scholarly journals Tree Species Diversity and Spatial Distribution of Aleppo Pine Stands in Northeastern Algeria

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Insaf Hani ◽  
Malika Rached-Kanouni ◽  
Ammar Menasri
Keyword(s):  
Spatial Distribution ◽  
Pinus Halepensis ◽  
Alpha Diversity ◽  
Ecological Processes ◽  
Aggregation Index ◽  
Tree Patterns ◽  
Tree Inventory ◽  
Structural Indices ◽  
Differentiation Index ◽  
Diameter Differentiation

The spatial pattern of species is one of the key studied parameters in ecology so as to better understand the ecological processes and the functioning of forest ecosystems. This paper describes the classification of structural indices measuring the alpha diversity and examines typical representatives of the classification groups such as the Shannon’s index, aggregation index by Clark and Evans, the mingling index, the diameter differentiation index and the coefficient of segregation by Pielou. The tree inventory made it possible to count 7 species that are divided into six (06) families. Only Pinus halepensis Mill. trees were taken into account via calculation in spatial distribution. Western exposure shows the most regular tree patterns (1.6±0.1) according to the aggregation index by Clark and Evans, while the species mingling index for south- and east-facing stands indicates segregation of Pinus halepensis Mill. groups. The diameter differentiation index for the majority of the studied stands is assumed through estimated values within the range that starts from 0.4 to 0.9 for the four exposures. The distribution shows that western and eastern exposures belong to the fourth class of differentiation (very large differentiation), which means that the trees with the smallest DBH have less than 30% of the size of the neighbouring trees since the diameter differentiation index for the two exposures is 0.9±0.05 and 0.7±0.2.

Microbial ecological processes in MBBR biofilms for biological phosphorus removal from wastewater

2019 ◽  
Vol 79 (8) ◽  
pp. 1467-1473 ◽  
Author(s):  
Knut Rudi ◽  
Inger Andrea Goa ◽  
Torgeir Saltnes ◽  
Gjermund Sørensen ◽  
Inga Leena Angell ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Phosphorus Removal ◽  
Alpha Diversity ◽  
Fold Increase ◽  
Environmental Pollutant ◽  
Biofilm Reactor ◽  
Operational Performance ◽  
Biological Phosphorus Removal ◽  
Ecological Processes ◽  
Biological Phosphorus

Abstract Phosphorus is both a major environmental pollutant and a limiting resource. Although enhanced biological phosphorus removal (EBPR) is used worldwide for phosphorus removal, the standard activated sludge-based EBPR process shows limitations with stability and efficiency. Recently, a new EBPR moving bed biofilm reactor (MBBR) process has been developed at HIAS (Hamar, Norway), enabling a phosphorus removal stability above 90% during a whole year cycle. To increase the knowledge of the HIAS (MBBR) process the aim of the current work was to characterize the MBBR microbiota and operational performance weekly for the operational year. Surprisingly, we found a major succession of the microbiota, with a five-fold increase in phosphorus accumulating organisms (PAOs), and major shifts in eukaryote composition, despite a stable phosphorus removal. Temperature was the only factor that significantly affected both phosphorus removal and the microbiota. There was a lower phosphor removal during the winter, coinciding with a higher microbiota alpha diversity, and a lower beta diversity. This differs from what is observed for activated sludge based EBPR. Taken together, the knowledge gained from the current microbiota study supports the efficiency and stability of MBBR-based systems, and that knowledge from activated sludge-based EBPR approaches cannot be translated to MBBR 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.

Spatial diffusion modelling of juvenile Atlantic salmon (Salmo salar) shows ontogenetic increase in movement rates

2017 ◽  
Vol 74 (2) ◽  
pp. 202-207 ◽  
Author(s):  
A. Foldvik ◽  
S. Einum ◽  
A.G. Finstad
Keyword(s):  
Spatial Distribution ◽  
Atlantic Salmon ◽  
Salmo Salar ◽  
Continuous Distribution ◽  
Diffusion Models ◽  
Ontogenetic Changes ◽  
Ecological Processes ◽  
Breeding Sites ◽  
Atlantic Salmon Salmo Salar ◽  
The Individual

For organisms with extensive ontogenetic changes in phenotypes, knowledge of how movement of individuals changes throughout life is pivotal to understanding ecological processes. Here, we study the spatial distribution of a cohort of Atlantic salmon (Salmo salar) from hatching to their third summer of juvenile life, during which they go through a fourfold change in body size. The fish originated from three distinct breeding sites, and their distribution was mapped using electrofishing throughout the river at 10 sampling periods. The spatial distribution throughout ontogeny was analysed using diffusion models. The distribution changed from three distinct nonoverlapping distributions centred on the individual breeding sites at the early first summer stage to a single continuous distribution at the end of the study. The diffusion coefficient increased throughout ontogeny, and spatial distributions were well-described using diffusion models, explaining 46%–89% of the variation. This highlights the utility of diffusion models when considering spatial habitat structure both in conservation and research.

