Changes in tropical forest vegetation along an altitudinal gradient in the Udzungwa Mountains National Park, Tanzania

This study describes changes in woody vegetation in the Mwanihana forest, Udzungwa Mountains National Park, Tanzania, over an altitude range of 470–1700 m. Two methods, fixed‐ and variable‐area plots, are compared to elucidate altitudinal variation in tropical forest structure, diversity and community composition. Six 25 m × 100 m fixed area plots recorded a total of 2143 woody stems of ≥3 cm d.b.h. from 204 species. The 78 variable‐area plots recorded the nearest twenty trees of ≥20 cm d.b.h. to an objectively chosen point, giving a total of 1560 stems in 9.1 ha from 156 species. A linear trend of increasing stem density with altitude was seen for variable‐area plots. Species diversity is highest at high elevations. There was no clear zonation of elevational vegetation types. Restricted range taxa occur at all altitudes sampled. The study also revealed some methodological considerations. Bias in sample size and plot area can be tested by employing two sampling methods. Of the two methods used, fixed area plots are preferred as variable area plots are impractical in tangled understorey. Plot size must be controlled for in order to make reliable observations of diversity. Sampling along a continuous or near‐continuous altitudinal gradient with sufficient replication is also important.     

Elevational variation in diversity and composition of land-snail faunas in a Tanzanian forest

We sampled terrestrial molluscs at fifteen elevations between 400 and 2000 m in Mwanihana Forest Reserve, Tanzania and recorded 84 taxa. Four diversity measures – species density (D_P), species richness (D₂₀) and observed (S_O) and interpolated (S_I) alpha diversity – were measured; beta diversity and abundance were also investigated. Mean elevational range was 470 m. D_P, D₂₀, alpha diversity and mollusc abundance increased with elevation, but alpha diversity peaked at 1695 m (S_O) or 1500 m (S_I) and declined at higher elevations. Maximum beta diversity was at 1000 m. Soil pH was negatively correlated with elevation and D_P. Cluster analysis divided the sites into lowland (400–900 m) and highland (>1000 m) groups. Axis 1 of a canonical correspondence analysis was associated with altitude and suggested a faunal discontinuity at 1000 m. Variation within the highland (>1000 m) and lowland faunal sets was related to elevation and forest structure respectively. The findings indicate that mollusc diversity peaks at intermediate elevations. This may be related to the combined effects of low rainfall conditions at low elevations and increasing effects of soil leaching at high elevations, both of which may limit mollusc diversity and abundance. Diversity at intermediate altitudes may be further elevated because of faunal mixing of lowland and highland groups.     

Developing management plans for the mangrove forest reserves of mainland Tanzania

The mangroves of Tanzania are currently not being managed although they are legally gazetted as forest reserves. The management of this overexploited and under estimated natural resource rests with the Forest and Beekeeping Division in the Ministry of Natural Resources and Tourism. It is the Division's intention to conserve the mangroves of Tanzania, therefore steps are being taken to reach that goal. So far the Division, through its established mangrove project, has done an inventory of all the mangroves of mainland Tanzania with the assistance of NORAD. Aerial photography and ground checks were used to assess the state of all the mangrove reserves in the country. Literature search and a socio-economic study was also undertaken.The inventory revealed that the area covered by mangrove vegetation is 115 901 ha while the previous records indicate about 80 000 ha. If the bare saline areas, water bodies, and salt pans which are part of the mangrove reserves are included, the area amounts to 172 879 ha for the Tanzania mainland. The mangrove reserves have already been mapped in 30 sheets. Some sheets are mapped using a scale of 1:25 000 while others are mapped in 1:50 000 scale. The maps show the vegetation types, the area of each vegetation type, and the stand density and height of each compartment.The paper therefore presents the current status of the mangroves of Tanzania in respect to area, distribution and vegetation types. Included are the strategies being used to develop the mangrove management plans for Tanzania.     

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.     

