Light, not nitrogen, limits growth of the grass Deschampsia flexuosa in boreal forests

2004 ◽  
Vol 82 (4) ◽  
pp. 430-435 ◽  
Author(s):  
Joachim Strengbom ◽  
Torgny Näsholm ◽  
Lars Ericson
Keyword(s):  
Boreal Forests ◽  
Vegetation Change ◽  
Light Availability ◽  
Relative Importance ◽  
Deschampsia Flexuosa ◽  
Belowground Competition ◽  
Aboveground Competition ◽  
N Treatment ◽  
Vaccinium Myrtillus L ◽  
Positive Effect

Increased nitrogen (N) input in boreal forests has previously been shown to induce a shift from Vaccinium myrtillus L. to Deschampsia flexuosa (L.) Trin. as the dominant understory species. We investigated the relative importance of increased light and N for this shift, in a field experiment. We increased light availability, that is, we reduced aboveground competition from V. myrtillus, and increased N by adding 50 kg N·ha–1. Increased light availability had a positive effect on both the growth rate and final biomass of D. flexuosa. Although N addition increased the uptake of fertilizer N by both species, it had no effect on the growth or biomass of either species. Thus, aboveground competition from V. myrtillus prevented expansion of D. flexuosa, regardless of N treatment. The results suggest that aboveground competition may be more important than belowground competition for structuring understory boreal forest communities. As light availability is important, both the structure and total amount of standing crop will be important for the outcome of species interactions.Key words: aboveground competition, belowground competition, fertilization, natural enemies, nitrogen deposition, vegetation change.

scholarly journals You are what you eat: relative importance of diet, gut microbiota and nestmates for honey bee, Apis mellifera, worker health

Apidologie ◽  
2021 ◽  
Author(s):  
Gina Retschnig ◽  
Johannes Rich ◽  
Karl Crailsheim ◽  
Judith Pfister ◽  
Vincent Perreten ◽  
...  
Keyword(s):  
Body Weight ◽  
Apis Mellifera ◽  
Gut Microbiota ◽  
Honey Bee ◽  
Exposure Period ◽  
Short Exposure ◽  
Relative Importance ◽  
Worker Health ◽  
Negative Effect ◽  
Positive Effect

AbstractIn eusocial honey bees, Apis mellifera, diet, gut microbiota and nestmates can all contribute to the health of freshly emerged individual workers, but their relative importance for longevity and body weight is currently unknown. Here, we show that diet is most relevant, followed by gut microbiota and the presence of nestmates. Freshly emerged workers were randomly assigned to eight treatments (with or without honey/pollen, protein-substitute lactalbumin, antibiotic tetracycline and nestmates for 24 h) and maintained under standardised laboratory conditions. Longevity and food consumption were measured daily and fresh body weight was assessed at day 7. The data show a significantly better survival and a higher body weight in workers supplied with honey/pollen. Survival was higher in the lactalbumin treatments compared to the ones restricted to sucrose only, but lower compared to those with honey/pollen, highlighting the importance of micronutrients. In contrast, antibiotic treatment had a significant negative effect on longevity and body weight, which may be explained by inactivated gut microbiota and/or toxicity of the antibiotics. There was no positive effect of nestmates, probably due to the short exposure period. In contrast, nestmates showed a negative effect on survival in antibiotic-treated workers, possibly by transmitting pathogens and antibiotic-induced gut dysbiosis. In conclusion, a macro- and micronutrient-rich diet appears to be the key to individual honey bee worker health. Providing an optimal diet and possibly gut microbiota appears to be a promising way to promote managed A. mellifera health.

Dispersal of Goeppertia marantifolia clonal offspring increases with greater canopy openness and larger plant size

2017 ◽  
Vol 33 (2) ◽  
pp. 107-113 ◽  
Author(s):  
David P. Matlaga ◽  
Rachel K. Snyder ◽  
Carol C. Horvitz
Keyword(s):  
Leaf Area ◽  
Light Availability ◽  
Plant Size ◽  
Dispersal Distance ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Parent Plant ◽  
Analysis Model ◽  
Corcovado National Park ◽  
Positive Effect

Abstract:Many plants within the neotropical understorey produce both seeds and clonal offspring. Plant attributes (i.e. size) and variability in light can influence seed dispersal but it is not known if these factors influence the dispersal of clonal offspring. Our goal was to determine if canopy openness and plant size influence clonal-offspring dispersal of the herb Goeppertia marantifolia, which produces clonal bulbils on above-ground shoots. We monitored plants in permanent plots with varying levels of canopy openness in Corcovado National Park, Costa Rica. We recorded canopy openness, leaf area and the distance clonal offspring travelled from their parent plant (N = 283). Our path analysis model demonstrated that canopy openness had a strong positive effect on dispersal distance, while the association between clonal-offspring dispersal distance and parent plant leaf area was only weakly positive. On average, plants experiencing high canopy openness dispersed their clonal offspring further than plants under low canopy openness (124 cm vs. 79 cm, respectively). Contrary to studies on species that utilize rhizomes and stolons for clonal reproduction, we found that in this bulbil-producing species light availability is positively associated with clonal dispersal distance. Therefore, the influence of resource availability on spatial population dynamics of clonal species may be influenced by the species’ growth-form.

