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Edmond Alavaisha
Tanzania

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Original research article
Published: 28 July 2021 in Frontiers in Environmental Science
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Increasing agricultural land use intensity is one of the major land use/land cover (LULC) changes in wetland ecosystems. LULC changes have major impacts on the environment, livelihoods and nature conservation. In this study, we evaluate the impacts of investments in small-scale irrigation schemes on LULC in relation to regional development in Kilombero Valley, Tanzania. We used Remote Sensing (RS) and Geographical Information System (GIS) techniques together with interviews with Key Informants (KI) and Focus Group Discussion (FGD) with different stakeholders to assess the historical development of irrigation schemes and LULC change at local and regional scales over 3 decades. Overall, LULC differed over time and with spatial scale. The main transformation along irrigation schemes was from grassland and bushland into cultivated land. A similar pattern was also found at the regional valley scale, but here transformations from forest were more common. The rate of expansion of cultivated land was also higher where investments in irrigation infrastructure were made than in the wider valley landscape. While discussing the effects of irrigation and intensification on LULC in the valley, the KI and FGD participants expressed that local investments in intensification and smallholder irrigation may reduce pressure on natural land cover such as forest being transformed into cultivation. Such a pattern of spatially concentrated intensification of land use may provide an opportunity for nature conservation in the valley and likewise contribute positively to increased production and improve livelihoods of smallholder farmers.

ACS Style

Edmond Alavaisha; Victor Mbande; Lowe Börjeson; Regina Lindborg. Effects of Land Use Change Related to Small-Scale Irrigation Schemes in Kilombero Wetland, Tanzania. Frontiers in Environmental Science 2021, 9, 1 .

AMA Style

Edmond Alavaisha, Victor Mbande, Lowe Börjeson, Regina Lindborg. Effects of Land Use Change Related to Small-Scale Irrigation Schemes in Kilombero Wetland, Tanzania. Frontiers in Environmental Science. 2021; 9 ():1.

Chicago/Turabian Style

Edmond Alavaisha; Victor Mbande; Lowe Börjeson; Regina Lindborg. 2021. "Effects of Land Use Change Related to Small-Scale Irrigation Schemes in Kilombero Wetland, Tanzania." Frontiers in Environmental Science 9, no. : 1.

Journal article
Published: 18 April 2020 in Land
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The preservation of soils which provide many important services to society is a pressing global issue. This is particularly the case in countries like Tanzania, which will experience rapid population growth over coming decades. The country is also currently experiencing rapid land-use change and increasing intensification of its agricultural systems to ensure sufficient food production. However, little is known regarding what the long term effects of this land use change will be, especially concerning soil quality. Therefore, we assessed the effect of irrigation and fertilization in agricultural systems, going from low intensity smallholder to high intensity commercial production, on soil organic carbon (SOC), total nitrogen (TN), and total phosphorous (TP) concentrations and stocks. Soil sampling was conducted within Kilombero Plantations Ltd. (KPL), a high intensity commercial farm located in Kilombero, Tanzania, and also on surrounding smallholder farms, capturing a gradient of agricultural intensity. We found that irrigation had a positive effect on SOC concentrations and stocks while fertilization had a negative effect. Rain-fed non-fertilized production had no effect on soil properties when compared to native vegetation. No difference was found in concentrations of TN or TP across the intensity gradient. However, TN stocks were significantly larger in the surface soils (0–30 cm) of the most intensive production system when compared to native vegetation and smallholder production.

ACS Style

John Livsey; Edmond Alavaisha; Madaka Tumbo; Steve W. Lyon; Antonio Canale; Michele Cecotti; Regina Lindborg; Stefano Manzoni. Soil Carbon, Nitrogen and Phosphorus Contents along a Gradient of Agricultural Intensity in the Kilombero Valley, Tanzania. Land 2020, 9, 121 .

AMA Style

John Livsey, Edmond Alavaisha, Madaka Tumbo, Steve W. Lyon, Antonio Canale, Michele Cecotti, Regina Lindborg, Stefano Manzoni. Soil Carbon, Nitrogen and Phosphorus Contents along a Gradient of Agricultural Intensity in the Kilombero Valley, Tanzania. Land. 2020; 9 (4):121.

