Dispersal versus environmental filtering in a dynamic system: Drivers of vegetation patterns and diversity along stream riparian gradients

R.G.A. Fraaije, C.J.F. ter Braak, Betty Verduyn, J.T.A. Verhoeven, M.B. Soons

Research output: Contribution to journalArticleAcademicpeer-review

39 Citations (Scopus)

Abstract

Both environmental filtering and dispersal filtering are known to influence plant species distribution patterns and biodiversity. Particularly in dynamic habitats, however, it remains unclear whether environmental filtering (stimulated by stressful conditions) or dispersal filtering (during recolonization events) dominates in community assembly, or how they interact. Such a fundamental understanding of community assembly is critical to the design of biodiversity conservation and restoration strategies. Stream riparian zones are species-rich dynamic habitats. They are characterized by steep hydrological gradients likely to promote environmental filtering, and by spatiotemporal variation in the arrival of propagules likely to promote dispersal filtering. We quantified the contributions of both filters by monitoring natural seed arrival (dispersal filter) and experimentally assessing germination, seedling survival and growth of 17 riparian plant species (environmental filter) along riparian gradients of three lowland streams that were excavated to bare substrate for restoration. Subsequently, we related spatial patterns in each process to species distribution and diversity patterns after 1 and 2 years of succession. Patterns in initial seed arrival were very clearly reflected in species distribution patterns in the developing vegetation and were more significant than environmental filtering. However, environmental filtering intensified towards the wet end of the riparian gradient, particularly through effects of flooding on survival and growth, which strongly affected community diversity and generated a gradient in the vegetation. Strikingly, patterns in seed arrival foreshadowed the gradient that developed in the vegetation; seeds of species with adult optima at wetter conditions dominated seed arrival at low elevations along the riparian gradient, while seeds of species with drier optima arrived higher up. Despite previous assertions suggesting a dominance of environmental filtering, our results demonstrate that non-random dispersal may be an important driver of early successional riparian vegetation zonation and biodiversity patterns as well. Synthesis. Our results demonstrate (and quantify) the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced. Our results demonstrate and quantify the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced.

LanguageEnglish
Pages1634-1646
JournalJournal of Ecology
Volume103
Issue number6
DOIs
Publication statusPublished - 2015

Fingerprint

vegetation
seeds
biogeography
seed
biodiversity
habitats
plant communities
interspecific interaction
habitat
environmental gradient
filter
wet environmental conditions
plant community
riparian areas
seed dispersal
lowlands
riparian vegetation
riparian zone
recolonization
germination

Keywords

  • Community assembly
  • Determinants of plant community diversity and structure
  • Directed dispersal
  • Hydrological gradients
  • Lowland streams
  • Neutral versus niche
  • Plant diversity
  • Riparian vegetation
  • Riparian zone
  • Wetland restoration

Cite this

@article{91120b1803844bf88a644955a44ee0f1,
title = "Dispersal versus environmental filtering in a dynamic system: Drivers of vegetation patterns and diversity along stream riparian gradients",
abstract = "Both environmental filtering and dispersal filtering are known to influence plant species distribution patterns and biodiversity. Particularly in dynamic habitats, however, it remains unclear whether environmental filtering (stimulated by stressful conditions) or dispersal filtering (during recolonization events) dominates in community assembly, or how they interact. Such a fundamental understanding of community assembly is critical to the design of biodiversity conservation and restoration strategies. Stream riparian zones are species-rich dynamic habitats. They are characterized by steep hydrological gradients likely to promote environmental filtering, and by spatiotemporal variation in the arrival of propagules likely to promote dispersal filtering. We quantified the contributions of both filters by monitoring natural seed arrival (dispersal filter) and experimentally assessing germination, seedling survival and growth of 17 riparian plant species (environmental filter) along riparian gradients of three lowland streams that were excavated to bare substrate for restoration. Subsequently, we related spatial patterns in each process to species distribution and diversity patterns after 1 and 2 years of succession. Patterns in initial seed arrival were very clearly reflected in species distribution patterns in the developing vegetation and were more significant than environmental filtering. However, environmental filtering intensified towards the wet end of the riparian gradient, particularly through effects of flooding on survival and growth, which strongly affected community diversity and generated a gradient in the vegetation. Strikingly, patterns in seed arrival foreshadowed the gradient that developed in the vegetation; seeds of species with adult optima at wetter conditions dominated seed arrival at low elevations along the riparian gradient, while seeds of species with drier optima arrived higher up. Despite previous assertions suggesting a dominance of environmental filtering, our results demonstrate that non-random dispersal may be an important driver of early successional riparian vegetation zonation and biodiversity patterns as well. Synthesis. Our results demonstrate (and quantify) the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced. Our results demonstrate and quantify the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced.",
keywords = "Community assembly, Determinants of plant community diversity and structure, Directed dispersal, Hydrological gradients, Lowland streams, Neutral versus niche, Plant diversity, Riparian vegetation, Riparian zone, Wetland restoration",
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year = "2015",
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language = "English",
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Dispersal versus environmental filtering in a dynamic system : Drivers of vegetation patterns and diversity along stream riparian gradients. / Fraaije, R.G.A.; ter Braak, C.J.F.; Verduyn, Betty; Verhoeven, J.T.A.; Soons, M.B.

