Ecology of Riparian Forests in Japan: Disturbance, Life History, and Regeneration

335 Pages·2008·6.767 MB·English

by  Hitoshi Sakio (auth.), Hitoshi Sakio Ph.D., Toshikazu Tamura Ph.D. (eds.)

H. Sakio, T. Tamura (Eds.)
Ecology of Riparian Forests in Japan
Disturbance, Life History, and Regeneration
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H. Sakio, T. Tamura (Eds.)

Ecology of Riparian Forests
in Japan

Disturbance, Life History, and Regeneration

(cid:27)(cid:25)(cid:26)(cid:15)(cid:22)(cid:15)(cid:22)(cid:21)(cid:19)(cid:15)(cid:25)(cid:24)(cid:25)(cid:21)(cid:24)(cid:15)(cid:25)(cid:65)(cid:86)(cid:71)(cid:90)(cid:86)(cid:14804)(cid:2107)(cid:2150)(cid:2127)(cid:2021)(cid:2002)(cid:14805)(cid:16)(cid:82)(cid:70)(cid:21)(cid:2)(cid:2)(cid:2)(cid:21) (cid:20)(cid:18)(cid:18)(cid:26)(cid:17)(cid:18)(cid:27)(cid:17)(cid:19)(cid:19)(cid:2)(cid:2)(cid:2)(cid:19)(cid:26)(cid:28)(cid:19)(cid:23)(cid:28)(cid:21)(cid:18)
Hitoshi Sakio, Ph.D.
Professor, Sado Station
Field Center for Sustainable Agriculture and Forestry, Faculty of Agriculture
Niigata University
94-2 Koda, Sado, Niigata 952-2206, Japan

Toshikazu Tamura, Ph.D.
Professor, Department of Environment Systems, Faculty of Geo-environmental Science
Rissho University
1700 Magechi, Kumagaya, Saitama 360-0194, Japan

ISBN 978-4-431-76736-7 Springer Tokyo Berlin Heidelberg New York
eISBN 978-4-431-76737-4

