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Grewia tenax (Forssk.) Fiori is a wild fruit species with multiple uses in different parts of the Tropics and Subtropics. It is common on the Arabian Peninsula and has also been recorded in southern Oman. To date, no record of the species exists for the northern part of this country. To close this distributional gap, three sites in the al-Hajar mountains of northern Oman were surveyed in summer 2005 and spring 2006. During the botanical fieldwork, several flowering and fruiting plants were found in Wadi Bani Awf and Wadi Muaydin. In the latter area G. tenax fruits are eaten by local people. In addition to G. tenax, nine woody perennials with edible fruit were recorded. In northern Oman, fruits of Sideroxylon mascatense (A. DC.) Penn. and Ziziphus spina-christi (L.) Desf. are widely collected and sold on local markets. G. tenax shrubs were found to be heavily grazed indicating its high palatability to goats and sheep. The occurrence of G. tenax in the al-Hajar mountains is a new record to the flora of northern Oman and calls for further investigation of botanists and germplasm collectors.

In Ethiopia, population increase and the demand for more agricultural land and forest products have resulted in the destruction of natural vegetation and land degradation. Planting multipurpose trees and shrubs for the rehabilitation of severely degraded land has been suggested as a management option. A field experiment was conducted in Choroqo, one degraded land vegetation restoration site of Halaba zone in the Central Rift Valley, Ethiopia, to determine the suitability of 12 multipurpose trees and shrubs. The experiment was set in a randomized complete block design (RCBD), and data on plant survival and growth parameters were collected every 6‐month interval for 3 years. One‐way ANOVA and Tukey’s HSD test ( p < 0.05) were computed to determine the effect of species on the measured variable. SAS software was used for statistical analyses. The highest mean survival was recorded by Grevillea robusta R.Br (99.542 ± 1.05), followed by Senegalia polyacantha Willd (88.88 ± 1.05) and Eucalyptus camaldulensis Dehnh. (83.33 ± 1.05). The largest (20.67%) overall plant death was recorded within the first six months of field plantation. Acacia saligna (Labill.) Wendl (4.48 m ± 0.81), Eucalyptus camaldulensis (4.38 m ± 0.99), and Casuarina equisetifolia L. (3.14 m ± 0.49) exhibited better growth in height at the end of the experiment. Moreover, early management was found to be very important in reducing the mortality rate of planted species for rehabilitation programs. The higher use value was calculated for Eucalyptus camaldulensis , followed by Dodonaea angustifolia L.f. and Grevillea robusta. Therefore, Grevillea robusta, Eucalyptus camaldulensis , Dodonaea angustifolia , and Senegalia polyacantha are found to be ecologically suitable and socially acceptable species for the rehabilitation of degraded lands of Halaba and the Central Rift Valley. Further research is needed to know the impact of these species on the physicochemical properties of the soil and the undergrowth flora.

1. Oak savannas are biodiversity‐rich landscapes allowing sustainable livestock production throughout the world. The long‐term persistence of these ecosystems critically depends on the regeneration of the tree layer. Nevertheless, studies addressing the mechanisms involved for conservation planning are of limited value because they tend to focus on single explanatory factors. 2. We evaluated the combined effect of biotic and abiotic factors on recruitment of holm oak Quercus ilex in the Mediterranean savannas of western Spain. Transition probabilities from flower to seed to the established seedling were estimated in grazed, shrub‐encroached and cropped plus fenced habitats in two consecutive years. 3. Trees in cropped habitats produced more female flowers and larger acorn crops in both years. The physiological condition of trees was better in cropped habitats and worst in shrub‐encroached plots. Overall, resource‐mediated effects overrode the effects of biotic damage on tree fecundity in all habitats. 4. Acorn survival and seedling establishment were higher in cropped and shrub‐encroached plots, though in cropped plots saplings are predictably destroyed by subsequent grazing and/or by mechanical treatment used to restart the cropping cycle. 5. Complete regeneration failure was found in 6 out of 24 possible management scenarios, mostly in the presence of large vertebrate herbivores. However, even low positive cumulative transition probabilities between life stages exceeded a safe threshold for early regeneration. 6. Synthesis and applications. Natural early recruitment of oak savannas can be achieved through various management regimes. These include cereal cropping in fenced plots (provided established saplings were not subsequently destroyed) or shrub encroachment in undergrazed or livestock‐excluded plots. Among these, natural recruitment after encroachment is a cost‐effective tool as compared to artificial plantation.

