Efficient synthetic generation of ecological data with preset spatial association of individuals

2021 ◽  
Author(s):  
Bogdan Strimbu ◽  
Andrei Paun ◽  
Alexandru Amarioarei ◽  
Mihaela M Paun ◽  
Victor Felix Strimbu
Keyword(s):  
Forest Ecosystems ◽  
Spatial Association ◽  
Spatial Arrangement ◽  
Spatially Explicit ◽  
Forest Stands ◽  
Ecological Data ◽  
Aggregation Index ◽  
Spatial Indices ◽  
Functional Software ◽  
Individual Trees

Many experiments are not feasible to be conducted as factorials. Simulations using synthetically generated data are viable alternatives to such factorial experiments. The main objective of the present research is to develop a methodology and a platform to synthetically generate spatially explicit forest ecosystems represented by points with a predefined spatial pattern. Using algorithms with polynomial complexity and parameters that control the number of clusters, the degree of clusterization, and the proportion of nonrandom trees, we show that spatially explicit forest ecosystems can be generated time efficiently, which enable large factorial simulations. The proposed method was tested on 1200 synthetically generated forest stands, each of 25 ha, using 10 spatial indices: Clark-Evans aggregation index, Ripley’s K, Besag’s L, Morisita’s dispersion index, Greig-Smith index, the size dominance index of Hui, index of nonrandomness of Pielou, directional index and mean directional index of Corral-Rivas, and size differentiation index of Von Gadow. The size of individual trees was randomly generated aiming at variograms like real forests. We obtained forest stands with the expected spatial arrangement and distribution of sizes in less than one hour. To ensure replicability of the study we have provided a free fully functional software that executes the stated tasks.

scholarly journals Information use during movement regulates how fragmentation and loss of habitat affect body size

2018 ◽  
Vol 285 (1884) ◽  
pp. 20180953 ◽  
Author(s):  
Jasmijn Hillaert ◽  
Martijn L. Vandegehuchte ◽  
Thomas Hovestadt ◽  
Dries Bonte
Keyword(s):  
Body Size ◽  
Evolutionary Dynamics ◽  
Information Use ◽  
Spatial Arrangement ◽  
Habitat Choice ◽  
Spatially Explicit ◽  
Spatially Explicit Model ◽  
Feedback Effects ◽  
Body Sizes ◽  
Movement Ability

An individual's body size is central to its behaviour and physiology, and tightly linked to its movement ability. The spatial arrangement of resources and a consumer's capacity to locate them are therefore expected to exert strong selection on consumer body size. We investigated the evolutionary impact of both the fragmentation and loss of habitat on consumer body size and its feedback effects on resource distribution, under varying levels of information used during habitat choice. We developed a mechanistic, individual-based, spatially explicit model, including several allometric rules for key consumer traits. Our model reveals that as resources become more fragmented and scarce, informed habitat choice selects for larger body sizes while random habitat choice promotes small sizes. Information use may thus be an overlooked explanation for the observed variation in body size responses to habitat fragmentation. Moreover, we find that resources can accumulate and aggregate if information about resource abundance is incomplete. Informed movement results in stable resource–consumer dynamics and controlled resources across space. However, habitat loss and fragmentation destabilize local dynamics and disturb resource suppression by the consumer. Considering information use during movement is thus critical to understand the eco-evolutionary dynamics underlying the functioning and structuring of consumer communities.

A model for predicting the value of forest stands in various market conditions in British Columbia

2009 ◽  
Vol 85 (3) ◽  
pp. 387-391
Author(s):  
Mihai Pavel ◽  
Björn O Andersson
Keyword(s):  
British Columbia ◽  
Dynamic Programming ◽  
Dynamic Programming Algorithm ◽  
Inventory Systems ◽  
Programming Algorithm ◽  
Forest Stands ◽  
Market Conditions ◽  
Second Growth ◽  
Taper Equation ◽  
Individual Trees

