Avian communities’ preferences in recently created agricultural wetlands in irrigated landscapes of semi-arid areas

Numerous wetlands have been created spontaneously in the Ebro river basin as a consequence of new irrigation developments over the last 50 years. Water used for irrigating farmland drains into the lower parts of small valleys to form wetlands that are mostly dominated by common reed (Phragmites australis). Bird communities established in these wetlands are still simple, partly due to the lack of management to enable their ecological functions to improve. A knowledge of which environmental features favor these bird communities is essential in order to improve the design of newly created or restored wetlands associated to future irrigation developments. For this purpose, the habitat and vegetation features of 15 wetlands have been sampled. The structure of bird communities (richness, abundance and diversity) was monitored over 3 years during the breeding season and in winter at foraging and nocturnal roosting. The presence of bushes, height of stems and distance from large wetlands (>1 ha) proved to be the most influential variables on bird community structure and on most abundant species during the breeding season. Wetland area and compactness influenced species richness and the most abundant species during winter foraging and roosting. There was a maximum stem height at which only reed-dwelling birds remained. Uncontrolled winter burning had a severe negative effect upon these recently established populations. The ecological functions of newly created or restored wetlands, including those for run-off treatment in agricultural catchments, could be substantially improved taking into account simple guidelines from these results which relate bird community characteristics to wetland features.     

重庆地区主要作物重金属富集特征

采集了重庆地区6种主要作物(水稻、玉米、空心菜、红薯、土豆、南瓜)食用部分和对应根系土壤样品,分析了Pb、Cr、Zn、As、Hg、Cu、Ni、Cd 8种重金属元素的含量,讨论了作物对重金属的富集水平及重金属的协同和排斥关系。结果表明,不同作物食用部分重金属的含量为籽粒类>根茎类>瓜果类,南瓜对8种重金属的富集能力远远低于其他物种,水稻富集水平较高;红薯和空心菜对Cr的富集、水稻对Cd的富集分别较为依赖于土壤中Cr、Cd的含量,而土豆对As元素的富集与土壤中该元素的浓度含量呈显著负相关关系;不同重金属在植物体内的富集协同和排斥关系均存在,但总体协同大于排斥,Zn和Cu、Cd和Ni、Cr和Ni多数呈协同关系,这种协同关系可以应用于重金属复合污染区域的植物修复。     

Entomopathogenic fungi recorded from the harlequin ladybird, Harmonia axyridis

Entomopathogenic fungi were recorded from field samples of the harlequin ladybird Harmonia axyridis, an invasive coccinellid that has recently arrived in Denmark. Larvae, pupae and adults were found to be infected by Isaria farinosa, Beauveria bassiana and species of Lecanicillium. This is the first record of entomopathogenic fungi infecting larvae and pupae. Winter mortality due to fungal infection reached 17.9% in adults collected at one location. The larval stage was most susceptible to fungal infection, as confirmed through bioassay with I. farinosa.     

The timing of leaf fall affects cold acclimation by interactions with air temperature through water and carbohydrate contents

Three parameters (i.e. the water content, soluble sugar content and minimal air temperature) can be used to predict the cold acclimation process of walnut trees. In order to test this assumption, two-year-old walnuts were defoliated at two different dates, i.e. mechanical defoliation in early October (early leaf fall, EF) or natural defoliation in early November (natural leaf fall, NF) and conditioned in either outdoor freeze-deprived or cold-deprived (T_min > 13 °C) greenhouses over winter. Even if early defoliation date could have affected short day signal perception (SDSP), water balance and carbohydrate metabolism were more altered. EF treatment, by stopping transpiration, significantly increased tree's water content and at warm temperature high root activity stopped normal winter dehydration. Starch content decreased in all treatments, but there was only a significant increase in soluble sugar content when water content had sufficiently decreased. Thus, depending on date of defoliation, cold-deprived trees were or were not able to acclimate to frost (minimal frost hardiness = −21.8 °C vs. −22.1 °C in controls (freeze-deprived) for NF and −13.7 °C vs. −25.3 °C in controls for EF). Different treatments showed the relationship between minimal water content observed during winter and maximal soluble sugars synthesized. Thus, the cold acclimation process appeared dependent on these physiological parameters (water and soluble sugar contents) through the interaction between air temperature and timing of leaf fall.     

