Spatial patterns of two rodent-dispersed rain forest trees Carapa procera (Meliaceae) and Vouacapoua americana (Caesalpiniaceae) at Paracou, French Guiana

1999 ◽  
Vol 15 (3) ◽  
pp. 301-313 ◽  
Author(s):  
Pierre-Michel Forget ◽  
François Mercier ◽  
Frédérique Collinet
Keyword(s):  
Spatial Distribution ◽  
Spatial Patterns ◽  
Rain Forest ◽  
French Guiana ◽  
Soil Drainage ◽  
Complete Spatial Randomness ◽  
Adult Trees ◽  
Level Of Aggregation ◽  
Small Clusters ◽  
Carapa Procera

The spatial distribution of two rain forest tree species, Carapa procera (Meliaceae) and Vouacapoua americana (Caesalpiniaceae) was analysed within and between plots of different sizes (6.25 and 25 ha) at Paracou, French Guiana. The L(d) function was used to characterize spatial patterns, and the Lij(d) intertype to study independancy between young and adult trees. Although both species are known to be dispersed by caviomorph rodents within short distances (c. 10–20 m and up to 50 m) of parent tree crowns, the analysis of tree positions led to different spatial patterns between species depending on soil drainage characteristics. Overall, while V. americana showed a strongly aggregated spatial distribution, C. procera had a weaker propensity to depart from complete spatial randomness (CSR). A complex distribution, sometimes clustered in areas with hydromorphic soils (swamps and around streams) and sometimes very near CSR outside these areas characterized the C. procera population. When C. procera tree aggregation occurred, there was a slight attraction between juveniles and adults. The aggregation of V. americana trees was evidenced at different levels depending on the scale of investigation. Within small plots (6.25 ha), a first level of aggregation with short distance radii of c. 10–25 m giving small clusters, and a second level which is composed of small clusters aggregated at c. 40–50 m distance radius, were observed. A third level of aggregation was suggested by analysing the tree population at the larger scale (25 ha) whose boundaries outside the plot were not delimited. Aggregation of V. americana trees at all levels was enhanced by a strong attraction between juveniles and adults. These results were discussed in light of seed and seedling ecology, especially with regard to seedling and sapling gap-dependence and soil drainage, which likely affected the recruitment of juvenile trees, and henceforth final tree spatial pattern.

scholarly journals Spatial Patterns and Interspecific Associations During Natural Regeneration in Three Types of Secondary Forest in the Central Part of the Greater Khingan Mountains, Heilongjiang Province, China

Forests ◽  
2020 ◽  
Vol 11 (2) ◽  
pp. 152 ◽  
Author(s):  
Lingyu Zhang ◽  
Lingbo Dong ◽  
Qiang Liu ◽  
Zhaogang Liu
Keyword(s):  
Spatial Distribution ◽  
Spatial Patterns ◽  
Tree Species ◽  
Natural Regeneration ◽  
Random Distribution ◽  
Distribution Patterns ◽  
Forest Types ◽  
Development Stages ◽  
Interspecific Associations ◽  
Adult Trees

Seedling and sapling spatial patterns are important in community regeneration, and understanding the natural regeneration mechanisms of tree species in relation to spatial patterns will help improve forest management and community restoration efficiency. Based on data from three fixed plots established in birch forests (BF), coniferous and broadleaved mixed forests (CBMF) and coniferous mixed forests (CMF) in the central Greater Khingan Mountains in Heilongjiang Province, China, in 2017, we used the univariate and bivariate O-ring functions of the point pattern analysis method to evaluate the spatial patterns and associations of the main tree species in these three forest types at different development stages and identified the community successional stages according to the interspecific associations between dominant tree species and other tree species. The results showed that Betula platyphylla and Larix gmelinii in BF exhibited identical spatial distribution patterns and had a tendency to transition from an aggregated to a random distribution from saplings to adult trees, whereas every tree type in CBMF generally showed a random distribution. Adult trees of the main tree species in CMF, i.e., L. gmelinii and Picea koraiensis, mainly showed a random distribution, but P. koraiensis at other size classes generally showed an aggregated distribution. The intraspecific associations of the main tree species in BF and CMF at different development stages were constrained by the spatial scale within a given scope, while those in CBMF at different development stages were not significantly constrained by spatial scale. The results also show that the density of the three forest types was affected by the distance between the individuals of the various tree classes and adult trees, with different levels of influence. We analyzed the interspecific associations between dominant tree species and other tree species and then assessed community succession progress and found that the BF and CMF exhibited medium-term community succession, while the CBMF was in the primary stage. Our results further show that the spatial distribution patterns of the tree species in the small-diameter classes were jointly affected by adjacent habitats and diffusional limitations and that scale dependence existed in the intraspecific and interspecific associations. The analysis of the natural regeneration of spatial distribution and interspecific associations represents an efficient way to explore the stability of forest communities and dynamic changes in interspecific relationships during succession. The study results thus provide a theoretical basis for developing rational forest management measures.

