Parkland trees on smallholder farms ameliorate soil physical-chemical properties in the semi-arid area of Tigray,Ethiopia

Proposed agroforestry options should begin with the species that farmers are most familiar with,which would be the native multipurpose trees that have evolved under smallholder farms and socioeconomic conditions.The African birch(Anogeissus leiocarpa(DC.)Guill.&Perr.)and pink jacaranda(Stereospermum kunthianum Cham.)trees are the dominant species in the agroforestry parkland system in the drylands of Tigray,Ethiopia.Smallholder farmers highly value these trees for their multifunctional uses including timber,firewood,charcoal,medicine,etc.These trees also could improve soil fertility.However,the amount of soil physical and chemical properties enhanced by the two species must be determined to maintain the sustainable conservation of the species in the parklands and to scale up to similar agroecological systems.Hence,we selected twelve isolated trees,six from each species that had similar dendrometric characteristics and were growing in similar environmental conditions.We divided the canopy cover of each tree into three radial distances:mid-canopy,canopy edge,and canopy gap(control).At each distance,we took soil samples from three different depths.We collected 216 soil samples(half disturbed and the other half undisturbed)from each canopy position and soil depth.Bulk density(BD),soil moisture content(SMC),soil organic carbon(SOC),total nitrogen(TN),available phosphorus(AP),available potassium(AK),p H,electrical conductivity(EC),and cation exchange capacity(CEC)were analysed.Results revealed that soil physical and chemical properties significantly improved except for soil texture and EC under both species,CEC under A.leiocarpus,and soil p H under S.kunthianum,all the studied soils were improved under both species canopy as compared with canopy gap.SMC,TN,AP,and AK under canopy of these trees were respectively 24.1%,11.1%,55.0%,and 9.3% higher than those soils under control.The two parkland agroforestry species significantly enhanced soil fertility near the canopy of topsoil through improving soil physical and chemical properties.These two species were recommended in the drylands with similar agro-ecological systems.

Comparative Evaluation of Farmers’ Perception and Adaptation Strategies to Climate Change and Variability in Bako Tibe, Ethiopia and Abeokuta, Nigeria

Comparing the perception of farmers to climate change and variability in Bako Tibe, Ethiopia and Abeokuta, Nigeria is important in promoting sustainable agriculture and in understanding the impact of climate change and variability on agriculture in Africa. A total of 153 farmers were interviewed in both study areas using well structure questionnaire. The study describes the socioeconomic characteristics of farmers using descriptive statistics and thereafter the perception of Bako Tibe and Abeokuta farmers to climate change and variability was examined using Likert type scale. The binary logistics regression was later used to ascertain the effect of socioeconomic characteristics on perception of the farmers in both study areas. The farmers in both study areas believed that there have been changes in the amount of rainfall and temperature in the past thirty years. The farmers in Bako agreed that there have been increased temperature and decreased rainfall, contrary to the farmer’s perception in Abeokuta. The binary logistic regression results showed that socioeconomic characteristics of farmers in Bako Tibe, have no effect on the perception of farmers on climate change and variability. However, in Abeokuta, age, land ownership, and distance to market had an effect on the perception on the farmers on climate change and variability. The adaptation strategies to climate change and variability commonly used by Bako Tibe farmers was, improved seed (drought resistance) adaptation method, while most farmers in Abeokuta used soil moisture conservation adaptation method. The study recommends that government and Non-Governmental Organization of both countries should promote more adaptation and mitigation practices to climate change and variability through policy interventions to help curb the impact of climate change and variability to agriculture.

Influences of rootstock and agro-climatic condition on physico-chemical and bioactive compounds of Gunda Gundo orange(Citrus sinensis L.Osbeck)in the Northern Ethiopia