Agroforestry has potential to address the adverse effects of climate change through carbon sequestration, increasing biodiversity and improving adaptive capacity and resilience among smallholder farmers. However, this potential is context specific and insufficiently quantified in smallholder faming systems, partly because of inherent variability of smallholder farms. Our study aimed to determine the tree/shrub diversity and carbon stocks in different agroforestry systems within smallholder farms in two 100 km 2 sites, the so-called lower and middle Nyando sites, in western Kenya. In both, context-specific agroforestry adoption had been promoted among households of four community associations through an asset-based community development (ABCD) approach. Their farms were assessed and compared with those of relevant comparison samples. Trees and shrubs were inventoried on a total of 106 farms, and their formations classified in five major agroforestry practices: hedgerows, multipurpose trees on farm (MPT), riparian buffers, woodlots, and boundary planting. To assess above-ground biomass (AGB) of individual trees/shrubs, diameter at breast height measurements were taken. Strong regional differences were considered in data analysis and presentation. Altogether, 3,353 and 6,346 trees/shrubs were inventoried in the lower and middle Nyando sites, respectively. AGB was significantly higher in middle than in lower Nyando. Woodlots had the highest amount of AGB carbon stock, while MPT had the highest diversity of tree/shrub species in all the groups. Conversely, boundary planting had the highest number of trees/shrubs inventoried and hence was the most common agroforestry practice across all the samples in both regions. Dominant AGB contributor species were Grevillea robusta (37.8%) in middle, and Eurphobia tirucalli (16.5%) in lower Nyando. This study provides empirical evidence that asset-based and community-driven selection and implementation of both tree/shrub species and agroforestry practices can contribute positively to species and practice diversity, which are associated with AGB carbon stock levels and wider agro-ecosystem diversity. This study hence provides benchmark information that is relevant for SDG goal 15 on “life on land,” and various specific targets, and can inform sustainable establishment of carbon sink facilities by supporting smallholders to uptake contextually suitable and economically sensible agroforestry practices in an overall effort to foster and support sustainable development.

In Sidama, agroforestry represents land-use systems with deliberate management of multipurpose trees and shrubs that grow in intimate association with annual and perennial agricultural crops and/or livestock. The interaction of microbiota with the trees, shrubs and crops may make the system fertile, productive and sustainable. One of the beneficial microbiota which has symbiotic association with most of the plants in agroforestry is arbuscular mycorrhizal fungi (AMF). In November and December of 2012, root and rhizosphere soil samples of 21 plant species from nine peasant associations (PAs) (villages within districts where 300–500 families live) were collected from the agroforestry practices in Sidama of Southern Ethiopia for the determination of diversity and abundance of AMF under selected soil parameters and plant species density. Findings on the diversity of AMF based on soil properties showed that at moderate to low P and N concentrations the rate of AMF root colonization and spore density was high in comparison with the rhizosphere soils with the highest P and N concentration. The highest percentage of total AMF colonization was recorded for shade trees Millettia ferruginea (84 %) and Erythrina brucei (80 %) followed by intercropped perennial crops Ensete ventricosum (86 %), Catha edulis (85 %) and Coffea arabica (80 %) and the lowest percentage AMF colonization was recorded for Rhamnus prinoides (53 %) and Colocasia esculenta (52 %). Though found in almost all homegarden agroforestry practices and with broad coverage in Sidama agroforestry, some crops and vegetables such Brassica integrifolia and Cucurbita pepo, grown intercropped were found to be non-mycorrhizal as none of the AMF structures were recorded. The highest number of AM spore population was recorded in rhizosphere soils of Croton macrostachyus (1066 ± 19.33) and Catha edulis (1054 ± 53.12) and the lowest spore density was recorded for Dioscorea alata (100.00 ± 2.89) spore per 100 g of dry soil. The percentage fungal colonization in any individual plant species and spore population in the rhizosphere soils of that species did not correlate to each other and percentage AM root colonization and spore density of all plants in the agroforestry of Sidama were found significantly different at P < 0.05 level.

BackgroundForests are used for multiple purposes worldwide, which often include timber harvest, firewood extraction and livestock raising. An excessive pressure on multipurpose systems may decrease soil cover, promoting soil erosion and causing the loss of other resources, as litter and seeds. Retention forestry practices can help to decrease or mitigate resource loss in the managed stands. Specifically, retaining and redistributing biological legacies (e.g. logs, branches, woody debris) at strategic locations can create sediment, litter, and seed-sinks in the silvopastoral systems. In addition, grazing management could increase or, even, decrease the success of this practice. In this study, we assessed the effect of branch barriers and grazing management on resource run-off/run-on processes in silvopastoral systems of Arid Chaco (Córdoba, Argentina). To do this, a 2-ha area was divided in two paddocks that were randomly assigned to different grazing managements: winter vs. continuous grazing. We randomly selected 22 water run-off paths in each paddock, and in the half of them, we build elongated branch piles. In each run-off path (with and without branch barriers), we recorded the amount of accumulated and lost sediment (during the rainy season), litter biomass, germinable seed bank, richness and cover of plant species, and richness and density of seedlings and saplings of woody species.ResultsBranch barriers promoted sediment accumulation during the first and the second year of the study, depending on grazing management. The temporal and spatial scale of the effect of the branch barriers also depended on grazing management. Branch barriers also trapped litter and seeds, which may have increased the richness and density of seedlings and saplings of woody species.ConclusionsBy intercepting the dominant flow of erosive agents, branch barriers trapped sediment, litter, and propagules of different species. A greater amount of sediment and litter would have improved microsite quality, favouring seed germination and seedling emergence of tree and shrub species, which are key to maintain and/or reconstitute the structure and composition of the forest community in the long term. Therefore, redistributing biological legacies at strategic locations can be a useful and cost-less retention forestry practice to be applied in multipurpose forest management and conservation strategies.