Changes in abundance and spatial distribution of geese molting near Teshekpuk Lake, Alaska: interspecific competition or ecological change?

Polar Biology ◽  
2007 ◽  
Vol 31 (5) ◽  
pp. 549-556 ◽  
Author(s):  
Paul L. Flint ◽  
Edward J. Mallek ◽  
Rodney J. King ◽  
Joel A. Schmutz ◽  
Karen S. Bollinger ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Interspecific Competition ◽  
Ecological Change ◽  
Teshekpuk Lake

scholarly journals The Effects of Water Levels and Interspecific Competition on Two Carex Species in a Temperate Wetland of Northeast China

2020 ◽  
Vol 12 (24) ◽  
pp. 10654
Author(s):  
Wenwen Tan ◽  
Li Sun ◽  
Xinhou Zhang ◽  
Changchun Song
Keyword(s):  
Spatial Distribution ◽  
Water Level ◽  
Interspecific Competition ◽  
Distribution Patterns ◽  
Wetland Plants ◽  
Water Levels ◽  
Carex Lasiocarpa ◽  
Temperate Wetland ◽  
The Relationship ◽  
Spatial Distribution Characteristic

Zonation along a water level is the main spatial distribution characteristic of wetland plants. This is mainly because of the influences of hydrological conditions and interspecific competition, which finally narrow the fundamental niche of a species to its realized niche. In the present study, a controlled experiment was conducted in order to analyze the relationship between Carex lasiocarpa/Carex pseudocuraica and Glyceria spiculosa, in conditions of three competitive treatments at four water levels. The results showed that in no competition, C. lasiocarpa preferred low water levels, but this preference receded when competing with G. spiculosa. In contrast, C. pseudocuraica had greater preference for low water level when competing with G. spiculosa. The root/shoot ratios of the two Carex species decreased with increasing water levels, but they were almost unaffected by different competition treatments. With the increase in water level during full competition with G. spiculosa, the competitive ability of C. lasiocarpa showed an increasing trend, whereas a contrary trend was observed in C. pseudocuraica. Our results suggested the effects of water levels and their interactions with interspecific competition varied between the two Carex species and played an important role in determining spatial distribution patterns and potential community succession of wetland plants.

The effects of restoration on vegetation trends: spatiotemporal variability and influencing factors

2018 ◽  
Vol 109 (3-4) ◽  
pp. 473-481 ◽  
Author(s):  
Kun ZHANG ◽  
Yihe LÜ ◽  
Bojie FU ◽  
Ting LI
Keyword(s):  
Spatial Distribution ◽  
Loess Plateau ◽  
Vegetation Cover ◽  
Large Scale ◽  
Vegetation Change ◽  
Linear Process ◽  
Spatiotemporal Variability ◽  
Ecological Change ◽  
The Loess Plateau ◽  
Aid Decision

ABSTRACTSince the ‘Grain to Green Program' was launched in 1999 in the Loess Plateau, China, the processes and patterns of ecological change have become important. Through the use of the fractional vegetation cover (FVC) index, this study examines the spatial distribution and temporal change of vegetation cover in the Loess Plateau during 2000–2014. Over this period more than 60% of the Loess Plateau has remained with little vegetation cover (FVC <30%). The spatial distribution pattern shows an overall increase from the NW to SE. Temporally, the vegetation cover exhibits a general trend of improvement. In 2000–2005, 2000–2010 and 2000–2014, the percentages of restored vegetation (vegetation with significantly increased FVC, P<0.05) were 2, 21 and 52%, respectively. The rate of vegetation cover restoration was highly variable among different bioclimatic zones. The expansion of restored vegetation was greater in the N of the Loess Plateau than in the south. Both human restoration activities and climatic fluctuation influenced the vegetation cover change. The ‘Grain to Green Program' emphasised vegetation restoration. Regional precipitation also had clear effects on vegetation cover. The results of this study reveal that vegetation change shows a non-linear process in response to climate and ecological restoration measures, and that the change gradually emerges over time. This study highlights the importance of considering the spatiotemporal variability in vegetation cover during the implementation of restoration programs, which could aid decision-making for the effective and sustainable management of large-scale restoration programs.

scholarly journals Effects of grazing disturbance of spatial distribution pattern and interspecies relationship of two desert shrubs

2021 ◽  
Author(s):  
Lei Zhang ◽  
Yong Gao ◽  
Jinrong Li ◽  
Chao Zhang ◽  
Minyu Li ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Interspecific Competition ◽  
Positive Relationship ◽  
Random Distribution ◽  
Negative Relationship ◽  
Small Scale ◽  
Desert Shrubs ◽  
Interspecific Relationships ◽  
Grazing Area ◽  
Grazing Disturbance

