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Four common fallow tree species were tested for a response to nitrogen and phosphorus fertilization. Seedlings or cuttings of Melicope glabra (Rutaceae), Macaranga gigantea (Euphorbiaceae), Persea romosa (Laureaceae), Peronema canescens (Verbenaceae) were grown in pots of a 50:50 mix of native soil and sand under 18% full sun for 18 weeks. Every 2 weeks, plants received either added N, added P, added N+P, or no added nutrients (control). Persea, a shade-tolerant species, and Macaranga, a light-demanding pioneer, improved relative growth rate with the addition of both N and P. Neither responded to N or P alone. Peronema and Melicope demonstrated luxury consumption of both N and P but did not show enhanced growth. Two of the four species tested (Persea and Melicope) were more limited by P than N. Macaranga was equally limited by both and Peronema was more limited by N. Along with previous studies, evidence for positive growth response and luxury consumption among light-demanding species suggests that P, rather than N, should limit seedling performance and may ultimately influence tree diversity in young secondary tropical forests.

Summary • Leaf-stem size relationships over ontogeny were studied here in three different lineages of hollow-stemmed myrmecophytes in order to understand how a new stem function affects morphology. • In each of six taxa, the primary cross-sectional area of a terminal internode and the area of the leaf borne by it were measured on plants representing all stages of ontogeny. Cross-sectional areas of both the cavity and the ring of wood were determined. • The leaf-stem relationship over ontogeny was allometric, in contrast to the isometry previously found in solid-stemmed relatives. Stem cross-sectional area was initially larger relative to leaf area than for solid-stemmed species, increasing less than proportionally with increasing leaf size. • Because mechanical stability requires a minimum ratio of t (thickness of the solid ring) to R (external radius of the cylinder), cross-sectional area of the ring of wood must vary with that of the cavity; both contributed to leaf-stem allometry. Relative to leaves, both are initially large and increase more slowly over ontogeny, suggesting that domatia are particularly costly for plants early in development.

On a monoaxial erect stem of trees with continuous leafing, the older leaves would be quickly shaded by newer (upper) leaves if the trees did not have any compensating mechanisms to avoid self-shading. We hypothesized that the dynamic adjustment of leaf deployment, by regulating the patterns of leaf growth and by changing leaf orientation as leaves age, is a compensating mechanism. To verify this hypothesis, we analyzed leaf development and crown structure of a Far Eastern tropical pioneer tree species, Macaranga gigantea (Rub. f. et Toll.) M.A., which unfolds huge leaves directly on a monoaxial stem with a short leafing interval. Petioles required more than 90 days for full elongation and the petiole angle (the angle between the petiole axis and the vertical) increased over time. Thus, a series of leaves on a stem progressively increased in petiole length and petiole angle from the youngest to the oldest leaves. This is beneficial because it decreases the degree of self-shading within a crown. A simulation suggested that an average crown for the M. gigantea seedlings, which was constructed using empirically determined morphometric data cannot entirely eliminate self-shading within the crown. But an average crown had a lower degree of self-shading, with less dry mass allocation to the petiole than simulated crowns that were identical to the average crown in all but one respect: they had constant petiole lengths or petiole angles. We conclude that M. gigantea seedlings reduce self-shading by regulating elongation of the petiole and changes in the petiole angle with increasing leaf age.

