Tanzanian Forests Research Articles

Biomass Change Estimated by TanDEM-X Interferometry and GEDI in a Tanzanian Forest

Mapping and quantification of forest biomass change are key for forest management and for forests’ contribution to the global carbon budget. We explored the potential of covering this with repeated acquisitions with TanDEM-X. We used an eight-year period in a Tanzanian miombo woodland as a test case, having repeated TanDEM-X elevation data for this period and repeated field inventory data. We also investigated the use of GEDI space–LiDAR footprint AGB estimates as an alternative to field inventory. The map of TanDEM-X elevation change appeared to be an accurate representation of the geography of forest biomass change. The relationship between TanDEM-X phase height and above-ground biomass (AGB) could be represented as a straight line passing through the origin, and this relationship was the same at both the beginning and end of the period. We obtained a similar relationship when we replaced field plot data with the GEDI data. In conclusion, temporal change in miombo woodland biomass is closely related to change in InSAR elevation, and this enabled both an accurate mapping and quantification wall to wall within 5–10% error margins. The combination of TanDEM-X and GEDI may have a near-global potential for estimation of temporal change in forest biomass.

Detecting and predicting forest degradation: A comparison of ground surveys and remote sensing in Tanzanian forests

Societal Impact StatementLarge areas of tropical forest are degraded. While global tree cover is being mapped with increasing accuracy from space, much less is known about the quality of that tree cover. Here we present a field protocol for rapid assessments of forest condition. Using extensive field data from Tanzania, we show that a focus on remotely‐sensed deforestation would not detect significant reductions in forest quality. Radar‐based remote sensing of degradation had good agreement with the ground data, but the ground surveys provided more insights into the nature and drivers of degradation. We recommend the combined use of rapid field assessments and remote sensing to provide an early warning, and to allow timely and appropriately targeted conservation and policy responses.Summary Tropical forest degradation is widely recognised as a driver of biodiversity loss and a major source of carbon emissions. However, in contrast to deforestation, more gradual changes from degradation are challenging to detect, quantify and monitor. Here, we present a field protocol for rapid, area‐standardised quantifications of forest condition, which can also be implemented by non‐specialists. Using the example of threatened high‐biodiversity forests in Tanzania, we analyse and predict degradation based on this method. We also compare the field data to optical and radar remote‐sensing datasets, thereby conducting a large‐scale, independent test of the ability of these products to map degradation in East Africa from space. Our field data consist of 551 ‘degradation’ transects collected between 1996 and 2010, covering >600 ha across 86 forests in the Eastern Arc Mountains and coastal forests. Degradation was widespread, with over one‐third of the study forests—mostly protected areas—having more than 10% of their trees cut. Commonly used optical remote‐sensing maps of complete tree cover loss only detected severe impacts (≥25% of trees cut), that is, a focus on remotely‐sensed deforestation would have significantly underestimated carbon emissions and declines in forest quality. Radar‐based maps detected even low impacts (<5% of trees cut) in ~90% of cases. The field data additionally differentiated types and drivers of harvesting, with spatial patterns suggesting that logging and charcoal production were mainly driven by demand from major cities. Rapid degradation surveys and radar remote sensing can provide an early warning and guide appropriate conservation and policy responses. This is particularly important in areas where forest degradation is more widespread than deforestation, such as in eastern and southern Africa.

Modelling the impact of climate change on Tanzanian forests

AbstractAimClimate change is pressing extra strain on the already degraded forest ecosystem in Tanzania. However, it is mostly unknown how climate change will affect the distribution of forests in the future. We aimed to model the impacts of climate change on natural forests to help inform national‐level conservation and mitigation strategies.LocationTanzania.MethodsWe conducted maximum entropy (MaxEnt) modelling to simulate forest habitat suitability using the Tanzanian national forest inventory survey (1,307 occurrences) and environmental data. Changes in forest habitats were simulated under two Representative Concentration Pathways (RCPs) emission scenarios RCP 4.5 and RCP 8.5 for 2055 and 2085.ResultsThe results indicate that climate change will threaten forest communities, especially fragmented strips of montane forests. Even under optimistic emission scenario, the extent of montane forest is projected to almost halve by 2085, intersecting many biodiversity hotspots across the Eastern Arc Mountains. Similarly, climate change is predicted to threaten microhabitat forests (i.e. thickets), with losses exceeding 70% by 2085 (RCP8.5). Other forest habitats are predicted to decrease (lowland forest and woodland) representing essential ecological networks, whereas suitable habitats for carbon‐rich mangroves are predicted to expand by more than 40% at both scenarios.ConclusionsClimate change will impact forests by accelerating habitat loss, and fragmentation and the remaining land suitable for forests will also be subject to pressures associated with rising demand for food and biofuels. These changes are likely to increase the probability of adverse impacts to the country's indigenous flora and fauna. Our findings, therefore, call for a shift in conservation efforts, focusing on (i) the enhanced management of existing protected areas that can absorb the impacts of future climate change, and (ii) expanding conservation efforts into newly suitable regions through effective land use planning and land reclamation, helping to preserve and enhance forest connectivity between fragmented patches.