Rootstocks have a significant influence on adaptation to biotic and abiotic stress conditions and quality of fruit.So,choice of rootstock for a specific growing region is an important decision for a grower to make when establishing a commercial citrus orchard.This study was undertaken to assess effects of rootstock and location on quality of orange fruit.The study was conducted over two consecutive years(2017/18 and 2018/19).Scions from the Gunda Gundo orange grove were grafted on rough lemon and sour orange rootstocks and planted in Tigray and Afar,Ethiopia at four sites(Abala,Agulae,Adiha and Rama).The experiment was laid out in Randomized Complete Block Design(RCBD)with four replications.Data on different physico-chemical and bioactive compounds were collected and analyzed using R software(version 4).Compared to sour orange,rough lemon rootstock revealed higher fruit mass(151.96 g,195.38 g),fruit length(62.27 mm,68.88 mm)and fruit diameter(65.58 mm,71.3 mm),in 2017/18,2018/19,respectively.Among the four locations(Abala,Agulae,Adiha and Rama),higher juice percentage was found in Adiha(43.47%in 2017/18)and Abala(49.87%,in 2018/19).In 2017/18 higher total soluble solid(TSS,13.87%),TSS/acid ratio(19.18)and fruit rag(32.77%),were obtained at the Rama site.On the one hand,higher vitamin C(826.6 mg·kg^(-1))and total phenolic content(208 mg·kg^(-1 )GAE)were recorded at Agulae than Abala,Adiha and Rama sites from sour orange rootstock.High TSS,TSS/acid ratio and antioxidant were recorded from orange fruits at Rama site.This was expected to have resulted from hot climate conditions at the site.Besides,at a relatively cooler condition of the Agulae site,high phenolic,reduced ferric power and high vitamin C were recorded.Rough lemon rootstock improved fruit size,while rootstock did not affect the contents of TSS,TSS/acid ratio across the sites in both harvesting years.

Arbuscular mycorrhizal fungi improve biomass, photosynthesis, and water use efficiency of Opuntia ficus-indica (L.) Miller under different water levels

Opuntia ficus-indica(L.)Miller is a CAM(crassulacean acid metabolism)plant with an extraordinary capacity to adapt to drought stress by its ability to fix atmospheric CO_(2) at nighttime,store a significant amount of water in cladodes,and reduce root growth.Plants that grow in moisture-stress conditions with thick and less fine root hairs have a strong symbiosis with arbuscular mycorrhizal fungi(AMF)to adapt to drought stress.Water stress can limit plant growth and biomass production,which can be rehabilitated by AMF association through improved physiological performance.The objective of this study was to investigate the effects of AMF inoculations and variable soil water levels on the biomass,photosynthesis,and water use efficiency of the spiny and spineless O.ficus-indica.The experiment was conducted in a greenhouse with a full factorial experiment using O.ficus-indica type(spiny or spineless),AMF(presence or absence),and four soil water available(SWA)treatments through seven replications.Water treatments applied were 0%–25%SWA(T1),25%–50%SWA(T2),50%–75%SWA(T3),and 75%–100%SWA(T4).Drought stress reduced biomass and cladode growth,while AMF colonization significantly increased the biomass production with significant changes in the physiological performance of O.ficus-indica.AMF presence significantly increased biomass of both O.ficus-indica plant types through improved growth,photosynthetic water use efficiency,and photosynthesis.The presence of spines on the surface of cladodes significantly reduced the rate of photosynthesis and photosynthetic water use efficiency.Net photosynthesis,photosynthetic water use efficiency,transpiration,and stomatal conductance rate significantly decreased with increased drought stress.Under drought stress,some planted mother cladodes with the absence of AMF have not established daughter cladodes,whereas AMF-inoculated mother cladodes fully established daughter cladodes.AMF root colonization significantly increased with the decrease of SWA.AMF caused an increase in biomass production,increased tolerance to drought stress,and improved photosynthesis and water use efficiency performance of O.ficus-indica.The potential of O.ficus-indica to adapt to drought stress is controlled by the morpho-physiological performance related to AMF association.

