A spatial statistical analysis of cork oak competition in two Portuguese silvopastoral systems

2002 ◽  
Vol 32 (11) ◽  
pp. 1893-1903 ◽  
Author(s):  
M J Paulo ◽  
A Stein ◽  
M Tomé
Keyword(s):  
Shape Parameter ◽  
Quercus Suber ◽  
Cork Oak ◽  
Point Pattern ◽  
Spatial Point Pattern ◽  
Tree Crown ◽  
Spatial Statistical Analysis ◽  
Crown Shape ◽  
Crown Characteristics ◽  
Pattern Functions

This paper considers competition among cork oaks (Quercus suber L.) at three plots in two representative Portuguese stands. It uses spatial point pattern functions to describe densities and quantify differences among stands. Relations between cork oak characteristics and indices measuring intertree competition are modelled. Tree competition has a significant effect on tree crown characteristics. In particular, cork oaks with much competition have smaller and more elongated crowns. A standard model that relates crown diameter with diameter at breast height was improved. The R2 value increased from 0.53 to 0.63 by including a crown shape parameter and competition indices.

scholarly journals Spatial point-pattern analysis as a powerful tool in identifying pattern-process relationships in plant ecology: an updated review

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Mariem Ben-Said
Keyword(s):  
Spatial Patterns ◽  
Pattern Analysis ◽  
Biotic Interactions ◽  
Plant Ecology ◽  
Point Pattern Analysis ◽  
Point Pattern ◽  
Summary Statistics ◽  
Spatial Point Pattern ◽  
Spatial Point ◽  
Spatial Point Pattern Analysis

Abstract Background Ecological processes such as seedling establishment, biotic interactions, and mortality can leave footprints on species spatial structure that can be detectable through spatial point-pattern analysis (SPPA). Being widely used in plant ecology, SPPA is increasingly carried out to describe biotic interactions and interpret pattern-process relationships. However, some aspects are still subjected to a non-negligible debate such as required sample size (in terms of the number of points and plot area), the link between the low number of points and frequently observed random (or independent) patterns, and relating patterns to processes. In this paper, an overview of SPPA is given based on rich and updated literature providing guidance for ecologists (especially beginners) on summary statistics, uni-/bi-/multivariate analysis, unmarked/marked analysis, types of marks, etc. Some ambiguities in SPPA are also discussed. Results SPPA has a long history in plant ecology and is based on a large set of summary statistics aiming to describe species spatial patterns. Several mechanisms known to be responsible for species spatial patterns are actually investigated in different biomes and for different species. Natural processes, plant environmental conditions, and human intervention are interrelated and are key drivers of plant spatial distribution. In spite of being not recommended, small sample sizes are more common in SPPA. In some areas, periodic forest inventories and permanent plots are scarce although they are key tools for spatial data availability and plant dynamic monitoring. Conclusion The spatial position of plants is an interesting source of information that helps to make hypotheses about processes responsible for plant spatial structures. Despite the continuous progress of SPPA, some ambiguities require further clarifications.

scholarly journals Effect of Water Deficit on Gas Exchange Responses to Intercellular CO2 Concentration Increase of Quercus suber L. Seedlings

2019 ◽  
Vol 12 (1) ◽  
pp. 73
Author(s):  
Mokhtar Baraket ◽  
Sondes Fkiri ◽  
Ibtissam Taghouti ◽  
Salma Sai Kachout ◽  
Amel Ennajah ◽  
...  
Keyword(s):  
Water Deficit ◽  
Intercellular Co2 Concentration ◽  
Co2 Concentration ◽  
Quercus Suber ◽  
Cork Oak ◽  
Concentration Increase ◽  
Effect Of Water ◽  
Negative Effect ◽  
Photosynthetic Responses ◽  
Intercellular Co2

In north Tunisia, the Quercus suber L. forests have shown a great decline indices as well as a non-natural regeneration. The climate changes could accentuate this unappreciated situation. In this study, the effect of water deficit on physiological behavior of Quercus suber seedlings was investigated. Photosynthetic responses of 15 months old Cork oak seedlings grown for 30 days under 40% and 80% soil water water content (control) were evaluated. Results showed a negative effect of water deficit and a positive effect of the intercellular CO2 concentration increase both on photosynthesis and transpiration. Stomata conductance might play a major role in balancing gas exchanges between the leaf and its environment. Moreover, global warming could negatively affect carbon uptake of Cork oak species in northern Tunisia. Elevated CO2 leaf content will benefit Cork oak growing under water deficit by decreasing both photoysnthesis and transpiration, which will decrease either the rate or the severity of water deficits, with limited effects on metabolism. the results suggest that high intercellular CO2 concentration could increase water use efficiency among Cork oak species.

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