Taking farmers back to school

We trained 80 farmers over three days in the middle of the Tanzanian forests to help them become experts at adding value to cinnamon, one of the local treasures. We worked with a master trainer from Sri Lanka who was surprised by the fast progress farmers made in a short time. Sri Lankan producers, who have worked with cinnamon for 2,000 years, took only three months to perfect cinnamon quill-making for the farmers.

Survey and DNA barcoding of flat bugs (Hemiptera: Aradidae) in the Tanzanian Forest Archipelago reveal a phylogeographically structured fauna largely unknown at the species level

We report results of a faunal survey of Aradidae flat bugs sampled by sifting litter in 14 wet and discrete Tanzanian primary forests (= Tanzanian Forest Archipelago, TFA) of different geological origins and ages. Images, locality data and, when available, DNA barcoding sequences of 300 Aradidae adults and nymphs forming the core of the herein analyzed data are publicly available online at dx.doi.org/10.5883/DS-ARADTZ. Three Aradidae subfamilies and seven genera were recorded: Aneurinae (Paraneurus), Carventinae (Dundocoris) and Mezirinae (Afropictinus, Embuana, Linnavuoriessa, Neochelonoderus, Usumbaraia); the two latter subfamilies were also represented by specimens not assignable to nominal genera. Barring the six nominal species of Neochelonoderus and Afropictinus described earlier by us from these samples and representing 11 of the herein defined Operational Taxonomic Units (OTU), only one of the remaining 52 OTUs could be assigned to a named species; the remaining 51 OTUs (81%) represent unnamed species. Average diversity of Aradidae is 4.64 species per locality; diversity on the three geologically young volcanoes (Mts Hanang, Meru, Kilimanjaro) is significantly lower (1.33) than on the nine Eastern Arc Mountains (5.67) and in two lowland forests (5). Observed phylogeographic structure of Aradidae in TFA can be attributed to vicariance, while the depauperate fauna of Aradidae on geologically young Tanzanian volcanoes was likely formed anew by colonisation from nearby and geologically older forests.

Learning from the other: Benefit sharing lessons for REDD+ implementation based on CBFM experience in Northern Tanzania

A key challenge facing interventions in forestry sector is how to ensure that benefit-sharing arrangements meet the needs and aspirations of poor rural people. In particular, as interest and effort builds around REDD+, it is important to remember that it, and any other intervention, are likely to be shaped by the history of Tanzania’s forestry sector, especially community based forest management. This paper examines benefit lessons for REDD+ from a well-known Tanzanian Forest Reserve which has begun to participate in selling carbon. The example is particularly important as it is one of the oldest cases of village-based forest management in the country. To explore this case a total of 101 households from two reserve-adjacent villages were randomly interviewed along with key informant interviews, transect walks, participant observation, and focus group discussions. Findings of the study revealed that majority of respondents felt benefits are concentrated on an elite due to weak governance mechanisms. We argue that local governance and central oversight will enhance good benefit sharing under REDD+ and future interventions in the forest sector.

