Tool use by wild cebus monkeys at Santa Rosa National Park,Costa Rica

Although wild cebus monkeys have been observed to use tools, this behavior has been reported only rarely. No one has systematically examined tool use in wildCebus, and it is not known how prevalent tool use is in the species' natural repertoire. During 300 hr of observation on 21 wild capuchins (Cebus capucinus imitator) at Santa Rosa National Park in Costa Rica, 31 incidents of tool use, including eight different types of tool-use behavior, were observed. These observations indicate that tool use is a notable behavior pattern in this troop. Considering these incidents of tool use in conjunction with other reports on complex food-getting and preparation behavior byCebus suggests that tool use is a manifestation ofCebus' high behavioral adaptability. Since onlyCebus and the great apes (especially chimpanzees) have been observed to show such a diverse tool-use repertoire, to use tools so frequently, or to show such complex food-getting behavior in the wild, these observations also support the notion thatCebus and the great apes have followed a parallel evolutionary development of tool-using capacity.     

Characteristics of bird species using forest and agricultural land covers in southern Costa Rica

Our understanding of why tropical forest species differ in their ability to inhabit agroecosystems is limited, despite the link between this ability and the likelihood of population decline for species inhabiting regions undergoing widespread conversion of forest to agriculture. We used logistic regression and data from southern Costa Rica to develop a model based on natural history characteristics to distinguish between forest species that did or did not use agricultural land covers. We sampled birds along 15 3.0-km routes, seven in forest and eight in agriculture, five times over three years. Each species was classified as an F-species, detected only in forest, a G-species, detected in both forest and agriculture, or an A-species, detected only in agriculture. Thirty percent of species were F-species, 42% were G-species, and 28% were A-species. Based on the logistic regression model, the likelihood of being a G-species, as opposed to an F-species, was low for species that were dependent on forest interior, had a stenophagous diet, and a small elevational range. Weight, resident versus migrant status, and whether or not a species was insectivorous, were not significant predictors of being a G-species. For all F–G species pairs, the model correctly predicted the G-species 70% of the time. The model provides a first step in identifying those characteristics that predispose forest species to use agricultural land. In addition, our results indicate that the structurally simple agricultural systems of the study region are of limited value for a large proportion of the regional species pool.     

Holocene growth history of an eastern Pacific fringing reef,Punta Islotes,Costa Rica

Rock and sediment cores reveal that a well-developed fringing reef in Golfo Dulce, Pacific Costa Rica, up to 9 m thick was established on Cretaceous basalt about 5500 y BP. It is presently being smothered with fine sediments and is almost completely dead. This reef is made up of three main facies that are represented by comparable extant reef zones: reef-flat branching coral, fore-reef slope massive coral, and fore-reef talus sediment facies. Reef growth began with the establishment of small patch reefs dominantly formed by the branching coral Pocillopora damicornis. P. damicornis spread across the basalt bench and massive colonies of Porites lobata grew on the outer slopes, eventually blocking the seaward transport of Pocillopora fragments to the fore-reef talus sediments. The reef flourished until 500 years ago. Lower accumulation rates during the past 500 years may be due to deteriorating environmental conditions rather than slower growth after the reef reached sea level. Present-day reef communities are severely degraded with less than 2% living coral cover. The increased turbidity associated with the final stage of degradation of this reef is probably related to human activity on the adjacent shores, including deforestation, mining, and road construction.     

Holocene vegetation and water level history in two bogs of the Cordillera de Talamanca, Costa Rica

Pollen records of Holocene sediment cores from the Costa Rican Cordillera de Talamanca (La Chonta bog, 2310 m and La Trinidad bog, 2700 m) show the postglacial development of the montane oak forest zone from ca. 9500 to 1500 yr BP. During the early Holocene (ca. 9500–700 yr BP), alder vegetation covered the La Chonta and La Trinidad bogs and their adjacent hills. The upper forest line is inferred to be at 2800–3000 m elevation. A Podocarpus-Quercus forest characterised the middle Holocene (ca. 7000–4500 yr BP). The upper forest line is located at >3000 m reaching the present-day altitudinal distribution. A Quercus forest characterised the late Holocene (ca. 4500–1500 yr BP). Compared to modern conditions, the early Holocene has similar average temperatures, but the moisture level was probably higher. Pollen evidence for the late Holocene indicates drier environmental conditions than today. In order to improve the paleoecological interpretation, we described the local vegetation and used moss samples as pollen traps at both montane bogs along strong soil moisture gradients.The Netherlands Centre for Geo-ecological Research, ICG     

Stable carbon isotope analysis of soil organic matter illustrates vegetation change at the grassland/woodland boundary in southeastern Arizona,USA

