Juhrbandt, Jana

[["dc.bibliographiccitation.firstpage","619"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Journal of Applied Ecology"],["dc.bibliographiccitation.lastpage","629"],["dc.bibliographiccitation.volume","48"],["dc.contributor.author","Tscharntke, Teja"],["dc.contributor.author","Clough, Yann"],["dc.contributor.author","Bhagwat, Shonil A."],["dc.contributor.author","Buchori, Damayanti"],["dc.contributor.author","Faust, Heiko"],["dc.contributor.author","Hertel, Dietrich"],["dc.contributor.author","Hölscher, Dirk"],["dc.contributor.author","Juhrbandt, Jana"],["dc.contributor.author","Kessler, Michael"],["dc.contributor.author","Perfecto, Ivette"],["dc.contributor.author","Scherber, Christoph"],["dc.contributor.author","Schroth, Götz"],["dc.contributor.author","Veldkamp, Edzo"],["dc.contributor.author","Wanger, Thomas C."],["dc.date.accessioned","2017-09-07T11:54:53Z"],["dc.date.available","2017-09-07T11:54:53Z"],["dc.date.issued","2011"],["dc.description.abstract","1. Agricultural intensification reduces ecological resilience of land-use systems, whereas paradoxically, environmental change and climate extremes require a higher response capacity than ever. Adaptation strategies to environmental change include maintenance of shade trees in tropical agroforestry, but conversion of shaded to unshaded systems is common practice to increase short-term yield.2. In this paper, we review the short-term and long-term ecological benefits of shade trees in coffee Coffea arabica, C. canephora and cacao Theobroma cacao agroforestry and emphasize the poorly understood, multifunctional role of shade trees for farmers and conservation alike.3. Both coffee and cacao are tropical understorey plants. Shade trees in agroforestry enhance functional biodiversity, carbon sequestration, soil fertility, drought resistance as well as weed and biological pest control. However, shade is needed for young cacao trees only and is less important in older cacao plantations. This changing response to shade regime with cacao plantation age often results in a transient role for shade and associated biodiversity in agroforestry.4. Abandonment of old, unshaded cacao in favour of planting young cacao in new, thinned forest sites can be named ‘short-term cacao boom-and-bust cycle’, which counteracts tropical forest conservation. In a ‘long-term cacao boom-and-bust cycle’, cacao boom can be followed by cacao bust due to unmanageable pest and pathogen levels (e.g. in Brazil and Malaysia). Higher pest densities can result from physiological stress in unshaded cacao and from the larger cacao area planted. Risk-averse farmers avoid long-term vulnerability of their agroforestry systems by keeping shade as an insurance against insect pest outbreaks, whereas yield-maximizing farmers reduce shade and aim at short-term monetary benefits.5. Synthesis and applications. Sustainable agroforestry management needs to conserve or create a diverse layer of multi-purpose shade trees that can be pruned rather than removed when crops mature. Incentives from payment-for-ecosystem services and certification schemes encourage farmers to keep high to medium shade tree cover. Reducing pesticide spraying protects functional agrobiodiversity such as antagonists of pests and diseases, pollinating midges determining cacao yields and pollinating bees enhancing coffee yield. In a landscape perspective, natural forest alongside agroforestry allows noncrop-crop spillover of a diversity of functionally important organisms. Knowledge transfer between farmers, agronomists and ecologists in a participatory approach helps to encourage a shade management regime that balances economic and ecological needs and provides a ‘diversified food-and-cash crop’ livelihood strategy."],["dc.identifier.doi","10.1111/j.1365-2664.2010.01939.x"],["dc.identifier.gro","3150127"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/6857"],["dc.language.iso","en"],["dc.notes.status","final"],["dc.relation.issn","0021-8901"],["dc.subject","agricultural intensification; Arabica and Robusta coffee; boom-and-bust cycles; cacao yield; ecological-economic trade-offs; ecological resilience; functional biodiversity; household vulnerability"],["dc.title","Multifunctional shade-tree management in tropical agroforestry landscapes - a review"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","245"],["dc.bibliographiccitation.issue","1-3"],["dc.bibliographiccitation.journal","Forest Ecology and Management"],["dc.bibliographiccitation.lastpage","256"],["dc.bibliographiccitation.volume","202"],["dc.contributor.author","Juhrbandt, Jana"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Hölscher, Dirk"],["dc.date.accessioned","2017-09-07T11:45:43Z"],["dc.date.available","2017-09-07T11:45:43Z"],["dc.date.issued","2004"],["dc.description.abstract","The large-scale conversion of tropical old-growth forests to other land use types may subsequently increase the area covered by secondary forests. These tropical secondary forests are dominated by early successional tree species that may have elevated stomatal conductances and transpirational water loss. We studied eight abundant tree species of the tropical moist secondary forest in Sulawesi, Indonesia, for sun leaf stomatal conductance of water vapour (gsmax) in 4–7 m tall trees and related conductance to various leaf morphological (size, specific leaf area) and chemical