1 38 Journal of Tropical Forest Science 4 (199639 - 8(3) 1 ) :38 EARLY PERFORMANC SHAD2 1 F EO E TOLERANT TREE SPECIES INTER PLANTED WITH PARASERIANTHES FALCATARIA IMPERATAN O CYLINDRICA GRASSLAND Riikka Otsamo*, Jl. Lombok 5, 70711 Banjarbaru, Kalimantan Selatan, Indonesia Goran Adjers, EnsoPT. Forest Indonesia, WidjojoS. Centre, Floor,5th JenderalJl. Sudirman Jakarta71, Selatan, 12190, Indonesia Tjuk Sasmito Hadi, Balai Teknologi Reboisasi Banjarbaru, P.O. Box 65, Jl. Set Ulin 28 B, 70714 Banjarbaru, Kalimantan Selatan, Indonesia Jussi Kuusipalo & Antti Otsamo Enso Forest Development Ltd., Reforestation Tropicaland Forest Management Project, Balaic/o Teknologi Reboisasi Banjarbaru, 70714UlinB, Sei 28 Jl. Banjarbaru, 65, P.O. Box Kalimantan Selatan, Indonesia Received November 1994 ______ _ __ ______ OTSAMO, R., ADJERS, G., HADI, T. S., KUUSIPALO, J. & OTSAMO, A. 1996. Early performance of 12 shade tolerant tree species interplanted with Paraserianthes falcataria Imperatan o cylindrica grassland. Performanc slow-growin2 1 f o e g shade tolerant tree specie Imperatan o s cylindrica dominated grassland inter planted with Paraserianthes falcataria was studied for five years in South Kalimantan, Indonesia. The seedlings were planted unde two-year-ola r d plantatio randomizea n i n d complete block design with eight replications speciee th l higd Al .sha h survival unti thire th l d year, whe mortalite nth severaf yo l Shorea specie wels s a Durios a l zibethinus increased considerabl resula severa s y a f seasono ty edr . Non-dipterocarp species, Podocarpus polystachyus, Agathis borneensis and Pericopsis mooniana, had the best performance in the trial with survival rate 82-95f f fivso o ee heighyearsd %ag an e e 3.2-3.f th .Th t o t a 5m best dipterocarps were Vatica sp. leprosula. ,S Hopead an sangal with survival- rate49 f so Address* 1996: May after 31 Department of Forest Ecology, University of Helsinki, 28, P.O. Box Viikin Koetila 20, SF-00014 University of Helsinki, Finland 382 Journal of Tropical Forest Science 8(3): 381 - 394 (1996) and height of 2.9-3.4 m. The results suggest that rehabilitation of Imperata grasslands by interplanting shade tolerant species with fast-growing species is possible with proper species selection. Despite the long time period needed, the method will provide alternative monoculturr sfo e plantations bot termn hi woof so d production and restoration of natural forest ecosystem. Key words: Dipterocarp - snon-dipterocarp - snurs e tre e- shad e tre - eImperata cylindrica - grassland - reforestation - rehabilitation - Paraserianthes falcataria OTSAMO , ADJERSR. , , HADI , ,KUUSIPALOG. S. T , OTSAMO& . J , 1996. A , . Prestasi awa spesie2 1 l s pokok toleran naungan yang ditanam selang dengan Paraserianthes falcataria i atad s padang rumput Imperata cylindrica. Prestas spesie2 1 i s pokok toleran naungan yang lambat tumbu atae hk s padang rumput utama Imperata cylindrica ditanam selang dengan Paraserianthes falcataria telah dikaji Selama lima tahun di Kalimantan Selatan, Indonesia. Biji benih tersebut ditana i mbawad h ladang berumur dua tahun di dalam reka bentuk blok yang lengkap secara rawak dengan lapan pereplikaan. Kesemua spesies mempunyai kemandirian yang tinggi sehingga tahun ketiga, bila kematian beberapa spesies Shorea serta Durio zibethinus bertambah dengan banyaknya akibat musim kering yang teruk. Spesies bukan-dipterokarpa, Podocarpus polystachyus, Agathis borneensis Pericopsisn da mooniano, menunjukkan prestasi di tapak percubaan dengan kadar kemandirian 82-95% dan ketinggian 3.2 - 3.5 m ketika berumur lima tahun. Dipterokarpa terbaik adalah Vatica sp., S. leprosula dan Hopea sangal dengan kadar kemandirian 49-83% dan ketinggian 2.9 - 3.4 m. Keputusan menunjukkan bahawa pemulihan padang rumput Imperata dengan cara menanam selang spesies toleran naungan dengan spesies yang cepat tumbuh adalah baik melalui pemilihan spesies yang betul. Sungguhpun jangkamasa yang lama diperlukan, kaedah ini akan menyediakan alternatif kepada ladang-ladang monokultur baik dari segi pengeluaran kayu mahupun pemulihan ekosistem hutan semulajadi. Introduction The forest resources in tropical Asia are declining at an alarming rate. In Indonesia, ther ea sever wile b l e lac f wooko materia w yeade ra th r y 2000lb , if the utilization efficiency and forest management do not significantly improve [Indonesian Tropical Forestry Action Programme (ITFAP) 1991]. Direct causes of forest losd degradatioan s n include unsustainable large-scale commercial logging of valuable timbers particularly of Dipterocarpaceae family, and the subsequent encroachmen f shiftino t g cultivatio d illegaan n l loggine th o gt logged-over forests. Heavy logging destroy e structursth f foreseo tremovin y andb , g seed trees, reduce regeneratioe sth n potentia treef o l s (ITFAP 1991). Rehabilitatio f thesno e logged-over and secondary forests is considered possible through enrichment planting, assisted natural regeneration and maintenance of existing natural