Tree spatial patterns in three contrasting plots of a southern Indian tropical moist evergreen forest

1998 ◽  
Vol 14 (1) ◽  
pp. 1-16 ◽  
Author(s):  
RAPHAËL PÉLISSIER
Keyword(s):  
Spatial Patterns ◽  
Spatial Interaction ◽  
Pair Correlation ◽  
Process Models ◽  
Stochastic Simulations ◽  
Evergreen Forest ◽  
Dynamic Processes ◽  
Endogenous Factors ◽  
Spatial Interaction Models ◽  
Correlation Statistics

In a primary dense moist evergreen forest of southern India, spatial patterns of trees ≥30 cm gbh were investigated from three contrasting 0.4-ha plots that differed in topography and amount of disturbance due to treefall. Exploratory data analysis is based on second-order neighbourhood and pair-correlation statistics used to describe the degree of clustering/regularity in patterns of all trees, and the degree of attraction/repulsion between young trees and adults. Stochastic simulations from the Markov point process models are then used to fit spatial interaction models. The results show that spatial patterns can be related to particular dynamic processes which depend on both exogenous and endogenous factors: on steep slopes disturbed by many treefalls, spatial pattern displays large clusters which can be interpreted as within-gap regeneration stages of various ages, while in areas undisturbed over a long period, interactions between young trees and adults give rise to spatial patterns consistent with substitution dynamic processes implying standing mortality rather than treefalls. Characterizing forest dynamics through spatial patterns of trees opens up the possibility of mapping structural units that might be considered as elementary functional patches of the forest mosaic.

Spatial Flows and Spatial Patterns

1984 ◽  
Vol 16 (4) ◽  
pp. 529-543 ◽  
Author(s):  
A S Fotheringham
Keyword(s):  
Spatial Structure ◽  
Spatial Patterns ◽  
Spatial Interaction ◽  
A Priori ◽  
Parameter Estimates ◽  
Spatial Interaction Models ◽  
Significant Bias ◽  
Spatial System ◽  
Decay Parameters ◽  
Spatial Flows

The misspecification of gravity spatial interaction models has recently been described by the author. The bias in parameter estimates that results from such misspecification appears to produce the ‘map pattern effect’ or ‘spatial structure bias’ in estimated distance-decay parameters. A further aspect of the misspecification bias in gravity parameter estimates is explored here. The severity of the bias is shown to vary in a predictable manner with variations in spatial structure. In particular, the bias is shown to be dependent upon the pattern of accessibility that exists within a spatial system. The relevant aspects of this pattern are discussed for intraurban and interurban (or interregional) flow matrices. It is shown that from an examination of the spatial structure of centres in a spatial system it is possible, a priori, to identify whether significant bias will arise in the calibration of a gravity model. Certain configurations of centres are shown theoretically to produce maximal bias. The author thus answers the question, “why do gravity parameter estimates appear to be biased in some systems but not in others?”

On the Relationship between Alonso's Theory of Movement and Wilson's Family of Spatial-Interaction Models

1981 ◽  
Vol 13 (2) ◽  
pp. 217-224 ◽  
Author(s):  
J Ledent
Keyword(s):  
Input Data ◽  
Spatial Interaction ◽  
System Of Equations ◽  
Interaction Models ◽  
Spatial Interaction Models ◽  
Standard Family ◽  
Original Contribution ◽  
Standard Models ◽  
The Relationship

This paper compares the system of equations underlying Alonso's theory of movement with that of Wilson's standard family of spatial-interaction models. It is shown that the Alonso model is equivalent to one of Wilson's four standard models depending on the assumption at the outset about which of the total outflows and/or inflows are known. This result turns out to supersede earlier findings—inconsistent only in appearance—which were derived independently by Wilson and Ledent. In addition to this, an original contribution of this paper—obtained as a byproduct of the process leading to the aforementioned result—is to provide an exact methodology permitting one to solve the Alonso model for each possible choice of the input data.

Effects of scale in spatial interaction models

2013 ◽  
Vol 15 (3) ◽  
pp. 249-264 ◽  
Author(s):  
Giuseppe Arbia ◽  
Francesca Petrarca
Keyword(s):  
Spatial Interaction ◽  
Interaction Models ◽  
Spatial Interaction Models

scholarly journals Effect of Disturbance Regimes on Spatial Patterns of Tree Species in Three Sites in a Tropical Evergreen Forest in Vietnam

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Do Thi Ngoc Le ◽  
Nguyen Van Thinh ◽  
Nguyen The Dung ◽  
Ralph Mitlöhner
Keyword(s):  
Spatial Patterns ◽  
Tree Species ◽  
Interspecific Interactions ◽  
Abundant Species ◽  
Evergreen Forest ◽  
Small Scale ◽  
Forest Types ◽  
Disturbance Regimes ◽  
Tropical Evergreen Forest ◽  
Disturbed Forest

The effects of disturbance regimes on the spatial patterns of the five most abundant species were investigated in three sites in a tropical forest at Xuan Nha Nature Reserve, Vietnam. Three permanent one-ha plots were established in undisturbed forest (UDF), lightly disturbed forest (LDF), and highly disturbed forest (HDF). All trees ≥5 cm DBH were measured in twenty-five 20 m × 20 m subplots. A total of 57 tree species belonging to 26 families were identified in the three forest types. The UDF had the highest basal area (30 m2 ha−1), followed by the LDF (17 m2 ha−1) and the HDF (13.0 m2 ha−1). The UDF also had the highest tree density (751 individuals ha−1) while the HDF held the lowest (478 individuals ha−1). Across all species, there were 417 “juveniles,” 267 “subadults,” and 67 “adults” in the UDF, while 274 “juveniles,” 230 “subadults,” and 36 “adults” were recorded in the LDF. 238 “juveniles,” 227 “subadults,” and 13 “adults” were obtained in the HDF. The univariate and bivariate data with pair- and mark-correlation functions of intra- and interspecific interactions of the five most abundant species changed in the three forest types. Most species indicated clumping or regular distributions at small scale, but a high ratio of negative interspecific small-scale associations was recorded in both the LDF and HDF sites. These were, however, rare in the UDF.

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