PERMANENT GENETIC RESOURCES: Isolation and characterization of 10 tetranucleotide microsatellite loci in an enigmatic East African bird, the spot-throat (Modulatrix stictigula)

We describe the isolation of 10 tetranucleotide microsatellites from the spot-throat using an enrichment protocol. All loci were highly variable with the number of alleles ranging from six to 20 and observed heterozygosity ranging from 0.410 to 0.940. Although all loci were in Hardy-Weinberg equilibrium, locus Mst95 showed significant homozygote excess in both surveyed populations, possibly a consequence of the presence of null alleles at this locus. These loci will be used to determine the extent to which spot-throat populations are isolated in order to help set conservation priorities for this ancient African lineage.     

Effects of a hydropower plant on Coleopteran diversity and abundance in the Udzungwa Mountains, Tanzania

The effects of river flow diversion on biodiversity were assessed using Coleoptera as an indicator group in three habitats of the Kihansi Gorge (Udzungwa Mountains, Tanzania), before and after commissioning of a hydropower plant. Data collected using sweep netting and pitfall traps showed that the effect of diversion of the river flow was site-specific, affecting particularly the spray habitat. Rarefaction analysis of both sweep netting and pitfall samples indicated that the expected richness of Coleoptera declined significantly in all habitats after commissioning of the power plant. Sweep netting and pitfall samples showed that the highest Shannon–Wiener diversity index value before the diversion of the river flow was in the spray zone, but the index value decreased after diversion. Changes in the other two habitats were less prominent. Analysis of variance using diversity index values from five pitfall samples in each habitat type before and after commissioning indicated that there were no statistically significant differences in the diversity index between the two sampling periods or among the three habitat types. Renkonen's similarity index between habitats showed that pitfall samples had higher similarity (87%) than did samples from sweep netting (69%). It is suggested that for mitigation purposes, artificial spray systems, which have been installed in other wetlands of the Kihansi Gorge, also be installed to cover the whole Lower Wetland in which this study was undertaken. In order to maintain overall biodiversity in the Kihansi Gorge, it is suggested that the ecosystem conservation approach be prioritised.     

Phylogenetic diversity of forest trees in the Usambara mountains of Tanzania: correlations with altitude

The relationship between diversity of large trees and altitude was investigated in a Tanzanian tropical rain forest. In total, 231 samples of 20 trees of ≥ 20 cm d.b.h. from the East and West Usambara mountains, covering an elevation range from 280 m to 2180 m a.s.l., were analysed. An ordination demonstrated a constant turnover of species, genera, family and orders with elevation. There were no obvious zones or discontinuities. There was no decline in plot richness with respect to altitude for species, genera or orders. Family richness was shown to increase with altitude. A measure of genetic diversity, the avalanche index, was calculated for each plot to investigate the effect of incorporating phylogenetic relatedness of individuals into the diversity measure. Distances between taxa were extracted from a recent molecular phylogeny of the angiosperms. Incorporation of phylogenetic diversity at family level enhanced the positive correlation between plot diversity and altitude.  © 2005 The Linnean Society of London, Botanical Journal of the Linnean Society , 2005, 149 , 217–228.     

The implications of improved communications for participatory forest management in Tanzania

Following the 1998 National Forest Policy and Forest Act of 2002, participatory forest management (PFM) is being introduced in Tanzania. PFM has two key objectives: to reduce forest degradation thereby increasing ecosystem services, and to improve the livelihoods of local villagers. A unique data set collected in 2006 suggests that significant challenges remain with respect to communicating the new forest policies if the objectives of PFM are to be achieved. First, villagers as a group are much less well informed than other stakeholders, and their knowledge is often inaccurate. Second, women are less likely than men to have heard of the changes. Third, how PFM will contribute to poverty reduction (a key objective of PFM) is not always clear. Fourth, environmental degradation may not be reduced as much as anticipated – without alternatives sources, villagers often continue to cut trees for charcoal and firewood in the protected forests. Finally, several mismatches in perceptions are identified that could lead to difficulties in implementing PFM.     