A model for predicting the value of forest stands was developed at FPInnovations – Feric Division. The model uses standard cruise data collected in British Columbia (BC) and company sort descriptions to predict the distribution of wood volume by species and grade sort for each proposed harvest site. The model is capable of quickly analyzing different scenarios (i.e., different sort sets) to reflect changing market conditions. Within the model, a taper equation is applied to each tree to calculate the diameters inside the bark, and quality and pathological descriptors from cruise data are used. A Dynamic Programming algorithm is used to predict the combination of logs that maximizes the value of each stem, and results are summarized and extended from individual trees to cruise plots, then to harvest blocks and/or stands. The model was successfully tested for second-growth stands with relatively few defects on Coastal BC. Improvements are being implemented to enhance its applicability to more complex stands. Key words: value of forest stands, economic operability, optimal bucking of trees, Dynamic Programming, computer model, inventory systems

scholarly journals Spatial Distribution of Eggs of Alabama argillacea Hübner and Heliothis virescens Fabricius (Lepidoptera: Noctuidae) on Bt and non-BtCotton

2015 ◽  
Vol 87 (4) ◽  
pp. 2243-2253
Author(s):  
TATIANA R. RODRIGUES ◽  
MARCOS G. FERNANDES ◽  
PAULO E. DEGRANDE ◽  
THIAGO A. MOTA
Keyword(s):  
Spatial Distribution ◽  
Negative Binomial Distribution ◽  
Binomial Distribution ◽  
Heliothis Virescens ◽  
Negative Binomial ◽  
Model Fitting ◽  
Spatial Arrangement ◽  
Distribution Model ◽  
Aggregation Index ◽  
Alabama Argillacea

ABSTRACT Among the options to control Alabama argillacea (Hübner, 1818) and Heliothis virescens (Fabricius, 1781) on cotton, insecticide spraying and biological control have been extensively used. The GM'Bt' cotton has been introduced as an extremely viable alternative, but it is yet not known how transgenic plants affect populations of organisms that are interrelated in an agroecosystem. For this reason, it is important to know how the spatial arrangement of pests and beneficial insect are affected, which may call for changes in the methods used for sampling these species. This study was conducted with the goal to investigate the pattern of spatial distribution of eggs of A. argillacea and H. virescens in DeltaOpalTM (non-Bt) and DP90BTMBt cotton cultivars. Data were collected during the agricultural year 2006/2007 in two areas of 5,000 m2, located in in the district of Nova América, Caarapó municipality. In each sampling area, comprising 100 plots of 50 m2, 15 evaluations were performed on two plants per plot. The sampling consisted in counting the eggs. The aggregation index (variance/mean ratio, Morisita index and exponent k of the negative binomial distribution) and chi-square fit of the observed and expected values to the theoretical frequency distribution (Poisson, Binomial and Negative Binomial Positive), showed that in both cultivars, the eggs of these species are distributed according to the aggregate distribution model, fitting the pattern of negative binomial distribution.

scholarly journals Structure and development of forest stands on permanent research plots in the Krkonoše Mts.

2010 ◽  
Vol 56 (No. 11) ◽  
pp. 518-530
Author(s):  
S. Vacek ◽  
Z. Vacek ◽  
L. Bílek ◽  
I. Nosková ◽  
O. Schwarz
Keyword(s):  
Species Composition ◽  
Tree Species ◽  
Vertical Structure ◽  
Forest Stand ◽  
Forest Stands ◽  
Vegetation Zone ◽  
Aggregation Index ◽  
Tree Species Composition ◽  
Results Management ◽  
Management Recommendations

The research is focused on structure and development of forest stands from 5th to 8th forest vegetation zone in the Krkonoše Mts. The forest stand diversity according to tree species composition and representation, horizontal and vertical structure was evaluated by using following indices: Clark-Evans aggregation index (Clark, Evans 1954), standardised Arten-profil index (Pretsch 2005) and index of complex diversity after Jaehne, Dohrenbusch (1997). Growth model SIBYLA (Fabrika, Ďurský 2005) was used for visualizations and growth predictions of forest stands on particular plots. Based on research results, management recommendations were evaluated.