Vegetation responses to conifer encroachment in a western Cascade meadow: a chronosequence approach

2007 ◽  
Vol 85 (3) ◽  
pp. 285-298 ◽  
Author(s):  
Ryan D. Haugo ◽  
Charles B. Halpern
Keyword(s):  
Forest Structure ◽  
Vegetation Change ◽  
Light Availability ◽  
Basal Area ◽  
Tree Age ◽  
Long Term Effects ◽  
Conifer Encroachment ◽  
Forest Herbs ◽  
Meadow Species ◽  
Chronosequence Approach

Conifer invasion of mountain meadows is pervasive in western North America, but its consequences for plant composition and diversity have not been studied. We used a chronosequence approach to reconstruct temporal patterns of vegetation change in response to ~200 years of conifer encroachment of a dry, montane meadow in the western Cascade Range, Oregon. Tree age distributions, forest structure, light, and vegetation composition were determined for three hundred and fifty-six 10 m × 10 m samples representing a gradient from open meadow to old forest (>90 years). Nonmetric multidimensional scaling revealed strong turnover in species composition from open meadow to old forest. Ordination axes were highly correlated with light availability and density/basal area of encroaching grand fir, Abies grandis (Dougl. ex D. Don) Lindl., and lodgepole pine, Pinus contorta Dougl. ex Loud. Cover of meadow species declined steeply with establishment of A. grandis ; richness declined more gradually and extirpations of meadow species were rare. Forest herbs colonized within two decades of tree establishment and within 60–80 years dominated the understory flora. In contrast with meadow species, changes in richness and cover of forest herbs were weakly related to changes in forest structure. Rapid replacement of meadow by forest species and long-term effects of trees on soils may limit potential for restoration of these unique habitats.

The Role of External Interaction for Innovation in Irish High-Technology Businesses

2011 ◽  
Vol 12 (4) ◽  
pp. 248-256 ◽  
Author(s):  
Declan Jordan ◽  
Eoin O'Leary
Keyword(s):  
High Technology ◽  
Process Innovation ◽  
Relative Importance ◽  
Business Innovation ◽  
Negative Effect ◽  
Product And Process Innovation ◽  
Innovation Output ◽  
Product And Process ◽  
Positive Effect

There is growing empirical evidence that external interaction is an important source of knowledge for business innovation. This paper contributes to the innovation literature by using new measures of interaction to explore the relative importance of external interaction for innovation in Irish high-technology businesses. Based on survey data, the paper finds that external interaction increases the probability of product and process innovation, but the effect is inconsistent across all external interaction agents. Interaction along the supply chain has a positive effect on innovation, and interaction with competitors has an insignificant effect on innovation output. Notably, the paper finds that interaction with higher education institutions has a negative effect on the probability of product and process innovation.

scholarly journals Pattern and process of vegetation change (succession) on two northern New Zealand island volcanoes

2015 ◽  
Vol 13 ◽  
pp. 45-48
Author(s):  
Bruce D. Clarkson ◽  
Beverley R. Clarkson ◽  
James O. Juvik
Keyword(s):  
Vegetation Change ◽  
Light Availability ◽  
Patch Dynamics ◽  
Volcanic Eruptions ◽  
Vegetation Succession ◽  
Disturbance History ◽  
Pattern And Process ◽  
Island Species ◽  
New Information ◽  
Volcanic Islands

Pattern and process of vegetation change (succession) were compared on two northern North Island volcanoes: Whakaari (White Island) and Rangitoto Island where the endemic woody tree Metrosideros excelsa is the primary colonizer of raw volcanic substrates. Quantitative data from our previous publications (see References) and the references therein illustrate sequences of vegetation succession following significant volcanic eruptions. New information on Rangitoto Island M. excelsa patch dynamics and updated vascular species statistics for Whakaari have also been included. We also draw on supporting data from M. excelsa forest on the mainland and long-inactive volcanic islands in the Bay of Plenty, to provide a context for understanding the vegetation dynamics on Whakaari and Rangitoto Island. Species facilitation, light availability, humidity, substrate and disturbance history are all key determinants of vegetation succession across these volcanic landscapes.