Altitudinal species turnover in southern Tanzania shown by anurans: Some zoogeographical considerations

A transect was used to investigate the pattern of altitudinal species turnover shown by the rich fauna of frogs and toads in southeastern Tanzania, and to compare the pattern with those shown by transects taken further south. The transect, taken from the Udzungwa range to the southeastern coast, was divided into 50 m intervals. As with the southern transects, there appears to be a major grouping into lowland and highland sets, with opposing and overlapping subtraction margins that form a replacement‐transition zone. A distributionally complex assemblage of species occurs in this zone. When a similarity value (the Dice‐S?rensen index, expressed as a percentage) taken between the montane ridge and lowland faunas was compared with those of the southern transects, a markedly higher species turnover (low similarity value) is shown in Tanzania. Both lowland and highland faunas have more species than equivalent faunas to the south; the highland fauna is particularly rich in genera not known to occur further south. Yet overall, the pattern of altitudinal turnover shown in the Tanzanian transect is in agreement with the pattern shown in the southern transects. The transects discussed in this paper, combined with other evidence, suggest a need for re‐evaluating the common practice of including all sub‐Saharan Africa in a single so‐called Afrotropical Region.     

Elevational zonation of afrotropical forest bird communities along a homogeneous forest gradient

Aim This study analyses the distribution and abundance of birds from a forested tropical gradient in order to determine whether elevationally distinct communities are detectable in this habitat. Location An avifaunal census was carried out on a single transect within the tropical forest of the Udzungwa Mountains in the Eastern Arc, Tanzania, covering a range in elevation from 300 to 1850 m. Methods Two complementary data sets on forest birds were analysed, encompassing (1) data derived from standardized 20‐ha spot‐mapping censuses performed at nine elevations over 175‐m intervals from 400 to 1800 m a.s.l., and (2) all observations of birds binned into 32 data points at 50‐m intervals, from 300 to 1850 m a.s.l. The degree of zonation in the avian community along the elevational gradient was examined using the chronological clustering method, an agglomerative hierarchical clustering method that can be carried out with a range of similarity indices. Results The chronological clustering analysis of the data set based on standardized spot‐mapping revealed a clearly defined boundary at c. 1200 m a.s.l., separating lowland from montane communities. Most bird species could be categorized as belonging to one of these two communities. The data set based on all observations revealed a number of potential secondary boundaries, although these boundaries delimited the entire elevational ranges of individual species in only relatively few cases. Main conclusions In contrast to previously published studies, we find evidence of an elevational zonation of distinct communities within a seemingly homogeneous habitat. Although similar boundaries have been assumed to arise as a result of vegetational ecotones, or because of interspecific competition, these mechanisms are poorly corroborated. We suggest that the causes of patterns of zonation are not well understood, and that the interplay among species distributions, species richness, and environmental factors needs more consideration. The chronological clustering method is proposed as an appropriate tool for studying these specific patterns.     

High species diversity in one of the dominant groups of spiders in East African montane forests (Araneae: Pholcidae: Buitinga n. gen., Spermophora Hentz)

The six-eyed pholcid spiders of East Africa are revised. A new genus is recognized, Buitinga n. gen ., with 17 new species and three species transferred from Spermophora Hentz. The new genus is characterized by the presence of a scape on the epigynum. This scape may be straight or tightly curled up at rest, and is usually highly expandable. Seven additional African and Comoran species are newly described and tentatively assigned to Spermophora . A data matrix with 60 characters and 77 taxa (including 20 East African species and 25 additional Spermophora and ' Spermophora -like' species) is analysed cladistically. Buitinga is closer to the genera Paramicromerys Millot (endemic in Madagascar) and Spermophorides Wunderlich (Mediterranean and Canary Islands) as well as to several African and Comoran species tentatively assigned to Spermophora than to the type species of Spermophora . It is argued that current estimates of species numbers may be inaccurate and that pholcids may turn out to be one of the most diverse spider families.  © 2003 The Linnean Society of London. Zoological Journal of the Linnean Society, 2003, 137, 555−619     

The practice and principles of community-based wildlife management in Zimbabwe: the CAMPFIRE programme

