Mycorrhizal associations and soil properties of native Allanblackia stuhlmannii stands in the Eastern Usambara Mountains,Tanzania

Allanblackia stuhlmannii is a tree species currently under domestication. Potential mycorrhizal relationships of A. stuhlmannii and soil properties of native stands were investigated to determine the soil–environmental requirements of the species. Roots and soil samples were collected from five sites with A. stuhlmannii stands along an altitudinal transect in Amani Nature Reserve, Tanzania. Mycorrhizal status was investigated by combining microscopy with molecular analysis of the fungal communities. Soil adjacent to the A. stuhlmannii seedlings was analysed for physical and chemical properties and the sites were characterised. We showed that A. stuhlmannii form symbiosis with arbuscular mycorrhizal fungi, and that there was a diverse microbiome associated with the roots. The soils, classified as Ferralsol and Acrisol, were very well drained, had a pH_CaCl2 generally at or below 4, high exchangeable acidity and content of sesquioxides and low effective cation exchange capacity and concentrations of most nutrients. We conclude that A. stuhlmannii is tolerant to high Al availability and possesses mechanisms for acquisition of P and other macronutrients at low soil availability, possibly through mycorrhizal symbiosis. However, being adapted to low‐pH soils, it may be less efficient in acquiring Fe, Mn and/or Zn at higher soil pH. Thus, it may be most suited to introduction on farms situated on acid soils.     

Breeding seasonality and population dynamics of three rodent species in the Magamba Forest Reserve, Western Usambara Mountains, north-east Tanzania

We investigated breeding seasonality and population dynamics of three rodent species, Lophuromys flavopuncatus, Grammomys dolichurus and Praomys delectorum, in the Magamba Forest, Western Usambara Mountains, north‐east Tanzania. Capture–mark–recapture studies were conducted in 2002–2004. Reproductive conditions of males and females showed temporal variations, an indication of breeding seasonality. Animals were reproductively active between February and May. Rainfall in November–January was instrumental for the onset of breeding and continued throughout the wet season. The recruitment of new individuals born during the season led to highest population densities between end of May and August. Populations declined progressively towards the end of the dry season (September–October). Only P. delectorum showed a marked density increase during January–February, indicating greater survival and/or recruitment during the November–January rains. The study shows that despite a relatively stable environment of the forest reserve, rainfall has strong influence on reproduction and population dynamics, probably because of its effect on primary food resources.     

Seasonal patterns of rodents, fleas and plague status in the Western Usambara Mountains, Tanzania

Field and commensal rodents were live-trapped at three villages in an active focus of plague (Yersinia pseudotuberculosis pestis) in Lushoto District, Western Usambara Mountains, Tanga Region, Tanzania, from December 1983 to November 1984. Their flea ectoparasites were collected, identified and counted. The rodent carcasses were serologically examined for specific plague antibodies and antigens, and bacteriologically examined for bipolar staining bacilli. A total of 1758 traps were set during the 12-month period and 924 animals were caught. From these, 1037 fleas were collected. Rattus rattus (L.), Praomys natalensis (Smith) and Lophuromys flavopunctatus Thomas comprised the largest proportions of the rodent population, while Dinopsyllus lypusus Jordan & Rothschild, Ctenophthalmus calceatus Waterston and Xenopsylla brasiliensis (Baker) were the dominant flea species. Rodents were most abundantly trapped during December and January. Flea indices were highest from December to May. Human plague was most active from November to March. Rodents contained plague antibodies every month except May and July, with a peak in September. Plague antigens and bipolar bacilli were detected in rodent organs during January-April. From the product of abundance and infection rate, the most prevalent rodent hosts of plague appeared to be R. rattus, Otomys angoniensis Wroughton, P. natalensis and Pelomys fallax (Peters). Continuous integrated control of rodents and fleas was recommended, reinforced by quarantine and maintenance of a surveillance service for clinical detection, diagnosis and treatment of patients in the plague endemic area.     