International influence on forest governance in Tanzania: Analysing the role of aid experts in the REDD+ process

Forest governance in many African countries is characterised by a blatant gap between policy and implementation. Contrary to studies that explain this discrepancy mainly with deficient budgets and capacity shortfalls, this paper highlights aid as a cause of implementation failure: Analysing the REDD+ process in Tanzania, it reveals how donor experts employ their material and discursive power to convey ‘conservation fads’ to the country's policy domain, and to shape the latter in terms of substance and organisation. At the same time, it shows how local actors from government, civil society and academia utilise their international ‘partners’ for pursuing their own interests.The empirical findings presented in this paper are based on expert interviews and document analysis. Drawing on democracy theory and development studies, the paper points out the implications of aid and related expert advice for young democracies. In the Tanzanian forest sector, a far-reaching effect can be observed: Decision-makers routinely adjust their agenda to donor priorities without necessarily intending to put new policies into practice. While the uptake of ‘conservation fads’ promoted by the aid industry provides them direct and indirect access to resources, it prevents the emergence of responsive politics able to transform forest management on the ground.

English

Consumption of mushroom has increased remarkably because of their desirable aroma, taste and high nutritional content. Wild edible mushrooms (WEM) are well known for their nutritious and antioxidant properties. This study was conducted to measure and compare the antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) of six WEM from selected indigenous Tanzanian forests and one domesticated grown form in methanolic extracts. Results show that among the seven mushroom species extracts, the methanolic extract from Auricularia judae showed the most potent radical scavenging activity of 93.33% while Panus conchatus revealed lowest antioxidant activities of 46.53%. The strongest EC50 was observed in Auricularia judae 0.08 mg/ml while weakest was in P. conchatus >0.3 mg/ml. Nevertheless total phenolics in the methanolic extracts were the highest in P. tenuiculus (431.03±3.63 mg GAE/100 g) and lowest in Macrolepiota procera (136.21±0.98 mgGAE/100 g). Lentinus squarrosulus possessed highest content of β-carotene and flavonoids were 48.15±1.04 mg/100 g and 25.62±1.78 mg/100 g, respectively meanwhile the lowest concentration was found in wild L. sajor-caju 5.35±0.68 mg/100 g and 2.49±1.28 mg/100 g, respectively. Comparatively, domesticated mushroom showed higher scavenging ability of 76.61% than its wild counterparts 62.94%. In conclusion, high antioxidant activity in methanolic extract of WEM due to presence of phenolic content can potentially be used as a source of natural antioxidants.   Key words: Wild edible mushrooms, antioxidant activity, polyphenols flavonoids.

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. Resume Les forets tropicales hebergent une riche diversite d'especes, specialement des insectes. L'heterogeneite de l'habitat suivant le gradient vertical qui va du sous-bois jusqu’a la canopee des arbres influence cette diversite. La distribution verticale des insectes forestiers est mal connue en Afrique, specialement en Afrique de l'Est. Nous avons utilise des pieges appâtes avec de la nourriture pour etudier la stratification verticale de papillons nymphalides frugivores adultes dans la Reserve Forestiere de Mtai, dans le nord de la Tanzanie. Les pieges ont ete places dans la canopee et dans les sous-bois forestiers. Un total de 277 individus ont ete captures, appartenant a 24 especes. La composition des especes differait selon l'emplacement du piege : 33% des especes se trouvaient dans la canopee et a l’etage des sous-bois, mais il y eut plus d'especes capturees dans le sous-bois (54%) que dans la canopee (13%). Les mâles etaient significativement plus nombreux que les femelles et etaient captures aux deux niveaux. Une plus grande proportion de femelles etaient capturees dans le sous-bois que dans la canopee. L'heure de la journee affectait le taux de captures, et plus d'individus etaient captures l'apres-midi. Cependant, il n'y avait pas de lien entre l'heure et le sexe des individus captures dans la canopee vs dans le sous-bois. Le fait de comprendre comment le sexe des papillons varie dans le sous-bois par rapport a la canopee offre un nouvel apercu biologique de la stratification verticale des insectes.

Relationships between diameter and height of trees in natural tropical forest in Tanzania

The relationship between tree height (h) and tree diameter at breast height (dbh) is an important element describing forest stands. In addition, h often is a required variable in volume and biomass models. Measurements of h are, however, more time consuming compared to those of dbh, and visual obstructions, rounded crown forms, leaning trees and terrain slopes represent additional error sources for h measurements. The aim of this study was therefore to develop h–dbh relationship models for natural tropical forest in Tanzania. Both general forest type specific models and models for tree species groups were developed. A comprehensive data set with 2 623 trees from 410 different tree species collected from a total of 1 191 plots and 38 sites covering the four main forest types of miombo woodland, acacia savanna, montane forest and lowland forests was applied. Tree species groups were constructed by using a k-means clustering procedure based on the h–dbh allometry, and a number of different non-linear model forms were tested. When considering the complexity of natural tropical forests in general and in particular variations of h–dbh relationships due to high species diversity in such forests, the model fit and performance were considered to be appropriate. Results also indicate that tree species group models perform better than forest type models. Despite the fact that the residual errors level associated with the models were relatively high, the models are still considered to be applicable for large parts of Tanzanian forests with an appropriate level of reliability.