Vegetation cover density and disturbance affected arbuscular mycorrhiza fungi spore density and root colonization in a dry Afromontane forest, northern Ethiopia

Arbuscular mycorrhiza fungi(AMF) are vital in the regeneration of vegetation in disturbed ecosystems due to their numerous ecological advantages and therefore are good indicators of soil and ecosystem health at large. This study was aimed at determining how the seasonal, vegetation cover density, edaphic and anthropogenic factors affect AMF root colonization(RC) and spore density(SD)in Desa’a dry Afromontane forest. AMF RC and SD in the rhizosphere of five dominant woody species, Juniperus procera, Olea europaea, Maytenus arbutifolia, Carissa spinarum and Dodonaea angustifolia growing in Desa’a forest were studied during the rainy and the dry seasons in three permanent study vegetation cover density plots(dense, medium, and poor). Each plot(160 x40 m2) has two management practices(fenced and unfenced plots) of area. A 100 g sample of rhizosphere soil from moisturefree composite soil was used to determine spore density.Spore density ranged from 50 to 4467 spores/100 g soil,and all species were colonized by AMF within a range of 4–95%. Glomus was the dominant genus in the rhizosphere of all species. Vegetation cover density strongly affected SD and RC. The SD was significantly higher(p < 0.05) in the poor vegetation cover density than in the other two and lowest in the dense cover; root colonization showed the reverse trend. Management practices significantly(p <0.05) influenced AMF SD and RC, with the fenced plots being more favoured. Seasons significantly(p < 0.05) affected RC and SD. More RC and SD were observed in the wet period than the dry period. Correlating AMF SD and RC with soil physical and chemical properties showed no significant difference(p> 0.05) except for total nitrogen. Disturbance, vegetation cover density, season and total nitrogen are significant factors that control the dynamics and management interventions to maintain the forest health of dry Afromontane forests.

Tropical dry forest dynamics in the context of climate change:syntheses of drivers,gaps,and management perspectives

This review attempts to synthesize the available literature on tropical dry forests and their dynamics in the context of climate change and thereby identifies possible gaps and priority areas for further research and management endeavors.Tropical dry forests(TDFs)occur in dryland environments,which are characterized by prolonged periods of dry months.They experience distinct seasonality and high inter-annual variability in climatic variables,particularly rainfall.Despite the enormous ecological and livelihood importance of TDFs,these forests are highly threatened by global changes.So far,they have received far less attention from research and development interventions as compared to the humid tropical forests.Their significance is still overlooked in many countries’national policies.Current modeling frameworks show that drought,precipitation,and temperature are highlighted as strong drivers of tree growth and/or mortality in these forests.Well-valued and sustainably managed TDFs have the potential to contribute to climate change adaptation and mitigation,buffer against erosion and desertification,and contribute to economic development,food security,and poverty alleviation.TDFs suffer notable disregard from research and development strategies.Thus,greater awareness and appropriate policies and investments are needed at various levels to counteract the increasing vulnerability of people,forest ecosystems,and species living in these fragile ecosystems.Further research is also needed to generate knowledge on the status and significances of TDFs and their responses in the face of the changing climate so as to bring their sustainable management to the attention of policymakers and managers.

The impacts of armed conflict on vegetation cover degradation in Tigray,northern Ethiopia

Efforts made to restore the degraded landscape of the Tigray region,Northern Ethiopia,over the last three decades have been relatively successful.However,an armed conflict that broke out in the region in November 2020 has significantly destroyed the restored vegetation,either directly associated with conflict(environment,pollution,fire)or indirectly(agricultural abandonment).This study aimed at assessing spatio-temporal changes in vegetation cover in a 50 km radius zone centered on Mekelle city,Tigray.Vegetation cover dynamics was evaluated using Landsat Enhanced Thematic Mapper Plus(ETM+)and Operational Land Imager(OLI)datasets for the years 2000,2020,and 2022 and analysed using ENVI 5.3 and ArcGIS 10.8.1 software.These data were analysed using the Modified Normalized Difference Vegetation Index(MNDVI),Optimized Soil Adjusted Vegetation Index(OSAVI),and Moisture Adjusted Vegetation Index(MAVI).Based on the MNDVI,results show that vegetation cover increased in the period 2000-2020 by 179 km^(2)or 2%of the area,whereas in the period 2020-2022,there was a decrease in vegetation cover by 403 km^(2)or 5%of the area.This was accompanied by a decrease in vegetation density.These vegetation changes in 2020-2022 are attributed to the impact of armed conflict on the land surface which can include farmlands and village abandonment,spread of weeds and scrub vege-tation,or failure to harvest crops.Monitoring vegetation change using Landsat data can help understand the environmental impacts of armed conflict in rural agricultural landscapes,including potential food security risks.