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.

A PRELIMINARY STUDY ON VEGETATIVE PROPAGATION OF SALTTOLERANT TREE SPECIES

This experiment was undertaken primarily to study the influence of salinity onroot formation of curttings, taken from four promising salt-tolerant species,namely Acacia leucophioea (Katu andara), Cassia autriculata (Ranawara),Thespesia populnea (Suriya), and Salvadora persica (Malittha).Here, semi hard wood cuttings of each species were planted in poly bags filledwith soil, and arranged ReBD with four replicates. Saline solutions (i.e., 2, 4, 8and 12 dS/m) were applied at the rate of 100,1 per poly bag, once in two days lipto the period of one month. Sea water (40 dS/m) diluted to give varying salinitylevels and normal water (0.13 dS/m) was used as the control. The experiment wasconducted, during the period of March,-June 2000, at the Faculty of Agriculture,University of Ruhuna, Mapalana, Kamburupitiya, Sri Lanka.The results of the study indicated that any of four species did not form roots, evenin the control. Thus, experiment was repeated, and carried out up to the period oftwo months. At the end of two months. Suriya had formed several roots and other3 species did not form roots at all. Highest rooting percentage and highest rootelongation were obtained in low salinity levels «4 dS/m). However, number ofroots and lengths of roots were decreased as the level of salinity increased (>8dS/m).According to this study. rooting is considered as a very difficult task in cuttings ofKatu Andara, Ranawara and Malittha. But for Suriya it can be considered assuccessful method of propagation.

EFFECT OF DIFFERENT SALINITY LEVELS ON SEED GERMINATION OF SALT TOLERANT TREE SPECIES

An experiment was conducted, during March-July 2000,at the Faulty ofAgriculture, University of Ruhuna, Mapalana, Kamburupitiya, to study of theeffect of levels of salinity on seed germination of three salt tolerant species,namely Acacia leucoploea (Katu Andara), Parkinsonia aculeate (Parkinsonia) andCassia auriculate (Ranavara)The experimental design used, was Randomized Complete Block Design with 5treatment and 4 replications. Here, sea water (40 ds/m) was diluted to givevarying salinity levels (i.e. 2, 4, 8, and 12 ds/m) and normal water (0.13 ds/m)was used as the control. Saline solutions were applied to seeds and the rate andpercentage germination was observed.The results obtained from the experiment showed that, low salinity levels (4 ds/m)increased seed germination of all 3 species. But with increasing salinity beyond 8ds/m a decreasing in germination was observed. When the salinity level was 8ds/m, the percentage of germination in Katu Andara, Parkinsonia and Ranavaraabout 40,40 and 13 respectively.The percentage of germination in Ranavara was 0 at the salinity level of 12 ds/m.But in Katu Andara and Parkinsonia, 23% and 15% germination was observed at12 ds/m. Thus, these species can be ranked in oder of tolerance to salinity asfollows:Katu Andara > Parkinsonia > Ranavar

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.

Community based conservation as a tool to conserve freshwater fish in Sri Lanka: Evidence from Puntius bandula conservation programme

Puntius bandula is an endemic fish restricted to two unprotected small streams at Galapitamada. The streams are surrounded by habitats subjected to frequent anthropogenic threats such as destruction of floral assemblages of the catchment and stream banks, releasing of agrochemicals, fertilizers and kitchen waste, artificial constructions of the stream bank, narrowing of the stream and collapsing of the stream bank due to expanding paddy cultivations and illegal collection of fish by unauthorized parties. The population size of P. bandula has declined rapidly during the past two decades making it a Critically Endangered species. The main aim of this programme was to ensure long term survival of this species through a participatory conservation approach. First, a standardized questionnaire survey was done to determine the degree of awareness, the willingness of the community to conserve P. bandula, obtain a profile of the community and to introduce the objectives of the programme. Further, awareness was raised in the community through presentations and discussions held at monthly community meetings. An environment protection committee was established and an action plan was drawn up. Under this; two community awareness workshops, transect walk, school environment programmes and monthly community meetings were conducted. Further, several communication tools such as calendars, a brochure, a time table, powerpoint presentations, video clips and sign boards were produced. The degree of awareness of the community was increased up to 85% after the awareness programme from 54%. Also a tree planting campaign was conducted with the community to enhance the habitat of P. bandula. Finally a small stock of adult P. bandula (15 females and 5 males) was translocated to a new locality as a participatory approach to establish a second population and 10 adults and 7 fry were observed in the new locality three months after the translocation. It can be concluded that, this approach is useful in conserving endemic freshwater fish species in Sri Lanka by minimizing threats via self awareness, since most of them are located outside of the protected area net work and subjected to anthropogenic threats

The Three Dimensional Structure of EUV Accretion Regions in AM Herculis Stars: Modeling of EUV Photometric and Spectroscopic Observations

We have developed a model of the high-energy accretion region for magnetic cataclysmic variables and applied it to {\it Extreme Ultraviolet Explorer} observations of 10 AM Herculis type systems. The major features of the EUV light curves are well described by the model. The light curves exhibit a large variety of features such as eclipses of the accretion region by the secondary star and the accretion stream, and dips caused by material very close to the accretion region. While all the observed features of the light curves are highly dependent on viewing geometry, none of the light curves are consistent with a flat, circular accretion spot whose lightcurve would vary solely from projection effects. The accretion region immediately above the WD surface is a source of EUV radiation caused by either a vertical extent to the accretion spot, or Compton scattering off electrons in the accretion column, or, very likely, both. Our model yields spot sizes averaging 0.06 R$_{WD}$, or $f \sim 1 \times 10^{-3}$ the WD surface area, and average spot heights of 0.023 R$_{WD}$. Spectra extracted during broad dip phases are softer than spectra during the out-of-dip phases. This spectral ratio measurement leads to the conclusion that Compton scattering, some absorption by a warm absorber, geometric effects, an asymmetric temperature structure in the accretion region and an asymmetric density structure of the accretion columnare all important components needed to fully explain the data. Spectra extracted at phases where the accretion spot is hidden behind the limb of the WD, but with the accretion column immediately above the spot still visible, show no evidence of emission features characteristic of a hot plasma.Comment: 30 Pages, 11 Figure