Chicago/Turabian Style

John Livsey; Edmond Alavaisha; Madaka Tumbo; Steve W. Lyon; Antonio Canale; Michele Cecotti; Regina Lindborg; Stefano Manzoni. 2020. "Soil Carbon, Nitrogen and Phosphorus Contents along a Gradient of Agricultural Intensity in the Kilombero Valley, Tanzania." Land 9, no. 4: 121.

Journal article
Published: 31 March 2019 in Water
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Coupled change in land and water use due to increased farming intensity is a main factor affecting water quality and quantity, ecological functions and biodiversity globally. Prolonging growing seasons and increasing productivity in wetlands through irrigation have been targeted for increasing food security, particularly in developing countries. Nevertheless, irrigation and drainage have often been associated with degradation of water quality through increased agrochemical and fertiliser runoff and leaching at local scales. In this study, we investigated water quality in streams used for irrigation in a wetland area in Kilombero Valley, Tanzania. We measured physical-chemical water parameters and collected macroinvertebrates with different sensitivity to water quality across several small irrigation schemes covering various conditions. Turbidity, temperature, nitrate-N, and ammonium-N were significantly higher at sampling sites downstream of irrigation compared to upstream. Macroinvertebrate diversity, richness and average score per taxa (ASPT) were higher in general in sampling sites upstream of irrigation, with more sensitive macroinvertebrates decreasing in abundance downstream. There was a positive correlation between physical-chemical parameters and macroinvertebrate indices across the sites. We demonstrate that macroinvertebrate indices can be used as a quick assessment of water quality in response to irrigation schemes in small-scale farming systems of Tanzania. This in turn can allow us to track changes affecting wetland ecosystem function and biodiversity at higher trophic levels and across larger scales, thereby providing useful early warnings to help avoid widespread degradation under widespread agricultural intensification.

ACS Style

Edmond Alavaisha; Steve W. Lyon; Regina Lindborg. Assessment of Water Quality Across Irrigation Schemes: A Case Study of Wetland Agriculture Impacts in Kilombero Valley, Tanzania. Water 2019, 11, 671 .

AMA Style

Edmond Alavaisha, Steve W. Lyon, Regina Lindborg. Assessment of Water Quality Across Irrigation Schemes: A Case Study of Wetland Agriculture Impacts in Kilombero Valley, Tanzania. Water. 2019; 11 (4):671.

Chicago/Turabian Style

Edmond Alavaisha; Steve W. Lyon; Regina Lindborg. 2019. "Assessment of Water Quality Across Irrigation Schemes: A Case Study of Wetland Agriculture Impacts in Kilombero Valley, Tanzania." Water 11, no. 4: 671.

Journal article
Published: 01 March 2019 in Journal of Environmental Management
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Converting natural and semi-natural vegetation to agriculture is currently the most significant land use change at global scale. This conversion leads to changes in soil nutrients and increased CO emissions. However, knowledge of how soil organic carbon and nutrients change under various farming management is still limited, especially for small scale farming systems. This study evaluated the effects of different farming systems on soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) in subsistence farming at Kilombero, Tanzania. We applied an in-situ experimental setup, comparing maize and rice farming with and without irrigation and difference in fertilizers, with replicated soil sampling at five soil depths to a depth of 60 cm. The results show that irrigation had a positive effect on profile-averaged concentrations of SOC and TN, while fertilization had a positive effect on TN. Higher concentrations and stocks of TN were found in maize field soils compered to rice fields. In the vertical profile, irrigation and fertilization had positive effects on concentrations of SOC and TN of top soil layers, and the interaction between irrigation and fertilization extended the effect to deeper soil layers. Our results indicate that moderate irrigation and fertilization can help to improve carbon storage and nutrient availability (TN) in small-scale farming soils in Africa.

ACS Style

E. Alavaisha; Stefano Manzoni; R. Lindborg. Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania. Journal of Environmental Management 2019, 234, 159 -166.

AMA Style

E. Alavaisha, Stefano Manzoni, R. Lindborg. Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania. Journal of Environmental Management. 2019; 234 ():159-166.

Chicago/Turabian Style

E. Alavaisha; Stefano Manzoni; R. Lindborg. 2019. "Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania." Journal of Environmental Management 234, no. : 159-166.

