Resilience in mediterranean-type ecosystems

173 Pages·1986·8.647 MB·English

by  B. Dell, A. J. M. Hopkins, B. B. Lamont (auth.), B. Dell, A. J. M. Hopkins, B. B. Lamont (eds.)

Resilience in mediterranean-type ecosystems
Tasks for vegetation science 16
Series Editors
HELMUT LIETH HAROLD A. MOONEY
University of Osnabrock, F.R. G. Stanford University, Stanford, Calif., U.S.A.
1 Box, E.O. Macroclimate and Plant Forms. An introduction to predictive modelling in phytogeography.
ISBN 90 61939410
2 Navin Sen, D. & Singh Rajpurohit, K. Contributions to the Ecology of Halophytes.
ISBN 90 61939429
3 Ross, J. 'The Radiation Regime and Architecture of Plant Stands.
ISBN 90 6193607 1
4 Margaris, N.S. & Mooney, H.A. (eds) Components ofP roductivity ofM editerranean - Climate, Regions.
ISBN 90 61939445
5 Muller, M.J. Selected Climatic Data for a Global Set of Standard Stations for Vegetation Science.
ISBN 9061939453
6 Roth, I. Stratification in Tropical Forests as Seen in Leaf Structure.
ISBN 90 61939461
7 Steubing, L. & Jager, H.J. Monitoring of Air Pollutants by Plants: Methods and Problems.
ISBN 90 6193947 X
8 Teas, H.J. Biology and Ecology of Mangroves.
ISBN 90 61939488
9 Teas, H.J. Physiology and Management of Mangroves.
ISBN 90 61939496
10 Feoli, E., Lagonegro, M. & Orl6ci, L. Information Analysis of Vegetation Data.
ISBN 90 6193950 X
11 Sestak, Z. (ed) Photosynthesis during Leaf Development.
ISBN 90 6193951 8
12 Medina,E., Mooney, H.A. & Vazquez-Yanes, C. (eds) Physiological Ecology ofP lants oft he Wet Tropics.
ISBN 9061939526
13 Margaris, N.S., Arianoustou-Faraggitaki, M. & Oechel, W.C. (eds) Being Alive on Land.
ISBN 90 61939534
14 Hall, D.O., Myers, N. & Margaris, N.S. (eds) Economics ofE cosystem Management. ISBN 90 61935059
15 Estrada, A. & Fleming, T.H. (eds) Frugivores and Seed Disposal. ISBN 90 6193543 1
16 Dell, B., Hopkins, A.J.M. & Lamont, B.B. (eds) Resilience in Mediterranean-type Ecosystems.
ISBN 90 6193 5792
Resilience
in mediterranean-type
ecosystems
edited by
B. DELL, A.l.M. HOPKINS and B.B. LAMONT
1986 DR W. JUNK PUBLISHERS
a member of the KLUWER ACADEMIC PUBLISHERS GROUP
DORDRECHT I BOSTON I LANCASTER
Distributors
for the United States and Canada: Kluwer Academic Publishers, 101 Philip
Drive, Assinippi Park, Norwell, MA 02061, USA
for the UK and Ireland: Kluwer Academic Publishers, MTP Press Limited,
Falcon House, Queen Square, Lancaster LAI lRN, UK
for all other countries: Kluwer Academic Publishers Group, Distribution Center,
P.O. Box 322, 3300 AH Dordrecht, The Netherlands
Library of Congress Cataloging in Publication Data
Resilience in Mediterranean-type ecosystems.
(Tasks for vegetation science ; 16)
"Papers presented at the Fourth International Con
ference on Mediterranean Ecosystems (MEDECOS) held in
Perth, Western Australia, during August 1984"--Pref.
Includes index.
1. Ecology--Congresses. I. Dell, B. (Bernard),
1949- . II. Hopkins, A. J. M. (Angus John Malcolm),
1948- • III. Lamont, B. B. (Byron B.), 1945- .
