Mechanistic modeling of environmental drivers of woolly mammoth carrying capacity declines on St. Paul Island

Ecology ◽  
2018 ◽  
Vol 99 (12) ◽  
pp. 2721-2730 ◽  
Author(s):  
Yue Wang ◽  
Warren Porter ◽  
Paul D. Mathewson ◽  
Paul A. Miller ◽  
Russell W. Graham ◽  
...  
Keyword(s):  
Carrying Capacity ◽  
Mechanistic Modeling ◽  
Environmental Drivers ◽  
Woolly Mammoth

Model-data fusion depicting the key processes and environmental drivers of photosynthates δ13C and δ18O compositions in boreal Scots Pine

2021 ◽  
Author(s):  
Kersti Leppä ◽  
Pauliina Schiestl-Aalto ◽  
Yu Tang ◽  
Elina Sahlstedt ◽  
Pasi Kolari ◽  
...  
Keyword(s):  
Data Fusion ◽  
Time Scales ◽  
Scots Pine ◽  
Environmental Conditions ◽  
Isotope Composition ◽  
Mechanistic Modeling ◽  
Environmental Drivers ◽  
Model Data ◽  
Carbon And Oxygen Isotope ◽  
Over Time

<p>Stable isotopes can diagnose the response of plants to changing climate as the performance of trees in past climatic conditions is archived in the stable carbon and oxygen isotope composition (δ<sup>13</sup>C and δ<sup>18</sup>O, respectively) of tree rings. To take advantage of these records, understanding the formation of isotopic signals in newly assimilated photosynthates is necessary. Despite a voluminous literature, there exists a gap between the model- and data-oriented studies, which if welded together would benefit this line of inquiry. A unique dataset covering two growing seasons in a boreal Scots pine stand situated in Southern Finland (61.9°N, 24.3°E) is employed and is accompanied with mechanistic modeling driven by environmental conditions. Data includes: (i) shoot gas exchange of vapor, CO<sub>2</sub> and its δ<sup>13</sup>C composition, (ii) δ<sup>13</sup>C in needle bulk sugar and sucrose alone, (iii) δ<sup>18</sup>O in water in precipitation, soil, twigs and needles, and (iv) δ<sup>18</sup>O in needle bulk sugar. Overall, observed exchange rates and isotopic composition of fluxes as well as in water and sugar pools were well reproduced using the model. We further address challenges common to the analysis of isotopic signals. Firstly, time scales and integration over them is an unavoidable challenge of data sampled at different intervals, representing either snapshots or a longer history of processes. As an example of this, we illustrate that δ<sup>18</sup>O in needle water reacts instantaneously to environmental conditions, while the δ<sup>18</sup>O signal in needle sugars is an integration over time, and thus relating the latter to instantaneous environmental conditions is less evident. Given that tree-ring studies are more and more focused on intra-annual variation in δ<sup>13</sup>C and δ<sup>18</sup>O, integration over time scales cannot be neglected. Second, using model sensitivity analysis, we showcase the relative importance of environmental drivers on the variation in δ<sup>13</sup>C and δ<sup>18</sup>O – the typical aim of empirical research and paleoclimatological reconstruction. It is commonly acknowledged that the main environmental driver of δ<sup>13</sup>C or δ<sup>18</sup>O variation can differ between sites and time periods. At the study site here, the variation in δ<sup>18</sup>O seems solely driven by relative humidity, but we can, for instance, show that this would change if the δ<sup>18</sup>O signal of source water varied considerably. We are of the opinion that illustrating such points with a model-data fusion approach is a necessary (but not sufficient) first step to bridge the gap between modeling and empirical approaches, and fostering further interpretation of isotopic signals in trees.</p>

scholarly journals Untangling the dynamics of persistence and colonization in microbial communities

2018 ◽  
Author(s):  
Sylvia L. Ranjeva ◽  
Joseph R. Mihaljevic ◽  
Maxwell B. Joseph ◽  
Anna R. Giuliano ◽  
Greg Dwyer
Keyword(s):  
Microbial Communities ◽  
Biotic Interactions ◽  
Mechanistic Modeling ◽  
Environmental Drivers ◽  
Modeling Approach ◽  
Environmental Requirements ◽  
Hpv Types ◽  
Environmental Responses ◽  
Species Occurrences ◽  
Potential Signal