parameters (nutrient contents, δ13C). gsmax showed a considerable variability among the eight coexisting early successional trees (393–734 mmol m−2 s−1). With a mean of 590 mmol m−2 s−1 it was more than twice as high as the maximal conductance reported for mature late-successional trees in tropical moist forests. Among the tested leaf traits, gsmax showed the closest relation to leaf nitrogen per area and leaf size; gsmax was only weakly correlated to leaf nitrogen per unit dry mass; no correlation existed with leaf δ13C values and specific leaf area. A significant negative relationship existed between gsmax and leaf size, which could point at a reduction in leaf-specific hydraulic conductance of the leaf petiole in large leaves of tropical pioneer trees. Thus, our data indicate that the early successional tree species studied in Sulawesi are characterized by a high but relatively heterogeneous water turn-over, and that leaf size might be a good predictor for maximal stomatal conductance."],["dc.identifier.doi","10.1016/j.foreco.2004.07.021"],["dc.identifier.gro","3149077"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5723"],["dc.language.iso","en"],["dc.notes.intern","Hoelscher Crossref import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","0378-1127"],["dc.title","The relationship between maximal stomatal conductance and leaf traits in eight Southeast Asian early successional tree species"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","278"],["dc.bibliographiccitation.issue","3"],["dc.bibliographiccitation.journal","Trees"],["dc.bibliographiccitation.lastpage","285"],["dc.bibliographiccitation.volume","20"],["dc.contributor.author","Hölscher, Dirk"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Bohman, Kerstin"],["dc.contributor.author","Hagemeier, Marc"],["dc.contributor.author","Juhrbandt, Jana"],["dc.contributor.author","Tjitrosemito, Soekisman"],["dc.date.accessioned","2017-09-07T11:45:38Z"],["dc.date.available","2017-09-07T11:45:38Z"],["dc.date.issued","2006"],["dc.description.abstract","In the tropics, old-growth forests are converted to other land cover types at a high rate and young secondary forest may gain in importance. Information on associated changes in leaf gas exchange and other leaf traits can be valuable for modelling biogeochemical fluxes under altered land-use patterns. We studied in situ photosynthetic parameters and stomatal conductance for water vapour in eight abundant tree species of young secondary forest and eight tree species of natural old-growth forest in Central Sulawesi, Indonesia. In sun leaves, the average maximal stomatal conductance (g smax) in the secondary forest (SF) species was 2.1 times higher than in the old-growth forest (OGF) species. Species with a high g smax reduced g s sharply when vapour pressure deficit of the air increased, whereas species with a low g smax were much less sensitive to air humidity. For area-based photosynthetic capacity (A max-area), the SF species had a 2.3 times higher average than the OGF species. For both, g smax and A max-area the variation among species was higher in the OGF than in the SF. When all tree species (n=16) are considered, species means of specific leaf area (SLA), leaf N concentration and leaf P concentration were significantly correlated with g smax and A max-area. The strong correlation between A max-area and foliar P (r 2=0.8) is remarkable as the alluvial soils in the study region are rich in nutrients. If the eight OGF species are analysed separately, the only significant correlation was observed between SLA and mass-based A max; in the SF species strong correlations were found between leaf size and A max-area and g smax. These results show that the conversion of old-growth forest to young secondary forest in Sulawesi significantly alters tree leaf gas exchange characteristics and that chemical and structural leaf traits can be used for the prediction of these changes. The best correlations between leaf gas exchange parameters and leaf traits were obtained by different traits in the SF species, the OGF species and the entire pool of studied species."],["dc.identifier.doi","10.1007/s00468-005-0040-4"],["dc.identifier.gro","3149061"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5705"],["dc.language.iso","en"],["dc.notes.intern","Hoelscher Crossref import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","0931-1890"],["dc.title","Leaf gas exchange of trees in old-growth and young secondary forest stands in Sulawesi, Indonesia"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","351"],["dc.bibliographiccitation.lastpage","375"],["dc.contributor.author","Binternagel, N. B."],["dc.contributor.author","Juhrbandt, J."],["dc.contributor.author","Koch, S."],["dc.contributor.author","Purnomo, M."],["dc.contributor.author","Schwarze, S."],["dc.contributor.author","Barkmann, J."],["dc.contributor.author","Faust, H."],["dc.contributor.editor","Tscharntke, T."],["dc.contributor.editor","Leuschner, C."],["dc.contributor.editor","Veldkamp, E."],["dc.contributor.editor","Faust, H."],["dc.contributor.editor","Guhardja, E."],["dc.contributor.editor","Bidin, A."],["dc.date.accessioned","2017-09-07T11:44:45Z"],["dc.date.available","2017-09-07T11:44:45Z"],["dc.date.issued","2010"],["dc.description.abstract","Climate change poses a major threat to the livelihoods of many people, especially those dependent on agriculture. Adaptation