IV. International Conference on Mediterranean Ecosystems
(MEDECOS) (4th: 1984 : Perth, W.A.) V. Title:
Mediterranean-type ecosystems: VI. Series.
QH540.R47 1986 574.5 86-7230
ISBN-13: 978-94-010-8637-0 e-ISBN-13: 978-94-009-4822-8
DOl: 10.1007/978-94-009-4822-8
Copyright
© 1986 by Dr W. Junk Publishers, Dordrecht.
Softcover reprint of the hardcover 1st edition 1986
All rights reserved. No part of this publication may be reproduced, stored in a
retrieval system, or transmitted in any form or by any means, mechanical,
photocopying, recording, or otherwise, without the prior written permission of
the publishers,
Dr W. Junk Publishers, P.O. Box 163, 3300 AD Dordrecht, The Netherlands.
Contents
PREFACE VII
LIST OF CONTRIBUTORS VIII
1. INTRODUCTION 1
by B. Dell, A.J.M. Hopkins and B.B. Lamont
2. RESILIENCE: CONCEPTS AND MEASURES 5
by W.E. Westman
3. RESILIENCE AT THE LEVEL OF THE PLANT COMMUNITY 21
by P.J. Grubb and A.J.M. Hopkins
4. RESILIENCE OF ANIMAL AND PLANT COMMUNITIES TO HUMAN
DISTURBANCE 39
by B.J. Fox and M.D. Fox
5. RESILIENCE AT THE INDIVIDUAL PLANT LEVEL 65
by H.A. Mooney and R.J. Hobbs
6. RESILIENCE AT THE LEVEL OF THE INDIVIDUAL ANIMAL 83
by A.R. Main
7. RESILIENCE OF MEDITERRANEAN SHRUB COMMUNITIES TO FIRES 95
by J .E. Keeley
8. MAMMALIAN HERBIVORY AND RESILIENCE IN MEDITERRANEAN-CLIMATE
ECOSYSTEMS 113
by R.D. Quinn
9. INVASION OF MEDITERRANEAN ECOSYSTEMS BY WEEDS 129
by R.H. Groves
10. LAND USE CONFLICTS 147
by J.J. Havel
INDEX 161
V
Preface
This volume contains the texts of invited papers presented at the Fourth International Conference on
Mediterranean Ecosystems (MEDECOS) held in Perth, Western Australia during August 1984. It thus
follows three previous meetings, Chile (1971), California (1977) and South Africa (1980). There has been no
formal international body to organize these meetings, merely a continuity of purpose provided by the
common interests of the scientists concerned in the English-speaking world. Following previous themes on
structure, fire and role of nutrients in mediterranean ecosystems, MEDECOS was structured around the
theme 'Resilience in Mediterranean Ecosystems'. The invited speakers were requested to deal with particu
lar aspects of this subject, and offered papers were encouraged to do so as well. This provided a broad
framework for discussions which at the same time highlighted many of the major conservation issues arising
from extreme natural events and human-induced disturbances in the mediterranean regions. The proceed
ings were issued on the last day of the conference and provided two-page accounts of each of the contributed
papers and posters (Dell, B. (ed.) 1984 Proceedings of the 4th International Conference on Mediterranean
Ecosystems. Botany Dept., University of Western Australia). This volume was reserved for the review
papers whose aim was to explore general principles and unifying concepts at all levels in the study of
resilience.
Perth, December 1985.
VII
List of contributors
B. Dell 1.E. Keeley
School of Environmental and Life Sciences Department of Biology
Murdoch University Occidental College
PERTH 6155 AUSTRALIA LOS ANGELES CALIFORNIA 90041. U.S.A.
B.l. Fox B.B. Lamont
School of Zoology School of Biology
University of New South Wales Western Australian Institute of Technology
KENSINGTON 2033 AUSTRALIA BENTLEY 6102 AUSTRALIA
M.D. Fox A.R. Main
National Herbarium of New South Wales Department of Zoology
Royal Botanical Gardens University of Western Australia
SYDNEY 2000 AUSTRALIA NEDLANDS. 6009 AUSTRALIA
R.H. Groves H.A. Mooney
CSIRO Department of Biological Sciences
Division of Plant Industry Stanford University
CANBERRA 2601 AUSTRALIA STANFORD CALIFORNIA 94305-2493 U.S.A.