Library of Congress Control Number: 2008924622

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© Springer 2008
Printed in Japan
Typesetting: Camera-ready by the editors and authors
Printing and binding: Kato Bunmeisha, Japan
Printed on acid-free paper
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Foreword
The riparian forests in the Asia Monsoon Belt of Japan are subject to a variety of
geomorphic and fluvial disturbances that can vary longitudinally at the catchment
scale. This is due to a combination of seasonal and extreme floods caused by
snowmelt and heavy rainfalls initiated by monsoons and typhoons, as well as the
high gradient topography and extensive area of tectonic activity. The Japanese
riparian forest (JRF) research group, represented by Dr. Hitoshi Sakio, the editor of
this book, has examined various mechanisms for maintaining plant species diversity
in riparian zones, and contributed to the development of community and ecosystem
ecology.
Many riparian studies conducted in the United States, Canada, and European
countries have focused mainly on seasonal or relatively frequent flood disturbances
in large rivers, and on the responses of one group of species, the Salicaceae. In
contrast, the scope of riparian studies promoted by the JRF research group ranges
from headwaters to low-gradient alluvial rivers, and the group has clarified a
number of specific or facultative strategies, in various tree species, for coping with
the temporal and spatial reliability of safe sites. The group has focused not only on
niche partitioning along environmental gradients but also on niche partitioning in
life history stages, from reproduction and dispersal to seedling establishment, and
the further development of immature trees.
The Japanese River Law, which was revised in 1997, included “conservation and
improvement of river environments” as one of the purposes of river management,
and clearly stated that riparian areas should be protected. However, reservoirs and
erosion control dams built in headwater streams are thought to have had a
considerable effect on the structure, species diversity, and regeneration mechanisms
of riparian forests by regulating river flows and trapping sediment. Furthermore,
most alluvial rivers in Japan have been channelized for land development purposes
or through the construction of maintenance facilities. Natural riparian forests are
disappearing in all parts of the country at an alarming rate.
With regard to preserving riparian ecosystems that still remain in world streams
and rivers, and restoring riparian forests for the future, I believe that the papers
included in this book offer invaluable knowledge and open up important
perspectives for the future.
Futoshi NAKAMURA
Laboratory of Forest Ecosystem Management
Hokkaido University
V
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Preface
In this book we examine the dynamics, coexistence mechanisms, and species
diversity of riparian tree species, focusing on natural disturbances, life-history
strategies and the ecophysiology of trees. We reveal that natural disturbances,
including flooding, are important to regeneration and coexistence for riparian
forests with niche partitioning. This book offers useful information relating to a
number of urgent problems such as the conservation of endangered species and the
restoration or rehabilitation of riparian ecosystems.
Riparian forests are highly important because of their range of ecological
functions and services. They impede increases in water temperature, supply
abundant litter and coarse woody debris, and absorb nutrients such as nitrogen.
These effects extend to fishes and aquatic insects in well developed environments.
Riparian forests are diverse with respect to species, structure, and regeneration
processes, and are the most valuable part of many ecosystems. However, most
riparian landscapes in Japan were degraded during the 20th century, especially after
the Second World War, due to industrial development, agricultural land use and
inappropriate concrete construction for river management.
In this collection, more than 20 serious researchers undertook a range of diverse
studies from the fields of geography, ecology, and physiology in the context of the
remaining Japanese riparian forests. In this book, we discuss riparian forests from
the subpolar to warm-temperate zones, and cover headwater streams, braided rivers
on alluvial fans, and low-gradient meandering rivers. Topics covered include
current problems, such as the coexistence mechanisms of trees, tree demography,
tree responses to water stress and the conservation of endangered species.
Some parts of the compilation of these studies were carried out in Project 2 of the
Open Research Center Program of the Graduate School of Geo-environmental
Science, Rissho University, with financial assistance from the Ministry of
Education, Culture, Sports, Science and Technology. The production of this book
was supported, in part, from grants from the Ishibashi Tanzan Memorial Foundation
of Rissho University and the 8th Minamata Prize for the Environment.
We are deeply grateful to Dr. Yasuyuki Oshima for his encouragement, and for
numerous constructive comments on this book. In particular, he went to the many
research sites covered in this book, and spoke with authors about riparian research
at a workshop on riparian forests that he had organized. Sadly, he died on January
2006. We dedicate this book to Dr. Yasuyuki Oshima. Thanks are also due to the
staff of Springer for publication and to Dr. Motohiro Kawanishi, who assisted with
editing.
Hitoshi SAKIO
Toshikazu TAMURA
VII
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Contents
Foreword .................................................................................................. V
Preface ..................................................................................................... VII
Part 1: Introduction
1 Features of riparianforests in Japan
H. SAKIO .................................................................................... 3
1.1 Diverse riparian forests in Japan.................................................. 3
1.2 Climate, geography, and disturbance regimes............................. 8
1.3 Dynamics and coexistence of riparian forests.............................. 9
1.4 Research on riparian forestsin Japan........................................... 10
References ............................................................................................... 10
Part 2: Geography, disturbance regime and dynamics of
sediments in riparian zone
2 Occurrence of hillslope processes affecting
riparian vegetation in upstream watersheds of
Japan
T. TAMURA ................................................................................ 15
2.1 Introduction .................................................................................. 15
2.2 Segmentation of a valley-side slope............................................. 16
2.3 Groundsurface instability on lower sideslope.............................. 17
2.4 Function of a valley-head area in a watershed environment........ 22
2.5 Significance of deep-seated landslides and large-scale landslides
in an upstream watershed environment ........................................ 24
2.6 Effects of hillslope processes on riparian vegetation................... 25
2.7 Concluding remarks ..................................................................... 27
References ............................................................................................... 28
IX
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X Contents
3 Sediment dynamics and characteristics with
respect to river disturbance
S. YANAI .................................................................................... 31
3.1 Introduction: river and riparian geomorphology in Japan............ 31
3.2 Fluvial geomorphology: landformsand processes....................... 32
3.3 Natural disturbances ..................................................................... 35
3.4 Conclusions .................................................................................. 42
References ............................................................................................... 43
Part 3: Riparian community
4 Vegetation-geographic evaluation of the
syntaxonomic system of valley-bottom forests
occurring in the cool-temperate zone of the
Japanese Archipelago
K. OHNO ..................................................................................... 49
4.1 Introduction .................................................................................. 49
4.2 Methods ........................................................................................ 50
4.3 General views of valley-bottom forests in Japan......................... 51
4.4 Syntaxonomy and vegetation-geographic evaluation of the
valley-bottom forests .................................................................... 53
4.5 Relationship between the valley-bottom Pterocarya forests and
other azonal vegetation ................................................................. 65
4.6 Vegetation-geographic evaluations of the valley-bottom forests
in Japan ......................................................................................... 68
References ............................................................................................... 69
Part 4: Riparian forests in headwater stream
5 Coexistence mechanisms of three riparian species
in the upper basin with respect to their life
