People in my group started talking about reforestation. I thought it might be a good idea, and decided to look at sources for the reforestation, and refoestation techniques. Firtly i decided that we as a group would need to find a cheap, economical way of aquiring samples to grow. Where would the trees we want to reforest come from?

    The rooting ability of branch cuttings was evaluated for 100 tree species (including 41 families and 78 genera) collected in a tropical rainforest in Sarawak, Malaysia. Leafy cuttings of natural forest saplings were
planted in a non-mist propagation system with IBA treatment. During the 6-month experiment, 66 species were rooted with an overall mean rooting percentage of 37.7% (range 0¯100%). Species in the families
Dipterocarpaceae and Lauraceae had a low rooting ability, whereas those in Euphorbiaceae, Rubiaceae, and Annonaceae had a high rooting ability. Differences in rooting ability were related to species-specific mature
sizes, diameter growth rates and habitat preferences. Species of smaller mature sizes and faster diameter growth rates showed better rooting ability. Species whose forest saplings sprouted more vigorously after
experimental felling rooted better than those that showed less vigorous sprouting. Species whose habitats were on lower elevations, concave slopes, and/or clay-rich soils rooted significantly better than those that
preferred opposite habitats or habitat generalists that showed no significant habitat preference. The implications of these relations are discussed from the viewpoint of saplings' adaptation to physical damage in their
natural habitats.

Indigenous species are replacing exotic fast-growing species in the rehabilitation of degraded tropical rainforests. To properly restore degraded ecosystems, particularly in the moist tropics, a remarkable number of species
are required. For example, a tropical rainforest in Sarawak, east Malaysia, contained over 1000 tree species within an area of approximately 50 ha (Condit et al., 2000). Thus, it is important to maintain a regular planting
stock of various indigenous tree species to restore the diversity of tropical rainforests. However, the irregular flowering and fruiting habits (i.e., "general flowering"; Appanah and Ashton) and the recalcitrant nature of the
seeds of many species ( Tompsett, 1987) make seed collection problematic in southeast Asian rainforests. Collection of wildings have been used to supplement seedling stock, but mortality is high without proper handling
(e.g., Palmiotto, 1993).

To overcome the unpredictable supply of seeds, many studies have been conducted investigating the ability of cuttings to propagate vegetatively, and successful rooting has recently been reported for a considerable number
of southeast Asian rainforest species (reviewed by Dick and Aminah, 1994). However, most of the species chosen are economically important timber trees, including members of the Dipterocarpaceae, which dominate the
forests. Little information is available regarding the vegetative propagation of cuttings from species that are economically less important. In order to successfully rehabilitate the diversity of degraded forests, we need more
information on the rooting ability of non-timber tree species, especially since the majority of species in tropical rainforests are non-timber species.
 

The study selected 100 study species (41 families and 78 genera) from the LTER plot. Voucher specimens of the species are kept at the Forest Research Center of the Forest Department of Sarawak, Kuching. Branches were collected from saplings of the study species (n=2¯10 per species; height 2¯6 m) under the closed canopy of the forest around the LTER plot and transferred to the nursery (0.5¯1 km away from the collecting sites) in sealed .plastic bags containing 0.2 l water. Branches were collected in June¯July 1997, December 1997, and January 1998. Ten leafy cuttings of 2¯4 nodes (length~15cm) were prepared for each species. Two to four leaves
(depending on leaf size) were left attached to each cutting, and all other leaves were removed. Large leaves were trimmed to approximately 30 cm2 each. We adopted a non-misting cutting propagation method: cutting
beds were constructed of cylindrical plastic containers (50 cm in diameter and 25 cm deep) containing water-saturated fine river sand and sealed with transparent plastic. The cutting beds were kept under 50% natural
shade for 6 months. Cuttings of the same species were planted in the same cutting bed, thus, there was no replication for each species. Commercial rooting powder (Serbajadi Rooting Powder, Perniagaan Serbajadi,
Malaysia; active ingredient IBA) was applied to the base of each cutting. Preparation and planting of cuttings were completed within 8 h from the time of branch collection. The cutting beds were watered 1¯3 times during
the experiment when the sand appeared to be dry. All cuttings were harvested after 6 months. The number and length of all roots thicker than 1 mm at the base were measured on each cutting.

Of 100 study species, 66 successfully rooted during the experiment from at least one cutting. Rooting percentage of rooting species differed from 10 to 100%. Among the six families including >3 study species,
Dipterocarpaceae and Lauraceae had smaller proportions of rooting species: 5/16 and 1/4, respectively. In contrast, the majority of the study species successfully rooted in Euphorbiaceae (16/17), Rubiaceae (5/5) and
Annonaceae (5/7) (see Appendix A).

Mean root lengths were significantly different between groups based on mature size (K), growth rate (r) and sprouting ability (Table 1 and Table 2). Differences between cutting beds were also significant within each
group, which suggests that between-species variance was also large within the groups. Species groups with the smallest mature size (K<20 cm), the fastest growth rate (r>0.02 peryear), and the most vigorous sprouting
ability showed significantly longer mean root lengths compared to the other groups, between which there were no significant differences (Fig. 1 and Fig. 2).
 


 
 


 
 
 
 

The results suggest that the majority of species in a mixed dipterocarp forest have the potential for vegetative propagation from cuttings. We cannot conclude whether the observed proportion of rooting species (66%) is
high or low compared to other tropical forests, because no comparable studies have been conducted. However, the observed rooting abilities are likely underestimates for most of the study species, because the cuttings
were collected from suppressed forest saplings, and successful rooting from cuttings is affected by the age and the nutrient status of donor trees (Kantarli, 1993). Generally, rooting decreases with the age of donor trees (
Smits et al., 1990). Cuttings collected from donors in vigorous growing conditions root more successfully than cuttings from those growing in poor conditions (e.g., under low light), which generally have lower C:N ratios (
Kantarli and Veierskov). Most of the donor saplings in this study had been growing in shaded conditions for at least 10 years (A. Itoh, personal observation). The study results, therefore, should be considered to be a
conservative estimate of the rooting ability of these species. It is likely that more species would have rooted successfully if we had taken cuttings from more vigorous donors. For example, cuttings from Dryobalanops
aromatica, Shorea parvifolia, and Shorea macroptera did not root in our experiment, but were reported to produce roots when collected from young healthy seedlings grown under nursery conditions (e.g., Aminah; Smits;
Dick and Aminah). In addition, rooting percentage could be improved in the species that successfully rooted during this experiment by choosing more suitable donors. Therefore, vegetative propagation by cuttings seems
highly viable for many mixed dipterocarp forest species, especially for those that have small mature sizes.
 

This study showed that the majority of species in a mixed dipterocarp forest in Sarawak have significant potential for vegetative propagation by cuttings. Small and fast growing species showed especially good rooting
ability. Planting stock for these species can easily be produced from cuttings for restoration programs, even if seeds are unavailable. However, many upper canopy and emergent species, including dipterocarps, showed poor
rooting ability, suggesting that seedling production from cuttings of these species may be difficult. Variations in rooting ability were related to both phylogenetic and ecological factors. Thus, knowledge of the ecological
characteristics of species, especially sprouting ability, is useful for the preliminary selection of species for cutting propagation.