Drought Induced Fine Root Growth and Canopy Green-up of Tropical Dry Zone Vegetations in Sri Lanka

Fine roots in forest soils have important implications for global carbon (C) balance, but processesunderlying this C sink are not well understood. This study evaluates year round dynamics of fine roots ina tropical dry mixed evergreen forest and an arboretum in the dry zone of Sri Lanka. Monthly soil coresamples (up to 25 cm depth) were collected randomly to cover a whole annual cycle of the two sites. Thesoils were air dried, sieved (< 2 mm), and fine roots (≤ 2 mm) were separated by handpicking coupledwith a water floating technique. Then, fine root biomass and C density were calculated using oven dryweight. Annual mean fine root biomass of the dry zone forest and the arboretum were found to be 5.72 ±0.57 t/ha and 7.88 ± 0.81 t/ha, respectively, with C densities of 2.69 ± 0.27 t/ha and 3.7 ± 0.38 t/ha,respectively. Thus, dry zone arboretum showed a higher growth and biomass, and hence a C pool of fineroots, than the dry zone forest, possibly due to a younger forest stand with fast fine root turnover rate. Inboth sites during the dry spell, there was an increased production of fine roots and a simultaneous leafflush on the canopy with a green-up. The increased fine root growth during the dry season generallyallows the trees to absorb more water under water-stressed situations. These events may be due to anundisclosed survival mechanism of such ecosystems under drought, which needs further studies.Key words: Drought, Fine root growth and canopy green-up, Tropical dry zone vegetatio

The Distribution, Natural History and the Conservation Status of Batrachostomus Moniliger (Aves: Podargidae) in Last Two Decades from Sri Lanka

The Sri Lanka frogmouth (Batrachostomus moniliger) is a small-sized nocturnal bird largely restricted to tropical lowland forests with thick undergrowth. The motionless roosting posture as well as their plumage coloration and color patterns (which resemble that of tree stems and branches) enable them to camouflage and thereby avoid predation. Through opportunistic field surveys over a 20-year period (January 1998-February 2018), we surveyed different bioclimatic regions of Sri Lanka covering 500 sites, and documented presence of Sri Lankan frogmouth in 83 of sites. In these 83 sites, we recorded 136 birds including seven nesting pairs and chicks. Our survey confirmed frogmouth presence in four floristic regions of Sri Lanka, particularly from lower elevations (11-767 m). Most sightings were made in lowland rainforests while savannah woodlands had the least number of records; no frogmouths were recorded inside anthropocentric land-cover types such as commercial-scale farmlands or plantations. According to the habitat suitability model we constructed (MaxEnt-based), much of the lowland wet zone, particularly the southwestern corner, was predicted as the most suitable areas for Sri Lankan Frogmouth while the northeastern coastal plains, and the mid-western and northwestern parts of Sri Lanka seemed least suitable. According to The Maxent model’s internal jackknife test of variable importance, temperature seasonality is the most important predictor of frogmouth’s distribution. Sri Lanka frogmouths have a high fidelity for their roosting sites as they remained in the same tree at least for a week; preferred roosting trees were medium-sized Dicot species with a dense canopy cover and variable canopy heights. These roosting sites are relatively cool, humid with little exposure to direct sunlight. Both roosting and nesting trees were relatively isolated from neighboring canopy trees, thus, the understory surrounding the roosting tree was dense. Six of the nesting sites observed were located in the lowland wet zone rainforests while the other was in savannah woodlands of the intermediate zone. These nests were positioned approximately 66% of maximum canopy height of the host tree. Nests were constructed on relatively thin branches that formed an acute angle against the main stem. These nests are shallow, circular-shaped pads. The nest interior was cushioned with cotton, parts of fishtail palm, and down feathers while the nest exterior contained pieces of lichens and tree bark. Sri Lanka Frogmouth’s home ranges appeared to be very small in nesting season, a maximum of 60 m radius area around the roosting site. Both male and female birds alternate nest-guarding duties through most of the night-time. The major threat for the frogmouth in Sri Lanka includes habitat loss due to expansion of commercial-scale agriculture and monoculture plantations, illicit forest encroachments, and clear-cutting.Keywords: Ecology, Frogmouth, Habitat modeling, Nesting, Threat

Comparing Floristic Diversity between a Silviculturally Managed Arboretum and a Forest Reserve in Dambulla, Sri Lanka