histories, ecophysiology, and disturbance regimes
H. SAKIO, M. KUBO, K. SHIMANO and K. OHNO ............ 75
5.1 Introduction .................................................................................. 75
5.2 Disturbance regime of the upper basin riparian zone................... 76
5.3 Population structure ...................................................................... 77
5.4 Reproductive strategies of riparian tree species........................... 81
5.5 Responses to light and water stress.............................................. 84
5.6 Coexistence mechanisms of three riparian species...................... 87
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Contents XI
5.7 Conclusions .................................................................................. 88
References ............................................................................................... 88
6 Population dynamics and key stages in two
Japanese riparian elements
Y. KANEKOand T. TAKADA .................................................. 91
6.1 Introduction .................................................................................. 91
6.2 Riparian habitats and disturbance regimes................................... 91
6.3 Study species and their ecological niches.................................... 93
6.4 Spatio-temporal variations in population growth rate under
typhoon disturbances along a riparian environmental gradient ... 96
6.5 What are the key stages for population dynamics?...................... 99
6.6 Conclusion .................................................................................... 102
References ............................................................................................... 104
7 Rodent seed hoarding and regeneration of
Aesculus turbinata: patterns, processes and
implications
K. HOSHIZAKI ............................................................................ 107
7.1 Introduction .................................................................................. 107
7.2 Methods ........................................................................................ 108
7.3 Seed dynamics: cache generation, retrieval and consumption..... 109
7.4 End-points of seed dispersal......................................................... 111
7.5 Seedling regeneration ................................................................... 114
7.6 Ecological roles of seed dispersal by rodents............................... 116
7.7 Annual variation ........................................................................... 118
7.8 Implications for life history in the riparian habitats..................... 119
References ............................................................................................... 120
8 Longitudinal variation in disturbance regime and
community structure of a riparian forest
established on a small alluvial fan in warm-
temperate southern Kyushu, Japan
H. ITO and S. ITO..................................................................... 123
8.1 Introduction .................................................................................. 123
8.2 General description of the case study site.................................... 124
8.3 Disturbance regime and site conditions along the stream
gradient ......................................................................................... 125
8.4 Habitat segregation and species diversity pattern........................ 127
8.5 Occurrence of infrequent species................................................. 132
8.6 Conclusions .................................................................................. 133
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XII Contents
References ............................................................................................... 134
Part 5: Riparian forests on wide alluvial fan
9 Structure and composition of riparian forests with
reference to geomorphic conditions
S. KIKUCHI ................................................................................. 139
9.1 Introduction .................................................................................. 139
9.2 Overview of the Tokachi River system........................................ 140
9.3 Variation in site conditions on the floodplain in comparison to
the hillslope .................................................................................. 141
9.4 Site conditions for dominant tree species..................................... 144
9.5 Temporal and spatial variation among tree species..................... 147
9.6 Conservation of riparian forest dynamics.................................... 150
References................................................................................................ 151
10 Mosaic structure of riparian forests on the
riverbed and floodplain of a braided river: A case
study in the Kamikouchi Valley of the Azusa
River
S. ISHIKAWA .............................................................................. 153
10.1 Introduction .................................................................................. 153
10.2 Outline of the Kamikouchi Valley............................................... 153
10.3 Mosaic structure of riparian vegetation........................................ 156
10.4 Geomorphic process and disturbance regime of the floodplain in
Kamikouchi .................................................................................. 157
10.5 Young pioneer scrubs and forests................................................ 159
10.6 Seedling growth traits of salicaceous species.............................. 160
10.7 Old pioneer and late successional forests..................................... 161
10.8 Conclusion .................................................................................... 162
References................................................................................................ 163
11 Coexistence of Salix species in a seasonally flooded
habitat
K. NIIYAMA ............................................................................... 165
11.1 Introduction .................................................................................. 165
11.2 Seed dispersal and snowmelt floods............................................. 167
11.3 Micro topographic scale distribution of Salixspecies.................. 169
11.4 Soil texture and seedling establishment....................................... 169
11.5 Habitat segregation along a river.................................................. 171
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Contents XIII
11.6 Conclusion .................................................................................... 173
References................................................................................................ 173
Part 6: Riparian forests in lowland regions
12 Process of willow community establishment and
topographic change of riverbed in a warm-
temperate region of Japan
M. KAMADA .............................................................................. 177
12.1 Introduction .................................................................................. 177
12.2 Study area and willow communities on the bar........................... 178
12.3 Tolerance of willow seedlings against submerged and drought
conditions ..................................................................................... 180
12.4 Actual process of willow bands formation................................... 183
12.5 Stabilization of river-system and its influence on riparian
ecosystem ..................................................................................... 186
12.6 Conclusion .................................................................................... 188
References................................................................................................ 189
13 Growth and nutrient economy of riparian Salix
gracilistyla
A. SASAKI and T. NAKATSUBO ............................................. 191
13.1 Introduction .................................................................................. 191
13.2 Growth pattern of Salix gracilistyla............................................. 192
13.3 Biomass and production of Salix gracilistyla.............................. 194
13.4 Nutrient economy of Salix gracilistyla........................................ 196
13.5 Nutrient sources ............................................................................ 199
13.6 Conclusions .................................................................................. 200
References................................................................................................ 201
14 The expansion of woody shrub vegetation
(Elaeagnus umbellata) along a regulated river
channel
M. KOHRI................................................................................... 205
14.1 Introduction .................................................................................. 205
14.2 Study sites .................................................................................... 208
14.3 Spatial and temporal distribution of the population..................... 209
14.4 Seed germination and survival of the seedlings........................... 213
14.5 Life-history strategies of E. umbellata in relation to the river’s
disturbance regime ....................................................................... 216
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