Plant responses to nutrient addition and predictive ability of vegetation N:P ratio in an austral fen

2020 ◽  
Vol 65 (4) ◽  
pp. 646-656
Author(s):  
Olivia Rata Burge ◽  
Beverley R. Clarkson ◽  
Kerry A. Bodmin ◽  
Scott Bartlam ◽  
Hugh A. Robertson ◽  
...  
Keyword(s):  
Predictive Ability ◽  
N:P Ratio ◽  
Nutrient Addition ◽  
Plant Responses

scholarly journals Quantifying seasonal and diurnal variation of stomatal behavior in a hydraulic-based stomatal optimization model

2018 ◽  
Vol 5 ◽  
pp. e001
Author(s):  
William R. L. Anderegg
Keyword(s):  
Stomatal Conductance ◽  
Shadow Price ◽  
Stomatal Closure ◽  
Predictive Ability ◽  
Plant Responses ◽  
Seasonal And Diurnal Variation ◽  
Angiosperm Species ◽  
Term Response ◽  
Single Set ◽  
Optimization Theories

Plant responses to drought occur across many time-scales, with stomatal closure typically considered to be a critical short-term response. Recent theories of optimal stomatal conductance linked to plant hydraulic transport have shown promise, but it is not known if stomata update their hydraulic “shadow price” of water use (marginal increase in carbon cost with a marginal drop in water potential) over days, seasons, or in response to recent drought. Here, I estimate the hydraulic shadow price in five species – two semi-arid gymnosperms, one temperate and two tropical angiosperms – at daily timescales and in wet and dry periods. I tested whether the shadow prices varies predictably as a function of current and/or lagged drought conditions. Diurnal estimates of the hydraulic shadow price estimated from observed stomatal conductance, while variable, did not vary predictably with environmental variables. Seasonal variation in shadow price was observed in the gymnosperm species, but not the angiosperm species, and did not meaningfully influence prediction accuracy of stomatal conductance. The lack of systematic variation in shadow price and high predictive ability of stomatal conductance when using a single set of parameters further emphasizes the potential of hydraulic-based stomatal optimization theories.

Enhancement of Autotrophic Production by Nutrient Addition in a Coastal Rainforest Stream on Vancouver Island

1978 ◽  
Vol 35 (1) ◽  
pp. 28-34 ◽  
Author(s):  
John G. Stockner ◽  
K. R. S. Shortreed
Keyword(s):  
Algal Biomass ◽  
Algal Growth ◽  
N:P Ratio ◽  
Visual Observation ◽  
Nutrient Addition ◽  
Appreciable Effect ◽  
Blue Green Algae ◽  
Species Succession ◽  
Green Algal ◽  
Enrichment Experiments

In 1976 streamside nutrient-enrichment experiments were conducted using wooden troughs. Tripling of the PO4-P concentration, with or without a similar increase of NO3-N, increased algal biomass on the troughs by 8 times after 35 days. Increasing NO3-N alone had no appreciable effect on algal growth. A sloughing of algal biomass in August 1976 is believed to have been due to the instability of the heavy algal mat on the troughs and to the very poor light conditions that prevailed throughout August. Visual observation indicated that the relatively heavy algal population in Carnation Creek rapidly declined concurrent with the decline in the troughs. The percentage of diatoms in the algal assemblage remained the same in all troughs, and Fragilaria vaucheriae replaced Achnanthes minutissima as dominant on the phosphorus enriched trough. No shift to green or blue-green algal dominated assemblages occurred despite alteration of the N:P ratio. The dynamics of species succession, distribution, and growth, with and without nutrient addition, are discussed. Key words: stream fertilization, autotrophic production, algal succession, N:P ratio, algal distribution, rainforest, algal biomass, diatoms, blue-green algae

Different Responses and Links of N:P Ratio Among Ecosystem Components Under Nutrient Addition in a Temperate Forest

2019 ◽  
Vol 124 (10) ◽  
pp. 3158-3167
Author(s):  
Ying Shen ◽  
Dashuan Tian ◽  
Liangchao Jiang ◽  
Jinsong Wang ◽  
Xinli Chen ◽  
...  
Keyword(s):  
Temperate Forest ◽  
N:P Ratio ◽  
Nutrient Addition