Removal of seeds of Carapa procera (Meliaceae) by rodents and their fate in rainforest in French Guiana

1996 ◽  
Vol 12 (6) ◽  
pp. 751-761 ◽  
Author(s):  
Pierre-Michel Forget
Keyword(s):  
Seed Predation ◽  
Tree Species ◽  
French Guiana ◽  
Removal Rate ◽  
Seed Removal ◽  
Seed Fate ◽  
Wet Season ◽  
Adult Trees ◽  
Carapa Procera ◽  
Monthly Variations

ABSTRACTExperiments were performed to investigate monthly variations in seed fate of Carapa procera (Meliaceae), a rodent-dispersed subcanopy tree species in French Guiana. A total of 600 thread-marked seeds were placed on the ground in mature forest under 20 adult trees during different months (March, April and May 1991) of the species' fruiting season. In 1991 the seed crop reached 1536 seeds in the study area, with a majority of seeds being produced in March and May. On average, seed removal rate steadily increased from March (23%) to May (96%). Of the seeds removed, the proportion eached almost doubled between March (28%)-April (25%) and May (48%), whereas the proportion eaten (gnawed) steadily declined between March (43%) and May (9%). Approximately 75–100% seed removal was therefore associated with intense scatterhoarding and low seed predation, especially in May. Greater seed dispersal rates occurred during the late wet season when fruit diversity decreased but when overall fruit biomass peaked because of fruiting occurrence of large-seeded species. The seasonal hoarding behaviour of rodents is discussed.

Diversity and vertical distribution of epiphytic liverworts in lowland rain forest and lowland cloud forest of French Guiana

2013 ◽  
Vol 35 (4) ◽  
pp. 243-254 ◽  
Author(s):  
Christine Gehrig-Downie ◽  
André Obregon ◽  
Jörg Bendix ◽  
Robbert Gradstein
Keyword(s):  
Vertical Distribution ◽  
Rain Forest ◽  
French Guiana ◽  
Cloud Forest ◽  
Lowland Rain Forest

Ecological and isotopic discrimination of syntopic rodents in a neotropical rain forest of French Guiana

2003 ◽  
Vol 19 (2) ◽  
pp. 209-214 ◽  
Author(s):  
Jean-François Mauffrey ◽  
François Catzeflis
Keyword(s):  
Stable Isotopes ◽  
Isotopic Composition ◽  
Rain Forest ◽  
French Guiana ◽  
Ecological Studies ◽  
Carbon Isotope Ratios ◽  
Photosynthetic Pathways ◽  
Feeding Process ◽  
Neotropical Rain Forest

Stable isotopes are commonly used in ecological studies to infer food resources (Ambrose & DeNiro 1986, Bocherens et al. 1990,1991,1994;Yoshinaga et al. 1991) since isotopic composition is conserved during the feeding process. Moreover,for herbivorous (sensu lato) species, it is often possible to identify the main resource because different photosynthetic pathways generate different values of carbon isotope ratios (Park & Epstein 1961, Sternberg et al. 1984). This allows the characterization of broad biota such as savannas or forest and discrimination of grazers from sympatric folivorous species (DeNiro & Epstein 1978).

