Litter chemistry and abiotic effects on plant recruitment success in denuded areas of Patagonian Monte rangelands

BOSCO T; BERTILLER MB; CARRERA AL; SARAVÍ CISNEROS H

Foz do Iguassu

Workshop; VII World Conference on Ecological Restoration, V Congreso Iberoamericano y del Caribe de Restauración Ecológica, I Conferência Brasileira de Restauração Ecológica.; 2017

Grazing disturbance reduced the cover of preferred species and increasesoil gaps in arid ecosystems. Litter amendment is a managerial tool usuallyused for soil and plant restoration in denuded areas of these ecosystems. We evaluated the effect of litter chemistry (C/Nratio) combined with different levels of UV radiation exposure and soil water onsoil inorganic-N (SNin) and recruitment of two dominant perennialgrasses (Poa ligularis and Nassella tenuis) and an evergreen shrub(Atriplex lampa) preferred byherbivores and a dominant evergreen shrub (Larreadivaricata) non preferred and with chemical defenses against herbivores indenuded areas of the Patagonian Monte. Microcosms with soil of denuded areas weresowed with seeds of all species in separated cells subjected during 6 months tothe combined effects of litter cover (without litter (NL), litter with C/Nratio =15 and C/N ratio =48), UV radiation (near ambient (Am-UV) and reduced(Re-UV)), and volumetric soil water (high (15-25% HSW) and low (5-15% (LSW)). Weassessed SNin, concentration periodically andspecies recruitment (probability transition from seed to established plant) atthe end of the experiment. Low C/N ratio in litter and Am-UV increased SNin.Soil water enhanced SNin only at one date. Perennial grass speciesand A. lampa recruitment wasincreased with augmented SNin. None factor affected therecruitment of L. divaricata. Weconcluded that litter amendment combined with exposure to UV radiationthroughout the effect on soil inorganic N may modulate plant recruitmentsuccess of species preferred by herbivores in denuded areas.