DIVERSITY OF PLANTS NATURALLY GROW IN TROPICAL DRY FOREST (T-df) OF BUKIT JIMBARAN BALI

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Teknologi Indonesia © LIPI Press 2013

DIVERSITY OF PLANTS NATURALLY GROW IN TROPICAL DRY FOREST (T-df) OF BUKIT JIMBARAN BALI

Wawan Sujarwo1,2) and Ida Bagus Ketut Arinasa1)

“Eka Karya” Bali Botanic Garden - Indonesian Institute of Sciences (LIPI)1)

Candikuning, Baturiti, Tabanan, Bali 82191, Indonesia 1)

Department of Science, the University Roma Tre, Italy2)

Viale G. Marconi 446 Rome, Italy2)

E-mail: [email protected]; [email protected]

Received: 18/06/2013 Revised: 09/10/2013 Accepted: 29/10/2013

ABSTRACTBukit Jimbaran Bali is considered one of the dry areas on Bali Island. The climate is very dry during the year

and has very limited rainfall in the rainy season. The aim of our study is to review the ecology of natural regeneration of T-df, focusing on how the available information can be used to facilitate the recovery of these forests in disturbed areas. Tropical dry forest around Udayana University, which is situated in Bukit Jimbaran Bali, was selected as the investigation area since there was an ongoing CSR (corporate social responsibility) project for establishing urban forest at Udayana University. Sampling plots were established to determine plant diversity of seedlings, saplings, poles, and trees. Research results revealed high diversity of seedlings (40 species) and saplings (35 species) while trees were limited (11 species). We have come to the conclusion that groundcover diversity is high enough (75 species) even though the soil depth is very thin. In addition, there was abundant Acacia auriculiformis which is considered as an invasive species in the area.

Keywords: Floristic composition, natural regeneration, tropical dry forest, Bukit Jimbaran Bali.

ABSTRAKBukit Jimbaran Bali merupakan salah satu daerah kering di Pulau Bali. Iklimnya sangat kering sepanjang

tahun, dengan curah hujan yang sangat terbatas pada musim penghujan. Tujuan dari penelitian kami adalah untuk mengulas ekologi regenerasi alami hutan tropis kering, dengan berfokus pada bagaimana informasi yang tersedia dapat digunakan untuk memfasilitasi pemulihan hutan di daerah terganggu. Hutan tropis kering di sekitar Uni-versitas Udayana yang terletak di Bukit Jimbaran Bali dipilih sebagai obyek penelitian, mengingat di sana tengah berlangsung proyek CSR (corporate social responsibility) pembangunan hutan kota Universitas Udayana. Sam-pling plot dibuat untuk menentukan keanekaragaman tanaman bibit, pancang, tiang, dan pohon. Hasil penelitian mengungkapkan tingginya keragaman bibit (40 spesies) dan anakan (35 spesies) sementara pohon keragamannya terbatas (11 spesies). Kami menyimpulkan bahwa keragaman tanaman penutup tanah (groundcover) cukup tinggi (75 spesies) meskipun kedalaman tanah (solum) sangat tipis. Selain itu, ditemukan Acacia auriculiformis yang melimpah, yang diduga dapat menjadi spesies invasif di area hutan tropis kering sekitar Universitas Udayana Bukit Jimbaran Bali.

Kata kunci: Komposisi fl ora, regenerasi alami, hutan tropis kering, Bukit Jimbaran Bali.

INTRODUCTIONThere are three reasons to review the ecology of natural regeneration in dry tropical forests (T-df). First, T-df, which originally represented 42% of the tropical vegetation worldwide, is the most threatened tropical terrestrial ecosystem, due to the conversion of these areas into agricultural

land.[1,2,3] Thus, scientifi c knowledge, specifi cally regarding regeneration pathways, is crucial to the restoration of these forests. Second, there have been insuffi cient studies of T-df to date.[1,2,3] Third, T-df has particular natural regeneration attributes that need to be clarifi ed. Although these regeneration characteristics can be limiting in

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Teknologi Indonesia 36 (2) 2013

certain situations, they can also be used to assist in the recovery of these forests.

The tropical dry forest (T-df) encompasses 42% of all tropical forests and contains a wealth of unique biodiversity. It is, however, among the least protected ecosystems due to anthropogenic and economic pressures.[1] The T-df is character-ized by a bio-temperature (average of the Celsius temperatures where vegetation growth takes place relative to the annual period), a potential evapotranspiration to precipitation ratio of 1–2 and 500–2000 mm of precipitation a year with 4–6 months of little or no precipitation.