P.l. Grubb R.D. Quinn
Botany School Department of Biological Sciences
University of Cambridge California State Polytechnic University
ENGLAND CB2 3EA POMONA CALIFORNIA 91768 U.S.A.
1.1. Havel W.E. Westman
Department of Conservation & Land Management NASA Ames Research Center
CRA WLEY 6009 AUSTRALIA MOFFETT FIELD CALIFORNIA 94035 U.S.A.
A.l.M. Hopkins
Western Australian Wildlife Research Centre
WANNEROO 6065 AUSTRALIA
VITI
CHAPTER 1
Introduction
B. DELL, A.1.M. HOPKINS and B.B. LAMONT
Regions with mediterranean-type climates have a also in regard to composition of animal and plant
very restricted distribution but occur in five widely communities. Contributing factors have been re
separated parts of the world. These are: south viewed by di Castri (1973). Evergreen, sclero
western and Western parts of south-eastern Aus phyllous plants are characteristic of all five areas.
tralia, the southern Cape of South Africa, southern The distribution of the indigenous vegetation,
California on the west coast of the United States, which varies from herblands and shrublands to
central Chile on the west coast of South America, woodlands to tall forests, is the consequence of the
and the entire region surrounding the Mediterra interplay of the various biophysical factors.
nean Basin with extensions to the Black and Cas Pockets of non-evergreen communities include the
pian Seas and the Persian Gulf. The climates are drought-deciduous, coastal sage scrub of Califor
loosely equivalent to those of the Mediterranean nia and the macchia in the Mediterranean which is
Basin and share a warm to hot, dry summer and a dominated by winter-deciduous oaks. In addition
cool, moist winter. The annual rainfall may range to the overriding climatic control, other influences
from 250 to 1200 mm (up to 1500 mm in restricted such as soil type, soil fertility and water availability
areas) per year, of which most falls during winter are of paramount importance in shaping physiogn
spring. Mean monthly minima range from about 8 omy and composition of the biota. Taken together,
to 12° C with occasional snow or frost in some areas all but the richest of soils in the mediterranean
and mean monthly maxima of 18 to 30° C. Cold climate regions can be considered impoverished by
ocean currents are important in determining this world standards. Generally speaking, south-west
pattern. In general, these definitions cover 'areas ern Australia and South Africa (see Lamont et al.
slightly drier, hotter or wetter than accepted by 1985) contain the poorest substrates. Specht and
Koppen (1923), Aschmann (1973) or Schulze and Moll (1983) argue that the major environmental
McGee (1978) but they ensure pockets of c1osely factor affecting vegetation type and distribution in
related soils and vegetation are not excluded from mediterranean regions is the availability of soil
each region. Clearly mediterranean areas do not nutrients. They have proposed three major catego
have precise boundaries. In particular, many ani ries of substrate, each of which bears a characteris
mal species do not regard the boundaries, as de tic vegetation structure, as follows. Soils which are
fined here, as barriers of any sort. Rather they strongly leached, or derived from nutrient-de
identify with a climate having pronounced wet and pleted parent material, bear an overstorey of ever
dry seasons (Main, Chapter 6). green, sclerophyllous shrubs and low shrubs and
The mediterranean-ecosystems are highly het geophytes. On moderately-leached soils there is an
erogeneous, not only in vegetation structure but overstorey of sclerophyllous trees or shrubs with an
B. Dell, A.l.M. Hopkins and B.B. Lamont (eds.), Resilience in Mediterranean-type Ecosystems. 1
© 1986, Dr W. Junk Publishers, Dordrecht. ISBN 978-94-010-8637-0
understorey of grasses and herbs. There are also 1984) was selected at the meeting in Stellenbosch.
