Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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    Assessment of Grewia oppositifolia leaves as crude protein supplement to low-quality forage diets of sheep
    Khan, N.A. ; Habib, G. - \ 2012
    Tropical Animal Health and Production 44 (2012)7. - ISSN 0049-4747 - p. 1375 - 1381.
    tree leaves - northern grasslands - nutrient digestion - detergent fiber - pakistan - feed - degradability - rangeland - rumen
    In the tropical arid and semi-arid regions of many developing countries, sheep are predominantly grazed on low-quality pastures and stall-fed on crop residues. This study evaluated the potential of Grewia oppositifolia tree leaves as crude protein (CP) supplement to the low-quality diets of sheep in comparison with cottonseed cake (CSC). Changes in the chemical composition of the leaves with progressive maturation (December to March) were studied. The leaves maintained a high CP content (> 164 g/kg dry matter (DM)) during the prolonged maturation in the winter feed scarcity period. The leaves were rich in Ca (41 g/kg DM) and K (89 g/kg DM). The rate of degradation and effective degradability of CP were consistently higher (P <0.001) in CSC than in G. oppositifolia. A balance trial in a 4 x 4 Latin square design with four mature Ramghani wethers showed that DM intake, DM and CP digestibility, and N retention did not differ with the substitution of CSC with G. oppositifolia leaves, as a supplement to a basal diet of sorghum hay. Body weight (BW) gain and wool yield responses to the supplements were examined with 36 lambs (27 +/- 3 kg BW; age 11 +/- 1 months) for 15 weeks. The lambs were only grazed on local pasture (control group) or supplemented with CSC, G. oppositifolia leaves, and their mixture on iso-N basis. Addition of the supplements increased (P <0.05) BW gain and wool yield, and the leaves were as effective as CSC. These results demonstrated that G. oppositifolia leaves provide good quality green fodder during the prolonged winter feed scarcity period, and that the leaves can be efficiently utilized as a CP supplement to the low-quality diets of sheep.
    Influence of grazing on soil seed banks determines the restoration potential of aboveground vegetation in a semi-arid savanna in Ethiopia
    Tessema, Z.K. ; Boer, W.F. de; Baars, R.M.T. ; Prins, H.H.T. - \ 2012
    Biotropica 44 (2012)2. - ISSN 0006-3606 - p. 211 - 219.
    species composition - standing vegetation - southern ethiopia - woody-plants - dynamics - australia - germination - ecosystems - grassland - rangeland
    Species composition, number of emerging seedlings, species diversity and functional group of the soil seed banks, and the influence of grazing on the similarity between the soil seed banks and aboveground vegetation, were studied in 2008 and 2009 in a semi-arid savanna of Ethiopia. We tested whether the availability of persistent seeds in the soil could drive the transition from a degraded system under heavy grazing to healthy vegetation with ample perennial grasses. A total of 77 species emerged from the soil seed bank samples: 21 annual grasses, 12 perennial grasses, 4 herbaceous legumes, 39 forbs, and 1 woody species. Perennial grass species dominated the lightly grazed sites, whereas the heavily grazed sites were dominated by annual forbs. Heavy grazing reduced the number of seeds that can germinate in the seed bank. Species richness in the seed bank was, however, not affected by grazing. With increasing soil depth, the seed density and its species richness declined. There was a higher similarity in species composition between the soil seed bank and aboveground vegetation at the lightly grazed sites compared with the heavily grazed sites. The mean similarity between the seed banks and aboveground vegetation was relatively low, indicating the effect of heavy grazing. Moreover, seeds of perennial grasses were less abundant in the soil seed banks under heavy grazing. We concluded that restoration of grass and woody species from the soil seed banks in the heavily grazed areas could not be successful in semi-arid savannas of Ethiopia.
