Allokering av kol i Cheparerias betesmarker, västra Kenya : en jämförelse mellan allmänningar, inhägnader och odlingsmark

Carbon sequestration through restoration of degraded pastoral soils is an advocated way of mitigating global warming, and simultaneously alleviating poverty. An often proposed rehabilitation strategy is fencing of pastures, a method that was introduced to the farmers of Chepareria by the Vi-Agroforestry organization in 1987. The landscape of Chepareria changed from eroded, over-grazed grasslands, to a mixture of open-grazed commons, pastoral enclosures and cultivations. The aim of this study was to investigate (1) if the soil organic carbon (SOC) is higher inside the enclosures than on the open-grazed commons, (2) if SOC is affected by duration of fencing and (3) what effect cultivation of pastures has on the SOC. Estimations of vegetation cover and deep profile (100cm) soil sampling was performed on six clusters containing; (1) open-grazing (OG) (2) 1-5 years of fencing (FENCED(1)), (3) 7-10 years of fencing (FENCED(2)), (4) 15-23 years of fencing (FENCED(3)), (5) maize from OG (A(OG)), (6) maize from fenced pasture (A(FENCED)). Spectrometric analysis of SOC was performed and the results were statistically tested with correlations and ANOVA’s. The average mass of SOC in the 100cm soil profile was 77,76 ± 22,73 t/ha, or 0,68 ± 0,13%, ranging from 61,12 ±15,44 t/ha (0,55 ± 0,08%) on OG to 87,21 ±29,77 t/ha (0,78 ± 0,16%) on FENCED(2). A significant difference in SOC(%) could be distinguished on 0-20 cm were FENCED(1) and FENCED(2) exceeded the OG, and on 20-40 cm where FENCED(2) > OG. No significant difference was found when comparing SOC(t/ha). This was explained by high variation of SOC and BD, deriving from diverse management and environment. The SOC(%) in FENCED(3) was (insignificantly) lower than in FENCED(1) and FENCED(2). This was proposed as original differences in soil conditions, due to a consistent (insignificant) pattern of SOC and BD throughout the 100cm profile, with OG ≤ FENCED(3) ≤ FENCED(1) ≤ FENCED(2). The ground vegetation cover increased significantly from OG to FENCED(2) and FENCED(3). The maize-cultivations contained similar levels of SOC as the fenced pastures, e.g. more than OG. Fertilization, and farming of soils with initially high SOC contents, was used as explanations to why SOC did not decrease after plowing and harvest. The study area and method were considered as suitable for analysis of carbon sequestration on rehabilitated land, but more information about present and previous management, soil properties and vegetation is requested.Restaurering av degenererad betesmark leder till ökad inlagring av koldioxid och har blivit en etablerad strategi för att bromsa den globala uppvärmningen, samtidigt som fattigdom bekämpas. En rekommenderad restaureringsåtgärd är inhägnande av betesmark, en metod som Vi-skogen introducerade i den kenyanska byn Chepareria, år 1987. Cheparerias landsbygd förändrades från att ha varit ett eroderat och utarmat beteslandskap till att bestå av en mosaik av allmänningar, inhägnade hagar och odlingsmark. Syftet med den här studien var att undersöka (1) om mängden organiskt kol var högre i jorden på inhägnaderna än på allmänningarna, (2) om kolmängden påverkades av hur länge betet varit hägnat och (3) vilken effekt odling har på jordens kolinnehåll. På sex områden identifierades närliggande ytor med; (1) fri betestillgång, (2) 1-5 års hägn, (3) 7-10 års hägn, (4) 15-23 års hägn, (5) majsodling på f.d. allmänning, (6) majsodling på f.d. hägn. På samtliga ytor togs jordprover ner till 100cm och vegetationstäckningen uppskattades. Kolmängden erhölls genom spektometeranalys, varpå statistiska korrelationer och variationsanalyser (ANOVA) genomfördes. Det fanns utslaget på alla provytor och hela jordprofilen i medel 77,76 ± 22,73 t/ha, eller 0,68 ± 0,13% kol i marken, med en variation från som lägst 61,12 ±15,44 t/ha (0,55 ± 0,08%) på allmänningarna till som högst 87,21 ±29,77 t/ha (0,78 ± 0,16%) på medelålders stängslad mark. En signifikant skillnad i kolmängd kunde urskiljas i markens översta 20cm, där unga och medelålders hägn hade högre kolhalt (%) än allmänningarna, samt på 20-40cm där endast kolhalten på medelålders hägn översteg kolhalten på allmänningarna. Det fanns inga signifikanta skillnader i t/ha, vilket förklarades med en hög variation i kolmängd och bulkdensitet, grundad i varierande skötsel- och miljöfaktorer. Kolhalten i äldre hägn var lägre (ej signifikant) än i unga och medelålders. Ursprungliga skillnader i jordegenskaper mellan provytornas föreslogs, då skillnaderna i kolmängd, med allmänningar ≤ unga ≤ medelålders ≤ äldre, återfanns ända ner på 100cm jorddjup. Vegetationstäckningen var signifikant högre på medelålders och äldre hägn än på allmänningarna. Odlingarna innehöll liknande mängd kol som inhägnaderna, dvs. mer än allmänningarna. Gödsling och brukande av jord med hög initial kolhalt ansågs vara trovärdiga anledningar till att kolmängden inte minskat efter plöjning och skörd. Både studieområde och metod bedömdes lämpliga för att analysera inlagringen av kol i restaurerad betesmark. Dock efterfrågas mer information om skötselhistorik, jordegenskaper och vegetation

Indirekt effects on the abundance and diversity of terricolous lichens caused by an increased nitrogen level in the soil : a comparison between undisturbed and low-intensity utilized forest