Community-Based Forest Management: What Scope for Conservation and Livelihood Co-Benefits? Experience from the East Usambara Mountains, Tanzania

The Tanzanian Community-Based Forest Management policy is based on the assumption that formalized forest tenure by village communities results in increased incentives for sustainable forest management. We compared the policy expectations to village forest management practices in northeastern Tanzania. Findings suggest that the practices follow policy in terms of increased security of rights, but exclusionary management of village forests precludes livelihood benefits while costs are unevenly distributed. Management appears effective at the village scale, but concerted efforts are likely to be needed to increase its long-term and landscape-level sustainability, and to create more significant incentives for the communities involved.

Environmental Burden of Charcoal Production and Use in Dar es Salaam, Tanzania

Tanzanian forests are excessively threatened by increased charcoal production fuelled by increased demand crucially in Dar es Salaam city which consumes nearly 70% of all the charcoal produced in the country. Through use of ecological modeling software STELLA® the environmental burden of charcoal production and use in Tanzania has been established. The study has revealed that the country losses 150,433 ha of forest per year. Due to increase in population by year 2030 almost 2.8 million ha of forests will have been lost. This is equivalent to 8.5% of the total forest cover the country had in 2009. The environmental burden includes air pollution characterized by a total emission of 49, 1.0, and 9.0, 12 million tonnes of CO2, SO2, NOx, and CH4, respectively by 2030. Other adverse impacts include loss of forest cover which ultimately causes degradation of soil quality by increased soil erosion, degradation of water sources and disruption of rainfall pattern including inducing draught. Taking into account that the agriculture in Tanzania is primarily rain fed, this has an adverse impact in agricultural production. In the current exploitation of this important natural resource, its sustainability is severely challenged and the whole concept of the forest being renewable is put into question. From these findings, it is recommended that concrete and deliberate efforts be made to reduce and eventually prohibit the use of charcoal in cities and towns.

Clinal Variation and Its Taxonomic Consequences in the Common Tanzanian Forest Frog, Arthroleptis affinis

North-to-south clinal variation in morphology is described in Arthroleptis affinis of the Eastern Arc mountains of Tanzania. While northern populations are readily separable from other Arthroleptis species, southern populations are not. This complicates differential diagnosis. Despite this, it is concluded that in the present state of knowledge, it is more useful to include the clinal variation under the name A. affinis, rather than attempt to divide the species into groups that defy clear morphological definition.

Taxation Issues in Tanzanian Forest Decentralisation

Taxation Issues in Tanzanian Forest Decentralisation

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

AbstractWe 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 (DP), species richness (D20) and observed (SO) and interpolated (SI) alpha diversity – were measured; beta diversity and abundance were also investigated. Mean elevational range was 470 m. DP, D20, alpha diversity and mollusc abundance increased with elevation, but alpha diversity peaked at 1695 m (SO) or 1500 m (SI) and declined at higher elevations. Maximum beta diversity was at 1000 m. Soil pH was negatively correlated with elevation and DP. 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.

‘Something else to burn’: forest squatters, conservationists, and the state in modern Tanzania

In the last fifteen years, Tanzanian forest policy has embraced an agenda of biodiversity preservation coupled with privatisation that calls for the expansion of state oversight over forests and woodlands. Reflecting the hegemony of conservationist donors and international and local NGOs, and couched in a language of community conservation, this agenda decries peasant intrusion into forest reserves to burn charcoal for the urban market and to expand fields for agriculture. This agenda is a departure from over a century of state forestry that sought to exploit forests for domestic consumer and development needs, and to compete in export timber and charcoal markets. Following the Second World War, state forestry anchored peasants in selected forest reserves as licensed cultivators in the face of an ongoing labour shortage, in order to create tree plantations that replaced indigenous hardwoods with fast-growing exotic softwoods. This trend continued after independence as forestry was perceived as a means for agricultural modernisation and economic self-reliance, particularly after the Arusha Declaration. Current changes in forest policy prioritise forests more as ‘refugia’ for endemic plant and animal species, rather than as sources of timber and fuel, moving forest policy more in the direction of wildlife conservation, which has long aimed at excluding peasants and pastoralists from reserves. Recent evictions of peasants from forest reserves, and ongoing tensions between villagers, the state and conservationists, are the direct result of NGO pressure to protect forest reserves and to expand forest conservation into previously unreserved lands.

