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Infeksi pada rongga mulut terutama di saluran akar gigi sering dialami oleh orang Indonesia, dan salah satu penyebabnya adalah bakteri Enterococcus faecalis. Tanaman yang potensial sebagai anti bakteri adalah dari dua species Macaranga yaitu merkubung (Macaranga gigantea) dan mangpurang (Macaranga triloba). Penelitian ini bertujuan untuk menganalisis kandungan metabolit sekunder ekstrak kulit kayu dari dua species Macaranga dan kemampuannya dalam menghambat pertumbuhan bakteri faecalis. Metode penelitian yang dilakukan adalah pembuatan serbuk, pengukuran kadar air serbuk, penghitungan rendemen ekstrak, uji fitokimia dan pengujian aktivitas anti bakteri E. faecalis. Rendemen ekstrak etanol kulit kayu M. gigantea adalah 9,18% (KA 9,15%) dan M. triloba sebesar 9,70% (KA 8,56%). Ekstrak positif mengandung fenolik, tanin, saponin, terpenoid, flavonoid dan alkaloid. Level konsentrasi 100 mg/mL merupakan konsentrasi terbaik dari kedua jenis ekstrak untuk menghambat pertumbuhan bakteri E. faecalis, namun diantara kedua jenis ekstrak tersebut yang terbaik dalam menghambat pertumbuhan E. faecalis adalah M. gigantea.

Trade-offs in wood anatomical characteristics reflect different strategies used by trees to deal with water transport in response to variation in environmental conditions. To study vascular strategies for Bornean rainforest trees, we compared water transport-related anatomical characteristics in branch wood between the common tree species Vatica dulitensis (Dipterocarpaceae) from old-growth forest and the common pioneer tree species Macaranga gigantea (Euphorbiaceae) from selectively logged forest. We hypothesised that the vessel traits of the pioneer species would reflect the need to capture and transport resources to support its fast growth rate (resource-acquisitive strategy), while the species of the old-growth forest would display more conservative vessel traits (resource-conservative strategy). We found that M. gigantea had significantly greater vessel area, hydraulically weighted diameter, vessel area to number ratio, and potential hydraulic conductivity than V. dulitensis. These results suggest that vessel traits of the common old-growth species would ensure high hydraulic safety during occasional drought when soil moisture is limited, while the common species of selectively logged forest possesses an efficient water transport system but its vessels would confer lower hydraulic safety during drought conditions. These contrasting vascular strategies highlight the potential for divergent responses of species of Bornean forest trees to future climatic extremes.

Susanto D, Kusuma R, Amirta R. 2018. Nutrient distribution on soil and aboveground biomass of Macaranga gigantea five years after planting. Asian J For 2: 12-19. The aims of this study were to evaluate growth of M. gigantea and to calculate nutrient distribution in the soil and 5-year-old M. gigantea. Soil sampling was conducted in all research plots with drill ground at a depth of 0-30 cm and 30-60 cm. The tree biomass was sampled within one stand to calculate the biomass of all the trees within a particular plot. The research findings revealed that plot 5 produces the best growth performance and the plant accumulates 2 times of N, P, K, Ca, Mg nutrients on wood, bark, branches, and leaves, compared to the plants in plots 1. The most distributed nutrients in the soil were magnesium, nitrogen, calcium, and phosphorus. Whereas the most accumulated nutrient in plant was potassium. The relative portion of K nutrients accumulates in the soil is quite small that is 44.18% but in stand was higher that is between 55.82%. It concluded that if the M. gigantea harvested at 5 years, it needs to give attention to potassium nutrient for the next of planting cycles.