Lichens are adapted to bright and sparse forests on oligotrophic ground. Due to a slow growth rate and high light demand lichens will suffer from competition in eutrophic environments. Therefore, lichens have disappeared from managed forests where the forest industry has increased the productivity. A reduced abundance of lichens will affect both biodiversity of the forest and the reindeer winter graze lands. It is important to understand how and for how long fertilization affects the abundance and diversity of lichens in order to protect lichen rich ecosystems. We have registered the biomass and number of lichen species in eight plots (four nitrogen rich and four nitrogen deficient) and compared fertilized Sami settlements with their oligotrophic surroundings in the nature reserves of Tjeggelvas. We have assumed that all plots initially had the same nutritional status and that a supply of organic leavings fertilized the settlements more than hundred years ago. The results indicate a long lasting (>100 years) decrease in both number of lichen species and amount of biomass with increased levels of nitrogen in the humus layer. We also found a significant correlation between field vegetation (mostly Vaccinium vitis-ideae) and lichen abundance and diversity. Betula pendula was the only tree species affecting the abundance and diversity of lichens and no significant connection with soil nitrogen was found. Individual lichen species differed in nitrogen tolerance, with Cladina rangiferina and Cladina arbuscula being more widely abundant than for example Stereocaulon spp. A small set of data, restricted to eight plots, makes statistical calculations doubtful but the results are consistent with established studies.Lavar är anpassade till öppna och ljusa skogar på näringsfattig mark. I miljöer med mycket näring konkurreras de ut på grund av sin långsamma tillväxt och ett stort ljusbehov. Det har lett till att lavar missgynnats av många produktionshöjande skogsskötselåtgärder. Den biologiska mångfalden och renbetesmarker drabbas om lavmarker försvinner. För att skydda lavrika ekosystem är det viktigt att förstå hur lavars abundans och diversitet påverkas av ökad tillgång på marknäring och hur länge gödslingseffekten består. Vi har registrerat lavars biomassa och artantal på åtta provytor (fyra kväverika och fyra kvävefattiga) och gjort en jämförelse mellan kväveberikade samevisten och deras näringsfattiga omgivning i naturreservatet Tjeggelvas. Vi har utgått från att samtliga ytor ursprungligen haft samma näringsstatus och att organiskt avfall tillförts de kväverika vistena för mer än hundra år sedan. Resultaten indikerar att både artantal och biomassa hos lavar minskar med ökad kvävehalt i humuslagret och att effekten består efter hundra år. Ett signifikant samband påvisades även mellan fältvegetationens totala biomassa (främst lingon (Vaccinium vitis-ideae)) och lavarnas artantal och biomassa. I trädskiktet påverkade endast björkbiomassan (Betula pendula) lavarna och sambandet kunde inte kopplas till markkvävehalten. Det fanns en skillnad mellan enskilda lavarter där grå och gulvit renlav (Cladina rangiferina & C. arbuscula) tolererade högre näringshalt än till exempel påskrislavar (Stereocaulon spp.). På grund av ett litet dataset, begränsat till åtta provytor, kan statistiken inte säkerställas men resultaten ligger i linje med etablerad forskning

Enclosures in West Pokot, Kenya: Transforming land, livestock and livelihoods in drylands

Dryland livestock production systems are changing in many parts of the world, as a result of growing human populations and associated pressure on water and land. Based on a combination of social and natural science methods, we studied a 30-year transformation process from pastoralism to a livestock-based agro-pastoral system in northwestern Kenya, with the overall aim to increase the understanding of the ongoing transition towards intensified agro-pastoralist production systems in dryland East Africa. Key to this transformation was the use of enclosures for land rehabilitation, fodder production, and land and livestock management. Enclosures have more soil carbon and a higher vegetation cover than adjacent areas with open grazing. The level of adoption of enclosures as a management tool has been very high, and their use has enabled agricultural diversification, e.g. increased crop agriculture, poultry production and the inclusion of improved livestock. Following the use of enclosures, livelihoods have become less dependent on livestock migration, are increasingly directed towards agribusinesses and present new opportunities and constraints for women. These livelihood changes are closely associated with, and depend on, an ongoing privatization of land under different tenure regimes. The results indicate that the observed transformation provides opportunities for a pathway towards a sustainable livestock-based agro-pastoral system that could be valid in many dryland areas in East Africa. However, we also show that emergent risks of conflicts and inequalities in relation to land, triggered by the weakening of collective property rights, pose a threat to the sustainability of this pathway

Enclosures in West Pokot, Kenya: Transforming land, livestock and livelihoods in drylands

Dryland livestock production systems are changing in many parts of the world, as a result of growing human populations and associated pressure on water and land. Based on a combination of social and natural science methods, we studied a 30-year transformation process from pastoralism to a livestock-based agro-pastoral system in northwestern Kenya, with the overall aim to increase the understanding of the ongoing transition towards intensified agro-pastoralist production systems in dryland East Africa. Key to this transformation was the use of enclosures for land rehabilitation, fodder production, and land and livestock management. Enclosures have more soil carbon and a higher vegetation cover than adjacent areas with open grazing. The level of adoption of enclosures as a management tool has been very high, and their use has enabled agricultural diversification, e.g. increased crop agriculture, poultry production and the inclusion of improved livestock. Following the use of enclosures, livelihoods have become less dependent on livestock migration, are increasingly directed towards agribusinesses and present new opportunities and constraints for women. These livelihood changes are closely associated with, and depend on, an ongoing privatization of land under different tenure regimes. The results indicate that the observed transformation provides opportunities for a pathway towards a sustainable livestock-based agro-pastoral system that could be valid in many dryland areas in East Africa. However, we also show that emergent risks of conflicts and inequalities in relation to land, triggered by the weakening of collective property rights, pose a threat to the sustainability of this pathway.