Mortality and Ingrowth Pattern of Dipterocarps in Forest Recovery in East Kalimantan

In primary and logged-over natural forest, the stand conditions such as stand structure, mortality and ingrowth rates will vary according to the species characteristic. The study objective was to determine mortality and ingrowth/recruitment rates to formulate biometric characteristic variability of dipterocarps forest in logged-over forests based on time series data. The study site was located in Labanan, East Kalimantan Province. Permanent measurement plots within logged-over forest were located to represent threedifferent logging techniques, i.e., (a)reduced impact logging with limit diameter 50 cm (RIL 50), (b) RIL 60, (c) conventional logging and (d) primary forest as control. Total plot permanent area about 48 ha that measured 2 years periodically along 17 years after logging. Data analysis of stands were divided into two major groups, i.e., Dipterocarps and non Dipterocarps. The mortality rates on logged forest were 2.5-29.3% ha-1 2yr-1 then very closed to primary forest after the 5th year after logging. While the ingrowth rate in logged forest were 1.3 – 21.3% ha-1 2yr-1 that have higher value than the primary forest along 17 years. The mortality and ingrowth rates fluctuation of Dipterocarps species group having different pattern with non Dipterocarps

The dynamics of radial growth of three selected tropical tree species studied through knife-cutting method

Tropical trees which lack distinct growth rings have caused difficulty in estimating the growth rate of those trees. This has resulted in limited knowledge concerning tropical tree growth pattern and rate of increment. This study aimed to assess the radial growth and cell production rate of three selected tropical species, namely, Macaranga gigantea, Endospermum diadenum and Dipterocarpus costulatus, with different diameters at breast height. For this purpose, knife-cutting method was adopted in this study. A knife was inserted through the bark into the outer xylem of a tree to wound the cambium and remove immediately. Wood discs containing wound area were collected from living trees after a period of time. Transverse sections of 20-25 µm in thickness were obtained through sliding microtome and dehydrated in a graded series of ethyl alcohol before staining with safranin and fast green. Dibutyl phthalate xylene (DPX) was used as a mounting medium for preparation of permanent microscope slides. The species-related anatomical response to wounding was identified and used to define the time of marking. Results show that radial growth rate and cell production rate varied across species and tree sizes. M. Gigantean and E. Diadenum showed faster growth rates than D. Costulatus, especially in small diameter classes. Meanwhile, D. Costulatus had the lowest growth rate and cell production rate. Thus, both the pioneer species are thus considered to grow faster in smaller stem size than larger stem size, while the study succeeding species grow faster in larger stem size than smaller stem size

The effects of wild pigs (Sus scrofa) on woody understory vegetation in lowland rain forest of Malaysia

An increasingly urgent task in the field of conservation biology is to identify changes in abiotic and biotic interactions that result when large areas of forest are converted to small fragments surrounded by anthropogenic landscapes. My research, conducted in lowland dipterocarp rain forest at the 2,500-ha Pasoh Forest Reserve in Peninsular Malaysia, investigated a novel but strongly negative edge effect - namely, a tremendous increase in the density of wild pigs (Sus scrofa) and the resulting deleterious impacts on the understory plant community. The absence of feline predators due to the small size of the reserve and the presence of a year-round food supply in the agricultural areas surrounding the reserve are believed to be the main factors contributing to increased pig density. Line transects were conducted to determine pig density within Pasoh. Density in 1996 and 1998 was estimated to be 47 and 27 pigs/km2, respectively, or 10 – 100 times historical levels. Fences were constructed to exclude pigs from control plots to quantify the impact of soil rooting and seed predation on plants in the understory. After two years, plots inside exclosures had three times more recruits, greater species richness, and 53% more height growth among plants 1 – 7 m tall than did adjacent plots to which pigs had access. Surveys were conducted in 1995, 1996, and 1998 to determine the number of reproductive nests constructed by pigs. Pigs constructed an estimated 6.0 nests/ha/year during this time, with an average nest composed of 145 snapped saplings and 117 uprooted saplings. Nest building accounted for 28.9% of all mortality for trees 1 – 2 cm diameter at breast height. Uprooted stems died, but snapped stems produced a leafless stump that could resprout. Observations of \u3e1,800 stumps for 36 months revealed large differences in resprouting among species, families, and groups of plants with similar life history characteristics. Overall, the results of the different studies suggest that if elevated pig densities continue there could be a shift away from the currently dominant Dipterocarpaceae and Euphorbiaceae