Repeated slash and burn cultivation creates wasteland with thorny shrubs, which then takes a long time to become secondary forests through serial stages of succession. Assisted natural regeneration through silvicultural management is a useful restoration method to accelerate succession. This survey evaluates the effectiveness of a simple silvicultural method for the rehabilitation of degraded lands to productive forest, thereby increasing floristic wealth. Field-based comparative analyses of floristic composition were carried out at a silviculturally managed forest (Popham Arboretum) and a primary forest (Kaludiyapokuna Forest Reserve) which is located in Dambulla in Sri Lanka. Floristic analysis was used to examine the effectiveness of silvicultural techniques for successful restoration of degraded forest in the dry zone. Nine 20 m × 20 m plots in each forest were enumerated and the vegetation ≥ 10 cm girth at breast height was quantitatively analyzed. Cluster analysis resulted in five distinguishable clusters (two from Popham Arboretum and three from Kaludiyapokuna Forest Reserve). Similarity indices were generated to compare the plots within and between sites. Floristic similarity was higher in forest reserve plots compared to arboretum plots. A total of 72 plant species belonging to 60 genera and 26 families were recorded from the study sites. Of the recorded species, Grewia damine and Syzygium cumini (Importance Value Index, IVI = 24 and 23 respectively) were the ecologically co-dominant taxa at the Popham Arboretum. In contrast, Mischodon zeylanicus (IVI = 31), Schleichera oleosa (IVI = 25) and Diospyros ebenum (IVI = 21) were the abundant taxa in the forest reserve

Helena Fire Burn Severity and Effects on Vegetation

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Learning from Habitat Reconstruction Initiatives—New Approach for Reducing Vulnerability of Rural Housing in India

Post-disaster reconstruction offers an opportunity to address some of the fundamental causes of vulnerability that are an inherent part of mainstream housing processes located at the intersectionality of sectoral interdependencies. Well-designed initiatives in the aftermath of a disaster can help displaced populations enter a positive cycle of resilience-building using new approaches. This paper draws from a recent field study to examine the reasons for the poor performance of existing housing stock in the face of disasters and presents a chain of graded causal factors that contribute to their vulnerability. Specifically, in the context of rural housing, the paper looks at three case studies of innovative habitat reconstruction initiatives undertaken in the aftermath of major disasters in India and analyses them for their impact on building the resilience of displaced communities. The study highlights that in order to address the various causes of vulnerability of rural housing, it is important to leverage the existing connections between different dimensions of habitat development, including access to finance, choice of appropriate materials, skill-building, and safe construction methods. This is at the core of the ethos of “building back better.&rdquo

Drought induced fine root growth and canopy green-up of tropical dry zone vegetations in Sri Lanka

Fine roots in forest soils have important implications for global carbon (C) balance, but processes underlying this C sink have not been well understood. This study evaluates year round dynamics of fine roots in a tropical dry mixed evergreen forest and an arboretum in the dry zone of Sri Lanka. Monthly soil core samples (up to 25 cm depth) were collected randomly to cover a whole annual cycle of the two vegetations. The soils were air dried, sieved (2 mm), and fine roots (< 2 mm) were separated by handpicking coupled with water floating technique. Then, fine root biomass and C density were calculated using oven dry weight. Mean fine root biomasses of the dry zone forest and the arboretum were found to be 5.72 ± 0.57 t/ha and 7.88 ± 0.81 t/ha - respectively, with C densities of 2.69 ± 0.27 t/ha and 3.7 ± 0.38 t/ha - respectively. Thus, dry zone arboretum contained significantly higher amount of fine roots and C density than the dry zone forest, possibly due to younger forest stand with fast fine root turn over in the arboretum. During dry spell of both vegetations, there was an increased production of fine roots and a simultaneous leaf flush on the canopy with a green-up. The increased fine root growth during the dry season generally allows the trees to absorb more water under water stressed situations. These events may be due to an undisclosed survival mechanism of such ecosystems under drought, which needs further studies

Field Survey of Tsunami Effects in Sri Lanka due to the Sumatra-Andaman Earthquake of December 26, 2004

The December 26, 2004 Sumatra-Andaman earthquake that registered a moment magnitude (Mw) of 9.1 was one of the largest earthquakes in the world since 1900. The devastating tsunami that resulted from this earthquake caused more casualties than any previously reported tsunami. The number of fatalities and missing persons in the most seriously affected countries were Indonesia - 167,736, Sri Lanka - 35,322, India - 18,045 and Thailand - 8,212. This paper describes two field visits to assess tsunami effects in Sri Lanka by a combined team of Japanese and Sri Lankan researchers. The first field visit from December 30, 2004 – January 04, 2005 covered the western and southern coasts of Sri Lanka including the cities of Moratuwa, Beruwala, Bentota, Pereliya, Hikkaduwa, Galle, Talpe, Matara, Tangalla and Hambantota. The objectives of the first field visit were to investigate the damage caused by the tsunami and to obtain eyewitness information about wave arrival times. The second field visit from March 10–18, 2005 covered the eastern and southern coasts of Sri Lanka and included Trincomalee, Batticaloa, Arugam Bay, Yala National Park and Kirinda. The objectives of the second visit were mainly to obtain eyewitness information about wave arrival times and inundation data, and to take relevant measurements using GPS instruments