AbstractGrazing significantly affects the distribution, growth, and productivity of shrubs. In this study, we evaluated the effects of grazing disturbance on the spatial distribution patterns and interspecific relationships of two desert shrubs, Ammopiptanthus mongolicus and Sarcozygium xanthoxylon. Three types of grazing conditions were considered, including enclosed area (EA), seasonal rotational grazing area (SRGA), and grazing area (GA) (100 m × 100 m), in the West Ordos Nature Reserve of Inner Mongolia, China. The results showed that A. mongolicus and S. xanthoxylon populations were uniformly distributed at a small scale, and the distribution in EA and SRGA became gradually random. In GA, A. mongolicus population showed aggregated distribution but S. xanthoxylon population showed random distribution at a small scale. Moreover, both A. mongolicus and S. xanthoxylon populations at the 5–7 m scale showed random distribution. At the small and intermediate scales, the two species showed positive interspecific relationships of GA. However, no interspecific relationship was noted between the two species in EA and SRGA. A significant positive relationship (P < 0.01) was noted between the two species at 2–9 m and a negative relationship (P < 0.01) at 13–17 m scales in GA. Positive relationship (P < 0.01) was noted between the two species at 6–13 m scales and a significant negative relationship (P < 0.01) at 14–24 m scales in SRGA. The two species of desert shrubs showed positive interspecific relationships at the small scale, and they showed negative relationships as the interspecific competition intensified in the presence of grazing disturbance. When the grazing intensity exceeds a certain threshold, the interspecific relationships become weak. Therefore, moderate grazing would facilitate interspecific competition and species succession, whereas excessive grazing would disrupt natural competition causing desertification ultimately.

scholarly journals Spatial structure of Globularia bisnagarica L. (Plantaginaceae, Magnoliopsida) coenopopulations

2021 ◽  
pp. 35-46
Author(s):  
A. O. Kondratieva ◽  
A. S. Parkhomenko ◽  
A. V. Bogoslov ◽  
I. V. Shilova ◽  
A. S. Kashin
Keyword(s):  
Spatial Distribution ◽  
Spatial Structure ◽  
Interspecific Competition ◽  
Environmental Conditions ◽  
Bromus Inermis ◽  
Statistical Computing ◽  
Distribution Analysis ◽  
Elytrigia Repens ◽  
The Republic ◽  
Aggregation Tendency

The paper presents the results of the spatial distribution analysis of 18 Globularia bisnagarica L. coenopopulations in the Saratov, Samara, Ulyanovsk and Orenburg regions and the Republic of Tatarstan. The analysis was carried out with the Spatstat package of the R environment for statistical computing. The research reveals an aggregation tendency for the G. bisnagarica coenopopulations. It is suggested that this tendency may be attributed to the prevalence of seed reproduction and certain peculiarities of dissemination (barochory) in the studied coenopopulations as well as to the confinement of the species to eroded landforms (slopes of watersheds, gullies, runoff hollows, etc.) characterized by high heterogeneity of environmental conditions. It has been established that the majority of G. bisnagarica coenopopulations grow in heavily or moderately sodded habitats. Nevertheless, in the studied communities, G. bisnagarica occurs abundantly and dominates along with Stipa pennata, Bromus inermis, Salvia nutans, Elytrigia repens, Poa compressa, etc. Finally, the spatial structure of G. bisnagarica coenopopulations is impacted by the interspecific competition in calciphilous phytocenoses under the invasion of eurybiontic steppe grasses.

Nitrogen deposition changes the distribution of key plant species in the meadow steppe in Hulunbeier, China

2018 ◽  
Vol 40 (2) ◽  
pp. 129 ◽  
Author(s):  
Wang Xuan ◽  
Wang Xin Ting ◽  
Liang Cun Zhu ◽  
Niu Yong Mei
Keyword(s):  
Spatial Distribution ◽  
Plant Species ◽  
Niche Overlap ◽  
N Deposition ◽  
Nutrient Addition ◽  
Leymus Chinensis ◽  
Point Pattern ◽  
Ecological Change ◽  
Meadow Steppe ◽  
The Impact