Potential and Cost of Carbon Sequestration in the Tanzanian Forest Sector

The forest sector in Tanzania offers ample opportunities to reduce greenhouse gas emissions (GHG) and sequester carbon (C) in terrestrial ecosystems. More than 90% of the country's demand for primary energy is obtained from biomass mostly procured unsustainably from natural forests. This study examines the potential to sequester C through expansion of forest plantations aimed at reducing the dependence on natural forest for wood fuel production, as well as increase the country's output of industrial wood from plantations. These were compared ton conservationoptions in the tropical and miombo ecosystems. Three sequestrationoptions were analyzed, involving the establishment of short rotation and long rotation plantations on about 1.7 × 106 hectares. The short rotation community forestry option has a potential to sequester an equilibrium amount of 197.4 × 106 Mg C by 2024 at a net benefit of 79.5 × 106, while yielding a NPV of 0.46 Mg-1 C. The long rotation options for softwood and hardwood plantations will reach an equilibrium sequestration of 5.6 and 11.8 × 106 Mg C at a negative NPV of 0.60 Mg-1 C and 0.32 Mg-1 C. The three options provide cost competitive opportunities for sequestering about 7.5 × 106 Mg C yr-1 while providing desired forest products and easing the pressure on the natural forests in Tanzania. The endowment costs of the sequestration options were all found to be cheaper than the emission avoidance cost for conservation options which had an average cost of 1.27 Mg-1 C, rising to 7.5 Mg-1 C under some assumptions on vulnerability to encroachment. The estimates shown here may represent the upper bound, because the actual potential will be influenced by market prices for inputs and forest products, land use policy constraints and the structure of global C transactions.

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.

Changing Roles in Natural Forest Management: A Case Study From the Udzungwa Mountains

The new Tanzanian forest policy was cleared in early 1998, and empowers community groups to own and manage forest resources. The Tanzania Forest Conservation Group (TFCG), a local NGO, is now in a position to rethink its role and move towards facilitating the balancing of local peoples' rights, responsibilities, returns from forest resources and relationship to forest maintenance. This article tracks changes in Lulanda Forest, in the Udzungwa, Eastern Arc Mountains, and analyses the evolution of local control over forest management.

Carbon flows and economic evaluation of mitigation options in Tanzania's forest sector

This paper presents estimates of the rate of forest use, deforestation and forest degradation, as well as the corresponding carbon flows, in the Tanzanian forest sector. It is estimated that the country lost 525,000 ha of forests in 1990, with associated committed emissions of 31.5 Mt carbon (MtC), and 7.05 MtC of committed carbon sequestration. The paper then describes the possible response options in the forest sector to mitigate GHG emissions, and evaluates the most stable subset of these—i.e. forest conservation, woodfuel plantations and agroforestry. The conservation options were found to cost an average of U.S.$1.27 per tonne of carbon (tC) conserved. Five options for fuelwood plantations and agroforestry, with two different ownership regimes were evaluated. Each one of the options gives a positive net present value at low rates of discount, ranging from U.S.$1.06 to 3.4/tC of avoided emissions at 0% discount rate. At 10% discount, the eucalyptus and maize option has a highest PNV of U.S.$1.73/tC, and the government plantation gives a negative PNV (loss) of U.S.$0.13 tC sequestered. The options with a private/community type of ownership scheme fared better than government run options. This conclusion also held true when ranking the options by the BRAC indicator, with the government fuelwood plantation ranked the lowest, and the private agroforestry option of eucalyptus and corn performing best. The mitigation options evaluated here show that the forest sector in Tanzania has one of the most cost-effective GHG mitigation opportunities in the world, and they are within the developmental aspirations of the country.