20 research outputs found
Variação sazonal das trocas gasosas em folhas de mamoeiro cultivado em condições de campo
Effects of soil water stress and twospotted spider mites on net photosynthesis and transpiration of apple leaves
Opportunities and challenges in Asian bee research and conservation
The challenges of bee research in Asia are unique and severe, reflecting different cultures, landscapes, and faunas. Strategies and frameworks developed in North America or Europe may not prove applicable. Virtually none of these species have been assessed by the IUCN and there is a paucity of public data on even the basics of bee distribution. If we do not know the species present, their distribution and threats, we cannot protect them, but our knowledge base is vanishingly small in Asia compared to the rest of the world. To better understand and meet these challenges, this perspective conveys the ideas accumulated over hundreds of years of cumulative study of Asian bees by the authors, including academic, governmental, and other researchers from 13 Asian countries and beyond. We outline the special circumstances of Asian bee research and the current state of affairs, highlight the importance of highly social species as flagships for the lesser-known solitary bees, the dire need for further research for food security, and identify target research areas in need of further study. Finally, we outline a framework via which we will catalyze future research in the region, especially via governmental and other partnerships necessary to effectively conserve species.ISSN:0006-3207ISSN:1873-291
A simple field validation of daily transpiration derived from sapflow using a porometer and minimal meteorological data
The original publication can be found at www.springerlink.comHeat-pulse techniques are routinely used to estimate transpiration from canopies of woody plants typically without any local calibration, mainly because of the difficulty of doing so in the field and, frequently, lack of detailed weather data. This is despite concerns that the techniques may produce erroneous values under certain conditions, such as when evaporative demand is high. In this study, we used a micrometeorological approach to validate transpiration from irrigated olives deduced from heat-pulse technique by ascertaining precise values for the parameters that are critical for converting heat-pulse velocity to sapflow. The micrometeorological approach involved limited data on stomatal conductance (gs), obtained hourly with a porometer on four contrasting days, and was used to calibrate a simple model for predicting conductance. Predicted stomatal conductance (gsm) agreed well with that measured, and when both were used to calculate hourly transpiration, they produced values that were within 10% of each other. This was despite brief underestimations of transpiration based on gsm (Tm) in the early hours of the day that arose from poor determination of incident radiation at this time. We then used Tm to iteratively set the values for the various parameters, including the time-out value that accounts for zero-flow conditions, needed to convert heat-pulse velocity to sapflow, for the four days. The best fit between Tm and transpiration from sapflow (Ts) was obtained with time-out value set to 120 s. All heat-pulse velocity data were therefore analysed with this time-out value to obtain sapflow and, hence, transpiration (Ts). Comparison of Tm and Ts for the whole season showed that the former tended to produce higher values on certain days when vapour pressure deficit (D) was high in summer (December–February). While Ts occasionally produced larger values than Tm under the mild conditions of autumn (March–April). Totals of the daily transpiration during the 190-day period were within 10% of each other.Isa A. M. Yunusa, Ian K. Nuberg, Sigfredo Fuentes, Ping Lu and Derek Eamu