Due in part to the long dry season the common phenological response for the majority of the woody species is drought deciduousness. However, the number of species and individuals with this response varies strongly with suc-cessional stage (stage of regeneration) and topography. A mix of deciduous (with variable timing of leaf fall) and evergreen species gives the T-df a kind of phenological complexity not encountered in wet forests.

In Indonesia, the T-df in many areas is not a pristine old-growth forest, but rather a mosaic of successional stages due to extensive anthropogenic disturbance. The aim of our study is to review the ecology of natural regeneration of T-df, focusing on how the available information can be used to facilitate the recovery of these forests in disturbed areas.

METHODSStudy AreaSeveral areas of Bukit Jimbaran Bali are covered with a bare land and secondary growth in various stages of regeneration. The climate diagram for Bukit Jimbaran Bali illustrates an 8-month dry season and the total yearly precipitation in Bukit Jimbaran is highly variable (915–2558 mm per year). The entire region encompassing Bukit Jimbaran Bali has suffered from intense drought. One of the predominant causes for disturbing the forest was to make room for grazing. The other preferred land use in this area was agriculture.

Field MeasurementsIn 3 stage plots (20 m in diameter), we identifi ed and measured the diameter at breast height (DBH) of all living woody stems with a DBH equal to or greater than 5 cm. For multi-stemmed individuals, each stem with a DBH ≥ 5 cm was considered as an individual. We also measured the groundcover species in each plot.

RESULTS AND DISCUSSION The species composition for each plot is illus tra-ted in a Table as follows.

Table 1 shows the woody species in the fi rst plot from 3 species: Azadirachta indica, Santalum album, and Ziziphus nummularia. There are 3 families consisting of 6 individual trees. The diversity of woody species in this plot is very limited; in the area of 314 m2 only 3 species were found. If we look at the diameter and height of the trees, those trees are very small in diameter and height. This can be caused by limited solum (soil depth is very thin) as well as low precipitation. On the other hand, we found other disturbance from the local people because they always look at the trees for fi rewood. The fi rst plot is situated close to a settlement.

T-df occurs in tropical regions with several months of severe or absolute drought.[1] Tropical and subtropical dry forests occur in frost-free areas where the mean annual bio-temperature is above 17oC, annual mean precipitation ranges from 250 to 2,000 mm, and potential evaporation is greater than precipitation for a signifi cant part of the year. Tropical dry forests have 10 tree species (based on surveys of 300–1000 m2) and 5–15 m of canopy height, although there is a great variation among sites.

Table 2 shows there are 9 families consisting of 11 species, and 99 saplings. Those species are Azadirachta indica, Breynia microphylla, Calotropis gigantea, Cassia fistula, Cassia surattensis, Diospyros macrophylla, Flacourtia indica, Jatropha gossypiifolia, Lantana camara, Santalum album, and Ziziphus nummularia.

Seedlings identifi ed in the fi rst plot consist of 6 families, 9 species and more than 200 seedlings (Table 3). Those species are Amorphophalus

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Wawan Sujarwo And Ida Bagus Ketut Arinasa | Diversity of Plants Naturally Grow ...

Table 1. List of woody species/trees (DBH ≥ 5 cm) identifi ed in the 1st plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 15o)

No. Species Family Diameter (cm) Height (m)1 Azadirachta indica A. Juss. Meliaceae 14 42 Santalum album L. Santalaceae 10 33 Ziziphus nummularia (Burm. f.) W. & A. Rhamnaceae 10 2.54 Ziziphus nummularia (Burm. f.) W. & A. Rhamnaceae 10 35 Ziziphus nummularia (Burm. f.) W. & A. Rhamnaceae 14 36 Ziziphus nummularia (Burm. f.) W. & A. Rhamnaceae 20 3

Table 2. List of saplings identifi ed in the 1st plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 15o)

No. Species Family Popula on/individu1 Azadirachta indica A. Juss. Meliaceae 12 Breynia microphylla (Kurz ex T. B.) M. A. Euphorbiaceae 23 Calotropis gigantea (Willd.) Dryand.ex.W. T. Ait. Asclepiadaceae 14 Cassia fi stula L. Fabaceae 15 Cassia sura ensis Burm.f. Fabaceae 16 Diospyros macrophylla Bl. Ebenaceae 67 Flacour a indica (Burm.f.) Merr. Flacour aceae 108 Jatropha gossypiifolia L. Euphorbiaceae 569 Lantana camara L. Verbenaceae 8