Research article
Published: 28 September 2016 in International Journal of Forestry Research
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Mangrove forests offer important ecosystem services, including their high capacity for carbon sequestration and stocking. However, they face rapid degradation and loss of ecological resilience particularly at local scales due to human pressure. We conducted inventory of mangrove forests to characterise forest stand structure and estimate carbon stocks in the small estuarine mangroves of Geza and Mtimbwani in Tanga, Tanzania. Forest structure, above-ground carbon (AGC), and below-ground carbon (BGC) were characterised. Soil carbon was estimated to 1 m depth using loss on ignition procedure. Six common mangrove species were identified dominated by Avicennia marina (Forsk.) Vierh. and Rhizophora mucronata Lamarck. Forest stand density and basal area were 1740 stems ha−1 and 17.2 m2 ha−1 for Geza and 2334 stems ha−1 and 30.3 m2 ha−1 for Mtimbwani. Total ecosystem carbon stocks were 414.6 Mg C ha−1 for Geza and 684.9 Mg C ha−1 for Mtimbwani. Soil carbon contributed over 65% of these stocks, decreasing with depth. Mid zones of the mangrove stands had highest carbon stocks. These data demonstrate that studied mangroves are potential for carbon projects and provide the baseline for monitoring, reporting, and verification (MRV) to support the projects.1. IntroductionMangrove forests occur in fragmented stands along almost the entire coastline of Tanzania mainland. Mangroves flourish in river estuaries and deltas and in enclosed bays, lagoons, and tidal creeks. Despite representing only about 0.3% (108,000–115,000 ha) of the total forest area in the country [1, 2], these forests provide numerous ecosystem services including wood and nonwood products; buffering lands and coastal properties [1, 3]; and supporting fisheries as they serve as nursery, feeding, and shelter grounds for numerous commercially important fishes and invertebrates [4–6]. In global terms, mangroves are reported to be up to five times efficient carbon sinks compared to other forms of terrestrial forests [7–9]. However, there exists large nonlinearity in ecosystem services provided by different mangrove formations [8, 10] that hinder generalised estimates of mangrove forest ecosystems’ carbon sequestration and stocks which is complicated by local conditions such as climate and soil factors; forest age, growth, and structure; utilisation and management regime of respective forests [3, 7, 11–13]. As such, there is a considerable knowledge gap and uncertainty at local levels regarding the carbon pool size and variability of carbon sequestration within mangrove forests [14, 15]. Nonetheless, the reported high rate of mangrove carbon sequestration provides global benefits in mitigating the effects of climate change [9, 13, 14] and demonstrates potential for livelihood enhancement through community carbon market schemes for sustainable conservation [16, 17].Like in many other countries where mangroves occur, overexploitation and conversions to other land uses like solar salt pans, aquaculture, agriculture, and urban expansion are major threats to mangroves of Tanzania [1, 18]. While the global rate of mangrove loss is approximated at 1-2% per year [19–21], there are variations at regional, national, and local scales. In Tanzania, FAO [22] estimated the rate of mangrove loss at about 0.7% per year. In most cases there are no reliable records at local scales, and where they exist, they are potentially out dated [2]. In general, mangrove degradation jeopardizes their ability to provide ecosystem goods and services [7], but the full implication of the loss is not well understood and appreciated. This calls for urgent actions to design and implement new effective conservation strategies to protect and restore mangroves to sustain the ecosystem services that they provide [21, 23, 24].Over the recent past, international climate change agreements have highlighted Reduced Emissions from Deforestation and Degradation (REDD) as one of the possible cost-effective strategies for mitigating the effects of climate change [7, 14, 25]. Reducing emissions aim at maintaining forest carbon stores through financial incentives for forest conservation, for example, carbon credits [26]. With the emerging market-based conservation strategies involving carbon credits in schemes like REDD+ (Reducing Emissions from Deforestation and Forest Degradation, Sustainable Management of Forests, and Enhancement of Forest Carbon Stocks in Developing Countries) and PES (Payment for Ecosystem Services), mangroves are now increasingly recognized as promising natural solutions for carbon capture and long-term storage putting them on top of the agenda in the debates on climate change adaptation mechanisms due to their high rates of carbon sequestration [7, 8, 14]. This warrants for site-specific estimations of the carbon stocks in mangrove forests. In this paper, we