Managing Semi-Arid Rangelands for Carbon Storage: Grazing and Woody Encroachment Effects on Soil Carbon and Nitrogen

High grazing intensity and wide-spread woody encroachment may strongly alter soil carbon (C) and nitrogen (N) pools. However, the direction and quantity of these changes have rarely been quantified in East African savanna ecosystem. As shifts in soil C and N pools might further potentially influence climate change mitigation, we quantified and compared soil organic carbon (SOC) and total soil nitrogen (TSN) content in enclosures and communal grazing lands across varying woody cover i.e. woody encroachment levels. Estimated mean SOC and TSN stocks at 0–40 cm depth varied across grazing regimes and among woody encroachment levels. The open grazing land at the heavily encroached site on sandy loam soil contained the least SOC (30 ± 2.1 Mg ha^-1) and TSN (5 ± 0.57 Mg ha^-1) while the enclosure at the least encroached site on sandy clay soil had the greatest mean SOC (81.0 ± 10.6 Mg ha^-1) and TSN (9.2 ± 1.48 Mg ha^-1). Soil OC and TSN did not differ with grazing exclusion at heavily encroached sites, but were twice as high inside enclosure compared to open grazing soils at low encroached sites. Mean SOC and TSN in soils of 0–20 cm depth were up to 120% higher than that of the 21–40 cm soil layer. Soil OC was positively related to TSN, cation exchange capacity (CEC), but negatively related to sand content. Our results show that soil OC and TSN stocks are affected by grazing, but the magnitude is largely influenced by woody encroachment and soil texture. We suggest that improving the herbaceous layer cover through a reduction in grazing and woody encroachment restriction are the key strategies for reducing SOC and TSN losses and, hence, for climate change mitigation in semi-arid rangelands.     

Fusarium nygamai, a potential bioherbicide for Striga hermonthica control in sorghum

Glasshouse trials were performed to investigate the control of the parasitic weed Striga hermonthica by Fusarium nygamai and the performance of the host plant sorghum (Sorghum bicolor) using different inoculum substrates and inoculum amounts of the fungus. Optimal constant and alternating temperatures for the growth of the fungus were 25°C and 30/20°C, respectively. Striga incidence was decreased up to 100% when the fungus was incorporated into the soil preplanting. Emerged Striga plants at different stages of growth up to the flowering stage were killed by the fungus when the fungus was applied postemergent. In root-chamber trials none of the Striga seeds germinated when 10 ml inoculum suspension of 8 × 10⁶ spores/ml of F. nygamai was applied on seeds of the parasitic weed sprinkled on the surface of filter paper. F. nygamai has potential as a bioherbicide for Striga control. Further studies regarding its performance under field conditions and its safety to the environment and humans should be assessed.     

A commercial iron fertilizer increases the survival of Fusarium oxysporum f. sp. orthoceras propagules in a wheat flour-kaolin formulation

Fusarium oxysporum f.sp. orthoceras, a potential biocontrol agent against the parasitic weed Orobanche cumana Wallr., has proven to be efficacous under greenhouse conditions when formulated as wheat-kaolin granules. To help minimize the loss of viable fungal propagules during the formulation process, the addition of a commercial fertilizer containing the iron chelate of EDDHA to the formulation was investigated. The proportion of surviving propagules was significantly increased after adding the fertilizer. However, growing conidia in fertilizer-amended liquid medium did not reduce losses in viability during formulation. The efficacy of the formulated fungus and the storability at room temperature for the first 3 months was not affected by the iron fertilizer. The protective effect could neither be obtained with the chelator EDDHA alone nor with FeEDTA or FeSO_4.     

Diversity of Medicinal and Food Plants as Non-timber Forest Products in Naban River Watershed National Nature Reserve (China): Implications for Livelihood Improvement and Biodiversity Conservation

Diversity of Medicinal and Food Plants as Non-timber Forest Products in Naban River Watershed National Nature Reserve (China): Implications for Livelihood Improvement and Biodiversity Conservation. Non-timber forest products (NTFPs) play an important role in rural livelihoods. People living in and around forests are dependent on a variety of NTFPs for their subsistence and for income generation. This paper gives a general overview on the diversity of NTFPs in the Naban River Watershed National Nature Reserve, with a focus on medicinal and food plants. Data on NTFPs use were gathered through an ethnobotanical inventory with semistructured, free-listing, and household socioeconomic interviews. Interviews were supplemented with voucher collections. Bamboo shoots were analyzed further as proxy NTPF. It was hypothesized that there is no significant difference between collection amounts of bamboo shoots and their contribution to the household income between the villages studied. A rapid vulnerability assessment (RVA) was conducted to identify vulnerable and threatened species. A total of 480 plant species (25% of recorded flora) from 117 families and 334 genera are used as NTFPs by the local people. Results revealed that there is a significant difference in the collection and contribution of bamboo shoots to household income among the villages. However, their contribution to per-capita income is very low, and they are mainly used in households. Vulnerability assessment showed that most of the medicinal species have moderate vulnerable status and that most of the food species have less vulnerable status. Some medicinal plants, such as Paris polyphylla var. yunnanensis, are overexploited and getting scarce. Sustainable harvest and management strategies should be implemented to prevent overexploitation of these species.     