Individual tree detection and modelling aboveground biomass and forest parameters using discrete return airborne LiDAR data

Individual tree detection and modelling forest parameters using Airborne Laser Scanner data (Light Detection and Ranging (LiDAR) is becoming increasingly important for the monitoring and sustainable management of forests. Remote sensing has been a useful tool for individual tree analysis in the past decade, although inadequate spatial resolution from satellites means that only airborne systems have sufficient spatial resolution to conduct individual tree analysis. Moreover, recent advances in airborne LiDAR now provide high horizontal resolution as well as information in the vertical dimension. However, it is challenging to fully exploit and utilize small-footprint LiDAR data for detailed tree analysis. Procedures for forest biomass quantification and forest attributes measurement using LiDAR data have improved at a rapid pace as more robust and sophisticated modelling used to improve the studies. This thesis contains an evaluation of three approaches of utilizing LiDAR data for individual tree forest measurement. The first explores the relationship between LiDAR metrics and field reference to assess the correlation between LiDAR and field data at the individual-tree level. The intention was not to detect trees automatically, but to develop a LiDAR-AGB model based on trees that were mapped in the field so as to evaluate the relationships between LiDAR-type metrics under controlled conditions for the study sites, and field-derived AGB. A non-linear AGB model based on field data and LiDAR data was developed and LiDAR height percentile h80 and crown width measurement (CW) was found to best fit the data as evidenced by and Adj-R2 value of 0.63, the root mean squared error of the model of 14.8% and analysis of the residuals. This paper provides the foundation for a predictive LiDAR-AGB model at tree level over two study sites, Pasoh Forest Reserve and FRIM Forest Reserve. The second part of the thesis then takes this AGB-LiDAR relationship and combines it with individual tree crown delineation. This chapter shows the contribution of performing an automatic individual tree crown delineation over the wider forest areas. The individual tree crown delineation is composed of a five-step framework, which is unique in its automated determination of dominant crown sizes in a forest area and its adaption of the LiDAR-AGB model developed for the purpose of validation the method. This framework correctly delineated 84% and 88% of the tree crowns in the two forest study areas which is mostly dominated with lowland dipterocarp trees. Thirdly, parametric and non-parametric modelling approaches are proposed for modelling forest structural attributes. Selected modelling methods are compared for predicting 4 forest attributes, volume (V), basal area (BA), height (Ht) and aboveground biomass (AGB) at the species level. The AGB modelling in this paper is extracted using the LiDAR derived variables from the automated individual tree crown delineation, in contrast to the earlier AGB modelling where it is derived based on the trees that were mapped in the field. The selected non-parametric method included, k-nearest neighbour (k-NN) imputation methods: Most Similar Neighbour (MSN) and Gradient Nearest Neighbour (GNN), Random Forest (RF) and parametric approach: Ordinary Least Square (OLS) regression. To compare and evaluate these approaches a scaled root mean squared error (RMSE) between observed and predicted forest attribute sampled from both forest site was computed. The best method varied according to response variable and performance measure. OLS regression was to found to be the best performance method overall evidenced by RMSE after cross validation for BA (1.40 m2), V (1.03 m3), Ht (2.22 m) and AGB (96 Kg/tree) respectively, showed its applicability to wider conditions, while RF produced best overall results among the non-parametric methods tested. This thesis concludes with a discussion of the potential of LiDAR data as an independent source of important forest inventory data source when combined with appropriate designed sample plots in the field, and with appropriate modelling tools

Stem girth changes in response to soil water potential in lowland dipterocarp forest in Borneo: An individualistic time-series analysis.