Interspecific ecophysiological differences in response to different light environments are important to consider in regeneration behavior and forest dynamics. The diurnal changes in leaf gas exchange and chlorophyll fluorescence of two dipterocarps, Shorea leprosula (a high light-requiring) and Neobalanocarpus heimii (a low light-requiring), and a pioneer tree species (Macaranga gigantea) growing in open and gap sites were examined. In the open site, the maximum net photosynthetic rate (Pn), photosystem II (PSII) quantum yield (δ; F/Fm′), and relative electron transport rate (r-ETR) through PSII at a given photosynthetic photon flux density (PPFD) was higher in S. leprosula and M. gigantea than in N. heimii, while non-photochemical quenching (NPQ) at a given PPFD was higher in N. heimii. The maximum values of net photosynthetic rate (Pn) in M. gigantea and S. leprosula was higher in the open site (8–11 μmol m−2 s−1) than in the gap site (5 μmol m−2 s−1), whereas that in N. heimii was lower in the open site (2 μmol m−2 s−1) than in the gap site (4 μmol m−2 s−1), indicating that N. heimii was less favorable to the open site. These data provide evidence to support the hypothesis that ecophysiological characteristics link with plant’s regeneration behavior and successional status. Although Pn and stomatal conductance decreased at midday in M. gigantea and S. leprosula in the open site, both r-ETR and leaf temperature remained unchanged. This indicates that stomatal closure rather than reduced photochemical capacity limited Pn in the daytime. Conversely, there was reduced r-ETR under high PPFD conditions in N. heimii in the open site, indicating reduced photochemical capacity. In the gap site, Pn increased in all leaves in the morning before exposure to direct sunlight, suggesting a relatively high use of diffuse light in the morning.

During selective logging of tropical rainforest in Malaysia, the topsoil is removed from log landings and skid trails by bulldozers. The exposed subsoil is compacted, nutrient-poor, low in organic matter, drought-prone and hot. Vegetation on log landings and skid trails recovers extremely slowly. Tree seedlings planted on these degraded areas perform much less well than those planted in adjacent manually disturbed areas. An experiment was set up to investigate whether soil factors reduced early tree growth. The treatments used were: digging to reduce soil compaction; fertilizing to replace lost nutrients; mulching to reduce soil temperatures and evaporation rates; replacement of topsoil. Two pioneer tree species (Macaranga hypoleuca and M. gigantea) and two dipterocarp species (Dryobalanops lanceolata and Shorea leprosula) were planted in treated plots. Fertilizing of seedlings resulted in a dramatic improvement in height, basal diameter and dry weight increments of all species 6 months after planting. Digging improved seedling growth slightly, but mulching had little effect. This suggests that nutrient deficiency is the most important factor limiting early tree growth on degraded soil. Topsoil replacement resulted in growth as good as that of fertilized seedlings. The topsoil plots also contained 35 times more volunteer plants than any other treatment. Pioneer tree seedlings grew significantly faster than dipterocarp seedlings.

A new farnesylated flavonol derivative, macagigantin (1), together with two known flavonoids, glyasperin A (2) and apigenin (3), had been isolated from the acetone extract of the leaves of Macaranga gigantea. The structure of the new compound was elucidated as 6-farnesylkaempferol based on its spectroscopic data, including UV, IR, 1D and 2D NMR, and HR-EI-MS spectra. Compounds 1-3 were evaluated for their cytotoxic properties against P-388 cells, their IC(50) values being 11.3, 6.0, and 5.1 microM, respectively.

We hypothesized that pioneer and late successional species show different morphological and physiological responses in water use after gap formation. The magnitude of the responses was compared between two pioneer species (Macaranga gigantea and Trema orientalis) and four late successional species (Shorea sp.), in an experiment in which saplings were transferred from shade to sun. Although transpiration demand increased following the transfer, root hydraulic conductivity (Lp(r)) decreased. Lp(r) was sensitive to brief treatments with HgCl(2) (a specific inhibitor of aquaporins). This allows Lp(r) to be divided into two components: cell-to-cell and apoplastic pathways. The Lp(r) of cell-to-cell pathway decreased in all species following the transfer, relating to aquaporin depression in roots. Following the transfer, leaf osmotic potentials at full hydration decreased and both leaf mass per area [leaf mass/leaf area (LMA)] and fine-root surface area/leaf surface area (root SA/leaf SA) increased in almost all species, allowing saplings to compensate for the decrease in Lp(r). Physiologically, pioneer species showed larger decreases in Lp(r) and more effective osmotic adjustment than late successional species, and morphologically, pioneer species showed larger increases in root SA/leaf SA and LMA. Water balance at the whole-plant level should be regulated by coupled responses between the aboveground and the belowground parts. Interspecific differences in responses after gap formation suggest niche differentiation in water use between pioneer and late successional species in accordance with canopy-gap size.