Susanto D, Hayatudin, Setiawan A, Purnomo H, Ruhiyat D, Amirta R. 2017. Characterizing nutrient status and growth of Macaranga gigantea in tropical rainforest gaps after selective logging in East Kalimantan, Indonesia. Biodiversitas 18: 996-1003. Selective logging caused the formation of forest gaps, which stimulate the growth of the pioneer tree species. This study aims to determine the characteristic of soil nutrients status and plant growth of Macaranga gigantea in the tropical rainforest gaps after selective logging in East Kalimantan, Indonesia. We established research plots 50mx50m in natural forest production, 1 until 10 years after selective logging. The measured data of each plot is the number of trees of M. gigantea, its stem diameter, and its height, and also the soil and leaf nutrient concentration. The results showed that the soil has a pH (H2O) of 5.3 ± 0.27, cation exchange capacity of 10.6 ± 2.98 meq. 100 g-1, base saturation of 27.7 ± 10.44%, while the concentration of nutrients carbon of 1. 04 ± 0.27%, nitrogen of 0.10± 0.02%, phosphorus of 6.35 ± 3.4%, potassium of 67.15± 30.1%, calcium of 1.7 ± 1.09% and magnesium of 0. 99 ± 0.8%. The highest stem diameter and height of M. gigantea (19.5 cm; 18.07 m) was obtained in plots of 8 years after selective logging and then declined, while the highest diameter increment and height increment obtained in plants located in a plot of 4 years after selective logging and decline until 10 years after selective logging. The concentration of nutrients accumulated in the leaves of M. gigantea was N with 1.51 ± 0.19%, P with 0.16 ± 0.01%, K with 1.37 ±0.28%, Ca with 1.78 ± 0, 43% and Mg with 1.53 ± 0.37%. The soil nutrients concentration of N, K, Ca and Mg correlated with plant growth of M. gigantea (p≤ 0.05), potassium concentration of soil positively correlated with a potassium concentration of leaves (p≤ 0.05), whereas magnesium concentration in the leaf correlated with plant growth (p≤ 0.05). We suspect that bases nutrient elements, potassium, calcium, and magnesium are nutrients absorbed in large quantities by M. gigantea and extremely important to its growth.

Elucidating the invasion history of non-native species has been dependent on coarse-grain and expensive methods or long-term monitoring during which the spread may have proceeded beyond feasible control. We used the case of a relatively recent introduction and spread of the neotropical Cecropia pachystachya in Singapore to develop a method for reconstructing spatio-temporal patterns of spread through a low-cost, cross-sectional study. Size and growth rates were measured for C. pachystachya trees as well as the native Macaranga gigantea. A power-expansion exponential-decline function was a better fit than the probability density function of the log-normal distribution in describing the growth-rate to size relationship for both species. C. pachystachya trees generally grew faster (up to 5.4 ± 0.1 cm per year at 12.2 ± 0.2 cm DBH) than M. gigantea trees (up to 3.8 ± 0.2 cm per year at 11.5 ± 0.3 cm DBH). We demonstrated that the integral of the reciprocal of these growth equations provides an estimate of the age of the individuals from their size. Using the size and geographic coordinates of C. pachystachya trees from an island-wide search, we estimate that the invasion front of reproductive trees (>5 cm DBH) showed at least a 20-year lag phase from the time of initial establishment to the year 2005, before advancing exponentially at median rates between 5 and 466 m year−1 with maximum rates of several km year−1. The extent of occurrence expanded by nearly tenfold from 2004 to 2012. Consequently, the spatial dynamics of trees can be reproduced using ontogenetic growth functions.

Annual wood increment and cambial activity in Macaranga gigantea and Endospermum diadenum growing in tropical rainforest were monitored to examine their relationship with stem sizes and climatic factors. The monitoring period was done from March 2013 to February 2014. Wood blocks containing phloem, cambium and outer sapwood were collected monthly from the main trunk of selected trees. Results showed that M. gigantea with smaller stem diameter showed higher annual diameter increment (16.63 ± 7.2 mm) than those with larger stem diameters (3.30 ± 0.1 mm) The total amount of wood formed in E. diadenum with larger stem diameter (9.17 ± 0.3 mm) was higher than the trees with smaller stem size (3.33 ± 0.3 mm). The rhythm of cambial activity were found different among tree species and stem diameters within the same species. M. gigantea with smaller stem diameter had longer active cambial growth period and produced higher number of cell layers than trees with larger stem diameter. In contrast, E. diadenum with larger stem diameter showed longer active growth period and higher number of cell layers than trees with smaller stem diameter. This study showed no significant correlation between mean number of cambial and enlarging cell layers with monthly total rainfall, monthly mean relative humidity, vapor pressure deficit and day length. Significant negative correlations were detected between maximum temperature and number of cambial and enlarging cell layers in M. gigantea with smaller stem size. For E. diadenum with smaller stem size, monthly mean temperature had significant negative correlation with the number of cambial cell layer. This study concluded that the intra-annual wood formation patterns of this two pioneer species are species specific and stem sizes specific.