Does hypoxia reduce habitat quality for Lake Erie walleye (Sander vitreus)? A bioenergetics perspective

2011 ◽  
Vol 68 (5) ◽  
pp. 857-879 ◽  
Author(s):  
Stephen B. Brandt ◽  
Marco Costantini ◽  
Sarah Kolesar ◽  
Stuart A. Ludsin ◽  
Doran M. Mason ◽  
...  
Keyword(s):  
Habitat Quality ◽  
Lake Erie ◽  
Prey Availability ◽  
Spatial Arrangement ◽  
Spatially Explicit ◽  
Sander Vitreus ◽  
Light Conditions ◽  
The Impact ◽  
Favorable Temperature ◽  
East West

In Lake Erie, the duration and extent of hypoxia (dissolved oxygen (DO)  ≤ 2 mg·L–1) has increased in recent years, yet little is known on the corresponding impact on its fish, particularly the highly valued walleye ( Sander vitreus ) fishery. Here, we quantified the impact of hypoxia on walleye habitat quality, using a spatially explicit growth rate potential (GRP) modeling approach, which integrates the spatial arrangement of biological (prey availability) and environmental (DO, temperature, irradiance) measures. Data were collected along two types of transects: 60 km north–south transects (each sampled once during day and night) and 5 km east–west transects (sampled every 4 h for 24 h) during August (pre-hypoxia), September (peak-hypoxia), and October (post-hypoxia) 2005. Overall, the average monthly amount of high quality habitat (GRP > 0 g·g–1·day–1) for walleye declined slightly with hypoxia (<2.0%); however, hypoxia appeared to enhance habitat quality by concentrating prey in favorable temperature, DO, and light conditions. In September, percentages of walleye growth rates were at the upper end of the range, much more so than during August or October. Although an understanding of walleye distributions, foraging, and growth in relation to hypoxia is needed, our results do not suggest that hypoxia is negatively influencing walleye through reduced habitat quality.

Predicting basal area increment in a spatially explicit, individual tree model: a test of competition measures with black spruce

2003 ◽  
Vol 33 (3) ◽  
pp. 435-443 ◽  
Author(s):  
Daniel Mailly ◽  
Sylvain Turbis ◽  
David Pothier
Keyword(s):  
Black Spruce ◽  
Basal Area ◽  
Basal Area Increment ◽  
Spatially Explicit ◽  
Competition Index ◽  
Individual Tree ◽  
Spatial Indices ◽  
Crown Shape ◽  
Spruce Stands ◽  
Competition Indices

A current trend in the development of forest stand models is to use spatially explicit, individual-tree information to simulate forest dynamics with increased accuracy. By adding spatial information, such as tree coordinates, crown shape, and size, it is hypothesized that the computation of the model's driving function is improved over traditional competition indices, especially when simulating multistoried stands. In this paper, we want to test whether computationally demanding competition indices outperform traditional indices in predicting mean basal area increment. The study was undertaken in old, uneven-aged black spruce (Picea mariana (Mill.) BSP) stands in northeastern Quebec, Canada. The predictability of individual tree growth rates was related to crown dimensions and other stand and tree variables measured in the field. Data were collected from 90 trees coming from stands of varying site quality (range 9.6–16.5 m height at 50 years, age taken at 1 m) and age (range 66–257 years). Hegyis's distance-dependent competition index was found to be the most strongly correlated competition measure (r = 0.57) with mean basal area growth of the last 20 years. This value, 12% higher than the value obtained from the best distance-independent competition index (r = 0.45), clearly shows that precision gains can be achieved when estimating basal area increment with spatial indices in black spruce stands. Using indices computed from virtual hemispherical images did not prove superior to simpler distance-dependent indices based on their individual correlations with basal area increment. When included in a basal area increment model for the last 20 years of growth, however, the gains in precision were comparable to Hegyi's competition index. This indicates that indices derived from a hemispherical approach have some value in spatially explicit forest simulations models but that further tests using younger stands are needed to confirm this result in black spruce stands.

scholarly journals Improving Economic Management Decisions in Forestry with the SorSim Assortment Model