AbstractA central goal of community ecology is to infer biotic interactions from observed distributions of co-occurring species. Evidence for biotic interactions, however, can be obscured by shared environmental requirements, posing a challenge for statistical inference. Here we introduce a dynamic statistical model that quantifies the effects of spatial and temporal covariance in longitudinal co-occurrence data. We separate the fixed pairwise effects of species occurrences on persistence and colonization rates, a potential signal of direct interactions, from latent pairwise correlations in occurrence, a potential signal of shared environmental responses. We apply our modeling approach to a pressing epidemiological question by examining how human papillomavirus (HPV) types coexist. Our results suggest that while HPV types respond similarly to common host traits, direct interactions are sparse and weak, so that HPV type diversity depends largely on shared environmental drivers. Our modeling approach is widely applicable to microbial communities and provides valuable insights that should lead to more directed hypothesis testing and mechanistic modeling.

Analisis Daya Dukung Tanah Dan Bahan Pondasi Tiang Pancang Pada Pembangunan Jembatan Kab. Jombang

2020 ◽  
Vol 9 (1) ◽  
pp. 32-37
Author(s):  
Ruslan Hidayat ◽  
Saiful Arfaah
Keyword(s):  
Carrying Capacity ◽  
Pile Foundation ◽  
Heavy Traffic ◽  
Traffic Volume ◽  
Material Strength ◽  
Cone Penetrometer ◽  
The Village

One of the most important factors in the structure of the pile foundation in the construction of the bridge is the carrying capacity of the soil so as not to collapse. Construction of a bridge in the village of Klitik in Jombang Regency to be built due to heavy traffic volume. The foundation plan to be used is a pile foundation with a diameter of 50 cm, the problem is what is the value of carrying capacity of soil and material. The equipment used is the Dutch Cone Penetrometer with a capacity of 2.50 tons with an Adhesion Jacket Cone. The detailed specifications of this sondir are as follows: Area conus 10 cm², piston area 10 cm², coat area 100 cm², as for the results obtained The carrying capacity of the soil is 60.00 tons for a diameter of 30 cm, 81,667 tons for a diameter of 35 cm, 106,667 tons for a diameter of 40 cm, 150,000 tons for a diameter of 50 cm for material strength of 54,00 tons for a diameter of 30 cm, 73,500 tons for a diameter of 35 cm, 96,00 tons for a diameter of 40 cm, 166,666 tons for a diameter of 50 cm

Intra-seasonal and inter-annual patterns in the demographics of sand lance and response to environmental drivers in the North Pacific

2019 ◽  
Vol 617-618 ◽  
pp. 221-244 ◽  
Author(s):  
MR Baker ◽  
ME Matta ◽  
M Beaulieu ◽  
N Paris ◽  
S Huber ◽  
...  
Keyword(s):  
North Pacific ◽  
Environmental Drivers ◽  
Sand Lance ◽  
The North ◽  
The North Pacific ◽  
Annual Patterns

Agroforestry in Eastern Otago: results from two long-term experiments

2000 ◽  
pp. 93-98
Author(s):  
G.G. Cossens ◽  
M.F. Hawke
Keyword(s):  
Soil Ph ◽  
Tree Growth ◽  
Pinus Radiata ◽  
Carrying Capacity ◽  
Livestock Grazing ◽  
Tree Age ◽  
Rapid Decline ◽  
Pasture Production ◽  
Clover Content ◽  
Pasture Yield