Vascular Plant Species Inventory of a Philippine Lowland Rain Forest and its Conservation Value

The Philippines are one of the most important biodiveristy hotspots on earth. Due to the extraordinary rate of environmental destruction, leaving only 3% of the land with primary forest, this biodiversity is at high risk. Despite that situation information on Philippine forest vegetation is fragmentary and focused on trees. This study aimed at analysing forest remnants in the Leyte Cordillera on the Island of Leyte, and at evaluating their role as refuge to the largely destroyed lowland forest vegetation. A total of 49 plots (100 m² each) between 55 and 520 m a.s.l. were studied. All vascular plant species except epiphytes were included. Records include 685 taxa from 289 genera and 111 families, representing nearly 8% of the known Philippine vascular plant species. More than half (52%) of the species are Philippine endemics. A number of 41 tree species, or 6% of all taxa recorded, are included in the IUCN red list, either as vulnerable, endangered, or critically endangered. Life form composition was dominated by phanerophytes (65.3%), followed by lianas and chamaephytes (17.1 and 16.9%, respectively). The most common families were the Rubiaceae with 35 and the Euphorbiaceae with 32 species. All five Philippine dipterocarp forest types as well as the molave forest type were represented by typical tree species. The area provides an important gene bank of the highly threatened Philippine lowland forest vegetation and is of high value for biodiversity conservation. Additionally, it can play an important role as seed source of valuable tree species for the increasing initiatives to rehabilitate and reforest degraded land with native species.     

Microorganisms of Striga hermonthica in Northern Ghana with Potential as Biocontrol Agents

A survey of microorganisms of Striga hermonthica Del. Benth., a root parasite of graminaceous crops, was conducted in northern Ghana in 1992. Thirteen fungal species were isolated from infected S. hermonthica plants. Fusarium spp. were the most prevalent, and were isolated from more than 90% of the S. hermonthica samples collected. Other fungi isolated were Alternaria alternata, Bipolaris specifera, Cladosporium oxysporum, Curvularia falax, Macrophomina phaseolina, Nodulisporium gregarium, Phoma sorghina and Sclerotium rolfsii.     

People and wildlife: Conflicts arising around the Bia Conservation Area in Ghana

Human–wildlife conflicts have drastically increased around conservation areas in Africa over the last decades. Underlying causes are similar across regions and can most often be attributed to land-use changes and increasing human populations. However, wildlife species composition involved in conflicts can vary tremendously across sites. Conflict assessment often focuses on prominent species such as elephants or other large mammals, and information on smaller wildlife species involved in conflicts is often lacking. We conducted 100 interviews in 10 communities around the Bia Conservation Area (BCA), Ghana, to address the type and extent of damage as well as possible factors influencing the risk of crop-raids. We assessed wildlife presence and relative densities through indirect observations on transects and spoor-plots in the transition zone between BCA and agricultural land. Crop-raiding was present across all communities interviewed but was more than twice as high in the north compared to the south. Squirrels (Sciuridae spp.) were the most frequent crop-raiding species (92% of farmers experienced damage), but elephants (Loxodonta africana cyclotis [Matschie, 1900]) were nevertheless the major conflict generating species (84% of farmers experienced damage). Squirrel signs were 75 times as frequent as any other species recorded in the farmland. Cocoa (Theobroma cacao) was most frequently raided (99%), followed by cassava (Manihot esculenta) and yam (Dioscorea spp.). Raiding might have been promoted through inappropriate agricultural practices while only few current mitigation strategies have been successful so far. Promising strategies include chili fences and buffer zones, in which less susceptible crops such as chili pepper are planted. Further education of farmers on mitigation measures is needed, including training on improved farming practices.     

Proteolytic processing and oligomerization of bacteriophage-derived endosialidases

Bacteriophages infecting the neuroinvasive pathogen Escherichia coli K1 require an endosialidase to penetrate the polysialic acid capsule of the host. Sequence information is available for the endosialidases endoNE, endoNF, and endoN63D of the K1-specific phages phi K1E, phi K1F, and 63D, respectively. The cloned sequences share a highly conserved catalytic domain but differ in the length of the N- and C-terminal parts. Although the expression of active recombinant enzyme succeeded in the case of endoNE, it failed for endoNF. Protein alignments of all three endosialidase sequences gave rise to the assumption that inactivity of the cloned endoNF is caused by a C-terminal truncation. By reinvestigation of the respective gene locus in the phi K1F genome, we identified an extended open reading frame of 3195 bp, encoding a 119-kDa protein. Full-length endoNF contains the C-terminal domain conserved in all endosialidases, which may act as an intramolecular chaperone. Comparative studies carried out with endoNE and endoNF demonstrate that endosialidases are proteolytically processed, releasing the C-terminal domain. Using a mutational approach in combination with protein analytical techniques we demonstrate that (i) the C-terminal domain is a common feature of endosialidases and other tail fiber proteins; (ii) the integrity of the C-terminal domain and its presence in the nascent protein are crucial for the formation of active enzymes; (iii) proteolytic processing is not essential for enzymatic activity; and (iv) functional folding is a prerequisite for trimerization of endoNF.