Helium in superstrong magnetic fields

We investigate the helium atom embedded in a superstrong magnetic field gamma=100-10000 au. All effects due to the finite nuclear mass for vanishing pseudomomentum are taken into account. The influence and the magnitude of the different finite mass effects are analyzed and discussed. Within our full configuration interaction approach calculations are performed for the magnetic quantum numbers M=0,-1,-2,-3, singlet and triplet states, as well as positive and negative z parities. Up to six excited states for each symmetry are studied. With increasing field strength the number of bound states decreases rapidly and we remain with a comparatively small number of bound states for gamma=10^4 au within the symmetries investigated here.Comment: 16 pages, including 14 eps figures, submitted to Phys. Rev.

Superhumps in Cataclysmic Binaries. XXIII. V442 Ophiuchi and RX J1643.7+3402

We report the results of long observing campaigns on two novalike variables: V442 Ophiuchi and RX J1643.7+3402. These stars have high-excitation spectra, complex line profiles signifying mass loss at particular orbital phases, and similar orbital periods (respectively 0.12433 and 0.12056 d). They are well-credentialed members of the SW Sex class of cataclysmic variables. Their light curves are also quite complex. V442 Oph shows periodic signals with periods of 0.12090(8) and 4.37(15) days, and RX J1643.7+3402 shows similar signals at 0.11696(8) d and 4.05(12) d. We interpret these short and long periods respectively as a "negative superhump" and the wobble period of the accretion disk. The superhump could then possibly arise from the heating of the secondary (and structures fixed in the orbital frame) by inner-disk radiation, which reaches the secondary relatively unimpeded since the disk is not coplanar. At higher frequencies, both stars show another type of variability: quasi-periodic oscillations (QPOs) with a period near 1000 seconds. Underlying these strong signals of low stability may be weak signals of higher stability. Similar QPOs, and negative superhumps, are quite common features in SW Sex stars. Both can in principle be explained by ascribing strong magnetism to the white dwarf member of the binary; and we suggest that SW Sex stars are borderline AM Herculis binaries, usually drowned by a high accretion rate. This would provide an ancestor channel for AM Hers, whose origin is still mysterious.Comment: PDF, 41 pages, 4 tables, 16 figures; accepted, in press, to appear December 2002, PASP; more info at http://cba.phys.columbia.edu

Spitzer Space Telescope observations of magnetic cataclysmic variables: possibilities for the presence of dust in polars

We present Spitzer Space Telescope photometry of six short-period polars, EF Eri, V347 Pav, VV Pup, V834 Cen, GG Leo, and MR Ser. We have combined the Spitzer Infrared Array Camera (3.6 -8.0 microns) data with the 2MASS J, H, K_s photometry to construct the spectral energy distributions of these systems from the near- to mid-IR (1.235 - 8 microns). We find that five out of the six polars have flux densities in the mid-IR that are substantially in excess of the values expected from the stellar components alone. We have modeled the observed SEDs with a combination of contributions from the white dwarf, secondary star, and either cyclotron emission or a cool, circumbinary dust disk to fill in the long-wavelength excess. We find that a circumbinary dust disk is the most likely cause of the 8 micron excess in all cases, but we have been unable to rule out the specific (but unlikely) case of completely optically thin cyclotron emission as the source of the observed 8 micron flux density. While both model components can generate enough flux at 8 microns, neither dust nor cyclotron emission alone can match the excess above the stellar components at all wavelengths. A model combining both cyclotron and dust contributions, possibly with some accretion-generated flux in the near-IR, is probably required, but our observed SEDs are not sufficiently well-sampled to constrain such a complicated model. If the 8 micron flux density is caused by the presence of a circumbinary dust disk, then our estimates of the masses of these disks are many orders of magnitude below the mass required to affect CV evolution.Comment: 58 pages, 14 figures, ApJ accepte

The Palomar Testbed Interferometer Calibrator Catalog

The Palomar Testbed Interferometer (PTI) archive of observations between 1998 and 2005 is examined for objects appropriate for calibration of optical long-baseline interferometer observations - stars that are predictably point-like and single. Approximately 1,400 nights of data on 1,800 objects were examined for this investigation. We compare those observations to an intensively studied object that is a suitable calibrator, HD217014, and statistically compare each candidate calibrator to that object by computing both a Mahalanobis distance and a Principal Component Analysis. Our hypothesis is that the frequency distribution of visibility data associated with calibrator stars differs from non-calibrator stars such as binary stars. Spectroscopic binaries resolved by PTI, objects known to be unsuitable for calibrator use, are similarly tested to establish detection limits of this approach. From this investigation, we find more than 350 observed stars suitable for use as calibrators (with an additional $\approx 140$ being rejected), corresponding to $\gtrsim 95$ sky coverage for PTI. This approach is noteworthy in that it rigorously establishes calibration sources through a traceable, empirical methodology, leveraging the predictions of spectral energy distribution modeling but also verifying it with the rich body of PTI's on-sky observations.Comment: 100 pages, 7 figures, 7 tables; to appear in the May 2008ApJS, v176n