scholarly journals Patterns of diversity on the Paleozoic shelf: implications for controls on clade history

1992 ◽  
Vol 6 ◽  
pp. 266-266 ◽  
Author(s):  
J. John Sepkoski ◽  
Arnold I. Miller
Keyword(s):  
Beta Diversity ◽  
Spatial Scales ◽  
Alpha Diversity ◽  
Physical Geography ◽  
Local Communities ◽  
Dominant Factor ◽  
Ecological Processes ◽  
Alpha And Beta Diversity ◽  
Global Diversity ◽  
Local Ecology

Global diversity often is treated as a barometer of evolutionary success of clades without reference to their occurrence in ecological or biogeographical space. But global diversity is a composite of various spatial scales: alpha diversity, the number of taxa co-occurring in local communities; beta diversity, the distinction in taxonomic composition among local communities; and gamma diversity, the distinction, or degree of endemism, among geographic provinces, It has been argued by some workers that global diversity correlates strongly with alpha (and beta) diversity but by others that provinciality is the principal control of global patterns. The distinction is important, implicating either ecological processes (“adaptation”) or physical geography (“contingency”) as the major factor in expansion of clades.We have examined the ecological half of this problem with a data base comprising 505 fossil assemblages sampled from Paleozoic strata of Laurentian North America. On the basis of associated sedimentary characteristics, each assemblage has been assigned to one of six environmental categories, ranging from onshore peritidal situations to offshore basinal conditions. For each taxonomic order and class, average numbers of genera in each category have been determined for each of 18 time units. These average alpha diversities have been contoured on time-environment diagrams and compared to patterns of global diversity.Three major generalizations are derived from these diagrams:1. Major groups tend to be environmentally conservative, maintaining their life zones of maximum and minimum alpha diversity over vast stretches of time.2. Onshore-offshore shifts are most common during early expansion or late contraction of groups, when their global diversity is rapidly waxing or (more slowly) waning.3. Maxima and minima in global diversity within the groups through time, with few exceptions, are reflected in alpha diversity as fluctuations within the environments of maximum richness and/or as variations in the range of environments occupied.The last observation indicates a tight link between local ecology and global diversity, although the direction of causation is not unambiguous: alpha diversity could be reflecting only the global pool from which species can be recruited into local communities. However, in view of the onshore-offshore shifts during early and late histories of clades we conclude that local ecology is the dominant factor in controlling global diversity, and provinciality is secondary.

scholarly journals Trophic states regulate assembly processes and network structures of small chromophytic phytoplankton communities in subtropical coastal ecosystem

2020 ◽  
Author(s):  
Xing Chen ◽  
Huaxian Zhao ◽  
Gonglingxia Jiang ◽  
Jinli Tang ◽  
Qiangsheng Xu ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Community Assembly ◽  
Significant Proportion ◽  
Alpha Diversity ◽  
Beibu Gulf ◽  
Coastal Eutrophication ◽  
Nitrogen And Phosphorus ◽  
Ecological Processes ◽  
Phytoplankton Communities ◽  
Estuarine Coastal

Abstract Small chromophytic phytoplankton (SCP) are anticipated to be more important for a significant proportion of primary production in estuarine-coastal ecosystems. However, responses of SCP community to coastal eutrophication are still unclear. In this study, we investigated diversity, co-occurrence and assembly features of SCP communities, as well as their relationship with environmental factors in the subtropical Beibu Gulf. The results exhibited that the alpha diversity (ANOVA, p < 0.001) and beta diversity (ANOSIM, p < 0.001) of SCP communities were significantly different among eutrophic states. Co-occurrence network analysis revealed a complex interaction between SCP community and environmental factors. Most ASVs in modules of the network were specific to trophic states. Further, phylogenetic based β-nearest taxon distance analyses revealed that stochastic processes mainly provided 69.26% contribution to SCP community assembly, whereas deterministic processes dominated community assembly in a heavy eutrophic state. Importantly, increased environmental disturbances, such as nitrogen and phosphorus nutrients, could alter SCP community structure and disrupt ecological processes. Overall, our findings elucidate the mechanism of diversity and assembly in marine SCP community and promote the understanding of SCP ecology related to subtropical coastal eutrophication.

scholarly journals Preliminary study on micro area based spatial distribution of powdery mildew in an organic apple orchard

