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Propagating framework tree species to restore seasonally dry tropical forest: Implications of seasonal seed dispersal and dormancy

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One effective approach to forest restoration in degraded tropical forestland is the so-called ‘framework species method’ which involves planting 20–30 indigenous forest tree species to re-establish a basic forest structure that catalyses the recovery of biodiversity. For the seasonally dry tropical forests of Doi Suthep-Pui National Park in northern Thailand, a provisional list of 36 potential framework species was compiled, from 19 different families representing a broad spectrum of the tree flora. This paper examines the seed germination characteristics of these species when grown as a nursery ‘crop’ for planting to restore degraded sites, focussing on germination phenology and dormancy. It considers how such characteristics affect the first stage of nursery production from seed collection to pricking out seedlings in the nursery. Twenty-nine species had a germination percentage of 60% or greater, which is acceptable for nursery production. The median length of dormancy (MLD) ranged from 7 days in the case of Erythrina subumbrans to 219 days for Lithocarpus garrettianus. Germination was defined as rapid if the MLD occurred within 3 weeks, and slow if occurring after 12 weeks. Twelve species germinated rapidly and eight germinated slowly, the remainder being intermediate. Seedling emergence ranged over a period of 7 days in the case of Erythrina stricta and E. subumbrans to 322 days in the case of L. garrettianus.
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Propagating framework tree species to restore seasonally
dry tropical forest: implications of seasonal seed
dispersal and dormancy
David Blakesley
a,*
, Stephen Elliott
b
, Cherdsak Kuarak
b
, Puttipong Navakitbumrung
b
,
Sudarat Zangkum
b
, Vilaiwan Anusarnsunthorn
b
a
Horticulture Research International, East Malling, West Malling, Kent ME19 6BJ, UK
b
Science Faculty, Biology Department, Forest Restoration Research Unit, Chiang Mai University, Chiang Mai 50200, Thailand
Received 4 December 2000; received in revised form 10 April 2001; accepted 10 April 2001
Abstract
One effective approach to forest restoration in degraded tropical forestland is the so-called ‘framework species method’
which involves planting 20–30 indigenous forest tree species to re-establish a basic forest structure that catalyses the recovery
of biodiversity. For the seasonally dry tropical forests of Doi Suthep-Pui National Park in northern Thailand, a provisional list
of 36 potential framework species was compiled, from 19 different families representing a broad spectrum of the tree flora.
This paper examines the seed germination characteristics of these species when grown as a nursery ‘crop’ for planting to
restore degraded sites, focussing on germination phenology and dormancy. It considers how such characteristics affect the
first stage of nursery production from seed collection to pricking out seedlings in the nursery. Twenty-nine species had a
germination percentage of 60% or greater, which is acceptable for nursery production. The median length of dormancy (MLD)
ranged from 7 days in the case of Erythrina subumbrans to 219 days for Lithocarpus garrettianus. Germination was defined
as rapid if the MLD occurred within 3 weeks, and slow if occurring after 12 weeks. Twelve species germinated rapidly
and eight germinated slowly, the remainder being intermediate. Seedling emergence ranged over a period of 7 days in
the case of Erythrina stricta and E. subumbrans to 322 days in the case of L. garrettianus.#2002 Elsevier Science B.V. All
rights reserved.
Keywords: Tropical forest restoration; Seed dormancy; Germination; Seedling development; Framework tree species
1. Introduction
Deforestation is a serious environmental problem
throughout the tropics causing rural poverty, water-
shed degradation and loss of biodiversity. Efforts to
restore forests are increasing, but such efforts are
often limited due to lack of knowledge about how to
propagate the majority of indigenous tree species. One
effective approach to forest restoration is the ‘frame-
work species method’ (Goosem and Tucker, 1995;
Lamb et al., 1997; Tucker and Murphy, 1997) first
developed to restore forest in degraded areas of
Queensland’s Wet Tropics World Heritage Site in
Australia. The method depends on tree planting to
restore basic forest structure which then encourages
Forest Ecology and Management 164 (2002) 31–38
*
Corresponding author. Tel.: þ44-1732-84-3833;
fax: þ44-1732-84-9067.
E-mail address: david.blakesley@hri.ac.uk (D. Blakesley).
0378-1127/02/$ – see front matter #2002 Elsevier Science B.V. All rights reserved.
PII: S 0378-1127(01)00609-0
the recovery of biodiversity. Seven years after planting
2030 framework tree species in degraded grassland
sites in Queensland, the regenerating forests devel-
oped closed canopies up to 8.7 m tall and was
naturally colonised by up to 49 additional tree species
(Tucker and Murphy, 1997). Framework tree species
are fast growing with dense spreading canopies which
rapidly shade out weeds. They also provide resources
for wildlife (such as fruit, nectar or perching sites) at
an early age. Animals (especially birds and bats)
attracted by such resources, disperse the seeds of
additional non-planted tree species into the planted
sites, thus accelerating the return of biodiversity. Seed
of framework species should be easy to collect and
germinate in nurseries. A reasonable growth rate is
also required in the nursery to ensure efcient use of
nursery space and facilities.
Although detailed information exists on the propa-
gation of commercially valuable tree species, very
little is known about potential framework tree species,
which tend to be non-commercial, indigenous forest
tree species with high ecological value but low or
unexplored economic value. For the vast majority of
the huge diversity of forest tree species in Southeast
Asia owering, fruiting and germination phenology
are not known and propagation techniques have not
yet been developed. Of the 36 potential framework
species reported here, only Bishofia javanica,Dua-
banga grandiflora,Hovenia dulcis and Prunus
cerasoides have been studied previously (Datta and
Sharma, 1989; Frett, 1989; Kamaluddin and Grace,
1993; Kopachon et al., 1996; Hardwick et al., 1997)
and none within the context of producing a cropof
framework species.
Producing a wide range of framework tree species is
far more complex than mass propagation of a small
number of commercial plantation species. Indigenous
tree species in Thailand produce seeds at different
times throughout the year. However, seeds of tree
species in seasonally dry tropical forests in the neo-
tropics tend to germinate at the beginning of the rainy
season (Garwood, 1983), providing seedlings with
sufcient time to establish a good root system before
onset of drought conditions during the following dry
season. However, it is not clear how germination
phenology and year-round seed dispersal affect the
nursery operation. What may be the optimum strategy
to enable trees to establish themselves naturally may
work against the needs of small-scale tree nursery
managers.
A list of 36 potential framework species from 19
different families was drawn up, based on pilot studies
in the nursery, preliminary eld trials over 3 years and
fruiting characteristics. This included pioneers such as
Melia toosendan and climax species such as H. dulcis.
