BIOMASS AND NUTRIENT ACCUMULATION OF AN EARLY SUCCESSIONAL SHRUB SPECIES (Zizyphus oenoplia) IN AN UPROOTED RUBBER FIELD AT KAMBURUPITIYA

Restoration of degraded ecosystems has become a matter of great concern. Earlysuccessional species playa key roll in the process of restoration. Therefore here astudy was undertaken to assess the accumulation and partitioning of biomass andnutrient in widely occurring early successional shrub species, namely Zizyphusoenoplia (Eraminiya) of varying ages (i.e. 4, 6 and 8 years). The experiment wasconducted at the faculty of Agriculture, University of Ruhuna, Mupalana,Karnburupitiya, during March-August, 2000. Here, four plots were selected foreach age class and four plants were sampled for each plot and their distribution ofdry matter and major nitrient (NPK) in stem, branches and leaves were measuredin each plant.Findings clearly indicate that majority of biomass was concentrated in plant stemand as the age progressed, this proportion is increased. These results furtherindicate that the biomass allocation to the leaves was high in young ages and it isdecreasing as the age progressed. Total biomass of plant after 4, 6 and 8 yearswas 902, 2602 and 4552 g respectively.Results also show that major nutrient content in leaves, branches and stem werehigh in early stages of the growth and decreasing as the age progressed.Percentage of N. P and K in leaves at 4 years were 2.91, 0.116 and 1.54respectively. But after 8 years N. P and K content were 2.36, 0.093 nd 1.275%respectively, show a decreasing rend of concentration of major nutrient in leaftissues. Stem and branches show the same pattern of nutrient partitioning as theplant getting matured.

SOIL CHARACTERISTICS IN SOME HUMAN IMPACTED AREAS AT KAMBURUPITIYA FOLLOWING THE NILWALA PROJECT

The study involved characterization of physical, chemical, and biologicalproperties of a severely disturbed soil in Kamburupitiya, which has beenpreviously maintained under agroforestry.The bulk density, true density, and porosity of the soil were l.163 gcrrr', 2.14gcrrr' and 45.6% respectively, with a water holding capacity of 28.5%. The percent organic matter and N in the soil were 0.451 and 0.0088, respectively,whereas the corresponding values in an undisturbed neighboring site, were 1,214and and 0.095. The cation exchange capacity of the degraded soil was 4.71 m.e.per 100g. of soil and had a H value of 4.2. The corresponding figures for thereference site were 7.4 and 5.43, respectively. Biological activity of the soil asmeasured by soil respirometry, amounted to 0.716 mg COilOOOg of soil/hr andl.355 mg CO2/lOOOg. of soil/hr in disturbed and undisturbed soil, respectively.No macro fauna was evident in the soil. Even after 12 years of disturbance, soilregeneration was extremely slow, thus agronomic interventions prove important toaccelerate the soil restoration process

STUDIES ON DORMANCY AND GERMINATION DYNAMICS OF Macaranga peltata(KANDA), AN EARLY SUCCESSIONAL SPECIES

Macaranga peltata is one of the most widely occurring early successional woodyspecies, specially in low country wet zone. Although Macaranga spreadsprofusely by seeds, the seed biology and germination behavior has not beenstudied. According to the preliminary studies, it was revealed that, thegerminability of freshly isolated seeds is very low. Therefore this work wasundertaken to understand the germination behavior and measures to enhance seedgermination of Macaranga. The study was conducted during May-July, 2000, atthe faculty of Agriculture, University of Ruhuna, Mapalana, kamburupitiya, SriLanka.Three treatments used, i.e. mechanical scarification using sand papers (T I),Chemical scarification using H2S04 acid (T2) and hormone treatment using GA(T3)' with the control. Fully ripened seeds were harvested and thoroughly washedto remove the peel and air-dried for one day. Dried seeds were treated asindicated above and placed in petri dishes containing sand media and allowed togerminate. Three replications were used for each treatment and percentage ofgermination was recorded at 7,14,21 and 28 days after planting.Germination of Macaranga seeds started after 14-21 days in control by afterseven days in treated seeds. Mechanical and chemical scarifications were noteffecting in increasing the percentage of germination significantly. But thegibberelic acid treatment has made a tremendous important in the percentage ofgermination and at the same time resulted in significant reduction it time taken forgermination. Although scarification treatments may have improved permeabilityof seed coat, it has not contributed to the germinability of seeds, the significantimpact made by GA treatment both in increasing and accelerating the germinationprobably reveals that there exists a dormancy in Macaranga seeds which is ofphysiological or metabolic in nature GA treatment of more effectively at higherconcentration: (20mm) was capable of breaking the dormancy and thus enhancedgermination.

SEED PROPAGATION OF RATH HADUN (Pferocarpus santalinus Linn.) AS EFFECTD BY METHOD OF SOAKING AND SCARIFICATION

Red Sandalwood (Pterocarpus santalinus Linn.) is an evergreen tree species grownunder semi dry climates in well drained lateric soils. The reddish and fragrant heartwoodhas a range of medicinal, pharmaceutical, industrial and timber and economically placedin the same category as tusk and amber. The Red heartwood contains a range ofconstituents including santalin (Santalic Acid), Santaol, Pterocarpin, Homo-Petrocarpinand reported to have anticoagulant, anti inflammatory, anti expectorant, anti pyretic, antibacterial and anti tumor properties. Expensive natural fabric paint produced from thepowdered Red heartwood is used in wood carving of prestigious nature. The naturalhabitat of Red Sandalwood is India which is extensively exploited to the point of nearextinction, thus placing it in the red list of endangered species under IUCN guidelinesThere is only a limited number of Red sandalwood trees in Sri Lanka, which werebrought from India. Therefore, conservation and multiplication of Red sandal wood is oftimely importance. Even though a single tree of Red Sandalwood produces severalthousands of seeds, there is no single seedling under the tree. The local requirement ofRed Sanders is met partly by Indian suppliers while substitutes with similar medicinalproperties (Rath Kehiriya) are also being used.Two separate pot experiments(Complete Randomized Design with three replicates) wereconducted to study the seed germination as affected by method of soaking andscarification. Fully matured brown coloured fresh seeds were used for the experimentsand viability of the seeds used for the experiment was 70 to 72 %. Three differentsoaking methods (i.e. 24 hours dipping in normal water, 24 hour soaking in runningwater, alternatively soaked in running water for 12 hrs. followed by 12 hours of dryingfor 14 days) and again differentiated with scarification and without scarification wereused as treatments. Total germination percentage was counted up to 14 daysResults revealed that Seed germination was significantly higher (P>0.05) in scarifiedseeds (48.8%) when compared to those without scarification (6.1%). With regards to thesoaking method, highest germination percentage (3 1%) was observed in the treatment,12 hrs of alternate soaking and drying in running water for 14 days, which was notsignificantly different from the treatment that seeds were soaked in running water for 24hrs. Therefore it can be concluded that germination of Red Sandalwood seeds could besubstantially enhanced by scarification of the seed coat and seeds soaked in runningwater for 24 hrs. as well as 12 hrs of alternate soaking and drying for 14 days.