The effects of human disturbance on a stingless bee community in a tropical rainforest     

Hiromitsu Samejima  Marfaizal Marzuki  Teruyoshi Nagamitsu  Tohru Nakasizuka 《Biological conservation》2004,120(4):577-587

Human disturbance of tropical rainforests may change pollinator communities indirectly as a result of changes in resource availability. We studied the mechanisms by which human disturbance affects a community of major pollinators, stingless bees, in Sarawak, Malaysia. We surveyed forest structure and flowering activity, and conducted a nest census and a bait-trap survey of stingless bees, both in primary forests and in forests disturbed by logging and shifting cultivation. The densities of late successional trees and large trees (diameter at breast height >50 cm) were higher in the primary forests than in the disturbed forests. The density of flowering trees was lower one year after logging, but recovered in old disturbed forests because of the active flowering of pioneer trees that became established after the disturbance. Stingless bees nest only in large trees, and nest density was positively correlated with the density of large trees. However, we found no relationship between the numbers of foragers and floristic parameters. Some species preferred nesting in dipterocarps, while others preferred dead trees. The results of the bait-trap survey also indicated that some species were abundant in the primary forests, whereas other species were abundant in the disturbed forests. These results suggest that human disturbance alters the species composition of the stingless bee community. Such changes in the bee community may affect the reproductive success of plants, and ultimately forest composition.  相似文献   

African origin of modern humans in East Asia: a tale of 12,000 Y chromosomes     

Ke Y  Su B  Song X  Lu D  Chen L  Li H  Qi C  Marzuki S  Deka R  Underhill P  Xiao C  Shriver M  Lell J  Wallace D  Wells RS  Seielstad M  Oefner P  Zhu D  Jin J  Huang W  Chakraborty R  Chen Z  Jin L 《Science (New York, N.Y.)》2001,292(5519):1151-1153

To test the hypotheses of modern human origin in East Asia, we sampled 12,127 male individuals from 163 populations and typed for three Y chromosome biallelic markers (YAP, M89, and M130). All the individuals carried a mutation at one of the three sites. These three mutations (YAP+, M89T, and M130T) coalesce to another mutation (M168T), which originated in Africa about 35,000 to 89,000 years ago. Therefore, the data do not support even a minimal in situ hominid contribution in the origin of anatomically modern humans in East Asia.  相似文献   

Capillary flow responses in a soil–plant system for modified subsurface precision irrigation     

Mohamad Shukri Bin Zainal Abidin  Sakae Shibusawa  Motoyoshi Ohaba  Qichen Li  Marzuki Bin Khalid 《Precision Agriculture》2014,15(1):17-30

Water movement in a soil–plant system was evaluated based on capillary flow in a modified subsurface irrigation system that incorporates a plant-water measuring device. Water from a reservoir tank located underneath the plant pot was supplied to the root zone through a fibrous medium. Evapotranspiration was measured from the water uptake and evaluations were performed based on soil moisture distribution and mass balance. Potential evapotranspiration was used as a reference for the plant–water uptake. Data were obtained from a test plant provided with the modified subsurface irrigation system. The plant was grown in a phytotron under controlled air temperature and humidity, and a comparison was made for different levels of soil moisture condition. The experimental results confirmed the operational efficiency of the modified subsurface irrigation system for precision irrigation.  相似文献