Key families include the Moraceae (four species),
Meliaceae (two species), Leguminosae (two species)
and Fagaceae (six species) (Table 1). The list is
necessarily provisional because long-term eld trials
are needed to determine the age at which the listed tree
species rst produce wildlife resources and the degree
to which they enhance biodiversity recovery. The
present paper examines seed germination character-
istics of potential framework species when grown as a
crop, focussing on dispersal, germination phenology
and dormancy. It considers how such characteristics
affect the rst stage of nursery production, from seed
collection to pricking out seedlings in the nursery. It
also reviews the suitability of the species as frame-
work species based on the essential criterion of seed
germination.
2. Materials and methods
2.1. Study site
Trees were propagated in a nursery at 1000 m
elevation near the headquarters of Doi Suthep-Pui
National Park, north-west of Chiang Mai, northern
Thailand (l88510N latitude and 988540E longitude).
The area experiences a monsoonal climate with
pronounced dry and wet seasons. Average annual
precipitation recorded at nearby weather stations at
similar elevations ranges from 1670 to 2094 mm. The
wet season lasts from May to October and the dry
season from November to April.
All the seed was collected in natural or slightly
disturbed forest ecosystems close to the nursery
between elevations of 7001600 m. This elevation
range covers all the major forest types in the park,
including the deciduous forest associations of the
lowlands (deciduous dipterocarp oak, bamboo decid-
uous forest and mixed evergreen deciduous forest) and
the evergreen forest of the uplands (Maxwell and
Elliott, in press).
32 D. Blakesley et al. / Forest Ecology and Management 164 (2002) 31–38
2.2. Seed germination
Seeds of the 36 potential framework species were
collected from single parent trees of each species
when fruits were mature and ripe. Fruits were cut from
branches or collected from the ground only if they
were freshand undecayed. Following the removal of
the fruit pericarp, seeds were sown within 23 days
of collection into modular plastic trays, on to the
surface of a medium of two parts forest soil to one
part coconut husk. For each species, 72 seeds were
divided into three replicate batches of 24 which were
Table 1
Forest types, altitudinal ranges (northern Thailand) and fruit types of potential framework species
Species Family Forest type
a
Altitude range (m) Fruit type
Balakata baccata (Roxb.) Ess. Euphorbiaceae MED/E 400500 Drupe
Bischofia javanica Bl. Euphorbiaceae BD/MED/E 5251250 Drupe
Callicarpa arborea Roxb. var. arborea Verbenaceae DDO/BD/MED 3751250 Berry
Castanopsis calathiformis (Skan) Rehd. and Wils. Fagaceae EP 10501500 Nut
Castanopsis tribuloides (Sm.) A. DC. Fagaceae MED/E/EP 9001685 Nut
Cinnamomum iners Reinw. ex Bl. Lauraceae MED/E 7001425 Berry
Debregeasia longifolia (Burm. f.) Wedd. Urticaceae MED/EP 5251685 Achene
Duabanga grandiflora (Roxb. ex DC.) Walp. Sonneratiaceae MED/E 6501450 Capsule
Eriobotrya bengalensis (Roxb.) Hk. f. forma
multinervata Vidal
Rosaceae E 10001650 Drupe
Erythrina stricta Roxb. Leguminosae BD/E/EP 4001680 Pod
Erythrina subumbrans (Hassk.) Merr. Leguminosae MED/E 5001680 Pod
Eugenia albiflora Duth. ex Kurz Myrtaceae MED/E/EP 8001525 Berry
Eurya acuminata DC. var. wallichiana Dyer Theaceae E 10001500 Berry
Ficus altissima Bl. Moraceae BD/MED 3501050 Fig
Ficus racemosa var. racemosa Moraceae MED 350500 Fig
Ficus semicordata B.-H. ex J.E. Sm. Var. semicordata Moraceae BD/E/EP 3501550 Fig
Ficus subulata Bl. var. subulata Moraceae MED/E 8251400 Fig
Gmelina arborea Roxb. Verbenaceae BD/MED/E/EP 3501475 Drupe
Heynea trijuga Roxb. ex Sims Meliaceae BD/MED/E/EP 5501680 Capsule
Hovenia dulcis Thunb. Rhamnaceae E 10251300 Capsule
Lithocarpus elegans (Bl.) Hatus. ex Soep. Fagaceae B/MED/EP 4501450 Nut
Lithocarpus garrettianus (Craib) A. Camus Fagaceae B/MED/E 5501100 Nut
Manglietia garrettii Craib Magnoliaceae E 10501600 Aggregate
follicle
Markhamia stipulata (Wall.)
Seem. ex K. Sch. var. kerrii Sprague
Bignoniaceae BD/MED/E/EP 9501500 Capsule
Melia toosendan Sieb. and Zucc. Meliaceae MED/E 7001450 Drupe
Michelia baillonii Pierre Magnoliaceae MED/E 6501100 Aggregate
follicle
Nyssa javanica Polygalaceae MED/E 5501400 Drupe
Ostodes paniculata Bl. Euphorbiaceae E 10001350 Capsule
Phoebe lanceolata (Nees) Nees Lauraceae MED/E/EP 5501550 Drupe
Planchonell punctata Flet. Sapotaceae DDO/BD/MED/E/EP 3501525 Berry
Prunus cerasoides D.Don Rosaceae MED/E/EP 10501685 Drupe
Quercus semiserrata Roxb. Fagaceae MED/E/EP 8001675 Nut
Quercus vestita Rehd. and Wils. Fagaceae E/EP 12001600 Nut
Rhus rhetsoides Craib Anacardiaceae MED/E/EP 6501550 Drupe
Sapindus rarak DC. Sapindaceae MED/E 6251620 Drupe
Spondias axillaris Roxb. Anacardiaceae MED/E/EP 7001600 Drupe
a
BD: bamboo and deciduous; DDO: deciduous dipterocarp oak; MED: mixed evergreen and deciduous; E: evergreen; EP: evergreen and
pine (sensu Maxwell and Elliott, in press).
D. Blakesley et al. / Forest Ecology and Management 164 (2002) 3138 33
randomly assigned to different benches and watered
daily. Each replicate consisted of 24 adjacent compar-
tments ð3:5cm3:0cm7:0cmÞin one-seed tray.
Seed trays were placed on the top of concrete benches,
partially shaded under a transparent plastic roof
(approximately 40% full sunlight, similar to the light
intensity in partially regenerating gaps). Once the rst
pair of leaves had fully expanded, seedlings were
Table 2
Seed germination data of potential framework tree species, suitable for forest restoration plantings in northern Thailand
Species Seed collection
month
Mean germination
percentage
a
(S.D.)