2019 ◽  
Vol 41 (1) ◽  
pp. 71-83
Author(s):  
Renato Lemm ◽  
Clemens Blattert ◽  
Stefan Holm ◽  
Leo Bont ◽  
Oliver Thees
Keyword(s):  
Optimal Allocation ◽  
Timber Harvest ◽  
Timber Harvesting ◽  
Forest Stands ◽  
Economic Management ◽  
Practical Advantage ◽  
Potential Applications ◽  
Forest Enterprises ◽  
Individual Trees

The sustainable supply of timber is one of the most important forest ecosystem services and a decisive factor determining the long-term profitability of forest enterprises. If timber production is to be economically viable, there must always be a way to analyse forest stands and trees felled for exploitation with regard to the wood assortments they contain. Only then can the expected timber yields, achieved by various silvicultural strategies or actions and different sorting options, be quantified with sufficient accuracy. The SorSim assortment simulator was developed for forest practitioners and forest scientists in Switzerland to realistically simulate the sorting of individual trees and entire forest stands based on defined specifications. SorSim has a simple user interface and comes in a number of different language versions (G, E, F). The software is implemented in Java, making it platform-independent. It can be downloaded for free at (https://www.wsl.ch/en/projects/sortimentsimulator-sorsim.html). This article provides an overview of how the simulator works and demonstrates its potential applications based on a practical and a scientific example. A particular practical advantage is that the composition of the assortments of the planned harvests can be estimated according to quantity and value. When used in strategic planning and especially in research, SorSim provides a basis for analysing either long-term developments in yields from forest stands or silvicultural treatment methods. Based on an even-aged and a selection forest stand, the scientific example shows how strongly the assessment of the advantageousness of two different silvicultural strategies depends on the time when the calculation was made (using historical and current assortment revenues and timber harvesting costs). In particular, the combination of SorSim with timber harvest productivity models enables differentiated forest economic insights. Various approaches for value-based optimisation in the sorting of individual trees and for the optimal allocation of harvesting activities to defined customer demands are currently being examined as further SorSim developments.

scholarly journals Disturbances and biodiversity in forest ecosystems: A temperate zone perspective

2012 ◽  
Vol 8 ◽  
pp. 1-9 ◽  
Author(s):  
Anton Fischer
Keyword(s):  
Forest Management ◽  
Bark Beetle ◽  
Forest Ecosystems ◽  
Temperate Zone ◽  
Permanent Plots ◽  
Native Forest ◽  
Main Task ◽  
Natural Disturbances ◽  
Forest Stands ◽  
Biodiversity Protection

In the temperate zone windstorms and bark beetle attacks represent the main natural forest disturbances; in steep mountain areas snow avalanches also may “destroy” forest stands completely. In the densely populated and intensively used temperate zone of Europe affected forest stands will be cleared and reforested immediately after such “catastrophes”. Therefore we have only little knowledge about the influence of such natural disturbances on both the stand development and the biodiversity of native forest ecosystems. And we do not have quantitative data on to which degree forest management changes the biodiversity compared to the natural disturbances. Since about two decades several permanent plot studies have been running in European forests affected by such natural disturbances, mainly with focus on plant species. Here we first outline the importance of disturbances for biodiversity in forest ecosystems and then discuss whether it is possible to combine both biodiversity protection and forest management. For that we use four recent case studies carried out in the two oldest national parks in Germany, three of them being long-term observations on permanent plots for up to two decades. Disturbances like wind throw, bark beetle outbreak and snow avalanche strongly influences the tree layer structure, creating micro-habitats for many plant, animal and fungi species, which naturally belong to the forest ecosystem. Such disturbances in future should be included into management schemes in forestry to improve biodiversity. We found evidence that it is really possible to combine timber utilization with biodiversity protection. As long as the management impact is reduced (e.g. single tree harvesting, using natural regeneration), species diversity of several taxonomic groups (in our study: vascular plants, soil living Carabidae, and soil living fungi) may not be different significantly from a pristine forest. Interconnecting resource use with biodiversity protection will be a main task for both foresters and conservationist in the decades to come – and it seems to be a possible option for a sustainable land use in many parts of the world.doi: http://dx.doi.org/10.3126/botor.v8i0.5552 Botanica Orientalis – Journal of Plant Science (2011) 8: 1-9

scholarly journals Analysis of Individual Tree Competition on Diameter Growth of Silver Birch in Estonia

