Food availability and nutrition in a seasonal perspective: A study from the Rukwa region in Tanzania

Most of the studies on seasonality in food supply and nutritional status have been carried out in areas characterized by extreme climatic conditions. This study was conducted in an area where the climate is favorable for grain cultivation. However, a large part of the population was found to face seasonal variations in food availability, most critically three to four months before the main harvest. Women lost about 3 percent of their weight in this period compared to the post harvest period. The nutritional status of preschool children declined in the lower socioeconomic group. These changes also coincided with a period of hard agricultural work, especially for women. The paper deals with factors affecting the duration of the maize stocks as well as strategies used when maize stocks are exhausted.     

Monitoring the health of selected eastern arc forests in Tanzania

The eastern arc mountains (EAMs) are a chain of isolated mountains (534,000 ha) in Kenya and Tanzania surrounded by arid woodlands and influenced by the Indian Ocean. In 1900 there was three times the amount of forest cover there is today. Much of the original forests have been converted into agricultural crops. These mountains are recognized as a globally important ‘hot spot’ by World Wide Fund for Nature (WWF) and World Conservation of Union (IUCN) for forest biodiversity and are major national, regional and local sources of hydropower, water and wide array of forest‐based benefits and agricultural production. In February 2000 we began a 3‐year evaluation of forest health, land‐use change and information sharing in the EAMs. Permanent sample plots were used to evaluate forest health. This paper summarizes the baseline data from eighteen permanent sample plots in the east Usambara's and nine in Ulugurus. The eastern arc web site ( http://www.easternarc.org ) was established, continues to expand and contains some detailed information on the project. Information gathered will assist land managers, planners, policy makers, interested communities (villages) and individuals in decision‐making. These data can also provide an early warning system of stresses on forest catchments.     

Atmospheric change causes declines in woodland arthropods and impacts specific trophic groups

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Elevational distribution of restricted range forest tree taxa in eastern Tanzania

The forests of eastern Tanzania are a globally important biodiversity hotspot. In this study 361 eastern Tanzanian restricted range forest tree taxa were assessed. Of these taxa, 223 occurred in the Eastern Arc, 150 in Coastal forests, 17 in Northern forests and 21 in the Lake Nyasa forests. The majority of the taxa had restricted elevational ranges with 76.3% occurring in no more than two 200 m elevational bands out of a total potential elevation range of 3000 m. The majority of the taxa occupied a small area in the eastern Tanzanian forests, with 201 taxa being only found at a few sites. In determining priority areas for conservation, selection of taxon definitions can have important effects. For example, tree size varies with elevation, so if only large trees are used then site selection will be biased towards particular areas.     

Assessment of the impact of the Lower Kihansi Hydropower Project on the forests of Kihansi Gorge, Tanzania

Construction of a hydropower project on the Kihansi river in Southern Tanzania will substantially alter the river's flow. On the basis of both qualitative and quantitative botanical surveys, forest in the Kihansi gorge below the dam site was found to be mostly typical species and endemic-rich Eastern Arc forest. An unusual forest type, dominated almost entirely by Filicium decipiens was also present. Eastern Arc forests are of both global and national importance for biodiversity conservation, and measures to mitigate impact of the dam on the forest are suggested. Further environmental monitoring is recommended in order to evaluate the choice of mitigation measures.     

青岛近岸水域春、秋季鱼类群落结构

根据2004年春、秋季渔业资源底拖网调查数据,应用单元和多元统计方法分析了青岛近岸水域春、秋季鱼类群落结构。春、秋季调查分别渔获31、32种鱼类,平均每网渔获量分别为7.36kg/h和2.99kg/h,优势种类主要包括赤鼻棱鳀Thrissa chefuensis、大泷六线鱼Hexagrammo sotakii、方氏云鳚Enedrias fangi、黄鳍刺鰕虎鱼Acanthogobius flavimanus、细纹狮子鱼Liparis tanakai和长条蛇鲻Saurida elongata等。聚类分析表明,春、秋季青岛近岸水域鱼类群落都可划分为3个站位组,分别对应于北部、中部和南部调查水域。不同站位组的优势种组成变化较大,不同站位组间种类组成差异显著。分析了造成站位组内种类组成相似的特征种和造成不同站位组间相异的分歧种。不同站位组的特征种不同。赤鼻棱鳀、大泷六线鱼、黄鳍刺鰕虎鱼、方氏云鳚、星康吉鳗Conger myriaster、角木叶鲽Pleuronichthys cornutus和细纹狮子鱼是春季所有站位组间的分歧种;赤鼻棱鳀、白姑鱼Argyrosomus argentatus、大泷六线鱼、带鱼Trichiurus lepturus、短吻红舌鳎Cynoglossus joyneri、方氏云鳚、细条天竺鱼Apogonichthys lineatus、小黄鱼Pseudosciaena polyactis和矛尾鰕虎鱼Chaeturichthys stigmatias是秋季所有站位组间的分歧种。大多数特征种也是不同站位组间的分歧种,主要是由于这些种类的数量分布的空间变化造成的。青岛沿海鱼类群落结构存在明显的时空异质性。     