In southeastern Arizona, Prosopis juliflora (Swartz) DC. and Quercus emoryi Torr. are the dominant woody species at grassland/woodland boundaries. The stability of the grassland/woodland boundary in this region has been questioned, although there is no direct evidence to confirm that woodland is encroaching into grassland or vice versa. We used stable carbon isotope analysis of soil organic matter to investigate the direction and magnitude of vegetation change along this ecotone. ¹³C values of soil organic matter and roots along the ecotone indicated that both dominant woody species (C₃) are recent components of former grasslands (C₄), consistent with other reports of recent increases in woody plant abundance in grasslands and savannas throughout the world. Data on root biomass and soil organic matter suggest that this increase in woody plant abundance in grasslands and savannas may increase carbon storage in these ecosystems, with implications for the global carbon cycle.     

Impact of Male Takeovers on Infant Deaths,Births and Conceptions in Cebus capucinus at Santa Rosa,Costa Rica

Male takeovers are associated with infant wounding and death in 3 of 4 capuchin species. In this paper, I analyze the effects of male takeovers on infant mortality and the subsequent conceptions and interbirth intervals of their mothers over an 18-yr period and test predictions of the sexual selection model of infanticide for white-faced capuchins, (Cebus capucinus). Major findings are that infants are significantly more likely to die in the 3- and 12-mo periods following a takeover than in times of peace and that a female whose infant dies experiences a significantly shorter interbirth interval before her next infant is born than she would have had the former infant survived. In the vast majority of cases, the invading males become resident in the group and are present during the subsequent conceptions of the females in the group. However, overall conception rates do not rise significantly in the year after a takeover, there is no relationship between the age of the infant at death and the length of the mother's subsequent interbirth interval, and it is not yet clear if male infants are preferentially targeted by invading males. Most takeovers occur during the 6-mo dry season and most conceptions occur in the wet season, 3–6 mo later. My findings support the major predictions of the sexual selection model of infanticide in primates and demonstrate that male takeovers of social groups have substantial effects on infant survival and maternal parturition patterns in Cebus capucinus.     

Stable sulfur isotope analysis of SO2 pollution impact on vegetation

Summary The ³⁴S value of SO₂ emitted by natural gas refineries is about +25, which is higher than that for non-industrial sulfur sources in our study areas. Terrestrial mosses absorb SO₂ from the atmosphere and have a ³⁴S value which is directly related to the degree of SO₂ stress to which they are subjected. The ³⁴S values for conifer needles are lower than for mosses at the same collection site, which indicates that trees obtain sulfur from both atmospheric and soil sources.Potted conifers were transferred to sites differing in their degree of SO₂ stress. This difference is reflected by the change of ³⁴S values of their needles. SO₂ absorbant pot covers, such as charcoal and moss, reduce the amount of airborne sulfur which is available to tress. Moss also may reduce SO₂ absorbed by soils in forest stands. We have used analysis of ³⁴S values to (1) help define SO₂ dispersion patterns; (2) reveal the rates at which plants accumulate this pollutant; and (3) associate suspected SO₂ injury more closely to an emission source.     

Inshore cetaceans from the North and South Pacific coast of Costa Rica

Twenty nine cetacean species occur in Costa Rican waters but extensive research has been conducted only for three species. The latter shows there is a lack of general and local information about these mammals, even when the country, has shown a remarkable growth in whale watching activities. The increasing use of marine resources in coastal areas has also developed the need to determine the occurrence of cetaceans in areas showing high tourist presence, in order to propose sound conservation measures. In this study, environmental variables were determined and subsequently related to the presence of the species recorded, out of 166 sightings, between 2005 and 2006. The species with highest proportion of sightings were Stenella attenuata (68%), followed by Megaptera novaeangliae (13%) and Tursiops truncatus (10%). The presence of spotted dolphins is related to changes in salinity and water transparency, while that of the humpback whale was related to wave height (Beaufort scale) and water temperature. The presence of seven species of cetaceans was confirmed in two coastal areas of the Pacific coast of Costa Rica, from which three are present throughout the year. Environmental variables were found related to the presence of at least two species.     

Fertility change in Costa Rica 1960-84: analysis of retrospective lifetime reproductive histories

Lifetime reproductive histories of a 1984-85 nationally representative sample of 870 women aged 25-59 years provided data to describe the evolution of fertility, contraception, breast-feeding, and natural fecundability in Costa Rica between 1960 and 1984. The contraceptive prevalence rate increased from 23% in 1965 to 58% in 1975 and 66% in 1984. Duration of breast-feeding was stable during the 1960s, decreased in the early 1970s, and increased after about 1976. Fecundability among women who did not practise contraception was lower than expected and declined between 1960 and 1975, probably because of selection effects. Despite a high consistency between estimations from the reproductive histories and other sources of data, some suggestion of omissions of short periods of contraceptive use in the distant past was detected. The survey may have reduced recall errors by using a calendar that summarizes major life events together. The analysis demonstrated the feasibility and usefulness of asking for lifetime reproductive histories in fertility surveys in developing countries.     