2014 ◽  
Vol 20 (3-4) ◽  
Author(s):  
I. J. Holb
Keyword(s):  
Spatial Distribution ◽  
Powdery Mildew ◽  
Disease Incidence ◽  
Apple Orchard ◽  
Plant Part ◽  
Aggregation Index ◽  
Preliminary Study ◽  
Fruit Disease ◽  
Random Patterns ◽  
Symptomatic Plant

In this study, the objective was to report a preliminary study on micro area based spatial distribution of powdery mildew in an organic apple orchard. Results showed that number of symptomatic plant part ranged between 11 and 20 on shoot and between 9 and 24 on fruit. Number of asymptomatic plant part ranged between 85 and 109 on shoot and between 133 and 206 on fruit. Disease incidence ranged between 13.8 and 17.6% on shoot and between 9.1 and 11.3% on fruit. Disease aggregation index ranged between 0.098 and 0.228 on shoot and between 0.043 and 0.108 on fruit. One of the four trees showed significant within canopy aggregation of disease for shoot powdery mildew symptoms in both years. For leaf powdery mildew, all tree exhibited random patterns in both years.

STRUCTURAL CHARACTERISATION AND ASSESSMENT OF THE SPATIAL DISTRIBUTION OF PINUS HALEPENSIS IN THE EL HAMIMET FOREST (EASTERN ALGERIA)

2021 ◽  
Author(s):  
Yahi Djamel ◽  
Redjaimia Lilia ◽  
Haddad Amar ◽  
Zerrouki Alia ◽  
Rached-Kanouni Malika
Keyword(s):  
Spatial Distribution ◽  
Forest Management ◽  
Sustainable Management ◽  
Altitudinal Gradient ◽  
Pinus Halepensis ◽  
Pine Plantations ◽  
Structural Characterisation ◽  
Essential Step ◽  
Current State ◽  
Eastern Algeria

Aleppo pine plantations were studied in the region of El Hamimet, the diameter at 1.30m from the ground, the total height of P. halepensis individuals were measured on 4 plots according to an altitudinal gradient. The establishment and interpretation of diameter and height structures are essential for forest management decisions. Knowledge of these parameters is an essential step in their sustainable management. The diameter and height structures were established according to diameter or height classes. The stand on plot 4 is characterized by the lowest diameter and height values. The analysis of the diameter and height structures reveals an increase in the frequency of young individuals. These results contribute to the improvement of the knowledge on the indicators of the current state of the natural Pinus halepensis stands that can be used as a basis for the management of the El Hamimet forest.

scholarly journals Modelling the Spatial Structure of White Spruce Plantations and Their Changes after Various Thinning Treatments

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 740
Author(s):  
Emmanuel Duchateau ◽  
Robert Schneider ◽  
Stéphane Tremblay ◽  
Laurie Dupont-Leduc ◽  
Hans Pretzsch
Keyword(s):  
Spatial Distribution ◽  
Point Process ◽  
Spatial Information ◽  
Abies Balsamea ◽  
Basal Area ◽  
White Spruce ◽  
Process Modelling ◽  
Ecological Processes ◽  
Short Period ◽  
Modelling Approach

Research Highlights: The spatial distribution of trees results from several ecological processes that can be difficult to measure. We applied a point process modelling approach that uses the diameter and species of neighbouring trees to represent inter-tree interactions through repulsive and attractive processes. Thinning treatments slightly influence the tree spatial distribution of trees in white spruce plantations. Integrating this “spatialiser” into growth models could help improve stand simulations following various thinning treatments over larger areas and longer periods. It could also allow for the use of spatially explicit models when tree position is not available. Background and Objectives: Tree spatial patterns result from several ecological processes and have important implications in forest ecology and management. The use of spatial information can significantly improve our understanding of forest structures. However, this implies intensive field work that is rarely integrated into forest inventories. The aims of this study were to develop a spatial distribution simulator of trees in white spruce plantations and to evaluate the influence of thinning treatments. Materials and Methods: A point process modelling approach was used to represent inter-tree interactions through repulsive and attractive process in white spruce (Picea glauca (Moench) Voss) plantations in eastern Quebec, Canada, that had been commercially thinned five years ago. Balsam fir (Abies balsamea (L.) Mill.) and hardwoods together can represent 30–40% of the basal area of these plantations. Results: The diameter and species of each tree’s two closest neighbours were found to be the most important predictors in explaining the observed distances between trees. Despite the short period since thinning treatments, results showed that the treatment had slight significant effects on tree interactions. However, their impact on the global spatial distribution of stands is quite limited. Conclusions: Using only a few readily-available variables (species and diameter of trees), this “spatialiser” will make it possible to assign spatial coordinates to trees and generate realistic stand spatial structures even after various silvicultural treatments.

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