TY - JOUR

T1 - Mechanisms of purple moor-grass (Molinia caerulea) encroachment in dry heathland ecosystems with chronic nitrogen inputs

AU - Friedrich, Uta

AU - Oheimb, Goddert

AU - Dziedek, Christoph

AU - Selbmann, Katharina

AU - Härdtle, Werner

AU - Kriebitzsch, Wolf-Ulrich

PY - 2011/12/1

Y1 - 2011/12/1

N2 - We analysed growth strategies (biomass allocation, nutrient sequestration and allocation) of heather (Calluna vulgaris) and purple moor-grass (Molinia caerulea) seedlings in monocultures and mixtures in relation to N, P, and N + P fertilisation in a greenhouse experiment in order to simulate a heath's pioneer phase under high airborne nitrogen (N) loads. N fertilisation increased the total biomass of both species in monocultures. In mixtures, M. caerulea sequestered about 65% of the N applied, while C. vulgaris suffered from N shortage (halving of the total biomass). Thus, in mixtures only M. caerulea will benefit from airborne N loads, and competition will become increasingly asymmetric with increasing N availability. Our results demonstrate that the heath's pioneer phase is the crucial tipping point at which the competitive vigour of M. caerulea (high belowground allocation, efficient use of belowground resources, shortened reproductive cycles) induces a shift to dominance of grasses under increased N availability.

AB - We analysed growth strategies (biomass allocation, nutrient sequestration and allocation) of heather (Calluna vulgaris) and purple moor-grass (Molinia caerulea) seedlings in monocultures and mixtures in relation to N, P, and N + P fertilisation in a greenhouse experiment in order to simulate a heath's pioneer phase under high airborne nitrogen (N) loads. N fertilisation increased the total biomass of both species in monocultures. In mixtures, M. caerulea sequestered about 65% of the N applied, while C. vulgaris suffered from N shortage (halving of the total biomass). Thus, in mixtures only M. caerulea will benefit from airborne N loads, and competition will become increasingly asymmetric with increasing N availability. Our results demonstrate that the heath's pioneer phase is the crucial tipping point at which the competitive vigour of M. caerulea (high belowground allocation, efficient use of belowground resources, shortened reproductive cycles) induces a shift to dominance of grasses under increased N availability.

KW - Ecosystems Research

KW - Biology

KW - Biomass allocation

KW - Calluna vulgaris

KW - Competition

KW - N deposition

KW - Nutrient sequestration

UR - http://www.scopus.com/inward/record.url?scp=80053627786&partnerID=8YFLogxK

U2 - 10.1016/j.envpol.2011.08.010

DO - 10.1016/j.envpol.2011.08.010

M3 - Journal articles

C2 - 21872975

VL - 159

SP - 3553

EP - 3559

JO - Environmental Pollution

JF - Environmental Pollution

SN - 0269-7491

IS - 12

ER -