10 Santalum album L. Santalaceae 911 Ziziphus nummularia (Burm. f.) W. & A. Rhamnaceae 4

Table 3. List of seedlings identifi ed in the 1st plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 15o)

No. Species Family Popula on/individu1 Amorphophalus campanulatus (Roxb.) Bl. ex Decne Araceae 62 Cassia suratensis Burm.f. Fabaceae 33 Eleusine indica (L.) Gaertn. Poaceae 54 Eupatorium odoratum L. Asteraceae 555 Indigofera nctoria L. Fabaceae 206 Ipomoea maxima (L. f.) G. Don ex Sweet Convolvulaceae >1007 Mimosa pudica L. Fabaceae 18 Phyllanthus niruri L. Euphorbiaceae 409 Tephrosia candida (Roxb.) DC. Fabaceae 2

campanulatus, Cassia suratensis, Eleusine in-dica, Eupatorium odoratum, Indigofera tinctoria, Ipomoea maxima, Mimosa pudica, Phyllanthus niruri, and Tephrosia candida. In the fi rst plot, sapling is ranked fi rst, followed by seedling and tree in term of species richness.

T-df grows slower than wet forests; they can recover their relatively simple mature structure after disturbance more rapidly than wet forests which have a more complex structure.[4] For T-df, the timing of seed dispersal is very predictable.

Fleshy-fruit maturation is concentrated in the rainy season whereas wind-dispersed and gravity-dispersed fruits mature mostly in the dry season.[5] Although the dispersal of animal dispersed species occurs during the rainy season, most of these seeds remain dormant until the beginning of the next rainy season in seasonal forests. Thus, there has been selection for early rainy season germination in seasonal forests,[6] because it maximizes the length of the fi rst rainy season for the seedling, potentially increasing growth and the probability of survival.

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The arrival of consistent rainfall is unpredict-able, and at the beginning of the rainy season there may be dry spells that last for as long as 2 weeks. Delays in the fi rst rains and dry spells are strong sources of mortality due to desiccation in seeds and recently germinated seedlings in T-df.[7]

The woody species found in the second plot consist of 8 families, 9 species, and 16 individual

Table 4. List of woody species/trees (DBH ≥ 5 cm) identifi ed in the 2nd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No. Species Family Diameter (cm) Height (m)1 Azadirachta indica A. Juss. Meliaceae 10 52 Azadirachta indica A. Juss. Meliaceae 11 33 Azadirachta indica A. Juss. Meliaceae 11 34 Azadirachta indica A.Juss. Meliaceae 12 55 Cassia fi stulosa L. Fabaceae 20 56 Gliricidia sepium Steud Fabaceae 9 37 Flacour a indica (Burm.f.) Merr. Flacour aceae 12 38 Lannea grandis Engl. Anacardiaceae 14 79 Lannea grandis Engl. Anacardiaceae 15 7

10 Lannea grandis Engl. Anacardiaceae 15 711 Lannea grandis Engl. Anacardiaceae 16 712 Lannea grandis Engl. Anacardiaceae 16 713 Sterculia foe da L. Sterculiaceae 12 314 Streblus asper Lour. Moraceae 10 415 Unknown Euphorbiaceae 10 416 Ziziphus nummularia Burm. f.) W. & A. Rhamnaceae 13 5

trees (Table 4). Those species seem similar in term of diameter and height, but in fact they are different individuals even though some species are the same. This refers to T-df which was entering secondary succession after strong disturbance in the past.

Table 5 shows that there are 13 families consisting of 19 species, and 159 saplings. Those

Table 5. List of saplings identifi ed in the 2nd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No. Species Family Popula on/individu1 Azadirachta indica A. Juss. Meliaceae 122 Blighia sapida Koenig Sapindaceae 103 Bridelia monoica (Lour.) Merr. Euphorbiaceae 44 Capparis micracantha DC. Capparaceae 35 Capparis sp. Capparaceae 46 Cipadessa baccifera (Roth) Miq. Meliaceae 57 Clerodendrum sp. Verbenaceae 18 Dichroa febrifuga Lour. Hydrangeaceae 19 Diospyros macrophylla Bl. Ebenaceae 6