Spatial metrics effect of forest fragmentation on forest bird abundance and site occupancy probability: the influence of patch size and isolation

The persistence of species taxa within fragmented habitats is dependent on the source–sink metapopulation processes, and forest patch size and isolation are key factors. Unveiling species–patch area and/or species–patch isolation relationships may help provide crucial information for species and landscape management. In this study, relationship between forest patch size and isolation with abundance and occupancy probability of forest-dependent birds was investigated. This study was based within a coastal landscape that faces deleterious human activities such as clearing for agriculture. The study aimed to answer the question of whether the size and extent of isolation of forest patches influence abundance and/or occupancy probability of forest-specialist and generalist birds. Two bird species, namely Tiny Greenbul Phyllastrephus debilis subsp. rabai and Yellow-bellied Greenbul Chlorocichla flaviventris, were used as models. Birds were surveyed using distance sampling methods, and spatial metrics were measured from satellite imagery. Focal forest size and distance between forest patches were the most influential metrics whereby abundance and occupancy probabilities increased with increasing patch size, but were negatively influenced by increasing gaps between patches. These findings provide evidence of the existence of patch size/ isolation–occupancy relationships characterised by higher occupancy rate of large patches and distance-dependent dispersal, which decreased with increasing gaps between patches. Controlling deleterious human activities that reduce forest size should be a priority for the long-term conservation of forest-dependent birds.     

Herding Strategies of the Datoga Pastoralists of Tanzania: Is Household Labor a Limiting Factor

Datoga herding follows a cyclical pattern depending on the availability of grazing and water. This analysis focuses on two questions: (a) Is the herding strategy followed by individual households limited by the amount of labor available to that household? and (b) does the herding strategy followed by individual households influence the dynamics of cattle herds? The results show that the availability of labor on a household level does not influence either the herding strategies used by individual households, or the dynamics of cattle herds. This suggests that once minimum labor requirements are met, livestock productivity is insensitive to additional labor inputs.     

长江口及其邻近海域春季无脊椎动物群落时空变化

为了研究长江口及其邻近海域无脊椎动物群落结构和多样性的时空变化特征, 我们于1999-2012年春季在长江口及其邻近海域采用定点底层双拖网调查方式进行无脊椎动物调查。结果表明: (1)1999-2012年长江口水域共记录无脊椎动物41种, 隶属6纲10目23科, 其中甲壳动物种类最多(26种), 其次为软体动物(13种)。不同年份种类数量呈先下降后上升的趋势。(2)优势种主要包括日本枪乌贼(Loligo japonica)、三疣梭子蟹(Portunus trituberculatus)、葛氏长臂虾(Palaemon gravieri)和鹰爪虾(Trachypenaeus curvirostris)等, 其在年间存在剧烈变动, 但日本枪乌贼几乎每年都是优势种。(3)长江口无脊椎动物丰度、种类丰富度和多样性在年间均存在显著差异, 1999年和2001年最高, 2004年后呈先下降后恢复上升的趋势。(4)长江口水域的无脊椎动物在每个航次调查中都存在2-3个群聚类型, 并有不同的指示种类。(5)1999-2012年长江口无脊椎动物群落的时间变化可划分为3个阶段: 1999-2001年多样性程度最高, 2004-2007年下降至最低水平, 2009-2012年多样性显著回升, 但尚未恢复到1999-2001年的水平。与20世纪80年代相比, 蟹类减少导致长江口无脊椎动物生物量整体水平下降, 高营养级生物资源衰退带来了无脊椎动物中低营养级生物种群的迅速发展。     

Post-sampling dissolution and the consistency of nannofossil diversity measures: A case study from freshly cored sediments of coastal Tanzania

