title: Degradation of Root Community Traits as Indicator for Transformation of Tropical Lowland Rain Forests into Oil Palm and Rubber Plantations.
abstract: Conversion of tropical forests into intensely managed plantations is a threat to ecosystem functions. On Sumatra, Indonesia, oil palm (Elaeis guineensis) plantations are rapidly expanding, displacing rain forests and extensively used rubber (Hevea brasiliensis) agro-forests. Here, we tested the influence of land use systems on root traits including chemical traits (carbon, nitrogen, mineral nutrients, potentially toxic elements [aluminium, iron] and performance traits (root mass, vitality, mycorrhizal colonization). Traits were measured as root community-weighed traits (RCWTs) in lowland rain forests, in rubber agro-forests mixed with rain forest trees, in rubber and oil palm plantations in two landscapes (Bukit Duabelas and Harapan, Sumatra). We hypothesized that RCWTs vary with land use system indicating increasing transformation intensity and loss of ecosystem functions. The main factors found to be related to increasing transformation intensity were declining root vitality and root sulfur, nitrogen, carbon, manganese concentrations and increasing root aluminium and iron concentrations as well as increasing spore densities of arbuscular mycorrhizas. Mycorrhizal abundance was high for arbuscular and low for ectomycorrhizas and unrelated to changes in RCWTs. The decline in RCWTs showed significant correlations with soil nitrogen, soil pH and litter carbon. Thus, our study uncovered a relationship between deteriorating root community traits and loss of ecosystem functionality and showed that increasing transformation intensity resulted in decreasing root nutrition and health. Based on these results we suggest that land management that improves root vitality may enhance the ecological functions of intense tropical production systems.
authors.affiliation: Department for Forest Botany and Tree Physiology, Büsgen-Institute, Georg-August University Göttingen, Göttingen, Germany.
authors.forename: Josephine
authors.initials: J
authors.lastname: Sahner
authors.affiliation: Department of Sylviculture, Faculty of Forestry, Jalan Lingkar Akademik Campus, IPB Darmaga, Bogor, Indonesia.
authors.forename: Sri Wilarso
authors.initials: SW
authors.lastname: Budi
authors.affiliation: Department of Agrotechnology, Faculty of Agriculture, Tadulako University, Palu, Indonesia.
authors.forename: Henry
authors.initials: H
authors.lastname: Barus
authors.affiliation: Department for Forest Botany and Tree Physiology, Büsgen-Institute, Georg-August University Göttingen, Göttingen, Germany; Department of Agrotechnology, Faculty of Agriculture, Tadulako University, Palu, Indonesia.
authors.forename: Nur
authors.initials: N
authors.lastname: Edy
authors.affiliation: Institute for Geography, Georg-August University Göttingen, Göttingen, Germany.
authors.forename: Marike
authors.initials: M
authors.lastname: Meyer
authors.affiliation: Department for Soil Science of Tropical and Subtropical Ecosystems, Büsgen-Institute, Georg-August University Göttingen, Göttingen, Germany.
authors.forename: Marife D
authors.initials: MD
authors.lastname: Corre
authors.affiliation: Department for Forest Botany and Tree Physiology, Büsgen-Institute, Georg-August University Göttingen, Göttingen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Polle
mesh_terms: D028023:Arecaceae / Q000254:growth & development*; D028482:Hevea / Q000254:growth & development*; D007214:Indonesia; D008954:Models, Biological; D038821:Mycorrhizae / Q000254:growth & development*; D065947:Rainforest