    Cross-scale monitoring and assessment of land degradation and sustainable land management : a methodological framework for knowledge management
    Reed, M.S. ; Buenemann, M. ; Atlhopheng, J. ; Akhtar-Schuster, M. ; Bachmann, F. ; Bastin, G. ; Bigas, H. ; Chanda, R. ; Dougill, A.J. ; Essahli, W. ; Evely, A.C. ; Fleskens, L. ; Geeson, N. ; Glass, J.H. ; Hessel, R. ; Holden, J. ; Ioris, A.A.R. ; Kruger, B. ; Liniger, H.P. ; Mphinyane, W. ; Nainggolan, D. ; Perkins, J. ; Raymond, C.M. ; Ritsema, C.J. ; Schwilch, G. ; Sebego, R. ; Seely, M. ; Stringer, L.C. ; Thomas, R. ; Twomlow, S. ; Verzandvoort, S. - \ 2011
    Land Degradation and Development 22 (2011)2. - ISSN 1085-3278 - p. 261 - 271.
    natural-resource management - local-communities - kalahari - desertification - rangeland - science - system - impact
    For land degradation monitoring and assessment (M&A) to be accurate and for sustainable land management (SLM) to be effective, it is necessary to incorporate multiple knowledges using a variety of methods and scales, and this must include the (potentially conflicting) perspectives of those who use the land. This paper presents a hybrid methodological framework that builds on approaches developed by UN Food & Agriculture Organisation's land degradation Assessment in Drylands (LADA), the World Conservation Approaches and Technologies (WOCAT) programme and the Dryland Development Paradigm (DDP), and is being applied internationally through the EU-funded DESIRE project. The framework suggests that M&A should determine the progress of SLM towards meeting sustainability goals, with results continually and iteratively enhancing SLM decisions. The framework is divided into four generic themes: (i) establishing land degradation and SLM context and sustainability goals; (ii) identifying, evaluating and selecting SLM strategies; (iii) selecting land degradation and SLM indicators and (iv) applying SLM options and monitoring land degradation and progress towards sustainability goals. This approach incorporates multiple knowledge sources and types (including land manager perspectives) from local to national and international scales. In doing so, it aims to provide outputs for policy-makers and land managers that have the potential to enhance the sustainability of land management in drylands, from the field scale to the region, and to national and international levels. The paper draws on operational experience from across the DESIRE project to break the four themes into a series of methodological steps, and provides examples of the range of tools and methods that can be used to operationalise each of these steps.
    Desertification in the Sahel: a reinterpretation
    Hein, L.G. ; Ridder, N. de - \ 2006
    Global Change Biology 12 (2006)5. - ISSN 1354-1013 - p. 751 - 758.
    rain-use efficiency - semiarid grazing systems - vegetation dynamics - species composition - african sahel - nonequilibrium - rangeland - drought - precipitation - variability
    The impact of human management, in particular livestock grazing, on the vegetation cover of the Sahel is still debated. In a range of studies, satellite images have been used to analyze the development of the Sahelian vegetation cover over time. These studies did not reveal any significant degradation of the Sahel in the last two decades. In this paper, we examine the ecological assumptions underlying the use of satellite imagery to analyze degradation of the Sahel. Specifically, we analyze the variability of the rain-use efficiency (RUE), which is often used as an indicator for the state of the vegetation cover. We detect a fundamental flaw in the way RUE has been handled in most remote sensing studies; they ignored the relation between annual rainfall variation and RUE. Because of the upward trend in annual rainfall that occurred during the 1980s and 1990s, this leads to a bias in the interpretation of the satellite images. In this paper, we show the importance of the variability in RUE for the analysis of remote sensing imagery of semiarid rangelands. Our analysis also shows that it is likely that there has been anthropogenic degradation of the Sahelian vegetation cover in the last two decades. This has important consequences for the debate on the impacts of grazing on semiarid rangelands. Furthermore, the occurrence of anthropogenic degradation is relevant to explain the magnitude of 20th century Sahelian droughts. The analyses also indicate that the population of the Sahel may be more vulnerable for droughts than currently assumed
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