Jacob, Mascha

[["dc.bibliographiccitation.firstpage","1173"],["dc.bibliographiccitation.issue","7"],["dc.bibliographiccitation.journal","Annals of Forest Science"],["dc.bibliographiccitation.lastpage","1185"],["dc.bibliographiccitation.volume","68"],["dc.contributor.author","Fleck, Stefan"],["dc.contributor.author","Mölder, Inga"],["dc.contributor.author","Jacob, Mascha"],["dc.contributor.author","Gebauer, Tobias"],["dc.contributor.author","Jungkunst, Hermann F."],["dc.contributor.author","Leuschner, Christoph"],["dc.date.accessioned","2018-10-29T16:42:22Z"],["dc.date.available","2018-10-29T16:42:22Z"],["dc.date.issued","2011"],["dc.description.abstract","Introduction Sight-based field measurements of tree crown projection area and canopy height are common praxis in forest science but difficult to validate. We quantified their measurement errors based on the virtual representation of an 11-species old-growth forest provided by high-resolution terrestrial LIDAR (light detection and ranging) measurements. Objectives Based on the expectations (a) that violations of the triangulation theory are the main error source of height measurements, and (b) that approximations of tree crowns with fixed angles are not flexible enough for irregular crown shapes in natural stands, we investigated the relative accuracies of triangulation measurements of height of crown base (B T) vs. tree height (H T) and of different crown projection methods. B T (±0.52 m) showed lower measurement errors than H T (±2.4 m). Results and conclusions Larger deviations between field-measured and virtually executed crown projections could partly be attributed to structural differences of the crowns that were two-dimensionally quantified as space capture index (SCI). The largest deviations between both methods occurred on suppressed tree crowns and tall Quercus robur trees in the stand. Because of the method-inherent underestimation of crown projections with fixed angular grid, we propose the use of flexible angles by trained operators."],["dc.identifier.doi","10.1007/s13595-011-0067-1"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/7186"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/16133"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Comparison of conventional eight-point crown projections with LIDAR-based virtual crown projections in a temperate old-growth forest"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","1083"],["dc.bibliographiccitation.issue","4"],["dc.bibliographiccitation.journal","Oecologia"],["dc.bibliographiccitation.lastpage","1094"],["dc.bibliographiccitation.volume","164"],["dc.contributor.author","Jacob, Mascha"],["dc.contributor.author","Viedenz, Karin"],["dc.contributor.author","Polle, Andrea"],["dc.contributor.author","Thomas, Frank M."],["dc.date.accessioned","2017-09-07T11:49:19Z"],["dc.date.available","2017-09-07T11:49:19Z"],["dc.date.issued","2010"],["dc.description.abstract","We hypothesised that the decomposition rates of leaf litter will increase along a gradient of decreasing fraction of the European beech (Fagus sylvatica) and increasing tree species diversity in the generally beech-dominated Central European temperate deciduous forests due to an increase in litter quality. We studied the decomposition of leaf litter including its lignin fraction in monospecific (pure beech) stands and in stands with up to five tree genera (Acer spp., Carpinus betulus, Fagus sylvatica, Fraxinus excelsior, Tilia spp.) using a litterbag approach. Litter and lignin decomposition was more rapid in stand-representative litter from multispecific stands than in litter from pure beech stands. Except for beech litter, the decomposition rates of species-specific tree litter did not differ significantly among the stand types, but were most rapid in Fraxinus excelsior and slowest in beech in an interspecific comparison. Pairwise comparisons of the decomposition of beech litter with litter of the other tree species (except for Acer platanoides) revealed a “home field advantage” of up to 20% (more rapid litter decomposition in stands with a high fraction of its own species than in stands with a different tree species composition). Decomposition of stand-representative litter mixtures displayed additive characteristics, not significantly more rapid than predicted by the decomposition of litter from the individual tree species. Leaf litter decomposition rates were positively correlated with the initial N and Ca concentrations of the litter, and negatively with the initial C:N, C:P and lignin:N ratios. The results support our hypothesis that the overall decomposition rates are mainly influenced by the chemical composition of the individual litter species. Thus, the fraction of individual tree species in the species composition seems to be more important for the litter decomposition rates than tree species diversity itself."],["dc.identifier.doi","10.1007/s00442-010-1699-9"],["dc.identifier.gro","3147272"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/5981"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/4893"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.notes.submitter","chake"],["dc.relation.issn","0029-8549"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Leaf litter