Spatial Patterns of Urban Innovation and Their Evolution from Perspectives of Capacity and Structure: Taking Shenzhen as an Example

2021 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Erjie Hu ◽  
Di Hu ◽  
Handong He
Keyword(s):  
Spatial Distribution ◽  
Spatial Pattern ◽  
Distribution Pattern ◽  
Spatial Patterns ◽  
Spillover Effect ◽  
Tertiary Industry ◽  
Innovation Capacity ◽  
Structure Index ◽  
Secondary Industry ◽  
Spatial Spillover Effect

Innovation is a key factor for a country’s overall national strength and core competitiveness. The spatial pattern of innovation reflects the regional differences of innovation development, which can provide guidance for the regional allocation of innovation resources. Most studies on the spatial pattern of innovation are at urban and above spatial scale, but studies at urban internal scale are insufficient. The precision and index of the spatial pattern of innovation in the city needs to be improved. This study proposes to divide spatial units based on geographic coordinates of patents, designs the innovation capability and innovation structure index of a spatial unit and their calculation methods, and then reveals the spatial patterns of innovation and their evolutionary characteristics in Shenzhen during 2000–2018. The results show that: (1) The pattern of innovation capacity of secondary industry exhibited a pronounced spatial spillover effect with a positive spatial correlation. The innovation capacity and innovation structure index of the secondary industry evolved in a similar manner; i.e., they gradually extended from the southwest area to the north over time, forming a tree-like distribution pattern with the central part of the southwest area as the “root” and the northwest and northeast areas as the “canopy”. (2) The pattern of innovation capacity of tertiary industry also had a significant spatial spillover effect with a positive spatial correlation. There were differences between the evolutions of innovation capacity and innovation structure index of tertiary industry. Specifically, its innovation capacity presented a triangular spatial distribution pattern with three groups in the central and eastern parts of the southwest area and the south-eastern part of the northwest area as the vertices, while its innovative structure showed a radial spatial distribution pattern with the southwestern part of the southwest area as the source and a gradually sparse distribution toward the northeast. (3) There were differences between the evolution modes of secondary and tertiary industries. Areas with high innovation capacity in the secondary industry tended to be more balanced, while areas with high innovation capacity in the tertiary industry did not necessarily have a balanced innovation structure. Through the method designed in this paper, the spatial pattern of urban innovation can be more precise and comprehensive revealed, and provide useful references for the development of urban innovation.

scholarly journals Characteristics and factors influencing the natural regeneration of Larix principis-rupprechtii seedlings in northern China

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e12327
Author(s):  
Weiwen Zhao ◽  
Wenjun Liang ◽  
Youzhi Han ◽  
Xi Wei
Keyword(s):  
Spatial Distribution ◽  
Natural Regeneration ◽  
Pair Correlation ◽  
Principal Component ◽  
Northern China ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Adult Trees ◽  
Herb Diversity ◽  
Univariate Distribution

Larix principis-rupprechtii is an important and widely distributed species in the mountains of northern China. However, it has inefficient natural regeneration in many stands and difficulty recruiting seedlings and saplings. In this study, we selected six plots with improved naturally-regenerated L. principis-rupprechtii seedlings. A point pattern analysis (pair-correlation function) was applied to identify the spatial distribution pattern and correlation between adult trees and regenerated seedlings mapped through X/Y coordinates. Several possible influencing factors of L. principis-rupprechtii seedlings’ natural regeneration were also investigated. The results showed that the spatial distribution patterns of Larix principis-rupprechtii seedlings were concentrated 0–5 m around adult trees when considering the main univariate distribution type of regeneration. There was a positive correlation at a scale of 1.5–4 m between seedlings and adult trees according to bivariate analyses. When the scale was increased, these relationships were no longer significant. Generally, adult trees raised regenerated L. principis-rupprechtii seedlings at a scale of 1.5–4 m. Principal component analysis showed that the understory herb diversity and litter layer had a negative correlation with the number of regenerated seedlings. There was also a weak relationship between regenerated numbers and canopy density. This study demonstrated that the main factors promoting natural regeneration were litter thickness, herb diversity, and the distance between adult trees and regenerated seedlings. Additionally, these findings will provide a basis for the late-stage and practical management of natural regeneration in northern China’s mountain ranges.

scholarly journals INVESTIGATION AND EVALUATION OF SPATIAL PATTERNS IN TABRIZ PARKS USING LANDSCAPE METRICS

2017 ◽  
Vol 10 (2) ◽  
pp. 263-269
Author(s):  
Ali Majnouni Toutakhane ◽  
Mojtaba Mofareh
Keyword(s):  
Spatial Distribution ◽  
Spatial Patterns ◽  
Landscape Metrics ◽  
Shape Index ◽  
Quantitative Information ◽  
Green Spaces ◽  
Quantitative Results ◽  
Patch Density ◽  
Distribution Composition ◽  
Nearest Neighborhood