other landscapes with weakly-leached, often cal The general view was that, perhaps because of the
careous, soils with a stunted overstorey of scle rigours imposed by mediterranean-type climates,
rophyllous trees or shrubs with an understorey of the major plant and animal communities of regions
annual grasses, sclerophyllous shrubs or even suc with that climate appeared to display an excep
culents. tional capacity to recover after disturbance. If prin
By contrast, Beard (1983) believes that moisture ciples could be elicited, then these could be applied
relations are much more important than nutrient more widely to the study and management of com
availability in controlling gross physiognomy. munities throughout the world. Therefore the pro
Beard reached this conclusion after mapping the gram for the Perth conference was structured to
Western Australian vegetation and taking note of draw out these principles by examining issues of
soil physical characteristics. Clearly, the moisture resilience from a range of perspectives.
holding capacities, permeability properties and In defining the topics, we accepted the general
other structural soil factors do influence vegetation definition of resilience as the process of restoration
form. Whether these cause subtle modifications of of initial structure and function after a disturbance
an overall physiognomy characterized by low nu or a period of stress. The various components of
trient availability, or have contributed in a major resilience are further examined by Westman
way to the <;levelopment of scleromorphy in medi (Chapter 2). However, during the conference
terranean areas is open to question. some confusion emerged as to the definitions of
Mediterranean ecosystems have been a major disturbance and stress; this confusion is evident
testing ground for a number of ecological theories also in the present literature (e.g. Rapport et al.
and concepts, including the theory of ecological 1985, Sousa 1984). While disturbance often refers
convergence in plants (Day 1983). A comparative to the impact of human activities, some authors
research programme on structure and function in regard certain stresses as human-induced. For
mediterranean Chile and California was preceded others, stresses or disturbances can be annual fluc
by the first symposium in Valdivia, Chile during tuations about a mean, while some use these terms
March 1971 (di Castri and Mooney 1973). The re to refer to rare natural events such as landslips,
sults provided substantial support for the con volcanic eruptions, floods and cyclonic winds. Fur
vergence hypothesis. Other work since has pointed thermore, stress can be used to embrace both the
to major differences in environmental constraints applied force and the response of the biota.
and evolutionary histories between a number of the It is clear that there is a continuum of forces that
mediterranean regions which have produced clear may act on a system ranging from the relatively
divergences in structure and function (e.g. Cowling minor ones that merely limit biomass accumulation
and Campbell 1980, Lamont et al. 1985). (stresses) to the more severe ones which cause
Later, concern for serious management prob partial or complete reduction in biomass (disturb
lems within mediterranean regions led to a second ances). The term perturbation is appropriate to
symposium on the environmental consequences describe the most extreme disturbances. To be con
and management of fire at Stanford, California sistent, these terms should be used only to describe
during August 1977 (Mooney and Conrad 1977). the applied force or stimulus and not the response
The third meeting was held in Stellenbosch, South or internal effect. For the purposes of this volume,
Africa during August 1980. Attention once again the forces must be exogenous and can be human
focussed on the question of convergence, but this induced or natural.
time from the perspective of the role of nutrients, Recurrent (seasonal) events are not usually dis
rather than climate, in controlling the structure and turbances but, as shown by Main (Chapter 6), the
function of Illediterranean ecosystems (Kruger et responses to seasonal events may provide the only
al. 1983, Day i983). insight into responses to non-seasonal ones. Grubb
The theme for the resilience conference (Perth, and Hopkins (Chapter 3) analyse the nature of
2
disturbances by examining underlying mechanisms becoming prevalent. Havel (Chapter 10) argues
and how these might be measured. Clearly there is that we cannot consider environmental and cul
a need not only to standardize the use of common tural influences separately in the resolution of con
definitions but also the methods of quantifying the flict. Scientists should contribute here as well as
components of resilience. In their review on the providing the necessary background upon which
resilience of animal and plant communities to sound management practices can be developed.