Diet of the Silvery-cheeked Hornbill Bycanistes brevis during the breeding season in the East Usambara Mountains,Tanzania

The breeding season diet and nesting characteristics of the Silvery-cheeked Hornbill Bycanistes brevis are poorly known. To further understand these aspects of the breeding biology of this hornbill species, 14 nests were studied in and around Amani Nature Reserve located in the East Usambara Mountains, Tanzania. Nesting tree species were identified and the diet composition of nesting hornbills was evaluated between July and November 2001. The ejecta from each nest were collected, inventoried, identified (as completely as possible) and enumerated. Food items were categorised as plant, vertebrate or invertebrate. Plants, represented largely by fruits, were the dominant food type (n = 861), followed by invertebrates (n = 306; mainly millipedes and beetles), and vertebrates (n = 15; mainly smaller birds and chameleons). A comparison of results from the current study to other nesting observations made approximately seven decades earlier in the same area suggest that (1) the invasive tree species Maesopsis eminii, which was the most common food type consumed (n = 4 539 seeds), has become a favoured new food source in the breeding season, and (2) the breeding season appears to have shifted to an earlier period, potentially due to the fruiting phenology and abundance of Maesopsis eminii.     

Diel variation in the difference in air temperature between the forest edge and interior in the Usambara Mountains, Tanzania

The difference in air temperature between the forest edge and interior was simultaneously compared at ten sites at 2‐h intervals over a 229‐day period in the East and West Usambara Mountains in Tanzania. Measurements were recorded with data loggers placed 1.5 m above the ground on the shaded side of trees and positioned 1–2 and 100 m from the forest edge. The difference in air temperature between the forest edge and interior varied regularly over a 24‐h period with mean maximum difference in air temperatures of 0.85°C occurring at 15:00 h and mean minimum diel difference in air temperature of 0.02°C occurring at 21:00 h. Diel variation in the difference in air temperature between the forest edge and interior varied little by season and was unrelated to elevation.     

Reproductive ecology of three endangered African violet (Saintpaulia H. Wendl.) species in the East Usambara Mountains, Tanzania

Knowledge of the reproductive biology of endangered plants is essential for their effective conservation. It also provides important information for understanding the evolutionary processes that affect speciation, thus helping the definition of proper units for conservation in endangered plants with problematic taxonomy. We studied the reproductive potential and possibility for hybridization in the endangered genus Saintpaulia (Gesneriaceae) by examining flowering phenology, flower and seed production and pollination of three sympatric cross‐compatible Saintpaulia species in the East Usambara Mts., Tanzania. The synchrony observed in flowering in S. confusa and S. difficilis may enable hybridization between these two species, whereas partial phenological separation may contribute to the integrity of S. grotei. Although the level of flower abortion is high in S. confusa, each pollinated flower yields about 1000 seeds. Saintpaulia confusa produces fruits following both self‐ and cross‐pollination but spontaneous self‐pollination seems not to occur. Thus, seed production depends on sufficient pollinator service. Floral heteromorphy (i.e. enantiostyly) and bee pollination are likely to further enhance cross‐pollination, suggesting that the genus predominantly outcrosses. Thus, Saintpaulia populations are likely to suffer from negative effects of inbreeding if they become small and isolated.     

Seasonal elevational movements of Eastern Olive Sunbird Cyanomitra olivacea in the Uluguru Mountains,Tanzania

Little is known about the seasonal elevational movements for most tropical avifauna species. Seasonal elevational movements of the Eastern Olive Sunbird Cyanomitra olivacea were studied along an elevational gradient from 600 to 1 500?m above sea level in the Uluguru Mountains, Tanzania, between May 2005 and February 2006. The recapture of ringed individuals along an elevational gradient across seasons provided evidence for the seasonal elevational movement of the Eastern Olive Sunbird in the Uluguru Mountains and the first documented evidence for this species in the Eastern Arc Mountains as a whole. Due to forest fragmentation and lack of corridors connecting high- and low-altitude forests in the Uluguru Mountains, the results have implications for conservation of the forest along the entire elevational gradient as well as for other forest bird species that have been documented to make seasonal elevational movements in the Uluguru Mountains and the entire Eastern Arc Mountains.     