10 Flacour a indica (Burm.f.) Merr. Flacour aceae 2411 Glochidion sp. Euphorbiaceae 312 Gloriosa superba L. Liliaceae 113 Jathropa gossypifolia L. Euphorbiaceae 2514 Lantana camara L. Verbenaceae 2815 Phanera fulfa (Bl.ex Korth.) Bth. Fabaceae 1216 Premna corymbosa (Burm. f.) Ro l. & Willd. Verbenaceae 317 Schleichera oleosa (Lour.) Oken Sapindaceae 218 Uvaria rufa Bl. Annonaceae 319 Ziziphus sp. Rhamnaceae 12

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Table 6. List of seedlings identifi ed in the 2nd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No. Species Family Popula on/individu

1 Amorphophalus campanulatus (Roxb.) Bl. ex Decne Araceae 32 Amorphophalus paeoniifolius (Dennst.) Nicolson Araceae 33 Desmodium heterophyllum (Wild.) DC. Fabaceae 74 Eupatorium odoratum L. Asteraceae 255 Phanera fulfa (Bl.ex Korth.) Bth. Fabaceae 156 Tetras gma laevigatum (Bl.) Gagnep. Vitaceae 17 Zingiber purpureum Roxb. Zingibraceae 3

species are Azadirachta indica, Blighia sapida, Bridelia monoica, Capparis micracantha, Cap-paris sp., Cipadessa baccifera, Clerodendrum sp., Dichroa febrifuga, Diospyros macrophylla, Flacourtia indica, Glochidion sp., Gloriosa superba, Jathropa gossypifolia, Lantana camara, Phanera fulfa, Premna corymbosa, Schleichera oleosa, Uvaria rufa, and Ziziphus sp.

Seedlings identifi ed in the second plot con-sisting of 5 families, 7 species, and 57 seedlings (Table 6). Those species are Amorphophalus

campanulatus, Amorphophalus paeoniifolius, Desmodium heterophyllum, Eupatorium odora-tum, Phanera fulfa, Tetrastigma laevigatum, and Zingiber purpureum. In the second plot, sapling is more diverse and populous than seedling and tree. It is similar with results in the fi rst plot where sapling has highest diversity rather than seedling and tree.

The woody species identifi ed in the third plot is only Acacia auriculiformis with 23 different individual (Table 7). This species is considered

Table 7. List of woody species/trees (DBH ≥ 5 cm) identifi ed in the 3nd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No Species Family Diamater (cm) Height (m)1 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 5 32 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 5 33 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 5 34 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 5 55 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 5 66 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 6 47 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 6 48 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 6 59 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 7 4

10 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 7 411 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 7 512 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 7 513 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 8 514 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 8 715 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 8 716 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 8 817 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 10 518 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 12 919 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 12 1020 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 15 821 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 15 1022 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 15 1223 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 17 9

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Table 8. List of saplings identifi ed in the 3rd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No Species Family Popula on/individu1 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 122 Alstonia scholaris (L.) R.Br Apocynaceae 43 Bridelia monoica (Lour.) Merr. Euphorbiaceae 24 Cordia subcordata Lamk Boraginaceae 45 Euphorbia rucalli L. Euphorbiaceae 86 Ficus sep ca Burm.f. Moraceae 47 Flacour a indica (Burm.f.) Merr. Flacour aceae 38 Morinda citrifolia L. Rubiaceae 19 Phyllanthus offi cinalis Gaertn Euphorbiaceae 6

10 Raufolvia serpen na (L.) Bth.ex Kurz Apocynaceae 111 Ricinus communis L. Euphorbiaceae 112 Santalum album L. Santalaceae 113 Sapium sabiferum (L.) Roxb Euphorbiaceae 814 Zyzygium aqueum (Burm.f.) Alst. Myrtaceae 2

as an invasive species due to its abundance. In the third plot, Acacia auriculiformis dominates among other species, and can be found not only as tree but also as sapling and seedling.

Table 8 shows there are 9 families consisting of 14 species and 57 saplings. Those species are Acacia auriculiformis, Alstonia scholaris, Bridelia monoica, Cordia subcordata, Euphorbia tirucalli, Ficus septica, Flacourtia indica, Morinda citrifolia, Phyllanthus offi cinalis, Rau-folvia serpentina, Ricinus communis, Santalum album, Sapium sabiferum, and Zyzygium aqueum.