三江平原土地利用/覆被变化对区域植被碳储量的影响

通过历史时期地图数字化和遥感图像解译得到三江平原1954～2005年的6期土地利用/覆被数据。根据IPCC《2006指南》提供的方法,评估土地利用/覆被变化对三江平原植被碳储量的影响。结果表明:三江平原1954～2005年土地利用/覆被变化显著,农田大面积增加,沼泽湿地、林地、草地面积锐减;土地利用/覆被变化主要发生在农田、沼泽湿地、林地和草地之间;农田是沼泽湿地、林地、草地的主要转出对象,林地的主要转入来源为农田和草地,沼泽湿地的主要转入来源为农田和林地。1954～2005年共有1.07×10³km²林地、5.73×10³km²草地和2.59×10⁴km²沼泽湿地转出为农田。土地利用/覆被变化导致三江平原植被碳储量不断减少,1954～2005年三江平原植被碳储量共减少57.48Tg。林地、沼泽湿地、草地向农田的转化及林地向草地、沼泽湿地的转化导致植被碳储量减少97.06Tg,农田向林地、沼泽湿地、草地的转化及草地、沼泽湿地向林地转化导致植被碳储量增加39.58Tg。     

Extensive land use and the logic of the latifundio: A case study in Guanacaste Province,Costa Rica

Traditional explanations of extensive land use on large unproductive estates in Latin American have failed to understand important aspects of the economic and political logic behind such enterprises. This article examines the reasons for the low productivity of cattle ranches over a period which spans the consolidation of haciendas in a frontier zone and their subsequent integration into the international beef market. The persistence of extensive land use in a modern export economy is explained as resulting from characteristics of the world beef market, local ecology, the Costa Rican credit and tax systems, and the social composition and political power of the landowning class.     

Natural history of whitefly in Costa Rica: an evolutionary starting point

Abstract.  1. To understand evolution of foraging behaviour in the whitefly parasitoid Encarsia formosa (Hymenoptera, Aphelinidae), natural densities and distributions of whitefly (Homoptera, Aleyrodidae) were quantified in E. formosa 's presumed area of origin, the Neotropics.
2. Leaves were collected in Costa Rican nature areas along long transects (2–4 km), short transects (100 m), within 3-D plots (50 dm³−2.3 m³) and along suspension bridges within the canopy, and checked for presence of whitefly nymphs.
3. Generalised linear mixed modelling revealed that the number of hosts on the lower side of a leaflet of an average plant within an average spot of an average transect could be described by a Poisson distribution with mean and variance equal to 0.241, in a ratio of I1:I2:I3:I4 = 0.14:0.23:0.26:0.37. The Poisson mean was affected largely by the plant and less by the spot or transect. Variation in leaf area explained little of the variation between plants. Based on the shape of the opening in vacated puparia, the probability that a whitefly became parasitised eventually was 12% on an average leaflet. Whitefly density was much lower in the canopy than at the forest floor in the same area.
4. Semivariance analyses showed that in one of the three short transects, the numbers of whiteflies on leaves were spatially dependent. In four of seven 3-D plots at least one level of spatial dependence could be detected.
5. Results are discussed in the context of understanding evolution of foraging behaviour by E. formosa .     

中国未来土地利用变化对地上植被生物量的影响

土地利用变化通过改变生态系统结构对植被生物量产生很大影响.采用土地利用动态模型模拟了沿历史趋势情景(未来土地利用面积变化由1988-2005年的历史趋势推衍而来)和规划情景下(未来土地利用面积变化基于国家尺度上的土地利用规划来制定)中国至2030年土地利用变化的时空分布格局,基于此格局并结合密度法估算了植被生物量空间分布.模拟结果表明:沿历史趋势情景下,森林面积将减少,但随着林龄的增长,森林生物量密度增加,至2030年中国植被生物量为14619 Tg,比2005年增加了251.19 Tg;规划情景下,森林面积将增加,至2030年中国植被生物量为15468Tg,比2005年增加了1100Tg.在规划情景下,由于人工林面积较大,林龄普遍较低,导致至2030年植被生物量密度低于沿历史趋势情景,因此规划情景下中国植被作为碳汇的潜力更大.     