stands (ITTO 1990). However, secondary forests burned, cultivate abandoned dan y db shifting cultivators are most often converted to grasslands dominated by Imperata cylindrica (alang-alang). Annual fires promot spreae eth 7f d.o cylindrica prevend an t the grassland from being reforested by pioneer species (Eussen &Wirjahardjal973). Imperata cylindrica covers large area f formeso r forest land throughout moist tropical regions in Southeast Asia. In Indonesia alone, the estimated total area 3 38 Journal of Tropical Forest Science (19964 39 8(3)- )1 :38 of Imperata grassland varies fro millio0 m2 a (ITTnh O 1990 64.o t ) 5 millioa nh (Suryatna & Mclntosh 1980). Grasslands are difficult to reforest owing to harsh environmental conditions, grass competitio allelopathyd nan , fire susceptibility of the grass, and soil degradation (Dela Cruz 1986, Ohta 1992). The main interest in reforestation of Imperata grasslands has been in fast- growin d light-demandingan g exotic species, whic e abl ar hsuppreso t e e sth grass. Gmelina arborea, Paraserianthes falcataria and Acacia species, especially Acacia mangium have given promising widele resultsar d y an ,use d plantation specien si Indonesia (Dela Cruz 1986, Awang & Taylor 1993). On the other hand, planting of dipterocarps and other primary forest tree species directly on Imperata grass- lan s failedha d almost completely theio t e r sloDu . w growt wels h a shads la d ean moisture requirements, these species are not able to compete with the grass. Fast-growing plantations provide alternative source wida r esfo varietw ra f yo material extracted from natural forests. Fro ecologicamn a l poin viewf to , thee yar capabl restorinf eo gmicroclimatea wels ,soia s la l physica chemicad lan l properties more suitabl wida r eefo variet f foresyo t flord faunaan a e shad,th e.gr efo . demanding primary forest species (Lugo et al. 1993). In cleared logged-over and secondary forest lands, fast-growing trees have been used as shade trees for slow- growing dipterocarps (Kustiawan & Unger 1991, Priasukmana 1991, Appanah & Weinland 1993undated)k Mo , . Imperata cylindrica grasslands are regarded as unproductive wastelands and the need for their reforestation is widely acknowledged (Dela Cruz 1986). In the future, if large-scale reforestatio Imperatan no grasslands becomes essentia industriao t l l wood production, there neea wil e diversifo db lt speciee yth s selectioo t d nan search for alternatives to monocultures. Since slow-growing species cannot be used as primary species on grasslands, one possibility is to introduce dipterocarps and other primary species under fast-growing plantations established on Imperata grassland. Enrichment planting with indigenous species would also be a step in converting these monocultures towards more diverse natural ecosystems. However r knowledgou , interplantinf eo g dipterocarp Imperatan so grassland is very limited. The available scarce information is obtained from cleared logged- over and secondary forests, where the site conditions, especially the physical soil properties more b y e favorablema , differencese spitn th I . f eo speciee th , d san silvicultural practice applicable b y sma grasslanr efo d reforestation. The aim of this study was to examine the performance of slow-growing valuable timber trees under a temporary shade cover provided by a fast-growing tree, Paraserianthes falcataria, asseso t e possibilitd th s an f usinyo e methogth a r dfo gradual rehabilitatio plantationf no s towards mixed rain forest ecosystem. Material methodd san s Study area The Riam Kiwa trial and demonstration area is located in South Kalimantan, Indonesia (3° 30'S, 115°E, 100-200 m a.s.l.), and lies on the undulating basin of 384 Journal of Tropical Forest Science 8(3): 381-394 (1996) Riae th m Kiwa river meae Th . n annual precipitation measured throughoue th t study perio 2103ms dwa m (Table 1).A pronounce seasoy e ddr th f no wit% h17 total annual precipitation occurred from May to September. Tabl . Rainfale1 l distribution durin stude gth y perio Rian di m Kiwa, South Kalimantan, Indonesia Year Total rainfall Dry season rainfall Amount Rainy days Amount Of total Rainy days (mm) (N) (mm) (%) (N) 1 2547 149 593 23 35 2 1898 122 353 19 27 3 1599 110 225 14 13 4 2348 152 438 19 43 5 2123 144 167 8 22 Mean 2103 '135 355 17 28 The soils are deeply weathered, heavily textured acidic soils which have suffered various degrees of degradation. The soil in the trial site is fine-textured (50-60% of clay) and belongs to the red podzolic type (Simpson 1992). Soil analyses fro experimentae mth ltime site th plantinf et o , a g Paraserianthes falcataria, indicatevaluesH p w ,lo comparativel levelw ylo f nutrient catioo sw lo nd an s exchange capacity (Table 2). On undisturbed land the height of I. cylindrica above th d e grounan varie m biomasy 5 sd dr 1. betwee d san betwee0 nd 1. an 0 n1 20 t ha-1. Compared to some other former Imperata grasslands the soil is well suite trer dfo e plantation (Awan 1994).