An Ecohydrological Framework to Explain Shifts in Vegetation Organization Across Climatological Gradients

Jul 9, 2026

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Spatial patterns in vegetated ecosystems show distinct levels of organization that reflect ecosystem health through variations in stand density. In semiarid regions, vegetation transitions from over-dispersed individuals to under-dispersed, clumped configurations driven by different adaptation and optimization strategies. A theoretical ecohydrological framework characterizes individual dispersion using a generalized Double Poisson distribution and estimates landscape-scale statistics via a soil moisture model that includes canopy shading and overlapping root water partitioning, yielding climatic boundaries for optimal water use and stress.

LanguageEnglish

CategoryResearch & Report

FormatPDF

Pages31

Reading Time1 h 18 min

Introduction

Vegetation spatial patterns and self-organization

Over-dispersion to under-dispersion transitions

Competition and facilitation mechanisms

Drought history and vegetation age

Modeling approaches and framework motivation

An Ecohydrological Framework to Explain Shifts in Vegetation Organization Across Climatological Gradients Salvatore Manfreda 1 , Kelly K. Caylor2 , Stephen P. Good3 October 30, 2016 abstract Spatial patterns found in vegetated ecosystems exhibit di􀀋erent degrees of organization in stand density that can be interpreted as an indicator of ecosystem health. In semiarid environments, it is possible to observe transitions from over-dispersed individuals ([e.g. an](e.g. an) ordered lattice) to under-dispersed individuals (e.g. clumped points). These con􀀌gurations correspond to di􀀋erent strategies of adaptation or optimization, whose understanding may help to predict some of the consequences of environmental changes for both ecosystem services and water resources. For this reason, we have developed a theoretical framework that characterizes the dispersion of individuals through a generalized Double Poisson distribution and estimates the landscape wide statistics using a soil moisture model accounting for tree canopies and root systems overlapping. Considering both the shading e􀀋ect (light interception) of the canopies and the partitioning of water 􀀍uxes due to the presence of multiple individual root systems in one point, the optimum spacing between individuals at a given stand density is determined. This framework allows identifying the climatic boundaries for di􀀋erent landscape patterns in terms of optimal water use and stress. This simple scheme explains well the observed patterns of vegetation in arid and semiarid ecosystems. keywords: spatial patterns | water stress | self-organization | facilitation. Abbreviations: MAP, mean annual precipitation; 􀀊, clumping index, LAI, Leaf Area Index 1 Author a􀀎liations: 1) Department of European and Mediterranean Cultures, Universit􀀓a degli Studi della Basilicata, Matera, Italy. 2) Bren School of Environmental Science and Management & Department of Geography, UC Santa Barbara, California, USA. 3) Oregon State University, Corvallis, OR. This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process which may lead to differences between this version and the Version of Record. Please cite this article as doi: 10. 1002/eco.1793 1 Introduction Worldwide, vegetated ecosystems exhibit a wide range of spatial patterns in􀀍uenced by the scale and the physiological characteristics of vegetation, climate and soil properties (Holdridge, 1947; Whittaker, 1975; Woodward, 1987; Stephenson, 1990; Rodriguez-Iturbe, 2000; Rodriguez-Iturbe and Porporato, 2004; Caylor et al. , 2005; Pumo et al. , 2010) . Atthe local scale, coherent vegetation patterns are observed even when soil and topography are spatially uniform providing an intriguing evidence of self-organization (Lejeune et al. , 1999) . In arid and semi-arid ecosystems, it is possible to observe transitions from over-dispersed individuals (an ordered lattice) to under-dispersed individuals (clumped points) . These di􀀋erent degrees of spatial organization can be interpreted as an indicator of the state of the ecosystem (e.g. , Ke􀀌 et al. , 2007) . These various con􀀌gurations may correspond to alternate strategies of adaptation or optimization, whose understanding may help to predict some of the consequences of environmental change for both ecosystem services and water resources (Shuttleworth and Wallace, 1985; Wallace et al. , 1990; Levin, 1992; Ludwig et al. , 2000), including the susceptibility to abrupt shifts to desert state (van de Koppel et al. , 2002; Scanlon et al. , 2007; Manfreda and Caylor, 2013) . Several authors agree on the fact that the development of self-organized random con􀀌gurations is the result of synergies in the short term and long term competitions in space, which occur between plants and groups of plants (Lefever and Lejeune, 1997; Valentin et al. , 1999; D'Odorico et al. , 2006) . Regular patterns are

FAQs

What does the document use to interpret stand density and ecosystem health?

It interprets the degree of organization in spatial patterns of stand density as an indicator of ecosystem health, linking over- and under-dispersed configurations to ecosystem state and response.

How does the proposed framework estimate vegetation pattern statistics?

It characterizes dispersion using a generalized Double Poisson distribution and estimates landscape-wide statistics with a soil moisture model that accounts for canopy shading and overlapping root systems affecting water partitioning.

Why are different vegetation configurations possible under similar climatic conditions?

The document suggests configuration differences can relate to vegetation age and drought history, since younger plants may be clumped and become more regularly spaced over time.

Jul 9, 2026

Upload by Jiven