Time-series data offer a way of investigating the causes driving ecological processes as phenomena. To test for possible differences in water relations between species of different forest structural guilds at Danum (Sabah, NE Borneo), daily stem girth increments (gthi), of 18 trees across six species were regressed individually on soil moisture potential (SMP) and temperature (TEMP), accounting for temporal autocorrelation (in GLS-arima models), and compared between a wet and a dry period. The best-fitting significant variables were SMP the day before and TEMP the same day. The first resulted in a mix of positive and negative coefficients, the second largely positive ones. An adjustment for dry-period showers was applied. Interactions were stronger in dry than wet period. Negative relationships for overstorey trees can be interpreted in a reversed causal sense: fast transporting stems depleted soil water and lowered SMP. Positive relationships for understorey trees meant they took up most water at high SMP. The unexpected negative relationships for these small trees may have been due to their roots accessing deeper water supplies (if SMP was inversely related to that of the surface layer), and this was influenced by competition with larger neighbour trees. A tree-soil flux dynamics manifold may have been operating. Patterns of mean diurnal girth variation were more consistent among species, and time-series coefficients were negatively related to their maxima. Expected differences in response to SMP in the wet and dry periods did not clearly support a previous hypothesis differentiating drought and non-drought tolerant understorey guilds. Trees within species showed highly individual responses when tree size was standardized. Data on individual root systems and SMP at several depths are needed to get closer to the mechanisms that underlie the tree-soil water phenomena in these tropical forests. Neighborhood stochasticity importantly creates varying local environments experienced by individual trees

Biodiversity and sustainability in the Bulungan Research Forest, East Kalimantan, Indonesia: the response of plant species to logging

This study reports forest structure, regeneration and the soil properties from unlogged and logged forest in the Bulungan Research Forest, Malinau District, East Kalimantan, Indonesia. Four sites were compared by using four 1-ha replicate plots in each of primary forest (PF), 5, 10 and 30-yr old logged forest (LF-5, LF-10, LF- 30). The tree species composition differ among forest types, as it was shown that the mean value of similarity indices for all pairs were 0.215 (for the Jaccard index) and 0.353 (for the Sorensen index). The low values for similarities among forest types were most probably caused by low numbers of species shared between each forest type. Both correlation values, r = 0.023 for Jaccard index and r = 0.031 for Sorensen index, showed no strong correlation between the similarity index (C) and the distance between forest types. This supports the use of a chronosequence approach. A total of 914 tree species with ³ 10 cm dbh were recorded from 223 genera and 65 families. There were no significant differences in mean species numbers (166 – 180/ha) among treatments. Mean density of species was lower in LF-5 and LF-10 (501/ha) than in PF or LF-30 (605/ha and 577/ha); similarly to mean basal area (LF-5, 28.5 m2/ha; LF-10, 32.6 m2/ha) vs. PF (45.8 m2/ha) and LF-30 (46.9 m2/ha). Dead wood on the forest floor was significantly higher in LF-10 (75 m3/ha) than in the other treatments. Seedlings (2 – 9.9 cm dbh) of 802 species belonged to 241 genera and 65 families. There was a high variability in species richness across treatments (89 – 191/ha), but not in stem numbers. The Dipterocarpaceae family was dominant in all treatments, followed by the Euphorbiaceae. The soils were acidic, low in nutrients and had low to very low fertility. Both primary and logged forest areas are marginal or not suitable for sustained production of plantation crops. Logging caused soil compaction in LF-30. Although in terms of number of species and trees, amount of BA, number of saplings and seedlings LF-30 appeared to have satisfied prescriptions for a second harvest, ecologically the forest is far from mature. The Indonesian Selective Cutting and Replanting (TPTI) system may need to be revised to a 35 – 45 year cycle to ensure long-term forest productivity in terms of not only timber but other goods and ecosystem services, the value of which are never quantified in monetary terms, but can be higher than the timber revenue

Holocene Environmental Change in Mainland Southeast Asia: Pollen and Charcoal Records From Cambodia.