Wildfires in the Eastern Arc Mountains of Tanzania: Burned areas,underlying causes and management challenges

The Eastern Arc Mountains are one of the most important ecosystems that conserve biodiversity in the world. These ecosystems are threatened by the increasing occurrence of wildfires. Nevertheless, there is inadequate information useful for the development of effective strategies to prevent or respond to future fires. This paper analyses the current extent of dry season fires, underlying causes and the effectiveness of the fire management strategy being implemented in and around the Uluguru Nature Forest Reserve (UNFR) between 2016 and 2021. Differenced Normalised Burn Ratio derived from Landsat satellite images was applied to determine the extent of burned areas, and focus group discussions were held to determine the underlying causes of fires and the extent of implementation of fire management strategies. About 2% (472 ha) of reserved UNFR and 5% (2,854 ha) of unreserved forests were burned in 2017. Some of the fires impacted on 60% (370 ha) of the grassy Lukwangule plateau, which is home to a fire‐sensitive endemic species. The underlying causes of fires varied spatially across the mountains but generally, fire escaping from farm preparation and hunting activities were found to be the most prevalent. On average, survey participants perceived that fire management strategy objectives were achieved by only 29% mainly constrained by a shortage of financial and human resources. Our findings suggest that ignitions and fire spread in UNFR could be prevented or controlled through sustainable funding of fire management activities and the effective engagement of local communities in the management of the reserve.     

The discordance of diversification: evolution in the tropical‐montane frogs of the Eastern Arc Mountains of Tanzania

Species with similar geographical distribution patterns are often assumed to have a shared biogeographical history, an assumption that can be tested with a combination of molecular, spatial, and environmental data. This study investigates three lineages of Hyperolius frogs with concordant ranges within the Eastern Afromontane Biodiversity Hotspot to determine whether allopatric populations of co‐distributed lineages shared a parallel biogeographical response to their shared paleoclimatic histories. The roles of refugial distributions, isolation, and climate cycles in shaping their histories are examined through Hierarchical Approximate Bayesian Computation, comparative phylogeography, and comparisons of current and past geographical distributions using ecological niche models. Results from these analyses show these three lineages to have independent evolutionary histories, which current spatial configurations of sparsely available habitat (montane wetlands) have moulded into convergent geographical ranges. In spite of independent phylogeographical histories, diversification events are temporally concentrated, implying that past vicariant events were significant at the generic level. This mixture of apparently disparate histories is likely due to quantifiably different patterns of expansion and retreat among species in response to past climate cycles. Combining climate modelling and phylogeographical data can reveal unrecognized complexities in the evolution of co‐distributed taxa.     

Changing places: how the results of new field work in the Rubeho Mountains influence conservation priorities in the Eastern Arc Mountains of Tanzania

The Rubeho Mountains are a poorly studied mountain block within the Eastern Arc Mountain range of Tanzania and Kenya. We present the results of field surveys for vertebrates undertaken during the period February 2000 to December 2002. One hundred and twelve man‐days of surveys recorded 35 mammal, 107 bird, ten reptile and nine amphibian species, including eleven species endemic and seven near‐endemic to the Eastern Arc, with one species new to science. Of these, nine species are regarded as threatened with extinction. The new survey data significantly elevate the biological importance of the Rubehos within the Eastern Arc range. Further analyses highlight how the overall biological ranking of the Eastern Arc mountain blocks is correlated with survey effort. The majority of the forest habitat on the Rubehos is contained in three national (Central Government) Forest Reserves (Mang'alisa, Mafwomero and Ukwiva). Our surveys recorded high levels of disturbance to the forest habitat in all three reserves and we draw attention to the need for additional conservation investment in this area.     

