Rajab, Yasmin Abou

[["dc.bibliographiccitation.artnumber","191"],["dc.bibliographiccitation.journal","Frontiers in Plant Science"],["dc.bibliographiccitation.volume","6"],["dc.contributor.author","Hertel, Dietrich"],["dc.contributor.author","Barus, Henry"],["dc.contributor.author","Schuldt, Bernhard"],["dc.contributor.author","Kotowska, Martyna M."],["dc.contributor.author","Rajab, Yasmin Abou"],["dc.date.accessioned","2018-11-07T09:59:24Z"],["dc.date.available","2018-11-07T09:59:24Z"],["dc.date.issued","2015"],["dc.description.abstract","For decades it has been assumed that the largest vessels are generally found in roots and that vessel size and corresponding sapwood area-specific hydraulic conductivity are acropetally decreasing toward the distal twigs. However, recent studies from the perhumid tropics revealed a hump-shaped vessel size distribution. Worldwide tropical perhumid forests are extensively replaced by agroforestry systems often using introduced species of various biogeographical and climatic origins. Nonetheless, it is unknown so far what kind of hydraulic architectural patterns are developed in those agroforestry tree species and which impact this exerts regarding important tree functional traits, such as stem growth, hydraulic efficiency and wood density (WD). We investigated wood anatomical and hydraulic properties of the root, stem and branch wood in Theobroma cacao and five common shade tree species in agroforestry systems on Sulawesi (Indonesia); three of these were strictly perhumid tree species, and the other three tree species are tolerating seasonal drought. The overall goal of our study was to relate these properties to stem growth and other tree functional traits such as foliar nitrogen content and sapwood to leaf area ratio. Our results confirmed a hump-shaped vessel size distribution in nearly all species. Drought-adapted species showed divergent patterns of hydraulic conductivity, vessel density, and relative vessel lumen area between root, stem and branch wood compared to wet forest species. Confirming findings from natural old-growth forests in the same region, WD showed no relationship to specific conductivity. Overall, aboveground growth performance was better predicted by specific hydraulic conductivity than by foliar traits and WD. Our study results suggest that future research on conceptual trade-offs of tree hydraulic architecture should consider biogeographical patterns underlining the importance of anatomical adaptation mechanisms to environment."],["dc.description.sponsorship","Open Access Publikationsfonds 2015"],["dc.identifier.doi","10.3389/fpls.2015.00191"],["dc.identifier.isi","000352504600001"],["dc.identifier.pmid","25873922"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/11858"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/37578"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.relation","SFB 990 | B | B04: Pflanzenproduktivität und Ressourcenaufteilung im Wurzelraum entlang von Gradienten tropischer Landnutzungsintensität und Baumartenvielfalt"],["dc.relation.eissn","1664-462X"],["dc.relation.issn","1664-462X"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","Patterns in hydraulic architecture from roots to branches in six tropical tree species from cacao agroforestry and their relation to wood density and stem growth"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.artnumber","e0149949"],["dc.bibliographiccitation.firstpage","1"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","PLoS One"],["dc.bibliographiccitation.lastpage","22"],["dc.bibliographiccitation.volume","11"],["dc.contributor.author","Abou Rajab, Yasmin"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Barus, Henry"],["dc.contributor.author","Tjoa, Aiyen"],["dc.contributor.author","Hertel, Dietrich"],["dc.date.accessioned","2017-11-28T10:03:31Z"],["dc.date.available","2017-11-28T10:03:31Z"],["dc.date.issued","2016"],["dc.description.abstract","One of the main drivers of tropical forest loss is their conversion to oil palm, soy or cacao plantations with low biodiversity and greatly reduced carbon storage. Southeast Asian cacao plantations are often established under shade tree cover, but are later converted to non-shaded monocultures to avoid resource competition. We compared three co-occurring cacao cultivation systems (3 replicate stands each) with different shade intensity (non-shaded monoculture, cacao with the legume Gliricidia sepium shade trees, and cacao with several shade tree species) in Sulawesi (Indonesia) with respect to above- and belowground biomass and productivity, and cacao bean yield. Total biomass C stocks (above- and belowground) increased fivefold from the monoculture to the multi-shade tree system (from 11 to 57 Mg ha-1), total net primary production rose twofold (from 9 to 18 Mg C ha-1 yr-1). This increase was associated with a 6fold increase in aboveground biomass, but only a 3.5fold increase in root biomass, indicating a clear shift in C allocation to aboveground tree organs with increasing