Cecropia is a pioneer genus from the Neotropics, whilst Macaranga is an ecological analog with a center of distribution in Southeast Asia. In the past few decades, introduced populations of Cecropia spp. have spread rapidly in Singapore, Malaysia, and Indonesia. In Singapore, Cecropia pachystachya now occupies habitats that would have been expected to be occupied by Macaranga gigantea. We conducted germination experiments under 0, 20, 50, and 70 % shading and measured the survival rates and functional traits of the seedlings of these two species from material collected in Singapore. Seeds of C. pachystachya germinated in 3–12 days, whereas seeds of M. gigantea germinated from day 13 onwards. Germination success for C. pachystachya was between 90.3 % under full-light conditions and 55.8 % under 50 % shading, while for M. gigantea only 69.1 % of seed germinated under full-light conditions and germination completely failed when seeds were shaded by 20 % or more. The seedlings of C. pachystachya also had higher survival rates, faster shoot and root biomass accumulation, larger leaves, and lower total water content than those of M. gigantea. Thus overall, C. pachystachya possesses traits that may provide a competitive edge over the native M. gigantea and will be advantageous for its spread given the increasing proliferation of disturbed landscapes in tropical Southeast Asia.

Sprouting ability is highly variable among different tree species. In many cases, there are trade-offs in carbon allocations between growth and storage in seedlings. However, this trade-off is likely to change with growth stages from seedling to mature plant because carbon investments in reproductive activities and/or risk of disturbance also change by species and growth stage. To examine how sprouting ability and carbohydrate storage change with growth stage, we compared two tropical secondary-forest trees, Macaranga bancana and M. gigantea, which have different ecological traits. Maximum tree size and growth rate are higher in M. gigantea. We monitored sprout growth and stored resources, including total non-structural carbohydrate (TNC) and nitrogen in the root, among different tree sizes for 12 months following stem-cutting treatment. Sprouting ability (total sprout mass) and TNC concentrations were significantly higher in small individuals than in larger specimens in both species. TNC concentration decreased in all size classes after stem cutting. Macaranga bancana had greater sprout survivorship than M. gigantea, which had higher sprouting ability in larger tree-size classes. Thus, sprouting ability likely depends on root TNC concentration and tree-size class in both Macaranga species. Higher TNC concentration and sprout survival rates in M. bancana may be related to greater carbon allocation in survival than in growth. This hypothesis is consistent with the ecological traits of M. bancana, such as its growth rate, which was lower than that of M. gigantea.

Susanto D, Ruchiyat D, Sutisna M, Amirta R. 2016. Soil and leaf nutrient status on growth of Macaranga gigantea in secondary forest after shifting cultivation in East Kalimantan, Indonesia. Biodiversitas 17: 409-416. Macaranga gigantea is an important pioneer plant species in the tropical secondary forest of Kalimantan and as far the attractive wood species was not commercially cultivated. This study aims to determine the soil and nutrient status on growth of M. gigantea in the secondary forest particularly after shifting cultivation activity. For this purposes, the observation plots with 50m x 50m sizes were made and measured to collect the data of diameter, height, soil conditions and leaf nutrient concentrations -1 and 2.96 year -1 and it was gradually decreased until the 10 years old of plant. The negative correlations was observed from the soil nutrient K and growth of diameter and high of M. gigantea and this nutrient factor should be considered well when this species will be cultivated for the commercial purposes in the future.

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.

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.

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%).