Macaranga (Euphorbiaceae) has received much ecological and evolutionary research attention as a genus that includes some of the most conspicuous pioneer trees of Southeast Asian tropical rainforests and because of its manifold associations with ants, including about 30 species that are obligate ant-plants (myrmecophytes). We used sequence data from three chloroplast DNA loci (ccmp5, ccmp6, atpB-rbcL) to assess phylogeographical patterns in species of Macaranga, section Pruinosae, sampled from various regions of Borneo and the Malay Peninsula. Forty-nine chloroplast DNA haplotypes (HT) were identified among 768 specimens from five species, Macaranga gigantea (N = 329; 23 HT), Macaranga pearsonii (N = 347; 21 HT), Macaranga puberula (N = 24; 4 HT), Macaranga hosei (N = 48; 6 HT), and Macaranga pruinosa (N = 20; 5 HT). Forty-one haplotypes were species-specific, whereas eight haplotypes were shared by two, three, or four species and occupied internal positions in a parsimony network. Population genetic parameters based on haplotype frequencies proved to be in a similar range in the non-myrmecophytic M. gigantea and in the ant-associated M. pearsonii, which have overlapping distributions in northern and eastern Borneo. A comparison of GST and NST values revealed a strong phylogeographic structure in both species, whereas colonization pathways suggested by the network topology were different. Both species exhibited similar levels of haplotypic diversity and moderate to high levels of population differentiation. There were no obvious indications for an influence of the symbiotic ant partners on the population structure of their host plants.

Becerra and Venable (1989) proposed that the function of extrafloral nectaries (EFNs) may not exclusively be to attract ants which defend plants against herbivores. They questioned the protection hypothesis and proposed that EFNs may also function to defend plants from ant-Homoptera mutualisms. Arguments for their hypothesis were e.g. the lacking universality of ant protection for plants and the negative impact of ant-tended homopterans on their host plants. In general, effects of homopterans on plants are negative but the damages of ant-homopteran associations are difficult to assess. Becerra and Venable cited a few examples of beneficial by-products of these associations in form of protection for the plants by the visiting ants. However, they considered only facultative interactions. In most of the highly developed ant-plant mutualisms ants cultivate homopterans while EFNs are absent. Among plant species of 36 genera, for example, which possess permanent domatia formed by hollow stems, only four have EFNs, but in 18 of them ants were recorded to keep homopterans (Huxley 1986). In the eight best-studied obligate myrmecophytic associations (Table 1) most plant partners offer nesting space but no food in form of nectar. The only two exceptions are Acacia spp. and Leonardoxa africana. In this respect the genus Macaranga (Euphorbiaceae) is especially interesting. In SE Asia it comprises the full range of species which are obligatorily inhabited by ants to those which have only weak and unspecific associations with ants (Fiala et al. 1989, 1990). Most of the facultatively associated Macaranga species possess EFNs on the leaf margins and in addition on the lamina. Obligate myrmecophytes in this genus do not secrete sugar-containing fluids (Fiala and Maschwitz, in press) and colonizing ants keep scale insects inside the hollow stems of their Macaranga host plants. Contrary to Becerra's and Venable's hypothesis in this case a reduction of nectary production appears to be favoured. The hypothesis of superiority of extrafloral nectar to honeydew remains to be tested in facultative associations, but my preliminary observations in Malaysia do not support this view. Becerra and Venable list a number of questions which should be addressed experimentally. I will briefly comment here on the first one: Is it generally true that ants neglect Homoptera when an alternative sugar source is available? During studies on the tree genus Macaranga in Peninsular Malaysia I looked for plants with EFNs and the occurrence of homopterans on these plants. The main study sites were secondary forests and disturbed habitat which were rich in light-demanding, fast growing plants. Six common species which possess EFNs were studied: Macaranga gigantea, M. tanarius, Mallotus paniculatus, M. macrostachys, Endospermum diadenum and Croton argyratus (all Euphorbiaceae). I checked 10 specimens each for occurrence of homopterans. Two to five plants of each species were infested by Homoptera (mostly scales and membracids) despite the presence of EFNs. Other plant species without EFNs in the vicinity were not found with homopterans more often than the above mentioned species (random samples of up to five nearest neighbouring plants; giving a total of over 200 controls). All homopterans on leaves and stems of the plants were visited by various ant species (Anaplolepis longipes and three Crematogaster spp. were dominant). The ants also visited the extrafloral nectaries on these plants. However, often the ants seemed to prefer honeydew from the homopterans. On a leaf of Croton argyratus, for example, almost 2/3 of all ants visited the scale insects on the leaf lamina and only few took notice of the secreted extrafloral nectar. On Mallotus ants generally favoured membracids despite