decomposition in temperate deciduous forest stands with a decreasing fraction of beech (Fagus sylvatica)"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.peerReviewed","no"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","86"],["dc.bibliographiccitation.journal","iForest - Biogeosciences and Forestry"],["dc.bibliographiccitation.lastpage","88"],["dc.bibliographiccitation.volume","3"],["dc.contributor.author","Johnson, J. A."],["dc.contributor.author","Jacob, M."],["dc.date.accessioned","2018-11-07T08:41:21Z"],["dc.date.available","2018-11-07T08:41:21Z"],["dc.date.issued","2010"],["dc.description.abstract","Forest condition in Europe is monitored under the International Co-operative Program on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests). The focus of the program is to provide an overview of the status of forest ecosystems in Europe with respect to air pollution and contribute to the understanding of the relationship between pollution and forest health. Crown condition parameters, i.e., defoliation and discoloration, are used as the principal indicators of forest condition within the ICP Forest network. Crown condition assessments have been successful in disproving the \"forest die-back\" hypothesis. However, there are a number of limitations associated with this approach given the current monitoring objectives. Data from crown condition assessments indicate that stand age and country differences explain most of the variation in crown defoliation. It is difficult to clearly discern the effects of air pollution from other site and stress factors. The results do however indicate the role of meteorology and other factors. A better understanding of the relationships between forest condition and air pollution may be achieved if more specific, quantitative response variables are selected. However, we suggest that the original focus of the program on air pollution effects may need to be re-evaluated."],["dc.identifier.doi","10.3832/ifor0538-003"],["dc.identifier.isi","000290234900003"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/7276"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/19449"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","zu prüfen"],["dc.notes.submitter","Najko"],["dc.publisher","Sisef-soc Italiana Selvicoltura Ecol Forestale"],["dc.relation.issn","1971-7458"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Monitoring the effects of air pollution on forest condition in Europe: is crown defoliation an adequate indicator?"],["dc.type","journal_article"],["dc.type.internalPublication","yes"],["dc.type.peerReviewed","yes"],["dc.type.status","published"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]

[["dc.bibliographiccitation.firstpage","336"],["dc.bibliographiccitation.issue","2"],["dc.bibliographiccitation.journal","Ecosystems"],["dc.bibliographiccitation.lastpage","346"],["dc.bibliographiccitation.volume","16"],["dc.contributor.author","Jacob, Mascha"],["dc.contributor.author","Bade, Claudia"],["dc.contributor.author","Calvete, Héctor"],["dc.contributor.author","Dittrich, Sebastian"],["dc.contributor.author","Leuschner, Christoph"],["dc.contributor.author","Hauck, Markus"],["dc.date.accessioned","2018-08-13T16:15:17Z"],["dc.date.available","2018-08-13T16:15:17Z"],["dc.date.issued","2013"],["dc.description.abstract","Old-growth forests are important stores for carbon as they may accumulate C for centuries. The alteration of biomass and soil carbon pools across the development stages of a forest dynamics cycle has rarely been quantified. We studied the above- and belowground C stocks in the five forest development stages (regeneration to decay stage) of a montane spruce (Picea abies) forest of the northern German Harz Mountains, one of Central Europe’s few forests where the natural forest dynamics have not been disturbed by man for several centuries. The over-mature and decay stages had the largest total (up to 480 Mg C ha−1) and aboveground biomass carbon pools (200 Mg C ha−1) with biomass C stored in dead wood in the decay stage. The soil C pool (220–275 Mg C ha−1, 0–60 cm) was two to three times larger than in temperate lowland spruce forests and remained invariant across the forest dynamics cycle. On the landscape level, taking into account the frequency of the five forest development stages, the total carbon pool was approximately 420 Mg C ha−1. The results evidence the high significance of over-mature and decaying stages of temperate mountain forests not only for conserving specialized forest organisms but also for their large carbon storage potential."],["dc.identifier.doi","10.1007/s10021-012-9617-0"],["dc.identifier.purl","https://resolver.sub.uni-goettingen.de/purl?gs-1/10324"],["dc.identifier.uri","https://resolver.sub.uni-goettingen.de/purl?gro-2/15267"],["dc.language.iso","en"],["dc.notes.intern","Merged from goescholar"],["dc.notes.status","final"],["dc.rights","Goescholar"],["dc.rights.uri","https://goescholar.uni-goettingen.de/licenses"],["dc.title","Significance of Over-Mature and Decaying Trees for Carbon Stocks in a Central European Natural Spruce Forest"],["dc.type","journal_article"],["dc.type.internalPublication","unknown"],["dc.type.version","published_version"],["dspace.entity.type","Publication"]]