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Post-fire smoke induced germination in Mediterranean basin species: where is the missing link?
Roberto Crosti1,2,*, K.W.Dixon2, A.Tieu2,3, G.Fabrini4.
1
School of Environmental Science, Murdoch University, Murdoch, 6150, Western Australia
Science Directorate, Kings Park and Botanic Garden, West Perth, 6005, Western Australia.
3
Botanic Gardens Conservation International, Descanso House, 199 Kew Road, Richmond, Surrey TW9 3BW, UK .
4
Roma Botanic Garden, University ‘La Sapienza’, L.go Cristina di Svezia Roma, Italy.
2
*[email protected]
c/o Orto Botanico Roma L.go Cristina di Svezia, Roma, Italy
INTRODUCTION
In regions with a mediterranean-type climate wildfires are a frequent occurrence. In such habitats
fire tolerant/favoured species (which propagate in different ways after fire including resprouting,
seeding, flowering) are frequently encountered. In the Mediterranean basin, many species of fire
prone habitats are resprouters 1,2, some geophytes sprout and flower 3, while only few species,
are known to germinate specifically after fire 4,5.
In other regions with Mediterranean-type vegetation including the Californian chaparral, South
African fynbos and Western Australian kwongan, fire is an important component in the seed bank
dynamics with up to 40% of species having enhanced germination following fire. Fire has
properties in common with other disturbance agents (i.e. grazing, landslide). Smoke, however, is a
specific by-product of fire and has been found to be the most significant agent responsible for
much of the germination found in these ecosystems after fire.
In Kings Park and Botanic Garden in Perth, Western Australia, the effect of smoke has been
investigated for many years and as a result smoke has been (and is currently) utilised as a general
germination enhancing agent in horticulture, land restoration and research into germination of
native species; furthermore, a specific protocol has been developed and applied with success
across many ecosystems and species.
In the Mediterranean basin the role of smoke in germination has been examined sporadically and is
not fully understood. In 2002, researchers at the Kings Park and Botanic Garden started
investigating smoke induced germination on species of the Mediterranean basin using their
established research protocol 6.
AIM
This study investigated the response of seeds of species from the Mediterranean basin to
application of smoke.
MATERIALS AND METHODS
Seeds of most of the species were purchased from accredited commercial collectors and others were
self-collected, for a total of 31 species.
Seed processing and all experimental work was carried out in the Research Laboratory at Kings
Park and Botanic Gardens. Horticultural expertise, applied conservation advice and facilities of the
nursery division was provided.
Seeds were smoke treated according to the King Park & Botanic Gardens established protocol 6.
Data preparation, descriptive and analytical statistical analysis and library research were completed
at the Roma Botanic Garden (Ecology Laboratory). Test of the parametric assumption showed that
there were none or mild violations of the data distribution, consequently the two sample t-test, for
unpaired comparisons, was carried out; differences were considered significant if P<0.05.
The self-collected seeds were treated for pest control before entering Australia by Australian
Quarantine Services.
Seed viability was determined by the presence of white, healthy and intact endosperm thought cut
test method; of the initially 31 selected species, only 19 had the minimum viability values (>15%)
required and were used for the experiment.
RESULTS
Of the 19 tested species nine had no or low germination (<3%), consequently only ten species were
considered to assess differences in germination.
Main results of this ex situ (ex altera parte terrae!) sudy are summarized in Table 1 and figures.
DISCUSSION
The data confirms that as found for other ‘mediterraneoid’ sensu 3 ecosystems (California, southwest Western Australia, South Africa, Chile) that smoke affects germination and smoke-stimulated
germination occurs in some species. Further research is required to assess a broader range of species
from across the Mediterranean basin to confirm the full extent of smoke-stimulated germination in
this ecosystem. Outcomes of a study of this type may have important impacts both for the ecology
(e.g. to explore more accurately evidence about fire as direct cause of adaptation of vegetation) and
conservation (e.g. as in horticulture and restoration) of plants native to the Mediterranean basin.
HOWEVER
The results of the study also highlighted the need for stronger collaborative links between botanic
gardens and researchers. For example, this study was limited in scope by the poor quality, the
absence of information on the date of collection, the handling history and the exact provenance of
the commercially available seeds and by post-entry pest-control quarantine treatments to which the
collected seeds were subjected.
It can be indicative, of the poor quality of seeds, that of the three species of the genera Cistus, of
which seeds were available for the experiment, only one had a germination/viability capacity
sufficient to be included in the results, though the genus Cistus is known to have much higher
germinability 7,8.
Appropriate formalized links between botanic gardens would have made this study more effective
and efficient through the exchange of information, access to germplasm and technical and scientific
co-operation.
To effectively implement plant conservation, botanic gardens need to undertake a coordinated
strategy in research, conservation, propagation and cultivation (thus achieving the aims of the
Convention on Biological Diversity) in cooperation and collaboration not only with academic and
governmental institutions, but also with experts staff of other stakeholders such as local authorities,
non-governmental organizations and networks, and community groups (as proposed from the
Agenda 21 protocol).
BGCI provides the means for botanic gardens to share information about activities, programmes
and any new advances made that benefit conservation and education. With many botanic gardens
registered or in support of the International Agenda for Botanic Gardens in Conservation 9, more
effective and efficient plant conservation can be achieved in the future.
Links between, and created by, botanic gardens (networking expertise and capacity building) is
required and would have important impacts for the horticultural development and restoration of
native plants and may help join the missing link between the international, regional and local
institutions responsible/capable for/of plant conservation.
1 Naveh, Z. 1975. The evolutionary significance of fire in the Mediterranean region. Vegetatio
29:199-208.
2 Piotto, B., Piccini, C., Arcadu, P. (1999). La ripresa della vegetazione dopo gli inc endi nella
regione mediterranea. Sherwood 47: 15-20.
3 Grove,A.T., Rackman O. 2001. The nature of Mediterranean Europe. Yale University press.
4 Verdu, M. 2000. Ecological and evolutionary differences between Mediterranean seeders and
resprouters. J.of Veg. Sc. 11:265-268.
5 Ojeda F. (2001) El fuego como factor clave en la evolucion de plantas mediterraneas.
Ecosistemas mediterráneos. Análisis funcional (ed. by R. Zamora & F.I. Pugnaire), pp. 319349. CSIC-AEET.
6 Tieu A., Dixon, K.W., Sivasithamparam, K., Plummer, J.A. & Sieler, I. M. (1999).
Germination of four species of native Western Australian plants using plant-derived smoke.
Australian Journal of Botany 47: 207-19.
7 Thanos,C.A. & Georghiou, K. (1988) Ecophysiology of fire-stimulated germination in Cistus
incanus ssp. creticus (L.) Heywood and C. salvifolius L. Plant Cell and Environment 11, 841849.
8 Mazzoleni (1990). Fire and Mediterranean plants : Germination responses to heat exposure.
Annali di Botanica 47, 227-233.
9 International Agenda for Botanic Gardens (2000). Wyse Jackson, P.S.and Sutherland, L.A.
Botanic Gardens Conservation International
Figs. Time courses of germination events in uncontrolled temperature glasshouse. Figures
represent mean percentages (1 standard error) of sown seeds n=(25). Each test, smoked and
control, was replicated 4 times.
Germination results were not adjusted to account inviable seeds.