Winter climate change: Ice encapsulation at mild subfreezing temperatures kills freeze-tolerant lichens

While it has been widely proven that many lichens are extremely freeze-tolerant in the dry state, little is known about how moist lichens respond to freezing under oxic and anoxic conditions. In circumpolar areas where lichens are an important component of boreal and Arctic ecosystems, winter climate is changing, leading to increased frequency of winter thaw and ground-icing events. It is imperative to elucidate in further detail how northern vegetation responds to being encapsulated in ice. A winter icing simulation experiment was therefore undertaken, encapsulating two reindeer lichens (Cladonia stellaris and Cladonia rangiferina) and two epiphytic lichens (Parmeliopsis ambigua and Melanohalea olivacea) in ice at temperatures just below freezing for a maximum period of 98 d. Photosynthetic and chlorophyll fluorescence rates decreased strongly, clearly suggesting that the algal partner of the lichens was dying. Low but detectable respiration rates indicate that the fungal partner maintained some physiological activity. Ethanol accumulated in the lichens during ice encapsulation as a result of anaerobic respiration. The algae probably were dying from a combination of depletion of carbon reserves and toxic levels of ethanol and other stress metabolites. This experiment shows that boreal and Arctic-alpine lichens are sensitive to a warmer and more fluctuating winter climate. Increasing frequency of winter icing events may therefore have extensive and hitherto unknown effects on lichen-dominated ecosystems, their herbivores and the indigenous peoples whose livelihoods largely depend on them.     

四川老君山自然保护区红翅噪鹛冬季栖息地特征

摘要：2010年1月和2011年1月,在四川老君山国家级自然保护区对红翅噪鹛（Garrulax formosus）的冬季栖息地特征进行了初步研究。在研究区内,红翅噪鹛冬季多集小群活动,主要选择次生林,而回避原生林和人工林。2个冬季在野外共遇见红翅噪鹛21群78只。通过比较分析,发现红翅噪鹛喜欢在海拔较低、坡位较高、坡向...     

Life form spectra in the Hantam-Tanqua-Roggeveld, South Africa

The Hantam-Tanqua-Roggeveld subregion is situated in an area where the Fynbos, Succulent Karoo and Nama Karoo biomes meet. Life form spectra were compiled at a species richness and vegetation cover level in order to determine the affinities of the vegetation of the subregion with respect to its Succulent Karoo, Fynbos and Nama Karoo Biome status. A percentage succulence was also calculated for both species richness and cover. Comparisons of life form spectra and succulence were made across the eight vegetation associations found in the area and across three broad vegetation groups, i.e., Mountain Renosterveld, Winter Rainfall Karoo and Tanqua Karoo. Mountain Renosterveld vegetation was characterised by high chamaephyte, cryptophyte and therophyte species contributions. Compared to the other broad vegetation groups, the Mountain Renosterveld group showed phanerophyte contributions at the vegetation cover level to be highest, but the degree of succulence was low. Winter Rainfall Karoo vegetation was co-dominated by high levels of chamaephyte, cryptophyte and therophyte species with chamaephytes dominating the vegetation cover. Succulent contributions to species richness and cover values were higher than for Mountain Renosterveld vegetation. Tanqua Karoo vegetation was dominated by chamaephyte species or co-dominated by chamaephyte and cryptophyte species with therophyte species contributions lowest of all vegetation groups. Contributions by succulent species to richness and vegetation cover were high in the Tanqua Karoo. Life form spectra of the Mountain Renosterveld associations compared poorly to other sites in the Fynbos Biome. However, the low level of succulence in the Mountain Renosterveld associations also precludes its inclusion into the Succulent Karoo Biome. The large contribution of succulent species at a species and vegetation cover level in Winter Rainfall Karoo and Tanqua Karoo associations confirms that these two groups belong to the Succulent Karoo Biome. Affinities to the Nama Karoo Biome were indicated by the low level of succulence at a vegetation cover level in one of the Winter Rainfall Karoo associations (Roggeveld Karoo).     

7个冬小麦品种灌浆期抗旱性鉴定指标的综合评价

采用7个冬小麦(Triticum aestivum L.)品种,研究了不同水分处理下部分生理指标和部分农艺性状变化,以各单项指标的抗旱系数作为抗旱性衡量指标,利用主成分分析对其抗旱性进行评价,同时将综合评价值(D值)与抗旱指数(DRI)进行相关性分析。结果表明:(1)与对照相比,干旱胁迫后的超氧化物歧化酶(SOD)活性、过氧化氢酶(CAT)活性、相对电导率、丙二醛(MDA)含量、脯氨酸(Pro)含量、可溶性糖含量、胞间CO2浓度(Ci)均有不同程度上升;根系活力、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、株高、穗下节长度、叶面积、穗长、小穗数和穗粒数均下降;过氧化物酶(POD)活性和可溶性蛋白质含量在各品种间变化趋势不尽一致。(2)通过主成分分析综合评价值(D值),供试品种可分为3类:‘晋麦47’和‘小偃22’属于强抗旱型;‘矮抗58’、‘西农979’和‘西农509’属于中等抗旱型;‘郑麦366’和‘郑麦9023’属于弱抗旱型。(3)两种不同干旱胁迫下综合评价值(D值)与抗旱指数均显著相关(r分别为0.768和0.808,p0.05)。