New species of Septobasidium from southern Costa Rica and the southeastern United States

New species are described in Septobasidium, a genus of urediniomycete parasites on scale insects. One new species, S. gomezii, is described from Costa Rica, and another, S. meredithiae, is described from Louisiana. S. gomezii is most similar to S. septobasidioides, but macroscopic and microscopic differences support it being a distinct species. S. meredithiae is similar to S. alni and S. castaneum but differs from these species in several macroscopic and microscopic characters, especially when the species are observed on the same host tree and insect species. Another species collected only once in Costa Rica is listed with observations but it is not formally described here. This Septobasidium species shares some key characteristics with S. ramorum but combines a dense, compact, nearly black thallus and pigmented probasidia-like structures with spindle-shaped haustoria. Implications for taxonomy, morphological evolution and host specificity in Septobasidium are discussed.     

PCB contamination in marine sediments from Golfo Dulce, Pacific coast of Costa Rica

Twenty-nine marine sediment samples collected from 1996 through 2002 from the Golfo Dulce embayment of Costa Rica were analyzed for PCB concentrations. The Esquinas River and Rincon Bay in the northern and western part of the gulf had relatively low overall concentrations of PCBs, with no samples having greater than 2.1 microg/g dw sediment. The Port of Golfito had the highest overall concentrations, ranging up to 15.7 microg/g dw sediment. These samples were also dominated by higher chlorinated congeners. Samples from the deeper (> 100 m) waters in the northern part of the gulf, as well as within the sediment plume from the Rio Coto Colorado had intermediate values. Within the Rio Coto Colorado sediment plume the concentrations did decrease with increasing depth and the congeners showed a shift towards less chlorinated congeners with depth. However, the deep northern basin had some of the highest PCB concentrations and the shift towards less chlorinated congeners was not apparent or significant. Whether the anoxic conditions that exist in the deep waters are capable of initiating dechlorination is still unknown. Overall, the data from Golfo Dulce show moderate PCB contamination, despite the pristine nature of the gulf and surrounding lands.     

哥斯达黎加外海夏季表层浮游动物种类组成及分布

根据2009年7—8月在东热带太平洋哥斯达黎加外海(4°30’—10°24’N、91°20’—100°00’W)进行茎柔鱼探捕调查期间采集的表层浮游动物资料,对其种类组成、生物量及其分布进行了分析。结果表明,调查海域,鉴定出腔肠动物8目10科17属23种;甲壳动物8目30科43属74种;毛颚动物1目1科1属4种;尾索动物3目3科5属5种;环节动物为1目3科5属6种;软体动物1目1科3属3种;其他浮游动物有头足类的幼体、鱼卵和仔稚鱼以及浮游幼虫。调查海域总生物量和丰度的平均值分别为(124.78±176.83)mg/m3和(848±1219)个/m3,生物量较大的类群主要是甲壳动物的桡足类和毛颚动物的箭虫类其中桡足类的丰度(727个/m3)为最高,其次为箭虫类(373个/m3);出现频率较高的为桡足类、箭虫类、长尾类、头足类和鱼类仔稚鱼。     

Fifty years of geomorphologic change in Damas Island, Quepos, Costa Rica

Fifty years of geomorphologic change in Damas Island, Quepos, Costa Rica, were studied from a photographic record that is available since 1947. Coastal dynamics were accelerated by the El Ni?o Phenomenon in 1997 which was simultaneous with the August-September astronomical tide, one of the highest in the 4-5 year cycle. Additionally, waves with high energy were present in some periods of these months. Processes were enough to break the island in two blocks and to initialize erosion and transport sediment that continues to date. The frequency of tropical storms and the wave energy will be greater in the next years increasing sediment instability processes in parts of the island. Two topographic profiles have shown that the island is not in equilibrium and that adding all the possible mareographic components it will be prone to continued erosion. The marine habitats around the island should be changing because the fresh and salt water input has been modified, specially because alteration in the Parrita and Paquita hydrological river basins, and its effects on the sediments of this system.     

Behavioural development of howling monkey twins (Alouatta palliata) in Santa Rosa National Park,Costa Rica

Twins born to a young female howling monkey in Santa Rosa National Park, Costa Rica were observed during the first 96 days of their life. The comparison of their development to that of single infants and the comparison of the behaviour of the mother of the twins to that of mothers of single infants revealed few differences. However, qualitative observations suggests that high costs are associated with maternal care of infant twins. The mother had difficulty carrying both infants and was the only female observed to become sick during the study. Increased costs of lactation were not compensated for by an increase in foraging time. It would seem that howling monkey mothers possess a maternal care system which is capable of providing suitable care to twins. However, the costs on the mother of raising twins is suggested as a factor selecting for a litter size of one.