MLD (days)
b
Time over which
seeds germinated
(days)
b
Germination and
synchrony
categories
c
Balakata baccata (Roxb.) Ess. December 25 (6.3) 67 112 IG/AS
Bischofia javanica Bl. November 43 (14.6) 85 154 SG/AS
Callicarpa arborea Roxb. var. arborea August 67 (21.7) 86 63 SG/IS
Castanopsis calathiformis (Skan)
Rehd. and Wils.
June 61 (19.2) 16 42 RG/IS
Castanopsis tribuloides (Sm.) A. DC. September 83 (8.3) 31 42 IG/IS
Cinnamomum iners Reinw. ex Bl. April 75 (8.3) 17 63 RG/IS
Debregeasia longifolia (Burm. f.) Wedd. March 100 (0) 15 14 RG/S
Duabanga grandiflora (Roxb. ex DC.) Walp. April 86 (2.9) 31 42 IG/IS
Eriobotrya bengalensis (Roxb.)
Hk. f. forma multinervata Vidal
September 79 (3.6) 16 203 RG/AS
Erythrina stricta Roxb. May 67 (33.3) 10 7 RG/S
Erythrina subumbrans (Hassk.) Merr. April 39 (2.4) 7 7 RG/S
Eugenia albiflora Duth. ex Kurz May 71 (12.5) 24 147 IG/AS
Eurya acuminata DC. var. wallichiana Dyer March 69 (6.4) 60 126 IG/AS
Ficus altissima Bl. March 97 (2.4) 34 105 IG/AS
Ficus racemosa var. racemosa February 92 (4.2) 27 70 IG/IS
Ficus semicordata B.-H. ex J.E.
Sm. var. semicordata
March 92 (5.0) 52 41 IG/IS
Ficus subulata Bl. var. subulata January 71 (8.3) 60 175 IG/AS
Gmelina arborea Roxb. March 83 (18.2) 25 14 IG/S
Heynea trijuga Roxb. ex Sims November 83 (14.4) 96 203 SG/AS
Hovenia dulcis Thunb. August 71 (15.0) 97 154 SG/AS
Lithocarpus elegans (Bl.) Hatus. ex Soep. September 69 (9.6) 143 231 SG/AS
Lithocarpus garrettianus (Craib) A. Camus September 56 (37.3) 219 322 SG/AS
Manglietia garrettii Craib October 74 (4.8) 81 140 IG/AS
Markhamia stipulata (Wall.) Seem. ex K.
Sch. var. kerrii Sprague
March 56 (2.1) 13 15 RG/.S
Melia toosendan Sieb. and Zucc. April 67 (15.0) 15 70 RG/IS
Michelia baillonii Pierre June 31 (6.9) 101 63 SG/IS
Nyssa javanica July 67 (19.1) 39 70 IG/IS
Ostodes paniculata Bl. November 53 (16.8) 124 203 SG/AS
Phoebe lanceolata (Nees) Nees April 79 (4.2) 44 56 IG/IS
Planchonella punctata Flet. June 89 (1.7) 17 35 RG/IS
Prunus cerasoides D.Don March 74 (4.8) 52 63 IG/IS
Quercus semiserrata Roxb. June 92 (7.2) 18 35 RG/IS
Quercus vestita Rehd. and Wils. September 74 (13.4) 14 21 RG/S
Rhus rhetsoides Craib December 50 (50.0) 24 28 IG/IS
Sapindus rarak DC. January 83 (8.3) 45 98 IG/AS
Spondias axillaris Roxb. March 43 (4.8) 11 21 RG/S
a
Three replicates.
b
Pooled replicates.
c
RG: rapid germination; IG: intermediate germination; SG: slow germination; S: synchronous; IS: intermediate synchrony; AS:
asynchronous.
34 D. Blakesley et al. / Forest Ecology and Management 164 (2002) 3138
pricked out and transplanted into individual contain-
ers. Germination was monitored throughout the ger-
mination period and was dened as emergence of
any part of the shoot. The dates of the rst and last
seeds to germinate were recorded, and the median
length of dormancy (MLD) calculated (pooling
individuals of each species from the three replicate
batches) from the germination times of all seeds which
germinated.
3. Results
Germination percentage, one of the key selection
criteria for framework species, ranged from 25 to
100% (Table 2). However, 80% of species had a
germination percentage of 60% or greater, which is
more acceptable for this type of nursery operation.
Only three species had low germination percentages:
Balakata baccata (25%); Michelia baillonii (31%);
Erythrina subumbrans (39%). However, these species
still qualify as potential framework species due to
other attributes, such as high growth rate in containers
or good eld performance (unpublished data).
The MLD ranged from 7 to 219 days. For the
purposes of nursery production, germination was
dened as rapid if the MLD was 21 days or less,
and slow if the MLD was 84 days or more. Twelve
species could be classied as having rapid germina-
tion: Castanopsis calathiformis;Cinnamomum iners;
Debregeasia longifolia;Eriobotrya bengalensis;Ery-
thrina stricta;Erythrina subumbrans;Markhamia
stipulata;Melia toosendan;Planchonella punctata;
Quercus semiserrata;Quercus vestita;Spondias
axillaris. In contrast, Bischoa javanica,Callicarpa
arborea,Heynea trijuga,Hovenia dulcis,Lithocarpus
elegans,Lithocarpus garrettianus,Michelia baillonii
and Ostodes paniculata were categorised as having
slow germination. The remaining 16 species had
MLDs of between 3 and 12 weeks and could be
regarded as having intermediate germination rates.
Considering the framework species as a whole,
most species (28 or 78%) fell into the categories of
rapid or intermediate germination. Of the 21 species
collected in the late dry and early wet season, only one
species, Michelia baillonii germinated slowly (Fig. 1).
In contrast, of the 15 species collected in the late wet
and early dry season, seven species germinated slowly
(19% of the total); the remaining eight were inter-
mediate or rapid. This seasonal variation resulted in a
peak in nursery germination in the rst-half of the year,
when the median seeds of 72% of species germinated
(Fig. 2). This coincided with the end of the latter part of
the dry season and the early part of the wet season.
Fig. 1. The relationship between the MLD and the month of seed collection of species collected in Doi Suthep-Pui National Park (700
1600 m asl). Each point represents an individual species.
D. Blakesley et al. / Forest Ecology and Management 164 (2002) 3138 35
Seedling emergence ranged over 7 days for both
Erythrina spp. to 322 days for L. garrettianus. For tree
production in the nursery, germination was dened as
synchronous if all seedlings of a given species
emerged within 21 days, and highly asynchronous if
this occurred over a period of more than 84 days.
Seven species germinated synchronously, six of which
also had an MLD of less than 21 days (Table 2):
Debregeasia longifolia;Erythrina stricta;Erythrina
subumbrans;Markhamia stipulata;Quercus vestita;
Spondius axillaris. The other species which germi-
nated synchronously, Gmelina arborea, also germi-
nated relatively rapidly, with an MLD of 25 days.