Seedlings identifi ed in the third plot consist of 28 families, 35 species, and more than 550 seedlings (Table 9). The third plot is the richest site in term of groundcover diversity among others. This might be affected by wind-dispersed seeds that are not strongly affected by fragmentation. Wind-dispersed seeds arrive in higher density than vertebrate-dispersed seeds up to a few hundred meters from the source of propagules.[8,9] For instance, anemochoric seeds are 47 times more frequent than animal-dispersed seeds (3 vs. 141 seeds m-2 year-1) in open pastures up to 250 m from the adjacent forest.[10] Thus, the lack of seed arrival in open areas, a major limitation for forest regeneration, is overcome at some level by wind-dispersed seeds. This high capacity of colonization has contributed to an over-representation of wind-dispersed species in some tropical pastures and in some tropical

and subtropical secondary forests.[11,12] On the other hand, trees or shrubs present in abandoned agricultural areas provide perches for birds and bats, increasing the number of vertebrate-dispersed seeds up to one hundred times relative to open areas.[13,14]

Figure 1 shows an ordination diagram using DCA and reveals that mostly obtained species are grouped. It represents those species having positive correlation among others. If we look at the distance among grouped species, it is not wide in range. This is because T-df Bukit Jimbaran Bali is not a large forest and is fragmented by settlement and Udayana University.

Grouped species refers to a good regeneration by seeds. Few species have seed banks in tropical forests in general[15] and in T-df in particular.[15,16] Hence, autochthonous seed banks will rarely contribute to the regeneration of deforested tropical dry forest areas.[16] However, there is high seed availability in the soil at the end of the dry season. Therefore, collecting this transient seed bank (i.e., litter and soil) from forested areas at the end of the dry season and disposing it onto degraded areas seems to be a promising strategy for dry forest reforestation.

Seed germination and early seedling es-tablishment are highly limited by water in dry tropical forests.[6,7,17] Shaded sites become safe sites because the shade counteracts the water limitation in low rainfall periods and reduces

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seed and seedling desiccation.[7] Although many T-df tree species need large canopy gaps to regenerate,[18] seed germination and early seedling establishment are constrained in open areas, even for light demanding species.[7,18] However, interaction between precipitation, soil depth, and dominant species cover determines the facilitative or competitive role of plant cover. In harsh habitats, plant cover successfully facilitates recruitment and growth,[20] whereas seed germination is higher under plant cover. Seedling growth is reduced in these areas when compared to open areas during the rainy season

or with supplemental water. Seedlings growing in open areas reach the canopy faster and can develop into saplings and adults that will shade undesirable species

Different requirements for germination, survival, and growth make management dif-fi cult. If germination and early establishment are favored by shade, and established seedlings are favored in open areas, the recommended management would be clipping undesired plants around established seedlings and saplings.

Studies conducted in a T-df in Ghana, for instance, found high tree-seedling density and

Table 9. List of seedlings identifi ed in the 3nd plot in the dry forest of Bukit Jimbaran Bali (0–100 m elevation; slope 10o)

No. Species Family Popula on/individu1 Abu lon indicum (L.) Sweet. Malvaceae 52 Acacia auriculiformis A.Cunn. ex Bth. Fabaceae 453 Adiantum philippense Adiantaceae 104 Amorphophalus paeoniifolius (Dennst.) Nicolson Araceae 95 Andrographis paniculata (Burm.f.) Nees Acanthaceae 176 Anisomeles indica (L.) O.K. Lamiaceae 87 Bridelia monoica (Lour.) Merr. Euphorbiaceae 48 Caesalpinia bonduc (L) Roxb Fabaceae 99 Callotropis gigantea (Willd.) Dryand.ex. W.T.Ait. Asclepiadaceae 5