Major Holocene environmental changes in continental Southeast Asia are reconstructed using proxy data derived from analysis of 14C-dated changes in pollen, microscopic charcoal, and organic/inorganic carbon in sediment cores taken from permanent, closed-basin, volcanic lakes in Ratanakiri Province, northeastern Cambodia. Analysis focuses on the history of monsoon climate and land use, inferred from changes in vegetation, fire regime, and lake conditions. These data provide the first well dated palynological record, covering most of the Holocene and continuous up to the present, from an upland site in mainland Southeast Asia. The record from a 15-meter core retrieved from Yeak Kara Lake, representing the last 9300 years, shows that the Late Glacial period ended about 8500 BP, more than 1000 years later than sites in southwest China. Maximum summer monsoon intensity occurred ca. 8000--5400 BP, similar to most other sites in the Asian monsoon region. A subsequent increase in burning caused expansion of secondary forests at the expense of dense semi-evergreen forests. After ca. 3500 BP fire frequency may have increased further, leading to expansion of dry deciduous forests. From ca. 2500 BP up to the present, dense forest has recovered in a mosaic with annually-burned dry forest, due either to a Late Holocene strengthening of the monsoon or to more pervasive control of the fire regime by indigenous populations. The pattern of burning for the last 2500 years, corroborated by charcoal records from two other nearby lakes, shows lowest burning intensity perhaps coinciding with the development and demise of major civilizations (Funan, Chenla, Angkor) in the region

Phylogeography and Demography of Common Plant Species from the Philippine Islands.

The complex geologic history of the Philippines creating a diverse and highly endemic flora is reviewed. Apart from tectonic activity, the islands were subjected to changes in topography, temperature, and precipitation from Pleistocene glacial and interglacial periods. Comparative phylogeography is used to determine the effects of Pleistocene events on the population genetic structure of two endemic species, Daemonorops mollis (Arecaceae) and Macaranga bicolor (Euphorbiaceae). Limited variation and unique haplotypes in both species suggest that during periods of lowered sea levels, rainforest habitats were maintained as refugia. A land barrier between eastern and western Luzon and water around islands restricted dispersal among populations. A potential route of island colonization in the south- and west- ward direction from northeast Luzon was recovered in M. bicolor. An eastern Luzon population was studied to document spatial distributions and species-habitat associations, and determine possible mechanisms facilitating coexistence in species-rich communities. Torus translation tests showed contrasting patterns of stream- and elevation- microhabitat associations between three palm tree species and D. mollis, a liana, suggesting a potential for niche differentiation between growth forms. In 30 dominant tree species, each was associated with at least elevation, slope, or stream at one or more life stages (saplings, juveniles, or adults), but associations varied across life stages in most species. Species sharing a microhabitat show niche partition, in time if not in space. Distributions at different life stages were also analyzed to infer what processes resulted in the observed spatial patterns. Aggregation was exhibited in all species at multiple scales, and decreased with species abundance and long-distance dispersal. Correlation analyses measured relationships between clusters of saplings, or juveniles, with clusters of adults or distance to the nearest conspecific adult. Results show greater clustering of saplings around adults in three species, attributed to negative density dependent effects on juveniles. In ten species, juveniles clustered more around adults indicating negative density dependence before the sapling stage, while recruitment into the juvenile stage was successful for saplings located in suitable habitats near adults. Seed dispersal, negative density dependence, and niche differentiation, are therefore important in maintaining the diverse tree community in Palanan, Philippines.Ph.D.Ecology and Evolutionary BiologyUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/78857/1/slimyap_1.pd