Species exhibiting highly asynchronous germination
were distributed across intermediate- and slow-
germinating species. Of the latter group of species,
none germinated synchronously; 63 days was the
shortest time of seedling emergence, and the mean
emergence time for the eight species was 164 days.
4. Discussion
Few phenological studies have been reported with
the framework species described in this paper. The most
studied has been Hovenia dulcis, with several reports on
seed germination (Frett, 1988, 1989; Kopachon et al.,
1996) and the successful micropropagation of axillary
buds from mature trees (Echeverrigaray et al., 1998).
Hardwick et al. (1997) studied germination and
emergence of Prunus cerasoides collected on Doi
Suthep, and also found that it fruited late in the dry
season with a high germination percentage. Bischoa
javanica has previously been propagated from seed,
and grown in controlled environments to stimulate
different forest canopies (Kamaluddin and Grace,
1993). This study showed that B. javanica has a wide
acclimation potential to the changing light levels, which
may occur in gaps. There is a report of soft rot on
seedlings of Duabanga grandiora (Datta and Sharma,
1989). Although there are a number of other publi-
cations relating to related taxa within the families
reported here, particularly in America and the neo-
tropics, no other relevant work has been published
on the potential framework species described in this
paper.
Because of the rainfall patterns in a seasonally dry
tropical forest, the ideal time to plant out container-
grown tree seedlings is at the start of the wet season. It
is a considerable challenge to produce a crop of
seedlings, of a plantable size, of 36 framework tree
species, all to be dispatched at the same time of year
when seeds are available at different months through-
out the year and they exhibit widely different rates of
germination and growth in the nursery. The present
study has shown that nursery production of such a
collectionof native species, about which very little is
known, presents considerable logistical problems for
Fig. 2. Number of species located in Doi Suthep-Pui National Park (7001600 m asl), whose median seed emergence falls in each month.
36 D. Blakesley et al. / Forest Ecology and Management 164 (2002) 3138
the nursery manager, even to get the seedlings to the
point of pricking out into containers. The rst of these
is that to propagate 36 framework species, at least one
collection trip would be required in every month of the
year and probably more in March, April and
September when 18 species (50% of the framework
species) are available for collection. Furthermore,
these species exhibit considerable variation in dor-
mancy and germination synchrony. It can be clearly
seen from the scatter plot of MLD (Fig. 1) that species
with seeds dispersed in the late dry/early wet season
tend to germinate quickly in the nursery, whereas
those with species dispersed towards the end of the wet
season and into the dry season, are likely to have a
much longer dormancy period. Seven of the frame-
work species appear to be ideal for nursery production,
because they are collected at one time of the year in the
late dry/early wet season (with the exception of
Quercus vesita) and germinate rapidly and synchro-
nously. These species, therefore, require minimum
time in the germination facility where they are
particularly susceptible to pests and diseases. The
other species collected at this time (with the exception
of Michelia baillonii) have intermediate germination,
and vary in the synchronicity of germination, and
include species such as Eurya acuminata and Ficus
subulata which are highly asynchronous. Another
predictable group of species, in terms of nursery
planning, are those dispersed in the late wet/early dry
season which germinate slowly and also asynchro-
nously.
Whilst it is beyond the scope of this paper to
consider the manipulation of growth and development
of framework species in containers, it is clear from the
above discussion that seedlings will be ready for
pricking out throughout the year. Further work is now
underway to assess the second stage of nursery
production of these species, from pricking out through
to weaning and dispatch.
Acknowledgements
FORRU was funded with nancial support from
Riche Monde (Bangkok) Ltd. and United Distillers
PLC. Shell Forestry Limited, the Biodiversity
Research and Training Programme and the Science
Faculty of Chiang Mai University sponsored the
research described in this paper. Other donors have
included The Fagus Anstruther Memorial Trust, The
Peter Nathan Trust, The Robert Kiln Charitable Trust,
The Barbara Everard Trust for Orchid Conservation,
Mr. Alan and Mrs. Thelma Kindred, Mr. Nostha
Chartikavanij, Mr. R. Butterworth and Mr. James C.
Boudreau. The authors thank J.F. Maxwell for iden-
tifying the tree species named in this paper. Voucher
specimens are stored at the Chiang Mai University
Herbarium, Biology Department. The authors are
grateful to all research assistants and volunteers who
assisted with data collection and processing and care
of the plants in the nursery including: Jumpee
Bunyadit, Thonglaw Seethong, Tim Rayden, Kevin
Woods, Rungtiwa Bunyayod and Janice Kerby. The
Head and staff of Doi Suthep-Pui National Park
Headquarters provide essential collaboration for
FORRUs research. We are especially grateful to
the Head of the National Park, Mr. Paiboon Sawet-
melanon, Mr. Amporn Panmongkol (Deputy Head)
and Mr. Prasert Saentaam.
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38 D. Blakesley et al. / Forest Ecology and Management 164 (2002) 3138
... This method was first developed in Queensland, Australia and initially established in Chiang Mai in 1998. The oldest restored forest with this method was planted in 1998 in Ban Mae Sa Mai, Chiang Mai province (Blakesley et al., 2002). The main concepts of this method are planting 20-30 native tree species comprising both pioneer and climax species to enhance the reestablishment of a forest community. ...
... Six months of the wet season begin from May to October, while the remaining months are the dry season. This forest is defined as a seasonal tropical dry forest as mentioned in Blakesley et al. (2002). ...
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Soil seed banks have been used for investigation of natural regeneration of forests. In this study, we compared seed density and species composition of soil seed banks of trees among natural forests, restored forests of different ages, and abandoned agricultural land. The soil seed banks were collected from a natural forest (NF), 12-year-old and 17-year-old restoration sites (RF12y and RF17y), and 17-year-old abandoned site (AA) at Ban Mae Sa Mai, Chiang Mai, Thailand. A seedling emergence technique was used to assess seed density and species of emerged seedlings was identified. We found 5-8 tree species at each site. Seed densities in the study areas ranged from 43 to 298 seeds/m 2. The seed density of RF12y was significantly higher than that of both NF and AA but not significantly different than RF17y (p < 0.01). Although there was no significant relationship between the restoration ages and the seed densities of the soil seed banks, the species composition of standing vegetation was related to the seed bank species. Sorensen's similarities between the species composition of the soil seed banks and the existing trees in each area were between 0 and 13.79%, suggesting seed dispersal of both within and across study sites. Eight out of fourteen species in the soil seed banks were dispersed into restoration sites without standing vegetation of those species. Seven of those were animal-dispersed species. The selected native trees, framework species, attracted small seed dispersers into the study areas, especially at the restoration sites. This finding suggests that active forest restoration improved natural regeneration in restoration sites as well as neighboring areas via seed dispersal.