10 Canavalia sp. Fabaceae 711 Caparis micracantha DC. Capparacrae 712 Cayra a trifolia (L.) Domin Vitaceae 513 Cipadessa baccifera (Roth) Miq Meliaceae 514 Cordia subcordata Lamk Boraginaceae 315 Cyperus rotundus L. Cyperaceae 2816 Desmodium heterophyllum (Wild.) DC. Fabaceae 717 Diospyros macrophylla Bl. Ebenaceae 518 Eleusine indica (L.) Gaertn. Poaceae 1519 Eupatorium odoratum Lf. Asteraceae 5020 Flacour a indica (Burm.f.) Merr. Flacour aceae 921 Geodorum densifl orum (Lamark) Schltr. Orchidaceae 822 Indigofera nctoria L. Fabaceae 2423 Ipomoea maxima (L. f.) G. Don ex Sweet Convolvulaceae >10024 Jasminum mul fl orum (Burm. f.) Andr. Oleaceae 725 Jatropha gossypifolia L. Euphorbiaceae 3326 Lantana camara L Verbenaceae 3627 Momordica charan a L. Cucurbitaceae 1028 Mun ngia calabura L. Elaeocarpaceae 729 Oplismenus burmani (Retz.) Beauv. Poaceae 1030 Phyllanthus niruri L Euphorbiaceae 2531 Santalum album L. Santalaceae 632 Tacca palmata Bl. Taccaceae 433 Tephrosia candida (Roxb.) DC. Fabaceae 1934 Uvaria rufa Bl. Annonaceae 835 Zingiber purpureum Roxb. Zingibraceae 6

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diversity under pure stands of an aggressive pioneer shrub, and those seedlings had higher growth and survival rates after the shrubs were removed.[21] This management strategy could be applicable to any type of plant cover, such as grasses and forbs in abandoned agricultural areas and lianas in felling gaps.

There is still much speculation on this topic, but it is essential for understanding the traits or identities of strong sprouters to be able to (1) use branch cuttings of these species as nurse trees in reforestation plans; (2) invest in reforestation of weak or nonsprouter species in early succes-sional forests dominated by resprouters; and (3) help understand present and future community composition.[4,22]

Future research should focus on selecting species, and developing and testing methods of vegetative propagation for reforestation program (i.e. establishing urban forest). Most manage-ment strategies recommended in this study are applicable only for part of the community; each species should thus be evaluated for the suitability of the proposed management. Species that are not expected to benefi t from existing management strategies deserve special attention.

This study is a fi rst attempt to fulfi ll the demand for research into establishing urban forest which is close to the T-df. We expect that, before long, more studies will be available and that future research regarding this highly variable ecosystem will develop. Deciduousness,

Figure 1. Ordination diagram using DCA (detrended correspondence analysis)

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biomass, and other structural parameters, as well as abiotic aspects such as soil fertility, total precipitation, size and strength of the dry season, and its interactions with temperature, could be used to narrow the scope of a future review, which would generate more defi nitive and useful recommendations for reforestation.

The guidelines proposed here are based on the ecology of natural regeneration and have not been fully tested as tools for management. Each site in each region will have its own set of suitable management strategies. Available budget and other logistic limitations must also be taken into account in order to select the best tools to restore each forest. Because of economic limitations for the conservation of tropical forests, assisting natural regeneration seems the most reliable option.[21,23]

CONCLUSIONSThe high proportion of groundcover species, small seeded, wind-dispersed species, and the high ability of sprouting after disturbance, and the relatively simple community diversity and structure all confer a high potential for T-df recovery. In addition, the current dominance of Acacia auriculiformis is a consequence of wind-dispersed species.

ACKNOWLEDGEMENTThis work was supported by Indonesian State Bank (BNI 46) which has sponsored projects on “Establishment of Urban Forest in Bukit Jimbaran Bali” in collaboration with Udayana University. We also thank anonymous reviewers for their constructive comments to improve the manuscript.

REFERENCES[1] Mooney, H. A., S.H. Bullock., E. Medina.

1995. “Introduction”, In Mooney, H.A., S. H. Bullock, E. Medina (Eds.). Seasonally Dry Tropical Forests. Cambridge: Cambridge University Press, pp. 1–8.

[2] Khurana, E., and J. S. Singh. 2001. “Ecology of seed and seedling growth for conserva-

tion and restoration of tropical dry forest: a review”. Environmental Conservation 28, pp. 39–52.

[3] Sanchez-Azofeifa, G. A., M. Kalacska, M. Quesada, J. C. Calvo-Alvarado, J. M. Nas-sar, and J. P. Rodrı´guez. 2005. “Need for integrated research for a sustainable future in tropical dry forests”. Conservation Biology 19, pp. 285–286.

[4] Kennard, D. K. 2002. “Secondary forest succession in a tropical dry forest: patterns of development across a 50-year chrono-sequence in lowland Bolivia”. Journal of Tropical Ecology 18, pp. 53–66.

