TY - JOUR
T1 - Alleviating nitrogen limitation in Mediterranean maquis vegetation leads to ecological degradation
AU - Dias, Teresa
AU - Crous, Casparus J.
AU - Liberati, Dario
AU - Munzi, Silvana
AU - Gouveia, Catarina
AU - Ulm, Florian
AU - Afonso, Ana Catarina
AU - Ochoa-Hueso, Raul
AU - Manrique, Esteban
AU - Sheppard, Lucy
AU - Martins-Loucao, Maria Amelia
AU - Bernardes da Silva, Anabela
AU - Cruz, Cristina
PY - 2017
Y1 - 2017
N2 - Soils are being degraded at an alarming rate and thereby also crucial ecosystem goods and services. Nitrogen (N) enrichment is a major driver of this degradation. While the negative impacts of N enrichment on vegetation are well known globally, those on various ecological interactions, and on ecosystem functioning, remain largely unknown. Because Mediterranean ecosystems are N limited, they are good model systems for evaluating how N enrichment impacts not only vegetation but also ecological partnerships and ecosystem functioning. Using a 7-year N-manipulation (dose and form) field experiment running in a Mediterranean Basin maquis located in a region with naturally low ambient N deposition (<4kgNha(-1)y(-1)), we assessed the impacts of the N additions on (i) the dominant plant species (photosynthetic N-use efficiency); (ii) plant-soil ecological partnerships with ectomycorrhiza and N-fixing bacteria; and (iii) ecosystem degradation (plant-soil cover, biological mineral weathering and soil N fixation). N additions significantly disrupted plant-soil cover, plant-soil biotic interactions, and ecosystem functioning compared with ambient N deposition conditions. However, the higher the ammonium dose (alone or with nitrate), the more drastic these disruptions were. We report a critical threshold at 20-40kg ammonium ha(-1)y(-1) whereby severe ecosystem degradation can be expected. These observations are critical to help explain the mechanisms behind ecosystem degradation, to describe the collective loss of organisms and multifunction in the landscape, and to predict potential fragmentation of Mediterranean maquis under conditions of unrelieved N enrichment.
AB - Soils are being degraded at an alarming rate and thereby also crucial ecosystem goods and services. Nitrogen (N) enrichment is a major driver of this degradation. While the negative impacts of N enrichment on vegetation are well known globally, those on various ecological interactions, and on ecosystem functioning, remain largely unknown. Because Mediterranean ecosystems are N limited, they are good model systems for evaluating how N enrichment impacts not only vegetation but also ecological partnerships and ecosystem functioning. Using a 7-year N-manipulation (dose and form) field experiment running in a Mediterranean Basin maquis located in a region with naturally low ambient N deposition (<4kgNha(-1)y(-1)), we assessed the impacts of the N additions on (i) the dominant plant species (photosynthetic N-use efficiency); (ii) plant-soil ecological partnerships with ectomycorrhiza and N-fixing bacteria; and (iii) ecosystem degradation (plant-soil cover, biological mineral weathering and soil N fixation). N additions significantly disrupted plant-soil cover, plant-soil biotic interactions, and ecosystem functioning compared with ambient N deposition conditions. However, the higher the ammonium dose (alone or with nitrate), the more drastic these disruptions were. We report a critical threshold at 20-40kg ammonium ha(-1)y(-1) whereby severe ecosystem degradation can be expected. These observations are critical to help explain the mechanisms behind ecosystem degradation, to describe the collective loss of organisms and multifunction in the landscape, and to predict potential fragmentation of Mediterranean maquis under conditions of unrelieved N enrichment.
KW - ammonium
KW - ecosystems
KW - nitrogen
KW - soil degradation
UR - http://hdl.handle.net/1959.7/uws:44389
U2 - 10.1002/ldr.2784
DO - 10.1002/ldr.2784
M3 - Article
SN - 1099-145X
SN - 1085-3278
VL - 28
SP - 2482
EP - 2492
JO - Land Degradation and Development
JF - Land Degradation and Development
IS - 8
ER -