... En effet, l'évaluation de l'aptitude germinative ne dépend pas seulement du pourcentage de germination atteint mais aussi de sa vitesse ainsi que de son évolution au cours du temps (Poorter, 1999 ;Norden et al., 2009). Ces deux facteurs combinés sont souvent utilisés pour déterminer le succès d'un prétraitement sur la levée des dormances qu´elles soient de nature tégumentaire ou embryonnaire (Vázquez-Yanes et Smith, 1982 ;Blakesley et al., 2002). Ceci confirme nos résultats qui indiquent que le traitement idéal est caractérisé par un FGP et un GRI élevé et un MGT très bas par rapport aux autres traitements. ...
Book
La sécheresse et la salinité agissent simultanément dans la tolérance et l’acclimatations sous condition saline. Par conséquent, les plantes soumises à ces types de stress devraient avoir développé des adaptations structurelles spécifiques dès le stade de germination en passant par la croissance de la racine, les feuilles et la tige. La solution à ces problèmes environnementaux est de rechercher des espèces relativement économes en eau et résistantes à des épisodes récurrents de divers stress abiotiques tel que le stress salin. L’effet de la sécheresse s’est manifesté au niveau de la distribution des espèces d’acacia le long du territoire algérien, caractérisé beaucoup plus par la pluviométrie. En effet, La répartition géographique du genre Acacia Mill. (Fabales Mimosaceae) en Algérie a été déterminée après la prospection, la localisation et la description des populations de différentes espèces sur l’ensemble du territoire algérien. Vingt-quatre régions ont été prospectées en fonction de l'abondance relative des espèces. L'objectif de l’étude de l’effet de la salinité sur la germination contribue aussi à déterminer le seuil de tolérance des semences et de leur régénération dans un milieu salin. Seulement trois parmi les dix espèces répertoriées seront étudiées. Cette sélection est basée surtout sur la distribution géographique et la densité de chaque espèce choisie. A. saligna représente le Nord, A. tortilis pour le Sud, et A. karroo qui est une espèce qui est présente dans le Nord et dans le Sud en même temps. Le classement des espèces étudiées dans un ordre de tolérance décroissant, sur la base de leur capacité germinative, est alors le suivant : A. karroo > A. tortilis > A. saligna. La croissance, l'homéostasie ionique, l'osmoprotection, l’indice de tolérance à la salinité, ainsi que les ajustements anatomiques d'A. karroo et d’A. saligna cultivés à diverses concentrations de NaCl pendant 21 jours ont été évalués. Nos résultats montrent que l'adaptabilité d’une espèce à la salinité est étroitement liée à la sélectivité en ions, à l'accumulation d'osmoprotecteurs, aux ajustements anatomiques et à la production de la biomasse sèche. Nos résultats confirment qu'A. karroo et A. saligna sont deux espèces d'arbre appropriée pour la conservation du sol et de l'écologie, ce qui favoriserait la restauration des terres dans les zones arides et semi-arides tout en profitant économiquement des intérêts de ces espèces.
... In a research nursery in the former national park HQ compound at 1,000 m elevation, experiments determined the optimal methods to grow hundreds of tree species for testing in field trials. The nursery research resulted in production schedules, detailing the most efficient treatments and timings required to produce healthy, vigorous trees (30-50 cm tall) of each species, by the optimal planting time (mid-June in northern Thailand), despite large differences among species in fruiting periods, length of seed dormancy and seedling growth rates (Blakesley et al., 2002). The research included germination trials to test various techniques to break dormancy (Singpetch, 2002), seed storage experiments and seedling growth trials (testing various media, containers and fertilizer regimes) (Zangkum, 1998;Jitlam, 2001). ...
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Thirty years ago, reforestation in the tropics meant planting monocultures of economic trees. Ecosystem restoration was rarely practised, due to lack of effective techniques. Since then, ecologists have devised ways to: i) assist natural forest regeneration (ANR), ii) plant the right trees in the right places and iii) ameliorate soils on severely degraded sites. Such techniques can maximize recovery of i) biomass, ii) structural complexity, iii) biodiversity and iv) ecological functioning on sites at all stages of degradation. Forest restoration has now become a global priority, with the UN calling for restoration of 350 million hectares by 2030 (the Bonn Challenge). However most of the area pledged to the initiative will become monoculture plantations (45%) or agroforests (21%), even though ecological restoration sequesters 40 and 6 times more carbon respectively and supports far higher biodiversity. Whilst scientists have overcome the technical barriers to restoration, social "scientists" have yet to develop effective tools to overcome the socioeconomic barriers, such as poor governance, inadequate stakeholder motivation and ineffective funding mechanisms and science-policy interface. Scientists have delivered the technical tools for restoration-now the social scientists, economists and politicians must deliver the socioeconomic tools.
... Therefore, microtopographic position showed a greater influence on tree performance. The use of native pioneer tree species, characterized by a rapid increase in height and canopy cover, is the most favourable strategy in reforestation initiatives (Blakesley et al. 2002;Elliot et al. 2003;. This is because, fast growing, pioneer species are more adapted to grow in highly disturbed sites with harsh environmental conditions. ...