Nowadays, the green spaces in cities and especially metropolises have adopted a variety of functions. In addition to improving the environmental conditions, they are suitable places for spending free times and mitigating nervous pressures of the machinery life based on their distribution and dispersion in the cities. In this research, in order to study the spatial distribution and composition of the parks and green spaces in Tabriz metropolis, the map of Parks prepared using the digital atlas of Tabriz parks and Arc Map and IDRISI softwares. Then, quantitative information of spatial patterns of Tabriz parks provided using Fragstats software and a selection of landscape metrics including: the area of class, patch density, percentage of landscape, average patch size, average patch area, largest patch index, landscape shape index, average Euclidean distance of the nearest neighborhood and average index of patch shape. Then the spatial distribution, composition, extent and continuity of the parks was evaluated. Overall, only 8.5 percent of the landscape is assigned to the parks, and they are studied in three classes of neighborhood, district and regional parks. Neighborhood parks and green spaces have a better spatial distribution pattern compared to the other classes and the studied metrics showed better results for this class. In contrast, the quantitative results of the metrics calculated for regional parks, showed the most unfavorable spatial status for this class of parks among the three classes studied in Tabriz city.

scholarly journals Amplification and Suppression of Distinct Brain-wide Activity Patterns by Catecholamines

2018 ◽  
Author(s):  
RL van den Brink ◽  
S Nieuwenhuis ◽  
TH Donner
Keyword(s):  
Spatial Distribution ◽  
Human Brain ◽  
Spatial Patterns ◽  
Large Scale ◽  
Network Dynamics ◽  
Brain Network ◽  
Heterogeneous Distribution ◽  
Neurotransmitter Systems ◽  
The Brain ◽  
Catecholamine Levels

ABSTRACTThe widely projecting catecholaminergic (norepinephrine and dopamine) neurotransmitter systems profoundly shape the state of neuronal networks in the forebrain. Current models posit that the effects of catecholaminergic modulation on network dynamics are homogenous across the brain. However, the brain is equipped with a variety of catecholamine receptors with distinct functional effects and heterogeneous density across brain regions. Consequently, catecholaminergic effects on brain-wide network dynamics might be more spatially specific than assumed. We tested this idea through the analysis of functional magnetic resonance imaging (fMRI) measurements performed in humans (19 females, 5 males) at ‘rest’ under pharmacological (atomoxetine-induced) elevation of catecholamine levels. We used a linear decomposition technique to identify spatial patterns of correlated fMRI signal fluctuations that were either increased or decreased by atomoxetine. This yielded two distinct spatial patterns, each expressing reliable and specific drug effects. The spatial structure of both fluctuation patterns resembled the spatial distribution of the expression of catecholamine receptor genes: α1 norepinephrine receptors (for the fluctuation pattern: placebo > atomoxetine), ‘D2-like’ dopamine receptors (pattern: atomoxetine > placebo), and β norepinephrine receptors (for both patterns, with correlations of opposite sign). We conclude that catecholaminergic effects on the forebrain are spatially more structured than traditionally assumed and at least in part explained by the heterogeneous distribution of various catecholamine receptors. Our findings link catecholaminergic effects on large-scale brain networks to low-level characteristics of the underlying neurotransmitter systems. They also provide key constraints for the development of realistic models of neuromodulatory effects on large-scale brain network dynamics.SIGNIFICANCE STATEMENTThe catecholamines norepinephrine and dopamine are an important class of modulatory neurotransmitters. Because of the widespread and diffuse release of these neuromodulators, it has commonly been assumed that their effects on neural interactions are homogenous across the brain. Here, we present results from the human brain that challenge this view. We pharmacologically increased catecholamine levels and imaged the effects on the spontaneous covariations between brain-wide fMRI signals at ‘rest’. We identified two distinct spatial patterns of covariations: one that was amplified and another that was suppressed by catecholamines. Each pattern was associated with the heterogeneous spatial distribution of the expression of distinct catecholamine receptor genes. Our results provide novel insights into the catecholaminergic modulation of large-scale human brain dynamics.

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