human disturbance (Chapter 4), Fox and Fox re There is an urgent need to define future studies that
cognize a new property of resilience, damping, will provide the data for land management plan
which they define as the degree and manner by ning.
which the path of restoration is altered by any In conclusion, the major contributions to the
forces that change the normal restoring force. This 1984 MEDECOS Conference reproduced in this
concept should prove useful in a better understand book provide a range of insights into the principles
ing of responses to disturbance. governing the capacity of mediterranean climate
Plants in mediterranean-climate areas employ ecosystems to recover after disturbance. In doing
diverse regeneration strategies. Nowhere is this so there is clear recognition that more detailed
more visually obvious than the contrasting re studies on response mechanisms are required.
sponses of obligate seeders and obligate resprou
ters to fire (Chapter 7). Mooney and Hobbs (Chap
ter 5) provide a timely review of the types and References
locations of regenerative tissue and factors influ
encing regeneration. Considerable work is re Aschmann, H. 1973. Distribution and peculiarity of mediterra
quired to ascertain the costs of various resilience nean ecosystems. In: F. di Castri and H.A. Mooney (eds.)
Mediterranean-type Ecosystems: Origin and Structure. pp.
strategies. As Westman points out, the study of
11-19. Springer-Verlag, Berlin.
resilience in mediterranean ecosystems is still in its
Beard, J .S. 1983. Ecological control of the vegetation of south
infancy. Most contributors to this book agree that western Australia: moisture versus nutrients. In: F.J. Kruger,
there is a need for more work on the measurement D.T. Mitchell and J.U.M. Jarvis (eds.) Mediterranean-type
of resilience. We also need to know whether medi Ecosystems. The Role of Nutrients. pp. 66-73. Springer
Verlag, Berlin.
terranean ecosystems differ from non-mediterra
Connell, J.H. & Sousa, W.P. 1983. On the evidence needed to
nean ecosystems in their responses to disturbance.
judge ecological stability or persistence. The American Natu
Fox and Fox (Chapter 4) after examining this issue ralist 121, 789-824.
conclude that biota in regions of mediterranean Cowling, R.M. & Campbell, B.M. 1980. Convergence in vege
climate share a suite of characters, not necessarily tation structure in the mediterranean communities of Califor
nia, Chile and South Africa. Vegetatio 43, 191-198.
unique to the region, that facilitate rapid responses
Day, J.A. 1983. Mineral Nutrients in Mediterraneran Eco
to certain types of disturbance.
systems. South African National Scientific Programmes Re
As well as cultural interchange between the five port No. 71.
mediterranean areas, there has been extensive di Castri, F. 1973. Mediterranean-type shrublands of the world.
movement of crop and weed species. Disturbance In: F. di Castri and H.A. Mooney (eds.) Mediterranean-type
Ecosystems: Origin and Structure. Springer-Verlag, Berlin.
and the interaction between soil moisture levels
di Castri, F. & Mooney, H.A. (eds.), 1973. Mediterranean-type
and temperature appear to be the main features
ecosystems: Origin and structure. Springer-Verlag, Berlin.
which allow weeds to pass through the introduc Koppen, W. 1923. Der Klimate der Erde. Borntrager, Berlin.
tion, colonization and naturalization stages of in Lamont, B.B., Collins, B.G. & Cowling, R.M. 1985. Re
vasion (Groves, Chapter 9). As with the indi productive biology of the Proteaceae in Australia and South
Africa. Proc. Ecol. Soc. Aust. 14, 213-224.
genous flora and fauna, exotic species provide a
Mooney, H.A. & Conrad, e.E. (eds.), 1977. Proceedings ofthe
challenge for researchers and land managers.
symposium on the environmental consequences of fire and
Expanding human populations in the mediterra fuel management in mediterranean ecosystems. USDA For
nean areas are greatly increasing the occurrence of est Service, General Technical Report WO-3.
disturbance. As well, conflicts for land use are Rapport, D.J., Regier, H.A. & Hutchinson, T.e. 1985. Eco-
3