Susanto D, Ruchiyat D, Sutisna M, Amirta R. Flowering, fruiting, seed germination and seedling growthof Macaranga gigantea. Biodiversitas 17: 192-199. The stages of flower and fruit development of Macaranga gigantea, its seed germination behavior in nature and from fruit harvesting, as well as the process of raising its seedlings in the laboratory were studied to determine the potential for production of M. gigantea seedlings. Five reproductive trees of M. gigantea were chosen as sources of seed. To estimate natural germination rates, four sample plots of 1 x 1 m 2 in four cardinal directions below the crown of every tree were set up. In addition, dry and wet extraction processes were carried out to determine , which the more effective method for germination of M. gigantea seeds. The results showed that t he time required from flower development to fruit ripening in M. gigantea flowers was 5-6 months. The flower buds initiated in the dry season (August 2011) and the fruits ripened in the rainy season (December 2011-January 2012). The seeds that fell under the parent tree germinated in approximately 24 days with an average seedling density of 75 -267 per m 2 . The germination in laboratory showed that the percentage and the rate of germination of the seeds extracted through the wet extraction process were higher than those extracted through the dry extraction process. The highest rate of germination (65%) is by the combination of seeds extracted through wet extraction process and grown on compost media. The relative growth rate of seedlings planted on mushroom spawn waste media was the highest rate (0.36 ± 0.42%), followed by those planted on compost media (0.15± 0.09%), top soil media (0.10± 0.04%) and sand media (0.10± 0.07%).

In the year 2015, the plants that initially grow a lot of wild is increasing in popularity because many contested by the citizens. The reason is because the plant has an economic value. Based on the literature review it is known that apigenin, a flavonoid compound has been isolated from the ethyl acetate fraction of methanolic extract of Macaranga gigantia leaf. Compounds that have potential as antioxidants are generally compounds of flavonoids, phenolics, and alkaloids. Flavonoid and polyphenolic compounds are antioxidant, antidiabetic, anticancer, antiseptic, and anti-inflammatory, while alkaloids have antineoplastic properties that also inhibit the growth of cancer cells. Phenol content, antioxidant activity and antibacterial activity were also found in Macaranga gigantea, M. hosei, M. hypoleuca, M. kingii, M. pruinosa and M. triloba (Lim et.al., 2014). This leads to the notion that mahang leaves were obtained and collected from the Central Kalimantan region where this study carried out also contained similar content and activity. Determination of the value of antioxidant activity in this study using DPPH method performed on n-hexane extract ofmahang leaf obtained by maceration. N-hexane extract of mahang leaf have antioxidant activity, this can be seen from the preliminary TLC test results where the spots produced when sprayed with DPPH fluoresce when viewed at 366 nm uv. The average value of IC50n-hexane extract of mahang leaves was 141.3 ppm.