to climate change is a necessity to reduce social vulnerability. The adoption of agricultural innovations presents a suitable strategy to reduce negative impacts of increased inter-annual variability in rainfall and temperature. Focussing on the dominant agroforestry system cacao in the Indonesian province of Central Sulawesi, we investigate the adaptation strategies of agricultural smallholders to El Nico-Southern Oscillation (ENSO) related droughts. We apply a triangulation of Rapid Rural Appraisal Methods (RRA), semi-structured in-depth interviews and participatory observations. In addition, results from an intensive cacao-study (n=144) on yields, plot history, structure and location are used. The analysis shows that all interviewed households have been affected by extreme climatic effects such as ENSO related droughts which lead to a decline in agricultural outputs. Our study identifies various types of adaptation strategies on the micro level. Most common strategies are reactive or ex-post adaptations which support the household in coping with the effects of droughts. Further, the study assesses anticipatory adaptation strategies which, if precisely implemented, alter the household’s exposure to future droughts, increase the resilience to cope with changes and reduce the degree of sensitivity of affected households. On the basis of these results we examine why different household types do not implement certain strategies, which could enhance their social resilience. In this context we reveal that the adoption of anticipatory adaptation strategies is strongly influenced by social and human capital. The knowledge transfer - which promotes adaptation - is mainly taking place along ethnic lines and local institutions. For the successful adoption of innovations to cope with ENSO related droughts in the study area, membership in certain ethnic groups, local institutions and networks is of utmost importance."],["dc.identifier.doi","10.1007/978-3-642-00493-3_16"],["dc.identifier.gro","3148967"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5608"],["dc.language.iso","en"],["dc.notes.intern","Faust Crossref Import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.publisher","Springer"],["dc.publisher.place","Berlin, Heidelberg"],["dc.relation.doi","10.1007/978-3-642-00493-3"],["dc.relation.isbn","978-3-642-00492-6"],["dc.relation.ispartof","Tropical Rainforests and Agroforests under Global Change: Ecological and Socio-economic Valuations"],["dc.title","Adaptation to climate change in Indonesia - livelihood strategies of rural households in the face of ENSO related droughts"],["dc.type","book_chapter"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","157"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Journal of Tropical Ecology"],["dc.bibliographiccitation.lastpage","164"],["dc.bibliographiccitation.volume","20"],["dc.contributor.author","Hölscher, Dirk"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Bohman, Kerstin"],["dc.contributor.author","Juhrbandt, Jana"],["dc.contributor.author","Tjitrosemito, S."],["dc.date.accessioned","2017-09-07T11:45:43Z"],["dc.date.available","2017-09-07T11:45:43Z"],["dc.date.issued","2004"],["dc.description.abstract","Tropical pioneer tree species are considered as a functional group characterized by a suite of ecological characteristics such as high light demand and high photosynthetic capacities. This study compared the photosynthetic characteristics of eight co-existing pioneer tree species in 3–4-y-old and about 6-m-tall secondary forest stands in Sulawesi, Indonesia. Its objectives were (1) to determine the range and interspecific variation in six photosynthetic parameters, and (2) to identify morphological and chemical leaf traits that can predict light-saturated net photosynthetic rates (on a leaf area or leaf mass basis, Amax-area or Amax-mass). Species averages of Amax-area in sun leaves ranged between 14.2 and 20.3 μmol m−2 s−1 (mean 17.5) which is high compared with literature data. Among the co-existing species, average leaf size (56–896 cm2) differed by a factor of 16, specific leaf area (SLA, 10.7–21.4 m2 kg−1) and leaf nitrogen content (19.6–33.9 g kg−1) twofold. At the species level, Amax-area was not correlated with leaf N content but decreased significantly with leaf size. Amax-mass showed a higher interspecific variation than Amax-area, and was positively correlated with SLA and leaf N content (slope: 13.4 nmol CO2 g N−1 s−1). Both, Amax-area and Amax-mass were more closely related to leaf morphological attributes than to leaf N. We conclude that the tropical pioneer tree species studied do not form a homogeneous functional group in terms of photosynthetic performance. Rather, a considerable variation in leaf morphology and nitrogen content exists, which also shows up in a substantial variation in Amax-mass and, to a lesser extent, in Amax-area."],["dc.identifier.doi","10.1017/s0266467403001251"],["dc.identifier.gro","3149063"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/5707"],["dc.language.iso","en"],["dc.notes.intern","Hoelscher Crossref import"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","0266-4674"],["dc.title","Photosynthetic characteristics in relation to leaf traits in eight co-existing pioneer tree species in Central Sulawesi, Indonesia"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dspace.entity.type","Publication"]]