Exotic plant invasion is one of the major causes of species extinction. In many contexts, mountainous forests are the last refuge for native species. There are several inventory studies conducted in mountainous and tropical forests in Indonesia. However, there are no studies yet on the factors that explain the abundance and richness of surveyed naturalized alien species. This study investigated whether the number of individuals and abundanceweighted species richness(AWR) of naturalized alien plant species in the hiking-trail of Mount GedePangrango National Park(MGPNP) forest area correlated with leaf traits(specific leaf area(SLA) and leaf thickness) and environmental factors(elevation, slope, and normalized difference vegetation index(NDVI)). We showed that leaf thickness and habitat elevation explained the AWR variations of naturalized alien species. We did not detect any important effect of leaf traits and environmental factors on the number of individuals per exotic species per plot. The influence of leaf thickness and habitat elevation indicates the important role of both biotic and abiotic factors on exotic species to develop a high species richness and become an invasive species in the tropical mountain forest ecosystem. 相似文献
In this work, the X-ray Photoelectron Spectroscopy (XPS) technique is utilized to analyze the surface chemical composition of particulate matter (PM) which was collected from various locations at Jeddah, Saudi Arabia. The main elements found on the surface of PM are carbon (C), oxygen (O) and silicon (Si) with combined percentage of 89.4–94.9 while traces of nitrogen (N), calcium (Ca), aluminum (Al), sodium (Na), chlorine (Cl), manganese (Mg), and sulfur (S) were also present. The analyzed XPS chemical state of C, O and Si was further used to determine their bonding with other elements occurring over the surface of PM. Carbon was found in the form of carbides (18.86%), fluorides (2.39%) and carbonates (78.75%); oxygen was observed as oxides (21.05%) and hydroxides (73.42%) of other metals; and silicon was detected as silicones (12.16%), nitrides (82.53%) and silicates (5.25%). The particle size of a PM is also of great concern for health issues, and thus has been investigated by the Field Emission Scanning Electron Microscope (FESEM). The Energy Dispersive X-ray Spectroscopy (EDS) was employed for cross verification of detected elements by XPS. 相似文献
A long-term (1948 to 2012) trend of precipitation (annual, pre-monsoon, monsoon, and post-monsoon seasons) in Bangladesh was analyzed in different regions using both parametric and nonparametric approaches. Moreover, the possible teleconnections of precipitation (annual and monsoon) variability with El Niño/Southern Oscillation (ENSO) episode and Indian Ocean Dipole (IOD) were investigated using both average and individual (both positive and negative) values of ENSO index and IOD. Our findings suggested that for annual precipitation, a significant increasing monotonic trend was found in whole Bangladesh (4.87 mm/year), its western region (5.82 mm/year) including Rangpur (9.41 mm/year) and Khulna (4.95 mm/year), and Sylhet (10.12 mm/year) and Barisal (6.94 mm/year) from eastern region. In pre-monsoon, only Rangpur (2.88 mm/year) showed significant increasing trend, while in monsoon, whole Bangladesh (3.04 mm/year), Sylhet (7.17 mm/year), and Barisal (6.94 mm/year) showed similar trend. In post-monsoon, there was no significant trend. Our results also revealed that the precipitation (annual or monsoon) of whole Bangladesh and almost all of the spatial regions did not show any significant correlation with ENSO events, whereas the average IOD values showed significant correlation only in monsoon precipitation of western region. The individual positive IODs showed significant correlation in whole Bangladesh, western region, and its two divisions (Rajshahi and Khulna). So, in the context of Bangladesh climate, IOD has the more teleconnection to precipitation than that of ENSO. Our findings indicate that the co-occurrence of ENSO and IOD events may suppress their influence on each other.
We investigate the composition of 63 C2-C10 nonmethane hydrocarbons (NMHCs), methane (CH4) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH4 in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (kOH) because of their great abundance and their relatively fast reaction rates with OH. 相似文献
Measurements of transpiration from individual trees of Eucalyptus from plantations at four different sites in Karnataka, Southern India, are presented. These show large (as much as tenfold) differences in the transpiration between premonsoon and postmonsoon periods, a reflection of the effects of soil-moisture stress in the premonsoon periods. For trees with diameters at breast height (DBH) less than 10 cm the transpiration rate of individual trees is proportional to the square of the DBH. For trees which are not experiencing soil-water stress the daily transpiration rate of individual trees, q, is well represented by the relation: q = (6.6 ± 0.3)g (m3 day−1 where g (m2) is the tree basal area. On a unit ground area basis the transpiration rate, expressed as a depth per day is given by the relation: Et = (0.66 ± 0.03)G (mm day−1 where g(m2ha−1) is the total basal area per hectare. For all the sites studied, although there is evidence for the ‘mining’ of soil water as roots penetrate deeper depths in the soil each year, there is no evidence for direct abstraction from the water table. 相似文献