Sungkai (Peronema canescens) a promising pioneer tree : an experimental provenance study in Indonesia

Sungkai ( Peronema canescens Jack.), Verbenaceae, is one among the fancy woods of Indonesia. Sungkai belongs to a small number of species recommended by The Ministry of Forestry for use in the development of industrial forest plantations (IFP). The IFPs are carried out in response to an increasing wood demand and aim at reducing pressure on the natural forests, thereby contributing to national land conservation objectives, as well as to the supply of industrial raw materials.The wood of Sungkai is used in various ways from roof trusses in the village more specific purposes (veneers). The attractive grain makes Sungkai suitable for veneer, furniture and cabinetwork (Martawijaya et al.1981). Hence, Sungkai has the potential to be planted by local people on their own land for their own use and as a cash crop, in addition to IFPs for industrial purposes. Among indigenous pioneers tested on grasslands in South Kalimantan, Sungkai has a survival rate close to 100%. Usually, Sungkai is regenerated by cuttings rather than by seeds, because this is easy and does not depend on the fruiting season.Although Sungkai is used in IFPs in Indonesia, no efforts have been made yet to develop the quality of Sungkai planting stock. Generally, availability rather than quality of Sungkai cuttings in a site is considered. Not all vegetative propagation nurseries or seed sources are managed professionally by the private sector. Genetic variation in wild populations is virtually unknown, and few attempts, if any, have been made at genetic improvement. Wild Sungkai can be found in many sites in Kalimantan and Sumatera.Only a few successful plantations exist, so most timber continues to be harvested non-sustainably. Domestication of Sungkai is crucial for the development of a sustainable, high-quality timber resource.A first field trial of Sungkai ( P. canescens) provenances from various sites in the Province of South Kalimantan (Hatta, 1992) showed growth differences among the provenances. More genetic diversity may be expected over the broad ecological and geographical range of P. canescens in Kalimantan and Sumatera.Clearly, provenance research on Sungkai ( P. canescens) will lead to genetic improvement and so provide silviculturally optimized P. canescens populations in the field. Wood industries require industrial forest plantations to produce long, straight stems, suitable for end-uses such as plywood and sawn timber. Tree conformity to these specifications depends on tree architecture and trunk formation in particular.Tree architecture codetermines the 'ecological profile' of the species. The architectural strategy of Sungkai, particularly its plasticity and flexibility is basic information for the optimization of the species for wood production. Such knowledge helps predict the tree's capacity to adjust.The present study pinpoints the best provenances of Sungkai, the tree architecture of Sungkai, and specifications for highly productive and low-risk plantations. This is useful especially for industrial forest plantations which have to meet high requirements. Using good quality Sungkai cuttings makes for good quality and quantity of Sungkai timber production, and successful reafforestation. For the Government successful reafforestation means reducing deforested land, raising wood supply, creating job opportunities, and increasing incomes.The original site and vegetation of each provenance are described in Chapter 2. The architecture of Sungkai and the ecological base of the silviculture of the tree are also presented.Site characteristics are latitude, longitude, altitude, topography, annual rainfall and rainy days per month, mean monthly temperature, maximum and minimum day temperature,.and soil characteristics. The name of the location where the cuttings were collected is also mentioned, including the name of the village and the district.The original vegetation surrounding each provenance was studied on the basis of a rapid diagnostic forest line profile of the direct forest environment. In addition, a diagnosis of trees was also made in order to distinguish a 'good phenotype'. Such trees were used to collect our cuttings. Seedling, sapling, pole and mature tree of Sungkai were sketched to assess its architecture.Sungkai architecture is part of the architectural models (Hall� and Oldeman, 1970; Hall� et al. 1978). It represents the model of Scarrone, converging when older to Leeuwenberg's model. In young Sungkai trees the architecture conforms to Scarrone's model, and in adult trees, fragmentation and reduction make it resemble Leeuwenberg's model.The original vegetation of ten provenances varies from old secondary forest (Samarinda provenance) and young secondary forest (Jambi provenance) to home gardens/farmyards (Padang provenance) and vegetation strips or river banks (Pontianak and Lampung provenances). There were also a natural stand dominated by Sungkai (Palangka Raya provenance), a mixed species stand (Samarinda and Jambi provenances), and artificially mixed species stands or gardens (Padang provenance).Only general statements about the geographic distribution of Sungkai in Sumatera and Kalimantan were published. Sungkai was known to occur naturally in the western Indonesian archipelago, especially in a large part of Sumatera and in the whole of Kalimantan. The latitudinal limits within the natural range were from 7 ^o20' South to 4 ^o10' North. In Kalimantan Sungkai occurs especially in the centre.Based on observations in the field and local information during the collection of the cuttings, we may now assume that the distribution of Sungkai in Sumatera and Kalimantan tends to be dense below the equator and sparse above it. Chapter 2 shows the distribution