Wick, Barbara

[["dc.bibliographiccitation.firstpage","195"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Plant and Soil"],["dc.bibliographiccitation.lastpage","205"],["dc.bibliographiccitation.volume","252"],["dc.contributor.author","Tiessen, Holm"],["dc.contributor.author","Menezes, RSC"],["dc.contributor.author","Salcedo, I. H."],["dc.contributor.author","Wick, B."],["dc.date.accessioned","2018-11-07T10:39:27Z"],["dc.date.available","2018-11-07T10:39:27Z"],["dc.date.issued","2003"],["dc.description.abstract","Planted silvo-pastoral systems are formed by sparing selected native trees when land is cleared for pasture establishment, or by planting selected species - often known agroforestry species - into the establishing pasture. Isolated trees within pastures and savannas are often associated with 'resource islands', characterized by higher fertility and organic matter levels under the tree canopies. We here examine the processes underlying the differences in fertility and organic matter in a buffel grass ( Cenchrus ciliaris L.) pasture that contained two tree species (Ziziphus joazeiro Mart., Spondias tuberosa Arruda Cam.) preserved from the native thorn forest and a planted agroforestry species (Prospois juliflora Swartz D. C). The objective is to distinguish effects of soil variability from those induced by the presence of trees or the planting of pasture. The delta(13)C signatures of the original ( largely C3) vegetation, the preserved and planted trees, and the planted C4 grass were used to distinguish the provenance of organic matter in the top soil (0 - 15 cm). This allowed the conclusion that all trees maintained C3 derived C at the original thorn forest level, while lower levels under pasture were due to mineralisation of organic matter. The net rates of forest-derived C loss under pasture varied with soil type amounting to between 25 and 50% in 13 years after pasture establishment. Only on Alfisol, C inputs from the pasture compensated for the C3-C losses. Analysis of organic and inorganic P fractions indicated Z. joazeiro and P. juliflora enriched the soil under their canopy with P, whereas S. tuberosa had no positive effect on fertility. A combination of ANOVA and spatial analysis and mapping was used to show vegetation effects."],["dc.identifier.doi","10.1023/A:1024762501920"],["dc.identifier.isi","000184191800002"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/46048"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Kluwer Academic Publ"],["dc.relation.issn","0032-079X"],["dc.title","Organic matter transformations and soil fertility in a treed pasture in semiarid NE Brazil"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","59"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Plant and Soil"],["dc.bibliographiccitation.lastpage","70"],["dc.bibliographiccitation.volume","222"],["dc.contributor.author","Wick, B."],["dc.contributor.author","Tiessen, Holm"],["dc.contributor.author","Menezes, RSC"],["dc.date.accessioned","2018-11-07T11:14:32Z"],["dc.date.available","2018-11-07T11:14:32Z"],["dc.date.issued","2000"],["dc.description.abstract","The presence of trees in grasslands frequently results in resource islands of higher soil quality. Therefore, some native trees are often preserved or agroforestry species are interplanted when land is cleared for pasture. We evaluated soil quality changes associated with the conversion of a native thorn forest (caatinga) into silvo-pastoral systems in semiarid NE Brazil. Soil nutrients, organic matter, microbial biomass and soil enzymes under native caatinga, the canopy of two preserved native (Ziziphus joazeiro and Spondias tuberosa) and one introduced tree species (Prosopis juliflora), and under a planted pasture of Cenchrus ciliaris were compared. The two preserved tree species maintained high nutrient and organic matter contents and high biological activity levels not only relative to the grass but also relative to the native caatinga. The non-deciduous Z. joazeiro was more effective than the deciduous S. tuberosa, and enriched surface soils by 100 mg P kg(-1). The complete replacement of natural caatinga with C. ciliaris pasture or a C. ciliaris-P. juliflora silvopastoral system had, after 14 years, decreased microbial biomass C and N contents, and ss-glucosidase activity, but did not affect soil nutrient or organic matter status. The biological activity under the trees of the tree-grass association was greater than under grass alone, although P. juliflora did not maintain higher nutrient or organic matter levels. The search for indigenous alternatives to the main agroforestry species may provide viable alternatives for improved land management and the conservation of biodiversity. Microbiological and biochemical parameters responded more readily to changes in land management than chemical fertility indices. They are important indices for the impact of vegetation changes and its associated land quality changes."],["dc.identifier.doi","10.1023/A:1004756416281"],["dc.identifier.isi","000088041000006"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/54143"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Kluwer Academic Publ"],["dc.relation.issn","0032-079X"],["dc.title","Land quality changes following the conversion of the natural vegetation into silvo-pastoral systems in semi-arid NE Brazil"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dspace.entity.type","Publication"]]