Thesis
With unprecedented changes in climate and land-use patterns, a decrease in global biodiversity and ecosystem services has been occurring at an alarming rate. This has resulted in widespread damage to the life-support systems upon which every living organism depends on. Reforestation of degraded forest ecosystems is now globally recognized as one of the best natural capital investment options, owing to its contribution to biodiversity conservation, climate change mitigation and adaptation, and ecosystem services provision. The aim of this study was (1) to unravel confusions caused by the inconsistent use of terminologies describing different reforestation initiatives; (2) to investigate motivations behind recent reforestation initiatives; (3) to demonstrate the use of a restoration decision-making tool, Robust offsetting (RobOff); (4) to investigate the influence of climatic and edaphic factors on reforestation initiative, (5) to assess reforestation initiative success, and (6) to assess the impact of drought on reforestation initiative. A comprehensive review was conducted to unravel the confusion caused by the inconsistent use terminologies describing different reforestation initiatives, and to gain insight into motivations behind reforestation initiatives in recent literature (2000 to 2016). The results showed that there are 10 most common terminologies used to describe different reforestation initiatives. These terminologies were categorized into five groups based on their motivations, namely, (1) Creation or Fabrication, Reallocation and Replacement, (2) Ecological engineering, (3) Ecological restoration, (4) Reclamation, Reconstruction, Remediation, Renewal or Redemption, and (5) Rehabilitation. The recent reforestation initiatives were motivated by the need to reinstate resilient and more functional forest ecosystems (through the planting of a higher diversity of native tree species). This is because species diverse forests are more resilient and functional with significant contributions to biodiversity conservation (fauna and flora), climate change mitigation (carbon storage) and adaptation (e.g., flood control) and ecosystem services that sustain society (e.g., food) and economy (e.g., employment opportunities). Using the Buffelsdraai Landfill Site Community Reforestation Project (BLSCRP) as a case study, RobOff was employed to plan complex large-scale reforestation. The complexity was caused by a mosaic of habitats (‗extant forest‘ and ‗former sugarcane fields‘) with varying levels of degradation, diverse reforestation actions (natural regeneration, current action, carbon action and biodiversity action), a limited budget and multiple goals (biodiversity, carbon stock and employment). RobOff results showed that investing in the v restoration of ‗former sugarcane fields‘ through biodiversity action is preferable because it achieved the highest biodiversity, carbon stock and employment opportunities. Field trials were conducted at the Buffelsdraai Landfill Site to assess the influence of microtopographic positions, and soil physical and chemical properties on the growth performance of the four most dominant planted native tree species (Bridelia micrantha, Erythrina lysistemon, Millettia grandis and Vachellia natalitia). Root-collar diameter, stem height and canopy width growth rates were assessed across the chronosequence of three habitats under restoration (0-, 3-, and 5-year-old), in the upland (dry) and lowland (wet) areas of each habitat. Erythrina lysistemon and V. natalitia were found to be good fast growing tree species suitable for restoration in both the upland and lowland areas, while B. micrantha was suitable for lowland area. Reforestation success of the BLSCRP was assessed using measures of plant richness, diversity, vegetation structure, invasive alien plants (IAPs) and ecological processes, contrasted across a chronosequence of habitats under restoration (0-year-old, 3-year-old and 5-year-old) and compared with a reference forest habitat (natural forest). The BLSCRP was largely successful, but low tree density and an increase in IAP cover with an increase in restoration age were identified as threats to the BLSCRP success. The 2015 El Niño event induced serendipitous drought occurrence in South Africa led to the assessment of its effect on planted tree sapling mortality and on the growth performance of the four most dominant planted tree species in the 0-year-old habitat. Drought effected mortality was highest in the lowland area (34.1%) and lower in the upland area (18.9%). The mortality rate of the nine most abundant species ranged from 10% to 52.5%. Erythrina lysistemon and V. natalitia had good growth rates in both the upland and lowland areas and B. micrantha in the lowland area. The BLSCRP is highly likely to achieve its climate change mitigation and adaptation, biodiversity and ecosystem services restoration and employment creation in the city of Durban, provided the identified threats are addressed as soon as possible. The overall findings from this study showed that future large-scale reforestation initiatives around the globe should be designed to achieve biodiversity conservation, climate change mitigation and adaptation, and ecosystem services supply.
... Microorganisms 2021, 9, 1024 ...
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Isoprene, a volatile hydrocarbon emitted largely by plants, plays an important role in regulating the climate in diverse ways, such as reacting with free radicals in the atmosphere to produce greenhouse gases and pollutants. Isoprene is both deposited and formed in soil, where it can be consumed by some soil microbes, although much remains to be understood about isoprene consumption in tropical soils. In this study, isoprene-degrading bacteria from soils associated with tropical plants were investigated by cultivation and cultivation-independent approaches. Soil samples were taken from beneath selected framework forest trees and economic crops at different seasons, and isoprene degradation in soil microcosms was measured after 96 h of incubation. Isoprene losses were 4–31% and 15–52% in soils subjected to a lower (7.2 × 105 ppbv) and a higher (7.2 × 106 ppbv) concentration of isoprene, respectively. Sequencing of 16S rRNA genes revealed that bacterial communities in soil varied significantly across plant categories (framework trees versus economic crops) and the presence of isoprene, but not with isoprene concentration or season. Eight isoprene-degrading bacterial strains were isolated from the soils and, among these, four belong to the genera Ochrobactrum, Friedmanniella, Isoptericola and Cellulosimicrobium, which have not been previously shown to degrade isoprene.
... Castanopsis tribuloides (Sm.) A.DC. (Fagaceae) is one of framework tree species for forest replanting in degraded tropical forestlands in northern Thailand (Blakesley et al., 2002). C. tribuloides is a mediumsized, evergreen tree, up to 18 m tall. ...
... Las diferencias en los resultados de escarificación en el trabajo de Fernández et al. (2019), quien obtuvo 42 % de germinación con escarificación, se explicarían por el mayor debilitamiento de las mencionadas estructuras logrado por nuestra técnica. Blakesley et al. (2002) afirman que, los valores de germinación superiores al 60 % son recomendados para la restauración ecológica, de manera que los resultados obtenidos en T3 pueden considerarse adecuados para este fin. ...
Article
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Para llevar a cabo proyectos de restauración ecológica a gran escala, por ejemplo mediante la siembra directa o plantación, es necesario contar con grandes cantidades de semillas capaces de germinar. Un gran obstáculo que se presenta en tierras secas es que un alto porcentaje de especies tienen semillas con latencia. Particularmente en las zonas áridas más del 80 % de las especies de arbustos nativos tienen semillas que no germinan sin ruptura de la dormición, por lo que sin conocimientos de tratamientos germinativos eficaces se limitan extremadamente las posibilidades de aplicación de las mencionadas técnicas de siembra y plantación. Un problema adicional es la dificultad en la extracción de las semillas del fruto (particularmente cuando se pretende hacer esta tarea en grandes escalas), como ocurre en las especies del género Larrea. En este trabajo se presentan los resultados de la evaluación de tres tratamientos que se aplicaron simultáneamente en frutos y semillas de Larrea cuneifolia Cav. Dos alternativas consistieron en el remojo de frutos y produjeron bajos porcentajes de germinación (32,67 % y 35,67 %), sin diferencias significativas con el control. En cambio, un sistema de lijas accionadas por un taladro eléctrico brindó un promedio de 61,33 % de semillas germinadas. En este último tratamiento también se registró el menor tiempo medio de germinación (8.60 días) y el menor índice de inicio de germinación (2.40 días). Los resultados obtenidos con el sistema de lijas constituyen un primer avance hacia el desarrollo de tecnologías de bajo costo, aplicables a grandes cantidades de frutos y/o semillas, accesibles para su uso en poblaciones rurales en la lucha contra efectos ecológicos y sociales provocados por la desertificación.
... Indeed, dispersal strategy significantly influences the success of a colonising species in a restoration process, and is positively related to the capacity of the species for long-distance dispersal (Bochet and García-Fayos, 2015). Likewise, in order to optimize species selection, technical information concerning reproductive characteristics, such as natural regeneration potential and germinative requirements for sexual propagation is indispensable (Blakesley et al. 2002a(Blakesley et al. , 2002bElliott et al., 2003;Meli et al., 2014). Moreover, considering that native plant species may have high utilitarian potential, cultural criteria should be included when planning restoration (Meli et al., 2014;Molares and Rovere, 2014). ...