centres of Sungkai in Kalimantan and Sumatera.Tree architecture is the strategic pattern of the tree to meet ecological factors. The particular state of the original vegetation surrounding each provenance influences the tree architecture. In healthy ecosystems the tree architecture is inclined to conform to the specifications for quality timber.Chapter 3 shows the initial performance of each provenance in the nursery. Among ten provenances, four show a complete survival (100%), i.e., Pontianak, Banjarmasin, Riau and Jambi. The rest varies between 50% and 95% (Table 3.1). Only the Padang and Lampung provenances show significantly poorer survival rates than the others, i.e., an unusually low survival rate for nurseries, which usually achieve at least 80%.The main determinants of shoot survival of the provenances are certainly the time it takes to transport the cuttings from their original site in Sumatera to the Banjarbaru nursery in South Kalimantan, and the source of the cuttings.The Palembang provenance was the first to show shoot initiation on its cuttings on the third day after the insertion of the cutting in the medium. The Riau and Lampung provenances took second and third position.Root formation started fastest in the Riau provenance, on the eighteenth day, followed by the Pontianak and Palangka Raya provenances.For the overall parameters the performances of the provenances rank as follow : Riau, Pontianak, Palembang, Banjarmasin, Jambi, Bengkulu, Palangka Raya, Samarinda, Padang and Lampung.Chapter 4 presents the performance of each provenance in the field. Individual characteristics from twenty-six-months old, planted Sungkai stands are shown, i.e., survival, height, diameter above root and at breast height, crown diameter, multistem reiteration, and h/d (height/diameter) ratio. Disturbances in the trial plots, e.g. fire, made it possible to discuss the survival strategy of Sungkai under fire. Attempts to optimize the mutual adaptability of provenance and new site are described.The plantation trial plot was laid out in alang-alang ( Imperata cylindrica (L.) Pal. Gramineae) grassland in Riam Kiwa, South Kalimantan. A randomized complete block design (RCBD) with three replications was used. Each provenance was represented by one 25 tree plot (5 x 5 trees), replicated three times. The spacing was 3x3m. The 25-tree plots were separated from each other by a 5 meter wi e fire break (unplanted border) which was manually weeded at regular intervals. As the area was dominated by alang-alang grassland, it was mechanically cultivated prior to planting, twice with a disc-plough and once with a rotovator. No fertilizers were used in the field. Manual weeding was carried out every four months, until the age of the plantation was about 18 months. The statistical computation followed the GLM-Anova procedure of the SPSS version 8.0 software.Statistically, two out of six parameters showed significant differences, i.e., survival rate and multistem reiteration. The survival rate was higher in provenances from Kalimantan than in those from Sumatera. The average survival rate of most provenances was above 69%, except for the Lampung, Padang and Bengkulu provenances. The upper group of five ranged from 73% to 92%. It is assumed that, without drought or fires in 1997, and without cattle disturbances, the figure would have been higher.At the original counts, the Kalimantan provenances once more dominated the upper group of five in mean tree height, but less so than in survival rates. First and third position were now taken by provenances from Sumatera (Padang and Riau provenances). The mean height of twenty-six-months-old Sungkai plantations varied from 195 to 280 cm for all provenances and from 255 to 280 cm for the upper group of five.The Kalimantan provenances once more ranked highest if judged by their diameter, both in diameter above root and diameter at breast height. The mean diameter at breast height varied from 2.5 to 4.3 cm for all provenances and from 3.8 to 4.3 cm for the upper group of five.The h/d (height/diameter above root) ratio of twenty-six months old, planted Sungkai trees has not yet shown any obvious tendency towards either h > 100d or h < 100d. This relationship still oscillated around h = 100d. In other words, the model-conform trees still showed a height-diameter ratio of h100d. This indicates a balanced metabolism with endogeneously and mutually adjusted cambial and height growths.This ratio is related to the architecture of the tree. Several authors found that nearly all model-conforming trees in French Guyana and elsewhere showed the ratio of h = 100 d. In the field, if a young tree breaks off, the ensuing regenerative reiteration pushes this ratio upward (h > 100 d); and when a tree expands its crown by abundant reiteration, the ratio become h < 100 dAll Sungkai provenances can form multistems. However, statistically they are significantly different. Most Kalimantan provenances have a high share of multistemmed trees (above 48%), except Samarinda (19%). Four provenances have fewer multistems, i.e. Lampung (5%), Bengkulu (5%), Jambi (17%) and Samarinda (19%). They may be considered "the best group" for timber quality. However, other factors must be considered for that purpose, i.e. survival, height and diameter growth. The formation of a multistem architecture should be counteracted if good timber is the production objective.Generally, at 26 months the provenances achieved a mean crown diameter above 132 cm, except Jambi (119 cm). As with other parameters, the Pontianak provenance maintained its highest rank (176 cm), in the group with the Palangka Raya (174 cm) and Padang (175 cm) provenances. If the results are related to the plantation with a 3x3 m spacing, only 3 or perhaps 5 provenances may have achieved fast canopy closure