In: Journal of Ecology, Vol. 103, No. 6, 2015, p. 1634-1646.

Research output: Contribution to journalArticleAcademicpeer-review

TY - JOUR

T1 - Dispersal versus environmental filtering in a dynamic system

T2 - Journal of Ecology

AU - Fraaije, R.G.A.

AU - ter Braak, C.J.F.

AU - Verduyn, Betty

AU - Verhoeven, J.T.A.

AU - Soons, M.B.

PY - 2015

Y1 - 2015

N2 - Both environmental filtering and dispersal filtering are known to influence plant species distribution patterns and biodiversity. Particularly in dynamic habitats, however, it remains unclear whether environmental filtering (stimulated by stressful conditions) or dispersal filtering (during recolonization events) dominates in community assembly, or how they interact. Such a fundamental understanding of community assembly is critical to the design of biodiversity conservation and restoration strategies. Stream riparian zones are species-rich dynamic habitats. They are characterized by steep hydrological gradients likely to promote environmental filtering, and by spatiotemporal variation in the arrival of propagules likely to promote dispersal filtering. We quantified the contributions of both filters by monitoring natural seed arrival (dispersal filter) and experimentally assessing germination, seedling survival and growth of 17 riparian plant species (environmental filter) along riparian gradients of three lowland streams that were excavated to bare substrate for restoration. Subsequently, we related spatial patterns in each process to species distribution and diversity patterns after 1 and 2 years of succession. Patterns in initial seed arrival were very clearly reflected in species distribution patterns in the developing vegetation and were more significant than environmental filtering. However, environmental filtering intensified towards the wet end of the riparian gradient, particularly through effects of flooding on survival and growth, which strongly affected community diversity and generated a gradient in the vegetation. Strikingly, patterns in seed arrival foreshadowed the gradient that developed in the vegetation; seeds of species with adult optima at wetter conditions dominated seed arrival at low elevations along the riparian gradient, while seeds of species with drier optima arrived higher up. Despite previous assertions suggesting a dominance of environmental filtering, our results demonstrate that non-random dispersal may be an important driver of early successional riparian vegetation zonation and biodiversity patterns as well. Synthesis. Our results demonstrate (and quantify) the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced. Our results demonstrate and quantify the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced.

AB - Both environmental filtering and dispersal filtering are known to influence plant species distribution patterns and biodiversity. Particularly in dynamic habitats, however, it remains unclear whether environmental filtering (stimulated by stressful conditions) or dispersal filtering (during recolonization events) dominates in community assembly, or how they interact. Such a fundamental understanding of community assembly is critical to the design of biodiversity conservation and restoration strategies. Stream riparian zones are species-rich dynamic habitats. They are characterized by steep hydrological gradients likely to promote environmental filtering, and by spatiotemporal variation in the arrival of propagules likely to promote dispersal filtering. We quantified the contributions of both filters by monitoring natural seed arrival (dispersal filter) and experimentally assessing germination, seedling survival and growth of 17 riparian plant species (environmental filter) along riparian gradients of three lowland streams that were excavated to bare substrate for restoration. Subsequently, we related spatial patterns in each process to species distribution and diversity patterns after 1 and 2 years of succession. Patterns in initial seed arrival were very clearly reflected in species distribution patterns in the developing vegetation and were more significant than environmental filtering. However, environmental filtering intensified towards the wet end of the riparian gradient, particularly through effects of flooding on survival and growth, which strongly affected community diversity and generated a gradient in the vegetation. Strikingly, patterns in seed arrival foreshadowed the gradient that developed in the vegetation; seeds of species with adult optima at wetter conditions dominated seed arrival at low elevations along the riparian gradient, while seeds of species with drier optima arrived higher up. Despite previous assertions suggesting a dominance of environmental filtering, our results demonstrate that non-random dispersal may be an important driver of early successional riparian vegetation zonation and biodiversity patterns as well. Synthesis. Our results demonstrate (and quantify) the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced. Our results demonstrate and quantify the strong roles of both environmental and dispersal filtering in determining plant community assemblies in early successional dynamic habitats. Furthermore, we demonstrate that dispersal filtering can already initiate vegetation gradients, a mechanism that may have been overlooked along many environmental gradients where interspecific interactions are (temporarily) reduced.

KW - Community assembly

KW - Determinants of plant community diversity and structure

KW - Directed dispersal

KW - Hydrological gradients

KW - Lowland streams

KW - Neutral versus niche

KW - Plant diversity

KW - Riparian vegetation

KW - Riparian zone

KW - Wetland restoration

U2 - 10.1111/1365-2745.12460

DO - 10.1111/1365-2745.12460

M3 - Article

VL - 103

SP - 1634

EP - 1646

JO - Journal of Ecology

JF - Journal of Ecology

SN - 0022-0477

IS - 6

ER -