shade for both cacao and shade trees. Despite a canopy cover increase from 50 to 93%, cacao bean yield remained invariant across the systems (variation: 1.1–1.2 Mg C ha-1 yr-1). The monocultures had a twice as rapid leaf turnover suggesting that shading reduces the exposure of cacao to atmospheric drought, probably resulting in greater leaf longevity. Thus, contrary to general belief, cacao bean yield does not necessarily decrease under shading which seems to reduce physical stress. If planned properly, cacao plantations under a shade tree cover allow combining high yield with benefits for carbon sequestration and storage, production system stability under stress, and higher levels of animal and plant diversity."],["dc.description.sponsorship","Open-Access-Publikationsfonds 2016"],["dc.identifier.doi","10.1371/journal.pone.0149949"],["dc.identifier.fs","619834"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/13130"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/10611"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.relation","SFB 990: Ökologische und sozioökonomische Funktionen tropischer Tieflandregenwald-Transformationssysteme (Sumatra, Indonesien)"],["dc.relation","SFB 990 | B | B04: Pflanzenproduktivität und Ressourcenaufteilung im Wurzelraum entlang von Gradienten tropischer Landnutzungsintensität und Baumartenvielfalt"],["dc.relation.eissn","1932-6203"],["dc.rights","CC BY 4.0"],["dc.rights.uri","https://creativecommons.org/licenses/by/4.0"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","Cacao Cultivation under Diverse Shade Tree Cover Allows High Carbon Storage and Sequestration without Yield Losses"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","unknown"],["dc.type.subtype","original_ja"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","349"],["dc.bibliographiccitation.issue","1-2"],["dc.bibliographiccitation.journal","Plant and Soil"],["dc.bibliographiccitation.lastpage","369"],["dc.bibliographiccitation.volume","422"],["dc.contributor.author","Rajab, Yasmin Abou"],["dc.contributor.author","Hölscher, Dirk"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Barus, Henry"],["dc.contributor.author","Tjoa, Aiyen"],["dc.contributor.author","Hertel, Dietrich"],["dc.date.accessioned","2018-01-09T15:04:15Z"],["dc.date.available","2018-01-09T15:04:15Z"],["dc.date.issued","2018"],["dc.description.abstract","Background and Aims To increase yield, cacao is planted increasingly in unshaded monocultures, replacing a more traditional cultivation under shade. We investigated how shade tree cover and species diversity affect the root system and its dynamics. Methods In a replicated study in Sulawesi (Indonesia), we studied the fine and coarse root system down to 3 m soil depth in three modern and more traditional cacao cultivation systems: unshaded cacao monoculture (Cacao-mono), cacao under either the legume Gliricidia sepium (Cacao-Gliricidia), or a diverse (> 6 species) shade tree cover (Cacao-multi). We analysed the vertical distribution of fine, large and coarse roots as well as fine root production, turnover and morphology on the species level. Results Stand-level fine root biomass showed a doubling with increasing shade tree cover (from 206 to 432 g m−2), but a tendency for a decrease in cacao fine root biomass. The presence of Gliricidia roots seemed to shift the cacao fine roots to a more shallow distribution, while the presence of shade tree roots in the Cacao-multi systems caused a biomass reduction and relative downward shift of the cacao roots. The turnover of cacao fine roots was much higher in the Cacao-multi stands than in the other two cultivation systems, although stand-level root production remained unchanged across the three systems. According to the stable isotope signature, Gliricidia extracted water from deeper soil layers than cacao, while no soil water partitioning was observed in the Cacao-multi stands. Conclusions Our data suggest that the cacao trees altered their fine root distribution patterns in response to root competition. Both interspecific competition and root system segregation seem to play an important role in cacao agroforests with different shade tree cover."],["dc.identifier.doi","10.1007/s11104-017-3456-x"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/11617"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.notes.status","final"],["dc.relation","SFB 990: Ökologische und sozioökonomische Funktionen tropischer Tieflandregenwald-Transformationssysteme (Sumatra, Indonesien)"],["dc.relation","SFB 990 | B | B04: Pflanzenproduktivität und Ressourcenaufteilung im Wurzelraum entlang von Gradienten tropischer Landnutzungsintensität und Baumartenvielfalt"],["dc.subject.gro","sfb990_journalarticles"],["dc.title","Effects of shade tree cover and diversity on root system structure and dynamics in cacao agroforests"],["dc.title.subtitle","The role of root competition and space partitioning"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.subtype","original_ja"],["dspace.entity.type","Publication"]]