within 26 months, i.e. Pontianak, Palangka Raya, Padang, Banjarmasin and Palembang. Their capacity to suppress the grass may have increased by narrower spacing in plantation, e.g 3 x 2 m., so grass suppression and an acceptable rate of timber production may both have been achieved.Several facts emerge. First, the Kalimantan provenances show a faster growth than the Sumatera provenances, as proved by their high values of almost all parameters. Second, based on their individual characteristics, the Kalimantan provenances rank in decreasing order as follows : Pontianak, Palangka Raya, Banjarmasin and Sam rinda. For the Sumatera provenances this is : Riau, Padang, Palembang, Bengkulu, Jambi and Lampung. And overall : Pontianak, Palangka Raya, Banjarmasin, Riau, Padang, Samarinda, Palembang, Bengkulu, Jambi and Lampung. Third, as to its better growth performance, the Pontianak, Palangka Raya and Banjarmasin provenances are promising provenances for Industrial Forest Plantations (IFPs). Fourth, for experiments outside Sumatera, the Riau, Padang and Palembang provenances may be satisfactory as long as the transport time of the propagation material is short and cuttings are well packaged.In optimizing the mutual adaptability of provenance and a new site, at least two features are important, i.e., climate and soil of the site. A more detailed climatic analysis is needed, both for the original and the new site of the provenance in order to assess climatic stress. The climatically suitable region, the upper and lower limit of tolerance for a particular provenance, and the optimum time for planting, i.e., planting early in the rainy season, avoiding severe stress for young seedlings (pluriannual drought periods) have to be known. For large areas such as Kalimantan and Sumatera, site maps should be produced per provenance.The second feature is soil. There are at least three factors to be considered, i.e., physical soil structure including depth, nutritional soil status including organic matter content, and acidity of the soil (pH). Soil factors should be included in site maps, so, soil surveys of the new site are necessary.The combination (overlay) of climatic and edaphic factors of the home site and the new site will show the degree of hospitality of a new site towards a particular provenance. So, we will be able to deploy each provenance in each suitable region. The optimum mutual adaptability of provenance and site then is achieved.In Chapter 5 the optimization of the wood production and the design of the silvicultural system of Sungkai are discussed. Wood production is the usual aim in plantation forestry. A tree must grow well where it is planted. Healthy, vigorously growing trees are desired, which are highly productive in the given environment.Three points are essential in order to optimize Sungkai wood production : (1) to use the 'best' provenances, (2) to achieve provenance-site harmony and (3) to tend plantations well, including prevention of and protection against pests and diseases.Based on this present study five items should be paid attention to if a certain provenance is to grow well : (1) the home site of the provenance, (2) transport from the home site to the new site, (3) behaviour in the nursery, (4) transport from the nursery to the planting site, and (5) behaviour in the planting site. These five factors determine the performance of provenances.In designing a silvicultural system for Sungkai, there are four essential points : health of the plantation including the ecological profile of the tree, end use of the wood, secondary management aims, and cost of silvicultural measures.The 'ecological profile' or temperament of an organism is the strategy pattern of the organism as a response to environmental dynamics in order to meet its outside world. This profile is very important for the production of timber according to specifications. The ecological profile becomes visible as an architectural strategy in response to site dynamics.Different end uses need different characteristics. Sawn timber, pulpwood and plywood each have their specifications. Most users of sawn timber prefer long trunk lengths with straight, even grain; large width and depth, uniformity throughout the piece; branch knots absent or few, well scaterred, small; free of inclusions such as calcite, silica and resin pockets (Palmer, 1994).The design of a plantation often focuses on maximum yields, the volume of the investments, and the life-span of the tree. Meanwhile, secondary management aims are being neglected. Emphasizing the first objective without caring for ecosystem capacity will lead to the destruction of the producing system itself and to conomic instability.Silvicultural measures serve to yield healthy, vigorous trees so as to obtain the desired products. Certainly, those measures cost money. As long as silvicultural measures may increase the profits, their implementation should be considered. However, low cost is always desirable. The choice of cheap and adequate measures may well be a better guarantee for management success than a 'quantitative' yield forecast.Indeed, as shown by the present study, such forecasts are proved worthless by unexpected and unforseen events (fire, cattle, insects). Statistical forecasts, therefore, are to be treated with caution, because forecasts are only virtual reality. It is always safer to optimize the cost-benefit ratio in the present.In a complex situation the statistical approach may lose touch with reality. Therefore, statistical methods should be used carefully, otherwise, they may easily disappoint.The Local inhabitants should be involved in the plantation programme, if possible in all phases (identification, design, management, monitoring). Their involvement will be beneficial to both plantations and local inhabitants.