Article
Ecological functions, including pollination services, can be successfully restored in degraded ecosystems. In this study we propose a procedure for selection of target species to be employed in the restoration of plant-pollinator interactions in agricultural landscapes, which is illustrated by a case study located in the Tandilia System, in the Southern Pampa grasslands of Argentina. Based on information from a large pollination network dataset of 12 hills, composed of 172 pollinators and 96 plants (metaweb), we identified the plant species playing a major role in the maintenance of pollination mutualisms. We obtained a ranking of interaction frequency for each of the 96 plant species of the metaweb, and selected native plants that received more than 100 individual flower visitors. The targeted species were evaluated using ten criteria related to ecological, technical and cultural characteristics, and then ranked according to their suitability for use in restoration projects (species rank, SR). From the total number of plant species (96) registered for all sampled hills, we identified a total of 24 plant species that represented 90% of the total interactions and 25% of the plant species recorded in the metaweb. Six of the 24 selected species were excluded since they were non-native, leaving 18 targeted native plant species. The SR value ranged between 2.68 and 8, with a mean of 4.63 ± 1.40. Two genera presented the highest SR values (Eryngium sp. and Baccharis sp.), and are recognized as potential candidates for restoration of other ecosystems. A rank that evaluates plant species capable of rehabilitating plant-pollinator interactions will form a solid basis for planning restoration projects, which are crucial for biodiversity rehabilitation and conservation.
Article
This review provides a revised and expanded word-formula system of whole-seed primary dormancy classification that integrates the scheme of Nikolaeva with that of Baskin and Baskin. Notable changes include the following. (1) The number of named tiers (layers) in the classification hierarchy is increased from three to seven. (2) Formulae are provided for the known kinds of dormancy. (3) Seven subclasses of class morphological dormancy are designated: ‘dust seeds’ of mycoheterotrophs, holoparasites and autotrophs; diaspores of palms; and seeds with cryptogeal germination are new to the system. (4) Level non-deep physiological dormancy (PD) has been divided into two sublevels, each containing three types, and Type 6 is new to the system. (5) Subclass epicotyl PD with two levels, each with three types, has been added to class PD. (6) Level deep (regular) PD is divided into two types. (7) The simple and complex levels of class morphophysiological dormancy (MPD) have been expanded to 12 subclasses, 24 levels and 16 types. (8) Level non-deep simple epicotyl MPD with four types is added to the system. (9) Level deep simple regular epicotyl MPD is divided into four types. (10) Level deep simple double MPD is divided into two types. (11) Seeds with a water-impermeable seed coat in which the embryo-haustorium grows after germination ( Canna ) has been added to the class combinational dormancy. The hierarchical division of primary seed dormancy into many distinct categories highlights its great diversity and complexity at the whole-seed level, which can be expressed most accurately by dormancy formulae.
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The Thai government has recently embarked upon a nation-wide project to restore degraded forests. One approach could be to assist natural regeneration (ANR) by counteracting particular limiting factors, such as insufficient dispersal of tree seeds into cleared areas, lack of beneficial shade or excessive competition from weeds. This paper describes part of a 2-year project in northern Thailand which analysed, stage by stage, the regeneration from seed of a range of tree species in an abandoned agricultural clearing to identify limiting factors and develop appropriate ANR techniques to overcome them. Fruit production, seed dispersal, seed germination and seedling survival were monitored in the field. Experiments on selected species were carried out in the field and nursery to determine the effects of high light and low moisture on seed germination and the effect of above-ground weed interference on seedling performance in the first year. Three species are compared here to demonstrate how systematic study of regeneration processes can be of use in devising strategies to accelerate tree regeneration in deforested areas. Despite high levels of production of Beilschmiedia sp. seeds, the low rate of seed dispersal limited seedling recruitment in the clearing. In addition, seed germination was sharply reduced by lack of rainfall and the seedlings were highly susceptible to scorching by direct sunlight. Raising seedlings in nurseries and planting them out in degraded areas under the shade of existing herbaceous vegetation may be a suitable method of accelerating the regeneration of this species. Prunus cerasoides seeds were produced abundantly in both years of the study but seedling recruitment in the clearing was limited mainly by insufficient dispersal of its seeds into the cleared area. Under experimental conditions seeds germinated and seedlings established readily, so direct seed sowing in degraded areas may be appropriate. Alternatively, natural seed dispersal could be encouraged by improving the habitat for birds. Engelhardia spicata seeds were widely dispersed by wind and its regeneration was limited at the germination and early establishment stages. Physical obstruction by thick stem and leaf litter appeared to be a limiting factor. This barrier could be overcome by cutting back weeds (particularly grasses and ferns) or by shading them out with nurse trees.
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The nature of vegetation colonisation in four small rehabilitations and adjacent, protected control sites in tropical north Queensland were studied. Seven-year-old rehabilitation plots contiguous with forest had recruited up to seventy-two plant species across all growth forms and successional phases. Recruitment in 5-year-old plots was less abundant and diverse. Control sites by comparison were dominated by disclimax grasses and diversity of recruitment was reduced to only nineteen species at the upland control site. The effect of isolation on reducing abundance and diversity were demonstrated at one site located over 500 m from intact forest. Soil seed bank analysis was undertaken to examine any cumulative effect. Samples contained large numbers of weeds and grasses and only two native trees were recorded. The majority of species recorded in the plots were fleshy fruited zoochorous taxa, typical of plants in the early and intermediate stages of successional development, although a number of late successional species were also recorded. Fruit size and type suggests birds are responsible for most of the effective dispersal. The ability of ecologically rehabilitated areas to recruit and sustain new life forms is a true measure of their contribution to biodiversity conservation. In the tropics, the process of plant colonisation may be accelerated by establishing combinations of fleshy fruited native plant species from different stages of a normal forest succession, which attract seed dispersing birds and mammals.