During the first 20 years of a Pinus radiata tree rotation, tree growth and pasture yield were assessed under a range of tree spacings at Invermay and Akatore, two coastal sites in Eastern Otago. Pasture yield in association with trees thinned to 100 stems per hectare (sph) was comparable to that from open pasture up to a tree age of 12 years. By the 19th year, however, pasture production declined to 63% of open pasture yield at Invermay and to 42% at Akatore. At 200 and 400 sph at Akatore, pasture yield was similar to that from open pasture at tree age 12 years but declined to 27% and 0% of open pasture yield respectively by year 20. At both Invermay and Akatore, the ryegrass and clover content of open pasture was relatively constant throughout the term of the trial. However, both the ryegrass and clover content of pasture beneath trees began to decline by tree age 12 years with a very rapid decline at Akatore in the number of pasture species at 200 sph by the 19th year. No pasture remained at 400 sph, after 19 years. Livestock carrying capacity with sheep on tree treatments at Invermay decreased from 100% of open pasture at year 6 to 60% by year 10. At Akatore, livestock carrying capacity averaged over the 20-year life of the trial was 4.1 stock units per hectare with a maximum of 8.1 stock units at a tree age of 8 years. Tree growth at both sites was similar, averaging between 1 and 1.1 m/year in height over 20 years, with trees at Invermay at 100 sph averaging 9% greater height and diameter growth than at Akatore. Increasing tree stocking from 100 to 200 to 400 sph at Akatore, resulted in increased tree height, but decreased diameter at breast height. A comparison of the East Otago trees with those in a similar trial at Tikitere (Rotorua) 900 km further north indicated that the southern trees were about 6 years later in their growth pattern by tree age 20 years. On both sites, soil pH tended to be lower in the presence of trees and was significantly lower than in open pasture by year 20. The results and comparisons with the Tikitere data suggest that, in an integrated agroforestry regime, there will be livestock grazing under the trees further into the tree rotation in Otago than in North Island sites. However, slower tree growth would result in a longer rotation time to harvest. Current recommendations to farmers are to plant trees on the less productive areas of the farm and adopt a tree stocking rate which fully utilises the site. Keywords: agroforestry, livestock, pasture, Pinus radiata, soil pH, tree stocking

THE CLASSIFICATION OF LAND ACCORDING TO THE DEGREE OF RABBIT INFESTATION IN CENTRAL OTAGO

1987 ◽  
pp. 65-70
Author(s):  
I.G.C. Kerr ◽  
J.M. Williams ◽  
W.D. Ross ◽  
J.M. Pollard
Keyword(s):  
Carrying Capacity ◽  
Mediterranean Climate ◽  
Natural Habitat ◽  
Public Funding ◽  
Soil Survey ◽  
European Rabbit ◽  
Cultural Modification ◽  
Classification Information ◽  
Semi Arid

The European rabbit (Oryctolagus cuniculus) introduced into New Zealand in the 183Os, has consistently flourished in Central Otago, the upper Waitaki, and inland Marlborough, all areas of mediterranean climate. It has proved difficult to manage in these habitats. The 'rabbit problem' is largely confined to 105,000 ha of low producing land mostly in semi arid areas of Central Otago. No field scale modifications of the natural habitat have been successful in limiting rabbit numbers. The costs of control exceed the revenue from the land and continued public funding for control operations appears necessary. A system for classifying land according to the degree of rabbit proneness is described. Soil survey and land classification information for Central Otago is related to the distribution and density of rabbits. This intormation can be used as a basis for defining rabbit carrying capacity and consequent land use constraints and management needs. It is concluded that the natural rabbit carrying capacity of land can be defined by reference to soil survey information and cultural modification to the natural vegetation. Classification of land according to rabbit proneness is proposed as a means of identifying the need for, and allocation of, public funding tor rabbit management. Keywords: Rabbit habitat, rabbit proneness, use of rabbit prone land.

PASTURE ESTABLISHMENT ON EAST COAST NORTH ISLAND HILL COUNTRY

1984 ◽  
pp. 216-218
Author(s):  
B.J. Arnst ◽  
O.L. Park
Keyword(s):  
White Clover ◽  
Carrying Capacity ◽  
Return On Investment ◽  
East Coast ◽  
Close Association ◽  
Development Programme ◽  
Low Fertility ◽  
Stock Management ◽  
Hill Country

Large areas of North Island hill country are producing below potential as a result of low fertility and poor pasture composition. Removal of undesirable species and replacement with a higher producing pasture is essential for increased productivity but is difficult to achieve. A development programme is described where the use of glyphosate in close association with oversowing and stock management has allowed rapid pasture establishment, marked increase in carrying capacity and a quick return on investment. Keywords: Pasture establishment, glyphosate, oversowing, white clover, subdivision, productivity.

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