This paper describes Zimbabwe's wildlife-based CAMPFIRE programme. It suggests that community-based natural resource management is a potential solution to the inter-linked problems of poverty and conservation if it is based on sound management principles that also incorporate transparency, accountability and democracy because the unit of management is a community.This first section suggests that many of the causes of these natural resource problems in communal lands are a result of the failure of mechanisms to price and allocate resources efficiently. The second section describes the evolution of CAMPFIRE, while the third section summarizes the principles that underpin the programme. The fourth section discusses the governance of natural resources and describes the process by which rights to wildlife have been devolved. This emphasizes how important political and administrative systems are to wildlife conservation. CAMPFIRE can be viewed as a five-step process: getting an enabling political, legal, administrative and economic environment; creating awareness and a demand for the programme; generating revenues; using these revenues effectively; and, finally, setting in place the institutions and capacity for locally-based natural resource management. The first four sections of the paper deal with step on — the enabling environment, what it is and how it came about. The final section describes the actual implementation of the programme and is rather brief.     

Early survival and growth of Allanblackia stuhlmannii (Clusiaceae): a threatened tropical rainforest tree of high economic value in Tanzania

Rural households living in tropical ecosystems depend heavily on forest trees for valuable nontimber forest products that are, however, undergoing unsustainable harvesting. This study assessed early survival and growth of Allanblackia stuhlmannii (Clusiaceae), a nontimber tree species endemic to Tanzania. A total of 400 seedlings sourced from twenty elite female trees were planted in two adjacent locations. Data were collected over 59 months for survival, height and root collar diameter. Seedling survival at 59 months was significantly different between Emau and Shebomeza, being on average ~11% higher in Shebomeza. However, survival of the progenies of each female tree at 59 months was not significantly different. Overall, mean RCD (range: 6.8–59.7 mm) and height (range: 17.1–274.4 cm) were positively correlated (r = 0.84, P < 0.001). The correlations in heights of individuals between 17 and 59, and 23 and 59 months were positive (r = 0.34 versus 0.53, respectively). Results also suggested that if growth rate is related to ontogeny from juvenile to adult, then the progenies of ten female trees that have shown consistently higher growth rates may flower and fruit earlier than other progenies. Future planting for conservation of this threatened, overharvested tree species can therefore be based on data gathered from these field genebanks.     

A new species of giant sengi or elephant-shrew (genus Rhynchocyon) highlights the exceptional biodiversity of the Udzungwa Mountains of Tanzania

A new species of sengi, or elephant-shrew, is described. It was discovered in the northern Udzungwa Mountains of Tanzania in 2005. Sengis (Order Macroscelidea, super-cohort Afrotheria) include four genera and 15 species of mammals that are endemic to Africa. This discovery is a significant contribution to the systematics of this small order. Based on 49 camera trap images, 40 sightings and five voucher specimens, the new sengi is diurnal and distinguished from the other three species of Rhynchocyon by a grizzled grey face, pale yellow to cream chest and chin, orange-rufous sides, maroon back and jet-black lower rump and thighs. The body weight of the new species is about 700 g, which is 25–50% greater than any other giant sengi. The new Rhynchocyon is only known from two populations that cover about 300 km² of montane forest. It has an estimated density of 50–80 individuals km⁻². This discovery has important implications for the conservation of the high biodiversity that is found in the forests of the Eastern Arc Mountains.     

劳动力转移和森林管护水平对森林碳密度的影响——基于福建253个村的实证研究

森林生态系统具有重要的固碳功能,有效的森林管理是提升碳密度的重要方式。随着农村劳动力转移,森林管护水平也随之变化,进而可能影响森林碳密度。为了厘清劳动力转移和森林管护水平对森林碳密度的作用机理,以提升森林碳密度。利用福建5县（区）253个村1999年与2009年的林业二类调查数据和入村调研数据,采用转换因子连续函数法评价了森林碳密度,再运用层次回归模型分析了劳动转移对森林碳密度的影响,并检验了森林管护水平对二者的中介作用。结果表明：（1）10年间森林碳密度普遍提升,但区域差异明显;空间上森林碳密度呈由南向北递增,提升率呈由南向北递减。（2）劳动力转移对森林碳密度有显著促进作用,而森林管护水平对森林碳密度有显著削弱作用,并对劳动力转移与森林碳密度之间的关系具有显著中介效应。（3）劳动力特征、采伐方式及森林自然禀赋等因素,主要通过生计依赖、生境状况和生物量对森林碳密度产生显著影响。据此提出：适当减少对森林的人为干扰,丰富林农生计来源,转变林业经营目标,科学采伐成熟和过熟林,保护天然起源林,丰富人工林树种等政策建议。     