[5] Griz, L. M. S., and I. C. S. Machado. 2001. “Fruiting phenology and seed dispersal syn-dromes in caatinga, a tropical dry forest in the Northeast of Brazil”. Journal of Tropical Ecology 17, pp. 303–321.

[6] Marod, D., U. Kutintara, H. Tanaka, and T. Nakashizuka. 2002. “The effects of drought and fi re on seed and seedling dynamics in a tropical seasonal forest in Thailand”. Plant Ecology 161, pp. 41–57.

[7] McLaren, K. P., and M. A. McDonald. 2003. “The effects of moisture and shade on seed germination and seedling survival in a tropi-cal dry forest in Jamaica”. Forest Ecology and Management 183, pp. 61–75.

[8] Zimmerman, J. K., J. B. Pascarella, and T. M. Aide. 2000. “Barriers to forest regeneration in an abandoned pasture in Puerto Rico”. Restoration Ecology 8, pp. 350–360.

[9] Cubina, A., and T. M. Aide. 2001. “The effect of distance from forest edge on seed rain and soil seed bank in a tropical pasture”. Biotro-pica 33, pp. 260–267.

[10] Holl, K. D. 1999. “Factors limiting tropical rain forest regeneration in abandoned pas-ture: seed rain, seed germination, microcli-mate, and soil”. Biotropica 31, pp. 229–242.

[11] Finegan, B., and D. Delgado. 2000. “Struc-tural and fl oristic heterogeneity in a 30-year-old Costa Rican rain forest restored, on pas-ture through natural secondary succession”. Restoration Ecology 8, pp. 380–393.

[12] Marcano-Vega, H., T. M. Aide, and D. Baez. 2002. “Forest regeneration in abandoned cof-fee plantations and pastures in the Cordillera

96


Central of Puerto Rico”. Plant Ecology 161, pp. 75–87.

[13] da Silva, J. M. C., C. Uhl, and G. Murray. 1996. “Plant succession, landscape manage-ment, and the ecology of frugivorous birds in abandoned Amazonian pastures”. Conserva-tion Biology 10, pp. 491–503.

[14] Slocum, M. G., and C. C. Horvitz. 2000. “Seed arrival under different genera of trees in a neotropical pasture”. Plant Ecology 149, pp. 51– 62.

[15] Skoglund, J. 1992. “The role of seed banks in vegetation dynamics and restoration of dry tropical ecosystems”. Journal of Vegetation Science 3, pp. 357–360.

[16] Cabin, R. J., S. G. Weller, D. H. Lorence, S. Cordell, and L. J. Hadway. 2002. “Effects of microsite, water, weeding, and direct seeding on the regeneration of native and alien spe-cies within a Hawaiian dry forest preserve”. Biological Conservation 104, pp. 181–190.

[17] McLaren, K. P., and M. A. McDonald. 2003. “Seedling dynamics after different intensities of human disturbance in a tropical dry limestone forest inJamaica”. Journal of Tropical Ecology 19, pp. 567–578.

[18] Dickinson, M. B., D. F. Whigham, and S. M. Hermann. 2000. “Tree regeneration in felling and natural treefall disturbances in a semideciduous tropical forest in Mexico”. Forest Ecology and Management 134, pp. 137–151.

[19] Woods, K., and S. Elliott. 2004. “Direct seedling for forest restoration on abandoned agricultural land in northern Thailand”. Journal of Tropical Forest Science 16, pp. 248–259.

[20] Duncan, R. S., and C. A. Chapman. 2003. “Consequences of plantation harvest during tropical forest restoration in Uganda”. Forest Ecology and Management 173, pp. 235–250.

[21] Honu, Y. A. K., and Q. L. Dang. 2002. “Spatial distribution and species composition of tree seeds and seedlings under the canopy of the shrub, Chromolaena odorata Linn., in Ghana”. Forest Ecology and Management 164, pp.185–196.

[22] Saha, S., and H. F. Howe. 2003. “Species composition and fi re in a dry deciduous for-est”. Ecology 84, pp. 3118–3123.

[23] Hardwick, K., J. Healey, S. Elliott, N. Garwood, and V. Anusarnsunthorn. 1997. “Understanding and assisting natural regen-eration processes in degraded seasonal ever-green forests in northern Thailand”. Forest Ecology and Management 99, pp. 203–214.

DIVERSITY OF PLANTS NATURALLY GROW IN TROPICAL DRY FOREST (T-df) OF BUKIT JIMBARAN BALI

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