Volume 16 Nos. 1 & 2

Chemical changes in microbially infected forest tree seeds


Chemical changes in microbially infected seeds of seven forest tree species, three artificially inoculated and four naturally infected seeds were studied to determine the effect of microfungi on the food reserves of seeds such as starch, total sugar, and fat.

Chemical analysis showed significant reduction in total sugar content of all species, both the artificially inoculated and healthy seed samples. A decrease in starch content was observed on mahogany seeds inoculated with Fusarium moniliforme, F. solani and Lasiodiplodia theobromae; and Ldtheobromae; and kakawate with Ldtheobromae. For the fat content, the same results were observed except on ipil which had an increase. Insignificant changes in starch content were noted on narra seeds infected with C. gloeosporioides, Phoma sp. and F. moniliforme; and raintree seeds with F. solani comparable with the healthy samples. The changes in ion content, Ca, Mg, P and K of raintree, mahogany, narra and ipil seeds infected with various fungi cited above were insignificant as compared with the healthy seeds, decreased in bagtikan and increased in dagang seeds.

The presence of Microfungi on forest tree seeds not only affects the quality of the seedlot but also the morphological as well as the anatomical structures and the chemical components of the seeds.

Seeds contain principaly three major chemical components or food reserves, namely: carbohydrates, fats and oils, and proteins. Carbohydrates are universally found in living tissues and are very important for metabolic processes. They also provide the main structural component of plant tissue which is divided into two main groups, the polysaccharides including starch and monosaccharides including simple sugar. In cereals, oils are stored within the scutellum, while proteins are stored in the cotyledons and endosperm.

During seed germination, these stored food reserves undergo chemical changes so that they can be used in the different processes inside the seeds and hence seedling development begins. This is true in healthy and normal seeds. But what will happen to starch, sugar, fat and ion contents of the seeds when seeds become infected with pathogenic microfungi? Will there be an increase or reduction in their chemical components? What will be the effect of a specific fungus on the chemical components of the seeds? Will it affect seed germinability? Hence, this study.



Identification of important wood-decaying fungi associated with some Philippine dipterocarps at the Makiling forest


Field survey and laboratory experiment were conducted sequentially from May 2003 to January 2005. The study areas were the Dipterocarp Forest and Plantation, Makiling Botanical Garden, ERDB Experiment Station and the UP College of Forestry and Natural Resources campus at the Mt. Makiling Forest Reserve.

There were 27 species of Basidiomycetes belonging to 15 genera, i.e., Ganoderma, Polystictus, Auricularia, Phellinus, Polyporus, Fomes, Stereum, Poria, Daedalea, Hexagona, Lenzites, Hymenochaete, Trametes, Schizophyllum, and Corticum collected. These were characterized morphologically and anatomically prior to identification. The Ganoderma, Polystictus, Auricularia, Fomes and Polyporus were represented by species dominating the area. Among the dipterocarp host species, white lauan (Shorea contorta Vid.) had the widest range of fungal association.

Wood decay is a common occurence among all kinds of trees. Decay can affect the sapwood, or heartwood of a tree. This has been observed in dying trees or in trees which have smaller leaves and slower growth. In many dipterocarps, the decay losses caused by basidiomycetous fungi are enormous.

There are are two types of wood decay caused by basidiomycetous fungi. These are the white and brown rot. This type of decay can be distinguished by the color of the decayed wood. The white rot decomposes all components of the wood including lignin. The decomposed wood is white, and sometimes yellow, tan or even light brown in color and zone lines are present. The brown rot decomposes the cellulose and its associated pentosans leaving the lignin more or less unaffected. The decomposed wood is usually dark brown and without zone lines.



Effect of detopping and bending on the production of orthotropic shoots for vegetative propagation of palosapis [Anisoptera thurifera (Blanco) Blume]


The following rejuvenation methods were used to induce production of orthotropic shoots by reiteration: 1) detopping/hedging only at 1 m height; and 2) detopping at 1 m and bending. It was found that combined hedging/detopping and bending (method 2) or the manipulation of the orientation of stems from vertical to horizontal increased the ability of the species to produce more orthotropic shoots due to the increased ability to capture more light compared to detopping/decapitation alone.

Palosapis (A. thurifera) was found to have weak apical dominance because its stockplants were capable of producing multiple shoots per harvest cycle.