Biophysical analysis of afromontane forest community types at Mount Kasigau,Kenya

This study examines how biophysical site conditions differ in relation to the distribution of forest community types at Mount Kasigau, Kenya, in the Eastern Arc. Topographic measures of elevation, slope, curvature and aspect were derived from a 30‐m DEM and temperature and moisture conditions collected from 19 field data loggers for June 2011–2012 measured seasonal change along the steep elevational gradient (1000 m) from bushland to evergreen forest. Nonparametric statistical analyses then compared topographic and climatic conditions among eight ecologically classified forest types. Steep lapse rates in temperature and available moisture support abrupt changes in canopy physiognomy, but dew points declined with elevation. The Kruskal–Wallis test showed significant differences in the elevation, slope, temperature, dew point and relative humidity conditions among the eight forest types. These biophysical conditions are more discrete for Acacia‐Commiphora bushland and cloud forest but not significantly different between riverine forest, lower montane woodlands I and II and Euphorbia quinquecostata woodland, and between semi‐evergreen woodland and evergreen forest. Biophysical conditions and their influence on the distribution of forest types across a heterogeneous mountain landscape are important to understand and monitor in this unpredictably changing tropical seasonal climate.     

Vertical distribution of fruit‐feeding butterflies with evidence of sex‐specific differences in a Tanzanian forest

Tropical forests accommodate rich species diversity, particularly among insects. Habitat heterogeneity along the vertical gradient extending from the forest understorey to the tree canopy influences diversity. The vertical distribution of forest insects is poorly understood across Africa, most especially eastern Africa. Food‐baited traps were used to study the vertical stratification of adult fruit‐feeding nymphalid butterflies in Mtai Forest Reserve, north‐eastern Tanzania. Traps were located in the forest canopy and understorey. A total of 277 individuals of 24 species were captured. Species composition differed by trap locations: 33% of the species captured were found in both the canopy and understorey strata; however, significantly more species were captured in the understorey (54%) than canopy (13%). Males were significantly more abundant than females and captured in both strata. A greater proportion of females were captured in the understorey than the canopy. The time of day affected capture rates, with more individuals caught in the afternoon; however, there was no association between the time period and the sex of individuals captured in canopy versus understorey locations. Understanding how the sexes of butterflies vary in understorey versus canopy offers new biological insights into the vertical stratification of insects.     

A forest typology for monitoring sustainable forest management: The case of European Forest Types

Abstract

Sustainable forest management (SFM) is presently widely accepted as the overriding objective for forest policy and practice. Regional processes are in progress all over the world to develop and implement criteria and indicators of SFM. In continental Europe, a set of 35 Pan-European indicators has been endorsed under the Ministerial Conference on the Protection of Forests in Europe (MCPFE) to measure progress towards SFM in the 44 countries of the region. The formulation of seven indicators (forest area, growing stock, age structure/diameter distribution, deadwood, tree species composition, damaging agents, naturalness) requires national data to be reported by forest types. Within the vast European forest area the values taken by these indicators show a considerable range of variation, due to variable natural conditions and anthropogenic influences. Given this variability, it is very difficult to grasp the meaning of these indicators when taken out of their ecological background. The paper discusses the concepts behind, and the requirements of, a classification more soundly ecologically framed and suitable for MCPFE reporting than the three (un-informative) classes adopted so far: broadleaved forest, coniferous forest, mixed broadleaved and coniferous forest. We propose a European Forest Types scheme structured into a reasonably higher number of classes, that would improve the specificity of the indicators reported under the MCPFE process and its understanding.