Can variation in risk of nest predation explain altitudinal migration in tropical birds?

Migration is among the best studied of animal behaviors, yet few empirical studies have tested hypotheses explaining the ultimate causes of these cyclical annual movements. Fretwell’s (1980) hypothesis predicts that if nest predation explains why many tropical birds migrate uphill to breed, then predation risk must be negatively associated with elevation. Data from 385 artificial nests spanning 2,740 m of elevation on the Atlantic slope of Costa Rica show an overall decline in predation with increasing elevation. However, nest predation risk was highest at intermediate elevations (500–650 m), not at lowest elevations. The proportion of nests depredated by different types of predators differed among elevations. These results imply that over half of the altitudinal migrant bird species in this region migrate to safer breeding areas than their non-breeding areas, suggesting that variation in nest predation risk could be an important benefit of uphill migrations of many species. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

High variation in foliage and leaf litter chemistry among 45 tree species of a neotropical rainforest community

Distinct ecosystem level carbon : nitrogen : phosphorus (C : N : P) stoichiometries in forest foliage have been suggested to reflect ecosystem-scale selection for physiological strategies in plant nutrient use. Here, this hypothesis was explored in a nutrient-poor lowland rainforest in French Guiana. Variation in C, N and P concentrations was evaluated in leaf litter and foliage from neighbour trees of 45 different species, and the litter concentrations of major C fractions were also measured. Litter C ranged from 45.3 to 52.4%, litter N varied threefold (0.68-2.01%), and litter P varied seven-fold (0.009-0.062%) among species. Compared with foliage, mean litter N and P concentrations decreased by 30% and 65%, respectively. Accordingly, the range in mass-based N : P shifted from 14 to 55 in foliage to 26 to 105 in litter. Resorption proficiencies indicated maximum P withdrawal in most species, but with a substantial increase in variation in litter P compared with foliage. These data suggest that constrained ecosystem-level C : N : P ratios do not preclude the evolution of highly diversified strategies of nutrient use and conservation among tropical rainforest tree species. The resulting large variation in litter quality will influence stoichiometric constraints within the decomposer food web, with potentially far-ranging consequences on nutrient dynamics and plant-soil feedbacks.     

A revision of the genus Sclerosperma (Arecaceae)

Summary  A taxonomic revision of the palm genus Sclerosperma (Arecaceae) is presented. Three species are recognised: S. mannii H. Wendl., which is relatively widespread from Liberia to the Democratic Republic of Congo; S. walkeri A. Chev., which is apparently confined to the interior of Gabon and a band along the Congo River; and S. profiziana, a new species previously considered conspecific to S. mannii that is found in southwest Ghana, Congo, the Democratic Republic of Congo and Angola. The taxonomic history, morphology, distribution and conservation status of the genus and each species are discussed.     

Range expansion by moose into coastal temperate rainforests of British Columbia, Canada

Ranges of species are dynamic and respond to long‐term climate change and contemporary effects such as habitat modification. We report here that moose (Alces alces) have recently colonized coastal temperate rainforests of British Columbia, Canada. Contrary to recent publications, field observations of moose and their sign, combined with their occurrence in wolf (Canis lupus) faeces, suggest that moose are now widespread on the coastal mainland and occur on least three islands. Traditional ecological knowledge (information accumulated by aboriginal peoples about their environment) suggests that colonization occurred during the mid 1900s, concomitant with logging of major watersheds that bisect the Coast Mountain Range. Range expansion by moose may have ecological consequences such as alteration of predator–prey dynamics and transmission of disease to native deer (Odocoileus hemionus).     

Multiplicity in palm uses by the Huaorani of Amazonian Ecuador

An ethnobotanical study of the palms used by the Huaorani in the Yasuní National Park and Huaorani Ethnic Reserve in Amazonian Ecuador was carried out. In this inventory, 37 palm species were found; all were used by the Huaoranis. One hundred and ninety-one different uses were recorded in eight ethnobotanical categories. Most species (64.9%) were used for house construction and human food. More than half of the species were used for domestic utensils (59.4%) and hunting and fishing implements (54%). A comparison is made between these data and past studies for the other six indigenous communities from Amazonian Ecuador. This paper shows the highest diversity of useful palm species and the highest number of different uses ever recorded for an indigenous group in Amazonian Ecuador. The data combine quantitative and qualitative approaches.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 149–159.     

西双版纳热带季节雨林林窗内幼树叶生长与虫食动态

 研究了西双版纳热带季节雨林6种乔木幼树在林窗中的叶生长与叶虫食动态。6种幼树叶生长主要在雨季(5～10月),在旱季雾凉期(11～2月)叶停止生长。阳性树种旱季干热期(3～4月)开始叶生长,顶极树种至5月雨季初才开始叶生长。表明雾凉期低温抑制两类树种叶生长,干热期水分不足抑制顶极树种叶生长。叶生长同步性(每两个月的叶生长量变异系数C．V．)顺序为：望天树(Shorea chinensis,1.42)>金钩花(Pseuduvaria indochinensis,1.41)>八宝树(Duabanga grandiflora, 1.02)>云南石梓(Gmelina arborea,0.98)>团花树(Anthocephalus chinensis,0.84)和铁刀木(Cassia siamea,0.84)。旱季造成一些种类幼树出现落叶高峰,严重叶虫食也导致云南石梓在7～8月出现落叶高峰。叶虫食主要出现在雨季,团花树和云南石梓在干热期叶生长能减少昆虫取食,但此时铁刀木叶同步生长却不能降低食叶昆虫危害。6种幼树叶生长量年进程与叶虫食量年进程间存在正相关,其中望天树、金钩花、八宝树和团花树分别达到显著(p<0.05)或极显著(p<0.01)水平。望天树和金钩花在雨季初叶同步生长能减轻叶虫食。食叶昆虫偏爱取食幼叶,6种幼树平均幼叶的虫食量占总虫食量的72.9％,幼叶虫食速率平均为成熟叶的4.3倍。