Wind Characteristics of Mesquite Streets in the Northern Chihuahuan Desert, New Mexico, USA

Past research has shown that the most important areas for active sand movement in the northern part of the Chihuahuan Desert are mesquite-dominated desert ecosystems possessing sandy soil texture. The most active sand movement in the mesquite-dominated ecosystems has been shown to take place on elongated bare soil patches referred to as “streets”. Aerodynamic properties of mesquite streets eroded by wind should be included in explaining how mesquite streets are more emissive sand sources than surrounding desert land. To understand the effects of wind properties, we measured them at two flat mesquite sites having highly similar soil textures but very different configurations of mesquite. The differences in wind properties at the two sites were caused by differences of size, orientation, and porosity of the mesquite, along with the presence of mesquite coppice dunes (sand dunes stabilized by mesquites growing in the dune and on its surface) found only at one of the two sites. Wind direction, u_* (friction velocity), z₀ (aerodynamic roughness height) and D (zero plane displacement height) were estimated for 15-m tower and 3-m mast data. These aerodynamic data allowed us to distinguish five categories with differing potentials for sediment transport. Sediment transport for the five categories varied from unrestricted, free transport to virtually no transport caused by vegetation protection from wind forces. In addition, “steering” of winds below the level of the tops of mesquite bushes and coppice dunes allowed longer parallel wind durations and increased wind erosion for streets that aligned roughly SW–NE. U.S. Government right to retain a non-exclusive royalty-free licence in and to any copyright is acknowledged.     

生态旅游对欧洲意味着什么?

欧洲公园联盟 ( EUROPARC)制定了保护区可持续旅游的欧洲宪章 ,来促进完善的公园管理 .认证 的一个主要条件是保护区应具有一个经与当地的代表旅游、资源保护区和社区利益的利害攸 关者协商而精心制定的可持续旅游战略和行动计划 . 本文阐明了宪章制定的背景和一些有关 的问题及教训 .     

生态旅游对欧洲意味着什么?

欧洲公园联盟 ( EUROPARC)制定了保护区可持续旅游的欧洲宪章 ,来促进完善的公园管理 .认证 的一个主要条件是保护区应具有一个经与当地的代表旅游、资源保护区和社区利益的利害攸 关者协商而精心制定的可持续旅游战略和行动计划 . 本文阐明了宪章制定的背景和一些有关 的问题及教训 .     

Photoinhibition of photosynthesis in a sun and a shade species of the red algal genus Porphyra

Gametophytes of two species of Porphyra collected around San Juan Island, Washington in 1986 and acclimated to low light conditions in culture showed different resistances to photoinhibition of photosynthesis. The intertidal species P. perforata J. Agardh exhibited photoinhibition at one-third the rate exhibited by the subtidal species P. nereocystis Anderson following treatments at 2000 mol photons m^-2 s^-1 under conditions of full hydration and optimal temperature. The greater resistance of P. perforata to photoinhibition could not be attributed to reduced photosynthetic pigment concentration, higher photosynthetic capacity, avoidance of light by chloroplast movement or to enhanced rates of photorespiration. Total carotenoid concentrations were similar in the two species. It is probable that the mechanisms of this resistance are operating at the level of the thylakoid membranes. Resistance to photoinhibition represents an adaptation of photosynthesis in P. perforata which may contribute to its persistance in the extreme environment of its intertidal habitat.     

The effects of perceived conflict,resource scarcity,and information bias on emotions and environmental decisions

The failure to anticipate the public's response to environmental problems can lead to expensive delays, bad public relations, and litigation, as well as environmental decisions that do not represent public values and preferences. This study examines the influence of conflict between management goals, perceived resource scarcity, and information bias on evaluations of the importance of management goals; the perception of conflicts among the goals; and the emotions evoked in an urban forest management problem. Environmental problem scenarios were systematically manipulated as to the level of conflict between development and natural preservation goals, the scarcity of urban nature, and the bias of the presented information. Evaluations of the importance of urban nature and economic development were susceptible to manipulations of scarcity. The importance of urban nature was also higher when information was biased toward pro-preservation issues. Negative emotions were associated with high conflict and scarcity and with the propreservation information bias. Both evaluations of goal importance and conflict among goals appeared to be based on an underlying economics-versus-amenity dimension. These results are similar to previous studies of environmental decision making with regard to nonurban environmental problems. This research offers a beginning in understanding and anticipating the way members of the public may respond to information about environmental problems.     

Validation and global uncertainty of a gas chromatographic with mass spectrometry method for fenamidone analysis in grapes and wines

Fenamidone is an imidazolinone fungicide recently introduced in viticulture practices. This work reports the validation and assessment of global uncertainty of a gas chromatographic with mass spectrometry method to analyze fenamidone in grapes and wines. This method consists in a simple and fast liquid-liquid extraction step followed by chromatographic determination. Limits of detection for fenamidone in grapes and wines were, respectively, 0.05 mg/kg and 0.06 mg/L, precision was below 9.4% and average recovery was 89 ± 5%. In the concentration range from 0.05 to 1.00 mg/kg (or mg/L) of fenamidone, global uncertainty calculated following the EURACHEM/CITAC rules, and also by the Horwitz function, was below 25%. The EURACHEM/CITAC global uncertainty budget used gave lower estimates than those obtained from the Horwitz function.