scholarly journals An experimental test of the area–heterogeneity tradeoff

2020 ◽  
Vol 117 (9) ◽  
pp. 4815-4822 ◽  
Author(s):  
Eyal Ben-Hur ◽  
Ronen Kadmon
Keyword(s):  
Habitat Heterogeneity ◽  
Competitive Exclusion ◽  
Fundamental Property ◽  
Theoretical Models ◽  
Effective Area ◽  
Individual Species ◽  
Relative Importance ◽  
Average Area ◽  
Fixed Area ◽  
Positive Effect

A fundamental property of ecosystems is a tradeoff between the number and size of habitats: as the number of habitats within a fixed area increases, the average area per habitat must decrease. This tradeoff is termed the “area–heterogeneity tradeoff.” Theoretical models suggest that the reduction in habitat sizes under high levels of heterogeneity may cause a decline in species richness because it reduces the amount of effective area available for individual species under high levels of heterogeneity, thereby increasing the likelihood of stochastic extinctions. Here, we test this prediction using an experiment that allows us to separate the effect of the area–heterogeneity tradeoff from the total effect of habitat heterogeneity. Surprisingly, despite considerable extinctions, reduction in the amount of effective area available per species facilitated rather than reduced richness in the study communities. Our data suggest that the mechanism behind this positive effect was a decrease in the probability of deterministic competitive exclusion. We conclude that the area–heterogeneity tradeoff may have both negative and positive implications for biodiversity and that its net effect depends on the relative importance of stochastic vs. deterministic drivers of extinction in the relevant system. Our finding that the area–heterogeneity tradeoff may contribute to biodiversity adds a dimension to existing ecological theory and is highly relevant for understanding and predicting biodiversity responses to natural and anthropogenic variations in the environment.

scholarly journals Wildfire-mediated vegetation change in boreal forests of Alberta, Canada

Ecosphere ◽  
2018 ◽  
Vol 9 (3) ◽  
pp. e02156 ◽  
Author(s):  
Diana Stralberg ◽  
Xianli Wang ◽  
Marc-André Parisien ◽  
François-Nicolas Robinne ◽  
Péter Sólymos ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Vegetation Change

Public Satisfaction With Police: The Importance of Procedural Justice and Police Performance in Police-Citizen Encounters

2009 ◽  
Vol 42 (2) ◽  
pp. 159-178 ◽  
Author(s):  
Murphy Kristina
Keyword(s):  
Procedural Justice ◽  
Survey Data ◽  
National Sample ◽  
Police Legitimacy ◽  
Relative Importance ◽  
Police Performance ◽  
Different Types ◽  
Positive Effect ◽  
Satisfaction With Police

Alarge body of literature has demonstrated that when authorities use procedural justice with those they regulate, people will be more satisfied with those authorities and will be more willing to cooperate and comply with their directions and rules. In the context of policing, procedural justice has also been shown to be important for shaping citizens' views about police legitimacy, their satisfaction with police and also in fostering cooperation with police. What remains largely unexamined, however, is whether the positive effect of procedural justice varies across different types of police-citizen encounters. Using survey data collected from a national sample of 1,462 Australians, the present study will examine the relative importance of procedural justice on overall ratings of police satisfaction across two types of police-citizen encounters (citizen-initiated contacts and police-initiated contacts). It will be shown that procedural justice is most important in police-initiated contacts, while police performance is most important in citizen-initiated contacts.

The relative importance of stand and dead wood types for wood-dependent lichens in managed boreal forests

2016 ◽  
Vol 20 ◽  
pp. 166-174 ◽  
Author(s):  
Måns Svensson ◽  
Victor Johansson ◽  
Anders Dahlberg ◽  
Andreas Frisch ◽  
Göran Thor ◽  
...  
Keyword(s):  
Boreal Forests ◽  
Dead Wood ◽  
Relative Importance

Holocene forest dynamics in southern Ontario, Canada: fine-resolution pollen data

1997 ◽  
Vol 75 (10) ◽  
pp. 1714-1727 ◽  
Author(s):  
Janice L. Fuller
Keyword(s):  
Forest Dynamics ◽  
Vegetation Change ◽  
Relative Importance ◽  
Pollen Data ◽  
Southern Ontario ◽  
Factors Influencing ◽  
Main Factors ◽  
Temporal And Spatial ◽  
Fine Resolution ◽  
Closed Lake

Holocene fossil pollen data of fine temporal and spatial resolution were obtained from two small, closed lake basins in southern Ontario, Canada. Forest development is recorded in the pollen sequences, which document the invasion and expansion of tree populations during the early Holocene. Subsequent forest dynamics are discussed in terms of the main factors driving vegetation change, including climate, soil development, migration, disturbance regime (abiotic and biotic), and competition, which operate on a species pool with a variety of biological and ecological characteristics. The relative importance of these factors, influencing forest dynamics during the Holocene, appears to have varied over time. Key words: Fine resolution pollen data, forest dynamics, southern Ontario, Holocene.

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