2015 ◽  
Vol 24 (2) ◽  
pp. e023 ◽  
Author(s):  
Kobra Maleki ◽  
Andres Kiviste ◽  
Henn Korjus
Keyword(s):  
Growth Model ◽  
Spatial Competition ◽  
Predictor Variable ◽  
Specific Effect ◽  
Silver Birch ◽  
Spatially Explicit ◽  
Diameter Growth ◽  
Individual Tree ◽  
Spatial Indices ◽  
Competition Indices

<p><em>Aim of study:</em> The present study evaluates a set of competition indices including spatially explicit indices combined with different competitor selection approaches and non-spatially explicit competition indices. The aim was to quantify and describe the neighbouring effects on the tree diameter growth of silver birch trees.<em></em></p><p><em>Area of study:</em> Region throughout Estonia. <em></em></p><p><em>Material and methods:</em> Data from the Estonian Network of Forest Research Plots was used. After quantifying the selected indices, the best non-spatial indices and spatial indices (combined with neighbour selection methods) were separately devised into a growth model as a predictor variable to assess the ability of the diameter growth model before and after adding competition measures. To test the species-specific effect on the competition level, the superior indices were recalculated using Ellenberg’s light indicators and incorporated into the diameter growth model. <em></em></p><p><em>Main results:</em> Statistical analyses showed that the diameter growth is a function of neighbourhood interactions and spatial indices were better growth predictors than non-spatial indices. In addition, the best selections of competitive neighbours were acquired based on the influence zone and the competition elimination angle concepts, and using Ellenberg’s light values had no significant improvement in quantifying the competition effects. <em></em></p><p><em>Research highlights: </em>Although the best ranking spatial competition measures were superior to the best non-spatial indices, the differences were negligible.</p><p><strong>Keywords:</strong> Competition indices; zone of influence; stem diameter increment; <em>Betula pendula </em>Roth<em>.</em><strong></strong></p>

scholarly journals Investigation of The Relationships Between Image Spatial Resolution And Landscape Metrics

2021 ◽  
Author(s):  
Elif Sertel ◽  
Raziye Hale Topaloglu ◽  
Beril Varol ◽  
Asli Gul Aksu ◽  
Kubra Bahsi
Keyword(s):  
Spatial Resolution ◽  
Landscape Metrics ◽  
Satellite Images ◽  
Nearest Neighbor ◽  
Diversity Index ◽  
Spatial Arrangement ◽  
Shape Index ◽  
Current Status ◽  
Aggregation Index ◽  
The Impact

Abstract Land Use and Land Cover (LULC) maps derived from satellite images are a significant source of geo-information to better understand the current status of landscapes, to analyze the landscape changes, and to develop sustainable decisions for landscape and urban planning. Since the spectral and spatial resolution of satellite images directly impact the LULC classes to be identified and the accuracy of the classification, these will also affect the values of calculated landscape metrics. This research aims to propose the most appropriate functions and features to obtain highly accurate thematically extensive LULC classification results from multi-resolution satellite images and to investigate how the change in spatial resolution of satellite images would affect the landscape metrics values and landscape pattern analysis Sentinel-2, SPOT-7, Pleaides, and Worldview-4 images with respective 10 m, 1.5 m, 0.5 m, and 0.3 m spatial resolution were classified using Geographic Object-Based Image Analysis techniques to create multi-scale LULC maps with the overall classification accuracy values of 66.05%, 85.00%, 91.79%, and 95.71%, respectively. Patch Density, Total Area, Largest Patch Index, Shape Index, Euclidian Nearest Neighbor distance, Aggregation Index, and Shannon's Diversity Index metrics were found to be most appropriate metrics to analyze the impact of spatial resolution on landscape metrics calculations considering the ability of these metrics to capture the spatial details, spatial arrangement, spatial distribution and complexity of shapes of landscape and classes.Landscape metrics results obtained from different LULC maps were compared to analyze the effects of image spatial resolution on different landscape metrics.

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