Inbreeding and inbreeding depression in a threatened endemic plant,the African violet (Saintpaulia ionantha ssp. grotei), of the East Usambara Mountains,Tanzania

Mating among closely‐related individuals in small and isolated plant populations may result in reduced vigour of the inbred offspring, i.e. inbreeding depression, especially in naturally outbreeding plants. Occurrence of inbreeding and inbreeding depression was studied in Saintpaulia ionantha ssp. grotei, a threatened endemic plant species with a narrow ecological amplitude from the East Usambara Mountains. The level of inbreeding (measured as the fixation index, F) was investigated in twelve populations by analyzing variation at one microsatellite marker locus. The effect of one generation of selfing and outcrossing on the progeny fitness was studied by controlled crosses in two small patches that differ in the level isolation. The fixation index (F) across the populations was on the average 0.21 and varied among the populations from substantial inbreeding (F = 0.58) to surplus heterozygosity (F = −0.29). High inbreeding depression (δ) was observed at early and late stages of the life‐cycle. The isolated patch exhibited lower inbreeding depression than did the non‐isolated patch. The results of this study suggest that inbreeding and subsequent inbreeding depression are potential threats to the survival of Saintpaulia populations.     

Transmission of Onchocerca volvulus and prospects for the elimination of its vector, the blackfly Simulium neavei in the Mpamba-Nkusi focus in Western Uganda

The transmission of Onchocerca volvulus Leuckart (Spirudida: Onchocercidae) and the prospects of Simulium neavei Roubaud (Diptera: Simuliidae) vector elimination through ground larviciding were investigated in the Mpamba-Nkusi focus, western Uganda. Transmission levels and the initiated vector elimination activities were assessed to supplement the ongoing ivermectin mass distribution programme. Searches for breeding sites, adult fly catches, dissection of flies, river treatment with temephos (Abate) and a review of annual ivermectin treatment data were conducted. High levels of crab infestation with S. neavei sensu stricto immature stages were recorded; 57.9% and 100% for the Mpamba and Nyabugando river systems, respectively. The mean numbers of larvae/pupae per crab were 3.6 +/- 0.5 in the Mpamba and 20.6 +/- 1.8 in the Nyabugando systems. Pre-intervention mean biting densities were 39 and 32 flies/(man day) in 2001 and 2002, respectively, and an annual biting rate in 2001 of > 14 000. The bimodal biting pattern of S. neavei s.s. consisted of two peaks; one in the morning (09.00-10.00 hours) and one in the afternoon (14.00-15.00 hours) with a mid-day lull in biting. The infection/infective rates were 13.3%/2.8% and 16.6%/2.9% in the dissected parous flies from the Mpamba and Nyabugando river systems, respectively. Out of approximately 1000 parous flies, 129 and 109 were found to be harbouring infective larvae of Onchocerca volvulus in their heads from the Mpamba and Nyabugando river systems, respectively. In spite of the > 10 years of ivermectin treatment, at a mean coverage of 71.3%, infection remained relatively high. Ground larviciding with temephos (Abate) initiated in June and October 2002 had a significant impact. In the Mpamba river system there was a significant (P < 0.001) reduction in positive crabs from 57.9% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 3.6 +/- 0.5 in 2001 to 0.0007 +/- 0.0001 (P < 0.002) in 2003. Similarly, in the Nyabugando river system, a significant (P < 0.001) reduction in crab infestation from 100% in 2001 to 0.06% in 2003 and a decrease in the mean number of larvae/pupae per crab from 20.6 +/- 1.8 in 2001 to 0.06 +/- 0.03 in 2003. Drastic reductions were observed in the mean number of biting flies from 3 flies/h in 2001 to 0 flies/h in 2003 and the annual biting rates fell from 14,235 flies/year in 2001 to only 730 flies/year in 2003. These data suggest that substantial progress towards the goal of S. neavei s.s. vector elimination has been made and this will enhance the ongoing ivermectin treatment in this isolated focus.     