This study investigates the potentially deleterious effect of prolonged sample storage on the reliability of calcareous nannofossil species abundance and community diversity measures and their subsequent interpretation as paleoceanographic proxies. Nannofossil assemblages from two freshly cored successions of hemipelagic clay were documented over a one-year period using a series of paired smear-slides, the first made from sediment samples within a day of coring and the second either 6 months or 1 year later. Diversity measured by Shannon's H is consistent between the two sets for the majority of samples, however significant changes, both positive and negative, were recorded in a number of cases and appear to be largely due to variations in smear-slide thickness and not to post-sampling dissolution. There is no significant change in nannofossil fragmentation or abundance over time, although the relative abundances of small, dissolution susceptible placoliths of Reticulofenestra minuta do appear to decrease with time in some samples. Counts of mineral grains show that there is a significant loss of fine, 1–2 μm, cubic pyrite within months of drilling, and this, combined with the decline in abundance of R. minuta, suggests that limited pyrite oxidation coupled to carbonate dissolution is occurring. Geochemical analyses confirm that these sediments contain significant concentrations of sulphate one year after sample recovery, which may be the result of gypsum formation associated with the oxidation of pyrite. Estimates of pyrite oxidation suggest that up to 3% of the original calcium carbonate has dissolved in the year after coring, which could account for the observed loss of small placoliths. Effects of this kind are almost certainly confined to hemipelagic sequences rich in organic matter and/or reduced iron but are frequently offset by the exceptional preservation of calcareous microfossils that can occur within such sediments.     

闽东沿海防护林台风灾害的影响因子

以2010年台风"鲇鱼"(编号1013)为例,调查闽东主要海防林树种台风受灾情况,并对其影响因子进行分析,结果表明:1)不同树种受害程度差异明显,阔叶树种受害重于针叶树种,平均受害级和受害指数分别高出79.1%和76.7%。其中,桉树受灾最重,平均受害级和受害指数分别比湿地松、木麻黄高出90.5%、36.2%和86.7%、36.6%。受灾类型中,折干现象最严重,比例高达40.7%。2)林木不同形态特征受灾程度差异显著,折干类型集中于12～14cm径级,比例为56.8%,倒伏、掘根类型集中10～12cm,比例为57.9%,弯干、断稍现象径级分布较均匀,但同在14cm比例最高,分别为28.6%和18.3%。林木抗风性能与植株尖削度成正相关,而与树高、树冠面积、树冠相对高度成负相关。3)地形条件是影响林木受灾的重要因素,表现为受灾程度迎风坡大于背风坡,陡坡大于缓坡,同一坡向上,迎风坡下腹大于上腹,背风坡正好相反。4)割脂对湿地松抗风性能有较大影响,割脂林木受害指数比未割脂高40.6%,因割脂发生折干植株比例为92.7%。     

沙质海岸防护林入侵植物垂序商陆的防治

垂序商陆的入侵给我国沿海防护林造成了严重危害.本研究在入侵程度相对一致的刺槐林下设置样地,采用物理(刈割、切根)、化学(喷洒无公害除草剂)方法进行控制试验,并以林下紫穗槐发育良好、未进行处理的地段作为对照,探索控制垂序商陆生长的有效方法.结果表明:刈割能快速降低垂序商陆各项生长指标,但次年即恢复至对照水平.1/3切根仅减少了当年地上部分生长量,第3年又恢复至处理前水平,而2/3切根和完全切根处理一次即可有效地清除垂序商陆.精喹禾灵和百草枯仅能杀死其地上部分,次年即恢复至处理前水平,而45g·L-1草甘膦处理的垂序商陆死亡率达到100％,第3年新萌发垂序商陆生长与结实量已明显恢复.紫穗槐发育良好地段的垂序商陆各生长指标始终处于较低的平衡状态.采用紫穗槐替代法是长期控制垂序商陆的有效防治方法.     

A method for assessing evergreen habitats using phytodiversity and geospatial techniques in tropical rain forests of Southern Western Ghats (India)

We have used data generated using remote sensing and geographical information systems to categorize habitats, and then determined the relationship between the habitat categorizations and species-distribution patterns. A biologically rich hotspot—Kalakad-Mundanthurai Tiger Reserve, located at Southern Western Ghats, India, was chosen for this study. In order to spatially delineate areas of high species richness/diversity and endemic habitat zones, we have identified evergreen habitats in conjunction with landscape metrics, species assemblage, micro-habitats like slope, topography, species endemism, and proportion of core and edge species. A total of 236 species and 2,920 individuals were recorded using systematic stratified plots of 0.1 ha covering 47 plots. Hierarchical cluster analysis was done using Ward’s method. Plot information was used to identify clusters based on species density. The analysis showed five species assemblages that are quite distinct from each other in terms of dominant species. The distribution of endemic and edge species, land cover heterogeneity, and continuity of patches in these clusters were evaluated to understand the degree of disturbance and intactness at landscape scale. Integration of species assemblages and topography brought out four major elevation-slope complexes. Information on species composition (robust field survey) with spectral (hybrid classification) properties has shown 72% overall accuracy and distinguished four evergreen sub-groups and other land cover classes. The developed approach assumes great importance in the assessment of biodiversity and prioritizing the areas of conservation.     

