To determine the effectiveness of rehabilitation on improving ecosystem functions, we examined net photosynthetic rate (PN), tree species composition, soil enzyme activities, and the microclimate (air and soil temperature, relative humidity) of an area on Mt. Makiling that has been rehabilitated and protected from fire for over 12 years. After it was last burned extensively in 1991, restoration was initiated by planting Acacia mangium and Acacia auriculiformis. We selected three areas to study in 2003. Two areas were rehabilitated with A. mangium and A. auriculiformis, and one was still dominated by Imperata cylindrica and Saccharum spontaneum. PN of A. mangium and A. auriculiformis showed significantly lower values than those of I. cylindrica and S. spontaneum. The Acacia plantations had more naturally regenerated tree species than the grassland. Additionally, more tree species appeared in the A. mangium plantation than in the A. auriculiformis plantation. Ficus spetica was present in all of the study sites. Dehydrogenase and phosphatase activities were significantly higher in soil under the Acacia plantations than under grassland. Grassland showed higher air temperature, relative humidity, and soil temperature as well as a larger variation per hour in these parameters compared to the Acacia plantations. The highest air temperature, relative humidity, and soil temperature were measured in April during the dry season. From the regression analysis, soil temperature was significantly correlated with air temperature. Hence plantations, as a rehabilitation activity for grassland, promote natural regeneration and stabilize the microclimate. This stabilization of the microclimate affects establishment and growth of naturally occurring tree species. and Y. K. Lee ... [et al.].
The article deals with experimental determination of local head loss in straight polypropylene pipeline (PP) joint connected by butt-welding. A local loss coefficient is introduced for turbulent flow of water in plastic pipeline of circular cross-section. The value of local loss coefficient has not been experimentally quantified so far and hence its determination is significant for designers of plastic pipeline systems. and Článek pojednává o experimentálním stanovení místní ztráty ve spoji přímého potrubí z polypropylenu (PP), zhotoveného svařováním na tupo. Je uvedena velikost součinitele místní ztráty spoje plastového potrubí kruhového průřezu při turbulentním proudění čisté vody. Místní ztráta doposud nebyla experimentálně kvantifikována, a proto je její stanovení pro projektanty potrubních systémů z plastů významné.
In the Southeastern Black Sea Region, rivers are dammed for hydroelectric power and irrigation. The natural course of fluvial alluvium transport is almost completely altered because of planned and constructed dams and coastal protection measures. Decreasing volume of sediment carried to the sea cause intensification of the shore erosion. The Black Sea Rivers and coastal areas of Turkey and Georgia are under heavy anthropogenic pressure because of the bed material extraction and coastal erosion rate. In this study, environmental effects of dams and related effects of sediment transport on coastal erosion in the Eastern Black Sea region are discussed. and Rieky v juhovýchodnej časti regiónu Čierneho mora sú prehradené priehradami, ktoré slúžia na výrobu elektrickej energie a na závlahy. Prirodzený transport plavenín a splavenín sa v dôsledku výstavby plánovaných a realizovaných priehrad takmer úplne zmenil. Znížený objem sedimentov dopravovaných do mora spôsobuje intenzifikáciu erózie brehov riek. Rieky ústiace do Čierneho mora v oblasti pobrežia Turecka a Gruzínska sú výrazne ovplyvnené ľudskou činnosťou, ako je ťažba materiálu z riek a eróziou brehov. V tejto práci sa analyzuje vplyv priehrad na životné prostredie krajiny vo východnej časti Čierneho mora.