundra plots were surveyed in 1995 and 2006. Non-manipulated, permanently marked E. vaginatum tussocks were monitored for flowering frequency annually in 1992–2008. Results: The helicopter survey indicated that tussock tundra covers only few km2 in northernmost Sweden. A stand at the lower end of its altitude range was already in an advanced stage of transition into shrub tundra. In the OTCs at Latnjajaure, evergreen boreal dwarf-shrubs (particularly Vaccinium vitis-idaea) increased in above-ground biomass about eightfold between 1995 and 2006, and almost fourfold in the controls. There has been a significant warming trend in the study area of 0.12 °C per year, likely explaining why the control plots have also changed. The annual monitoring of E. vaginatum flowering indicated a tendency for relaxed synchrony of masting episodes in recent years, probably caused by longer growing seasons. Conclusions: Tussock tundra stands at the southern margin of the ecosystem's range are undergoing rapid changes at present. Increased air temperature and permafrost degradation are likely to be the main drivers of the observed change.
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