Data from: Degradation of root community traits as indicator for transformation of tropical lowland rain forests into oil palm and rubber plantations

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.