Temporal dynamics of mycorrhizal fungal communities and co-associations with grassland plant communities following experimental manipulation of rainfall

2019 ◽  
Author(s):  
Coline Deveautour ◽  
Sally Power ◽  
Kirk Barnett ◽  
Raul Ochoa-Hueso ◽  
Suzanne Donn ◽  
...  
Keyword(s):  
Community Composition ◽  
Plant Community ◽  
Plant Communities ◽  
Fungal Community ◽  
Mycorrhizal Fungi ◽  
Temporal Dynamics ◽  
Arbuscular Mycorrhizal ◽  
Fungal Communities ◽  
Plant Responses ◽  
Rainfall Regimes

Climate models project overall a reduction in rainfall amounts and shifts in the timing of rainfall events in mid-latitudes and sub-tropical dry regions, which threatens the productivity and diversity of grasslands. Arbuscular mycorrhizal fungi may help plants to cope with expected changes but may also be impacted by changing rainfall, either via the direct effects of low soil moisture on survival and function or indirectly via changes in the plant community. In an Australian mesic grassland (former pasture) system, we characterised plant and arbuscular mycorrhizal (AM) fungal communities every six months for nearly four years to two altered rainfall regimes: i) ambient, ii) rainfall reduced by 50% relative to ambient over the entire year and iii) total summer rainfall exclusion. Using Illumina sequencing, we assessed the response of AM fungal communities sampled from contrasting rainfall treatments and evaluated whether variation in AM fungal communities was associated with variation in plant community richness and composition. We found that rainfall reduction influenced the fungal communities, with the nature of the response depending on the type of manipulation, but that consistent results were only observed after more than two years of rainfall manipulation. We observed significant co-associations between plant and AM fungal communities on multiple dates. Predictive co-correspondence analyses indicated more support for the hypothesis that fungal community composition influenced plant community composition than vice versa. However, we found no evidence that altered rainfall regimes were leading to distinct co-associations between plants and AM fungi. Overall, our results provide evidence that grassland plant communities are intricately tied to variation in AM fungal communities. However, in this system, plant responses to climate change may not be directly related to impacts of altered rainfall regimes on AM fungal communities. Our study shows that AM fungal communities respond to changes in rainfall but that this effect was not immediate. The AM fungal community may influence the composition of the plant community. However, our results suggest that plant responses to altered rainfall regimes at our site may not be resulting via changes in the AM fungal communities.

Validation and inter-rater reliability of inexpensive, mini, no-touch infrared surface thermometry devices as an assessment tool for prediction of wound-related deep and surrounding infection

WCET Journal ◽  
2019 ◽  
pp. 18-22
Author(s):  
Hiske Smart ◽  
Eman Al Al Jahmi ◽  
Ebrahim Buhiji ◽  
Sally-Anne Smart
Keyword(s):  
Temperature Difference ◽  
Assessment Tool ◽  
Predictive Ability ◽  
Skin Surface ◽  
Infrared Thermometry ◽  
Health Care Clinics ◽  
Primary Health ◽  
Wound Assessment ◽  
The Times ◽  
Assessment Modality

Industrial infrared thermometry devices are large and, despite being less expensive than the current gold standard Exergen Dermatemp medical infrared thermometer, are still not affordable enough to ensure unrestricted and consistent use of this assessment modality in regular wound-related day-to-day practice. An increased skin surface temperature differentiation of 3°F associated with a wound has a positive predictive ability to detect deep or surrounding wound infection. This study hypothesised that inexpensive, pen- or pocket-sized, no-touch surface infrared thermometry devices will be equal in ability to detect a 3oF increased skin temperature compared to the Exergen Dermatemp infrared device and be reliable in the hands of any wound assessor. The odds of the control and other thermometers to detect a 3oF temperature difference, irrespective of the raters, were achieved in all five of the mini thermometers tested, with a correct temperature difference prediction that occurred in 90.933% of the times (odds determined 9/10). As a result of this study mini, no-touch infrared thermometry, to detect a 3oF temperature difference in wound assessment to determine tendency, could be implemented into primary health care clinics, rural clinics, day-to-day hospital practice and standard outpatients departments at a small financial cost, regardless of which thermometer is put to use.

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