Improved understanding of how nutrient levels affect the distribution of plants can provide important insights into the potential impacts of increasing global nitrogen (N) deposition. We used point pattern analyses to examine the impact of nutrient addition on heterogeneity in the spatial distribution of the three main plant species of the meadow steppe community of Hulunbeier, Inner Mongolia: Leymus chinensis (Trin.) Tzvel (aka Aneurotepidimu chinense), a rhizamotous grass; Stipa baicalensis Rasher, a bunch grass; and Artemisia tanacetifolia Linn, a rhizamotous forb. The six treatments tested added nitrogen N in three different concentrations, N with phosphorus (P), P alone and a Control. Although the three plant species were randomly distributed at the start of the experiment in 2011, the spatial distribution of some species in some treatments had changed at the end of 3 years of nutrient addition. There was a significant increase in aggregation of L. chinensis at fine scales of analysis from application of N and P in tandem. However, S. baicalensis and A. tanacetifolia distributions remained random under all treatments. Positive associations of L. chinensis with S. baicalensis and with A. tanacetifolia were apparent at the lowest concentration of added N, 2.5 g N m–2 year–1, which represented an approximate doubling of global N deposition. These associations, which represent clustering among individuals of these species were also apparent where only P was applied. Negative associations, representing dispersion, were prevalent with higher N concentrations. The results indicate that increases in global N deposition up to about double current levels may have a positive influence on meadow steppe communities by increasing the niche overlap of different species. However, increases beyond that level may trigger substantial ecological change through increased competition for other, more limited, environmental resources, and disassociation between plants of the different dominant species. Our findings suggest that studies of the spatial patterning of plant communities can contribute to understanding the potential impacts of climate change.

scholarly journals Influence of the spatial distribution of components on the productivity of sainfoin-cereal grass mixtures under different sowing methods in the conditions of the right-bank Forest-Steppe

2019 ◽  
pp. 79-84 ◽  
Author(s):  
K. P. Kovtun ◽  
Y. A. Veklenko ◽  
V. A. Yashchuk ◽  
L. I. Bezvuhliak
Keyword(s):  
Spatial Distribution ◽  
Interspecific Competition ◽  
Dry Matter ◽  
System Analysis ◽  
Phleum Pratense ◽  
Metabolic Energy ◽  
Forest Steppe ◽  
Environmental Resources ◽  
Cereal Species ◽  
The Right

Purpose. To investigate optimization of the spatial distribution of the component in binary legume-cereal grass mixtures by selecting a complementary composition of the phytocenosis, method of planting perennial grasses to create hay grass stands with Onobrychis arenaria in the right-bank Forest-Steppe. Adequate selection of legume and cereal species in a double-component sowing significantly reduces negative interactions at different stages of ontogenesis, reduces interspecific competition for environmental resources, balances the structure of phytocenosis, increases its productivity and prolongs the productive longevity of sown hayfields. Methods. System analysis, field, seeded haymaking, laboratory, comparative. Results. In the field experiment of the Department of Field Fodder Crops, Hayfields and Pastures, the influence of the spatial distribution of Onobrychis arenaria under various methods of sowing with Bromus inermis, Bromus riparius, Festuca arundinacea and Phleum pratense on the yield of dry matter, feed units, metabolic energy, and supply of fodder protein with digestible grass protein of the grass mass (phytomass) of double-component sainfoin-cereal grass mixtures of hay use is studied. It is established that, compared with the conventional mixed method of sowing sainfoin with different types of cereal components, on average for three years of using grass stands, the highest yield of dry matter, feed units, and metabolic energy was obtained under cross and cross-row sowing methods. Conclusions. The influence of the spatial distribution of Onobrychis arenaria and cereal grasses on the formation of grass stands and the productivity of grass mass is substantiated. The prospects of cross and cross-row methods of sowing binary sainfoin-cereal grass mixtures are outlined. This placement of legume and cereal components contributed to a decrease in interspecific competition for environmental resources, balancing the structure of the phytocenosis, increasing its productivity and the quality of grass mass and prolonging the productive longevity of the seeded hayfield in conditions of the right-bank Forest-Steppe.

Lithography below 100 nm

1983 ◽  
Vol 41 ◽  
pp. 96-99
Author(s):  
L. D. Jackel
Keyword(s):  
Spatial Distribution ◽  
Electron Beam ◽  
Electron Scattering ◽  
Electron Beam Lithography ◽  
Substrate Material ◽  
Local Electron ◽  
Electron Dose ◽  
Positive Resist ◽  
Exposure Process

Most production electron beam lithography systems can pattern minimum features a few tenths of a micron across. Linewidth in these systems is usually limited by the quality of the exposing beam and by electron scattering in the resist and substrate. By using a smaller spot along with exposure techniques that minimize scattering and its effects, laboratory e-beam lithography systems can now make features hundredths of a micron wide on standard substrate material. This talk will outline sane of these high- resolution e-beam lithography techniques.We first consider parameters of the exposure process that limit resolution in organic resists. For concreteness suppose that we have a “positive” resist in which exposing electrons break bonds in the resist molecules thus increasing the exposed resist's solubility in a developer. Ihe attainable resolution is obviously limited by the overall width of the exposing beam, but the spatial distribution of the beam intensity, the beam “profile” , also contributes to the resolution. Depending on the local electron dose, more or less resist bonds are broken resulting in slower or faster dissolution in the developer.

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