report on results of the inventory in the mangrove forests of Geza and Mtimbwani villages in the north-eastern region of Tanga, Tanzania, that aimed to (i) characterise the tree composition and structure; (ii) estimate the carbon stocks; and (iii) demonstrate the potential for community based carbon market schemes.2. Materials and Methods2.1. Description of Study SitesGeza village is about 26 km south of the city of Tanga whereas Mtimbwani village is 16 km north of the city on the north coast of Tanzania (Figure 1). Mangroves of Geza are approximately 84 ha and are fed seasonally by Bongoa River while those of Mtimbwani are about 326 ha and receive freshwater discharge throughout the year from Ngole River. Common species in both forests are Avicennia marina (Forsk.) Vierh., Rhizophora mucronata Lamarck, Ceriops tagal (Perr.) C. B. Robinson, Sonneratia alba J. Smith, Bruguiera gymnorrhiza (L.) Lamarck, and Xylocarpus granatum König. The forests receive normal tidal inundation twice a day though the extent of tidal influence in upstream varies during rain and dry season. The average annual precipitation is between 1100 mm and 1900 mm, relative humidity of about 76% during daytime and 96% at night, and the average range of atmospheric temperature is from 18°C to 35°C.Figure 1: Map and Google Earth snapshots showing study sites and sampling plot locations.2.2. Sampling PlotsEach mangrove site was divided into three zones along the river gradient from the sea landward using tidal range as criteria: lower, mid, and upper zone. In each zone, four circular nested plots of 10 m radius [27] spaced at approximately 200 m were established, giving a total of twelve sampling plots per each site (Figure 1). Plot locations were predetermined on Google Earth (GE), coordinates recorded and reached during field work by aid of the handheld GPS receiver (Garmin GPSMAP 64s).2.3. Vegetation InventoryMangrove forest inventory protocols described by Kauffman and Donato [27] were adopted and modified accordingly to suite local conditions. In each plot, all trees with 7.6 cm along a vertical sampling plane (transect). For the purpose of degradation, stumps were counted regardless of their species [27].2.4. Soil Sampling for CarbonSoil cores were retrieved from the centre of each sampling plot up to 1 m deep using a multistage sediment core sampler (AMS, Inc., American Falls, USA). The full length of core sampler was steadily inserted vertically into the soil at each depth stage. Soil samples were retrieved in divided segment depths of 0–30 cm, 30–60 cm, and 60–100 cm. Each retrieved core was subdivided in 5 cm and mean values of each segment depth were used for analysis.2.5. Data Analyses2.5.1. Forest Structure and CompositionForest inventory data were processed using standard analysis procedures as described by Cintron and Novelli [29] to derive forest stand characteristics: stand frequency distribution, density (stems ha−1), basal area (m2 ha−1), relative frequency (1), relative density (2), and relative dominance (3). Ecological importance values (IV) of each species were determined by summing the respective relative frequency, relative density, and relative dominance. Importance value measures relative dominance of species by criteria of how often it occurred, number of species, and area it occupies in a community. The species that attained the highest IV was considered the principal species: where is the number of trees sampled for species ; is the number of species; is number of plots in which species occurred, multiplied by 100.2.5.2. Above- and below-Ground Biomass and Carbon PoolsEstimation of above-ground biomass (AGB) and below-ground biomass (BGB) for roots in live trees used general allometric equations (4) and (5), respectively, developed by Komiyama et al. [28, 30]:where AGB and BGB are biomass (kg), DBH is diameter at breast height (cm), and is average general wood density (0.752 g cm−3). These general equations and wood density were used because local or regional species-specific models and respective wood density for all the species have not been developed and established.Biomass of standing dead wood was obtained by subtraction of a percentage factor from the supposed biomass of live tree derived by a general formula to account for the loss of leaf and twigs biomass. For standing dead trees of status 1 and status 2, factors of 2.5% an

ACS Style

Edmond Alavaisha; Mwita Mangora. Carbon Stocks in the Small Estuarine Mangroves of Geza and Mtimbwani, Tanga, Tanzania. International Journal of Forestry Research 2016, 2016, 1 -11.

AMA Style

Edmond Alavaisha, Mwita Mangora. Carbon Stocks in the Small Estuarine Mangroves of Geza and Mtimbwani, Tanga, Tanzania. International Journal of Forestry Research. 2016; 2016 ():1-11.

Chicago/Turabian Style

Edmond Alavaisha; Mwita Mangora. 2016. "Carbon Stocks in the Small Estuarine Mangroves of Geza and Mtimbwani, Tanga, Tanzania." International Journal of Forestry Research 2016, no. : 1-11.