Economic valuation of grassland degradation under different pasture classifications


Two valuation approaches for grassland degradation, namely, Production Function Approach (Based on forage production) and Process-Response Approach (based on erosion-induced lost productivity) were used in this study. Lost animal production was computed, based on what the difference in herbage yield between degraded pasture and non-degraded pasture could have supported, given an average herbage consumption of 25,000 kg/animal/year. The SCUAF model was used to predict the effects of changes in grazing practices on soil erosion over a 10-year period. Valuation approach using forage production closely reveals the actual rate and costs of degradation



Litterfall production in a natural mangrove forest in Davila, Pasuquin, Ilocos Norte


The study was undertaken to assess the monthly litterfall production of mixed mangrove species in Davila, Pasuquin, Ilocos Norte from May 2000 to April 2001. Two litter trays (1m x 1m) made of plastic mesh net were installed in each 15m x 15m experimental plot randomly laid-out within the mangrove forest. The trays were installed 0.5m from the forest floor to eliminate intrusion eliminate intrusion of other debris in the ground. Litter collection was done monthly from May 2000 to April 2001. Fresh litter from each tray were put into paper bags, properly labelled and dried at 70C0 in the oven for one week before final weight measurements were made. One kg composite soil samples, collected at the start and end of the study, were analyzed at the Department of Agriculture Regional Soils Laboratory.

A total of 11 species were recorded from the experimental plots. The mangrove species in the study site is dominated by malatangal (Ceriops decandra) with importance value of 22.32%, followed by bakauan babae (Rhizophora mucronata), with importance value of 21.97%. The least dominant are tabao (Lumnitzera littorea), buta-buta (Excoecaria agallocha) and putat (Barringtonia racemosa roxb.) with importance value of 1.97%.

Findings showed that the highest litterfall production of 1,506 kg/ha was observed in July followed by 1,398.5 kg/ha in June. The lowest was recorded in February with a litterfall production of 129.66 kg/ha.

Litterfall production is strongly correlated with rainfall and relative humidity with coefficient values of 0.6503 and 0.6369, respectively. This implies that the higher the rainfall, the higher is the litterfall.



Survival and growth response of selected reforestation seedlings to pure and mixed sludge media


Seedlings of Eucalyptus deglupta Blume, Triplaris cumingiana Fisch. and Mey., Pinus kesiyaRoyle ex Gordon, Alnus maritima Mersh. ex Nutt, Pterocarpus indicus Willd. and Swietenia macrophylla King were tested as to survival and growth response to sewer sludge mixed media. The height and diameter increments of Eucalyptus deglupta and Triplaris cumingiana were significantly influenced by the sewer sludge whether pure or in mixture with other media. Pinus kesiya Royle ex Gordon grown in sewer sludge + topsoil + sand, performed better in height and diameter growth than in the other media. The total dry matter yield of Triplaris cumingiana, Eucalyptus deglupta and Swietenia macrophylla were significantly influenced by the sewer sludge treatment.



Biomass and carbon sequestration of Gmelina arborea Roxb


One of the most pressing problems nowadays is climate change brought about by the increasing levels of greenhouse gases, particularly carbon dioxide (CO2), in the atmosphere. Trees take up carbon dioxide from the atmosphere and store the carbon in their biomass (roots, stems and foliage) through the process of photosynthesis.

This study was conducted to provide the basic information for accurate and reliable estimations of the biomass and amount of carbon being sequestered in yemane (Gmelina arborea Roxb. ) trees.

Aboveground biomass were determined for 50 felled yemane trees aged 2-12 years covering a wide range of diameter classes from seven provinces in Regions 3, 5, and 6. The total green biomass of a yemane tree ranged from 2.6 to 666.4 kg. The average tree contained 68.56% of the total dry weight in the merchantable stem, 6.45% in the foliage and 24.98% in the topwood, branches and twigs. On the average, 6.85% of the stem (trunk) dry weight was bark abd 61.71% was wood.

Prediction equations using allometric models were developed for estimating the fresh and oven dry weights of the whole tree and its components using easily measured variables such as diameter and height.

Based on the carbon analyses done on the tree samples taken, the oven dried stemwood, bark, branches and leaves have 46.06%, 43.53%, 44.48% and 44.89% total carbon in their biomass, respectively. On the average, a yemane tree has 44.73% stored carbon in its dry mass.