Article
Seed germination in the seasonal tropical forest on Barro Colorado Island, Panama, was studied at the community level to (1) determine the seasonal timing of germination of the community, (2) identify primary selective factors controlling timing of germination, (3) determine the relative importance of dormancy vs. timing of seed dispersal as mechanisms controlling timing of germination, (4) examine inter- and intraspecific components of variance in length of dormancy, and (5) identify major seed germination syndromes. Three community-level measures of seedling emergence indicated that there was a unimodal community peak in germination within the first 2 mo of the 8-mo-long rainy season. Of the @?185 dicot, mostly woody, species germinating each year, the median time of emergence of 75% of the species occurred within the 1st 3 mo. There was a unimodal peak in germination in pioneer tree species, lianas, canopy trees, wind- and animal-dispersed species, and seedlings with and without persistent seed reserves. In contrast, there was no distinct peak period of emergence in understory species and shade-tolerant tree species. Initial seedling height of species emerging sequentially throughout the rainy season did not increase. The early emergence of most species, including three-fourths of the 35 species fruiting in the late rainy season, indicated that the early rainy season was the optimal time to emerge. Maximizing the length of the first growing season was not an important factor selecting for early emergence, because later-emerging species did not compensate for the shorter growing season by being larger at germination or by having seed reserves for rapid growth. Seedling-seedling competition is a primary biotic factor selecting for early emergence in pioneer species growing in the intensely competitive light-gap habitat. In shaded understory habitats, where competition among seedlings is much less intense, understory and shade-tolerant tree species emerged throughout the rainy season. Mean length of dormancy (MLD),the time between sowing and germination, of 157 woody dicot species on Barro Colorado Island ranged from 2 to 370 d. In over half the species, MLD exceeded 4 wk; hence, delays in germination are common. The season in which seeds were dispersed and the dispersal mechanism explained small but significant portions of the variance in MLD among species; life form explained none; but differences among three germination syndromes explained two-thirds of this variance. In the delayed-rainy syndrome (18% of all species) seeds were dispersed in the rainy season but were dormant until the beginning of the next rainy season, 4-8 mo later. Dormancy is the primary mechanism controlling time of germination. In the delayed-rainy syndrome and the intermediate-dry syndrome which follows, the length of the dormant period decreased as the interval between seed dispersal and the beginning of the rainy season decreased. In the intermediate-dry syndrome (42% of all species) seeds were dispersed during the during the dry season and remained dormant until the beginning of the rainy season. Seeds are primarily dispersed 1-2 mo before the beginning of the rainy season, which reduces the number of false germination cues encountered and decreases the length of time seeds are exposed to postdispersal predation while dormancy prevents germination during dry season rains. In the rapid-rainy syndrome (40% of all species) seeds were dispersed in the rainy season and germinated during, but not early in, that season. Dormancy has been replaced entirely by timing of dispersal as a mechanism controlling time of germination. Half of these species germinated in
Article
Clonal propagation in vitro of raisin tree (Hovenia dulcis Thunb.) was achieved using axillary buds from mature trees and young plants. Explants cultured on Murashige-Skoog’s medium with 1/3 of the original salt concentration, supplemented with 0.5 mg l-1 BAP and 0.5 mg l-1 IAA, showed proliferation of new shoots in 4-5 weeks. Adventitious shoot proliferation was also stimulated in subsequent subcultures in the presence of BAP. The shoots rooted when transferred to 1/3 Murashlge and Skoog’s medium with 0.1 mg l-1 of IBA. Plantlets thus formed were successfully transplanted to the field after a short acclimatization period.
Article
Acclimation in seedlings of Bischofia javanica Blume, which are commonly found in canopy gaps in the moist forests of tropical Asia, to a change in light availability was examined in a controlled environment simulating forest shade and daylight. Seedlings were grown in a high (1000 micro mol m(-2) s(-1); red/far-red, 1.45) or low (40 micro mol m(-2) s(-1); red/far-red, 0.10) light regime and then transferred to the contrasting light environment for nine weeks. Control seedlings were maintained in the same light regime throughout the study. The availability of light influenced relative growth rate through morphological and physiological adjustments. Transferred seedlings retained the leaves that had been developed before transfer, and no leaf-shedding was observed till the end of the experiment. Leaves formed in the new light regime were physiologically and morphologically identical to those of the corresponding controls. High-light seedlings transferred to low light displayed significantly lower relative growth rate than the low-light controls because of a lower leaf area ratio carried over from the previous high-light environment. A reverse pattern of response with respect to relative growth rate was observed for the low-light seedlings transferred to high light compared to the high-light controls. The higher relative growth rate in the low-light seedlings transferred to high light was the result of higher net assimilation rate and higher leaf area ratio. The higher leaf area ratio in the low-light seedlings transferred to high light was the consequence of the effects of previous environment, and the relatively lower net assimilation rate in the high-light control seedlings was, at least partly, due to the effects of self-shading rather than to the photosynthetic capacity of the leaves. The results suggest that the species has a wide acclimation potential to a change in light availability that might occur in nature following gap creation or canopy closure.
Forest restoration research in northern Thailand. 1. D. Blakesley et al 37 rFruits, seeds and seedlings of Hovenia dulcis Thunb
  • S Kopachon
  • K Suriya
  • K Hardwick
  • G Pakaad
  • J F Maxwell
  • V Anusarnsunthorn
  • N C Garwood
  • D Blakesley
  • S Elliott
Kopachon, S., Suriya, K., Hardwick, K., Pakaad, G., Maxwell, J.F., Anusarnsunthorn, V., Garwood, N.C., Blakesley, D., Elliott, S., 1996. Forest restoration research in northern Thailand. 1. D. Blakesley et al./Forest Ecology and Management 164 (2002) 31–38 37 rFruits, seeds and seedlings of Hovenia dulcis Thunb. Nat. Hist. Bull. Siam. Soc. 44, 41–52
Germination requirements of Hovenia dulcis seeds
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Frett, J.J., 1989. Germination requirements of Hovenia dulcis seeds. Hortscience 24, 152.
Repairing the Rainforest— Theory and Practice of Rainforest Re-establishment in North Queensland's Wet Tropics Wet Tropics Management Author-ity Understanding and assisting natural regenera-tion processes in degraded seasonal evergreen forests in northern Thailand
  • S P Goosem
  • N I J Tucker
Goosem, S.P., Tucker, N.I.J., 1995. Repairing the Rainforest— Theory and Practice of Rainforest Re-establishment in North Queensland's Wet Tropics. Wet Tropics Management Author-ity, Cairns, pp. 71. Hardwick, K., Healey, J., Elliott, S., Garwood, N.C., Anusarnsun-thorn, V., 1997. Understanding and assisting natural regenera-tion processes in degraded seasonal evergreen forests in northern Thailand. For. Ecol. Manage. 99, 203–214.
Tropical Forest Remnants: Ecology, Management and Conservation of Fragmented Communities
  • D Lamb
  • J Parrotta
  • R Keenan
  • N I J Tucker
Lamb, D., Parrotta, J., Keenan, R., Tucker, N.I.J., 1997. Rejoining habitat remnants: restoring degraded rainforest lands. In: Laurence, W.F., Bierrgaard Jr., R.O. (Eds.), Tropical Forest Remnants: Ecology, Management and Conservation of Fragmented Communities. University of Chicago Press, Chicago, IL, pp. 366-385.