陕西秦岭东段南坡繁殖鸟类群落组成的30年变化

于2008和2010年每年5～7月在秦岭东段南坡的商洛地区商南、山阳、柞水和洛南4县根据海拔和植被类型选择样点,并采用样线法和网捕法相结合的方法对繁殖鸟类群落进行了调查。共观察记述鸟类159种,农田和栽培植物带(215～650 m)有鸟类96种,其中优势种是山麻雀(Passer rutilans),低山阔叶林带(650～1 200 m)鸟类种数最多,有135种,其中优势种是绿背山雀(Parus monticolus),针阔混交林带(1 200～2 200 m)有73种,其中优势种是橙翅噪鹛(Garrulax elliotii);秦岭东段南坡鸟类群落与中段南坡以及西段南坡和巴山北坡鸟类群落有较高的相似性,但是和秦岭北坡、巴山南坡的鸟类群落相似性较小,反映出秦岭和巴山对鸟类物种组成的阻隔作用和该地区鸟类区系组成的过渡性。和30年前相比,秦岭东段南坡鸟类物种增加了64种,但是有8种鸟类在2008和2010年的调查中未见到。总体上,秦岭东段南坡的繁殖鸟类群落组成在过去的30年里已经发生了明显的变化。     

Genetic Divergence During Long‐term Isolation in Highly Diverse Populations of Tropical Trees Across the Eastern Arc Mountains of Tanzania

The Eastern Arc Mountains are believed to support some of the oldest tropical forest in the world. The current distribution of this forest is highly fragmented due to a combination of long‐term effects of past changes in global climate and more recent deforestation. We sought to explore the hypothesized antiquity and long‐term isolation of the Eastern Arc montane forests based on an assessment of the geographical distribution and interspecies similarity of chloroplast DNA sequence variation in five forest trees. Data were used to investigate regional patterns of diversity and population structure based on intraspecific phylogenies, and results were interpreted against hypotheses on ecosystem age and connectivity. Regional diversity was high, with up to 22 chloroplast DNA haplotypes being recorded within a species across the sampled populations. Geographical concordance of genetic and geographic structure was weak to absent in all species and there was little similarity of genetic structure between species. Haplotype sharing between mountain blocks was extremely limited. The generally weak phylogeographical structure, in conjunction with high regional diversity and genetic uniqueness of individual mountain forests does not support the assumption of widespread genetic connectivity of the mountain forests, indicating instead a pattern of past isolation and ongoing diversification. Our findings substantially add to understanding patterns of diversity in this region and lend weight to calls to use more sophisticated biodiversity assessments when setting regional conservation and research funding priorities.     

西倾山地区植物区系研究

西倾山地区位于青海省东南部 ,北纬 33°80′～ 35°50′ ,东经 10 0°10′～ 10 2°4 0′。本地区共有种子植物 56科、 2 57属、 711种。区系特征如下 :(1)温带成分占 96 88% ,以绝对优势确定了本区系明显的温带性质。 (2 )世界成分多为衍生 ,更兼所含的中国特有属亦多为衍生 ,表明本区系的年轻性和衍生的性质。 (3)主要植被均属典型的高寒类型 ,它们的建群种亦多为典型的高寒植被的特征种。所以 ,本区系高寒植被典型 ,特征种典型 ,高寒区系特色明显。(4 )生态环境对本区系特征的塑造表现为高寒生态因子的选择和高山特化的作用强烈 ,而在一定程度上湿冷生性质和寒旱生性质的高山特化作用更为明显。西倾山地区的植物区系是唐古特地区的代表区系之一。但在中国特有种的分析中 ,本区系却与横断山和甘肃南部区系的联系最为密切 ,三者间的共有种最为丰富 ,有 36 3种 ,占本区中国特有种的 6 6 73%。如此大的相似性 ,无疑且有力地支持了李锡文等 (1993)关于横断山地区的“川西北、甘西南、青东南小区”划分的观点。     

关于小兴安岭东段沼泽形成问题

冷湿的气候和岛状多年冻土,以及低缓的地貌是本区沼泽形成的主要因素。沼泽形成的时代新,发育阶段全,类型复杂。上游形成时间较早,始于中全新世前期,中、下游形成时间较晚,始于晚全新世。中全新世为沼泽化和沼泽形成时期,晚全新世为沼泽扩展 时期,至今仍发育有富营养沼泽、中营养沼泽和贫营养沼泽。