Butterfly species richness and abundance in the Katavi ecosystem of western Tanzania

We sampled butterflies in six different habitat types in and around Katavi National Park, a remote reserve consisting primarily of miombo woodland and seasonal lakes in western Tanzania. Blendon traps set for 531 trap days and 143 h of butterfly netting at 35 sites yielded 186 species from five families over a 4‐month period during the wet season. Eight of these species constituted possible range extensions. Butterfly abundance and species richness were low in cultivated habitats but high in open riverine habitats; many butterfly species were found only in seasonally flooded grassland. This study constitutes the first butterfly species inventory from this poorly‐known national park, shows that protection of dry season water sources provides an important conservation service for invertebrates as well as large mammals, and that increased cultivation outside miombo parks can reduce local butterfly diversity.     

Subsistence hunting and bushmeat exploitation in central-western Tanzania

An ethnozoological research was carried out in the Tabora District (central-western Tanzania) from December '95 to February '96, to gather information on the sustainable exploitation of wildlife there and to outline the zoological culture of the native people (the Banyamwezi). The objective was to describe the hunting activity and the techniques employed in capturing wild mammals and to gather quantitative data on game harvest. An inventory of the mammal species living in the study area was conducted by three different methods: (1) direct field observation of animals and their tracks; (2) identification of animals captured by the villagers; (3) interviews with the hunters. The activities of 10 local hunters from seven villages were followed during a nine week period. The number of mammals killed and the techniques used for each species were recorded. Other data were collected through interviews of the villagers and concerned (1) the use of every species as food or for other purposes; (2) the species considered as pests; (3) the best places and time for hunting the different species; (4) the time spent hunting them; (5) the food restrictions and taboos; (6) the extent of the bushmeat market (quantity, price, etc.). A total of 236 animals belonging to 37 species were killed during the study period with the following breakdown into taxonomic groups: Bovidae (44.06%), Carnivora (22.88%), Lagomorpha (8.05%), Rodentia (7.2%), diurnal Primates (5.93%), Insectivora (4.23%), Hyracoidea (0.84%), nocturnal Primates (0.84%), Hippopotamidae (0.42%) and Pholidota (0.42%). Four different techniques were used by local hunters in the study area: guns (53.81%), traps (19.06%), spears (11.01%) and dogs (16.01%). Poaching is rampant because of the scarcity of ranger staff and vehicles for patrolling.     

On the relationships between leaf-litter lignin and net primary productivity in tropical rain forests

We investigated if tropical rainforest trees produced more-lignified leaves in less productive environments using forests on Mount Kinabalu, Borneo. Our investigation was based on two earlier suggestions that slower litter decomposition occurs under less productive forests and that trees under resource limitation invest a large amount of carbon as lignin as a defense substance to minimize the loss from herbivores. When nine forests at different altitudes (700–3100 m) and soil conditions (derived from sedimentary or ultrabasic rocks) but with the same gentle relief position were compared, the concentrations of leaf-litter lignin were positively correlated with litterfall rates and leaf-litter nitrogen concentrations. These patterns would be reinforced in intact leaves if the effects of resorption at the time of leaf shedding were taken into account, because greater magnitude of resorption of mobile elements but not of lignin would occur in less productive environments (i.e. dilution of lignin in intact leaves). These results did not support earlier suggestions to explain the variation of leaf-litter lignin. Instead, we suggest that lower lignin contents are adaptive to recycle minerals without retarding decomposition in less productive environments.     

Breeding patterns of Arvicanthis neumanni in central Tanzania

The breeding pattern of the grass rat, Arvicanthis neumanni, was investigated in central Tanzania in 2002/2003 . Nine hundred and forty-seven animals were captured in three age groups: juveniles, sub adults and adults. These age groups were present in the population for an extended duration, but there was an increase in the number of sexually active individuals and juveniles 2–3 months after the onset of the rains (December 2002–May 2003). A peak in reproductive activity occurred between January and April. Litter size ranged between 5.58 ± 0.42 and 6.1 ± 0.26 in two study sites. There were no significant differences in the number of embryos implanted in the right and left horns of the uterus of pregnant females (t₂₂ = 0, P  > 0.05 and t₃₆ = 1.68, P  > 0.05, respectively). Sex ratio of A. neumanni was not skewed to either males or females. Breeding was seasonal and seemed to be associated with seasonal variations in primary productivity, which relates to rainfall patterns.