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Vegetation recovery after fire in mountain grasslands of Argentina

Journal of Mountain Science 2020年第2期17卷 373-383页

作者： alejandro loydi Flavia AFUNK Andrés GARCíA Renewable Natural Resources Center of the Semi-Arid Zone(CERZOS)–CONICET-UNS Bahia BiancaArgentina Department of Biology Biochemistry and PharmacySouth National UniversityBahfa BiancaArgentina Argentine Institute of Oceanography(IADO) CONICET-UNSBahia BlancaArgentina

Fire is a natural disturbance occurring every few years in many grasslands ecosystems. However, since European colonization, fire has been highly reduced or even suppressed in Argentinean grasslands, fostering ignitable material accumulation. This has led to occasional catastrophic controldemanding fire events, extended for larger areas. The aims of this work are to study vegetation recovery and change after a non-natural fire event in mountain grasslands. The study area is located in the Ventania mountain system, mid-eastern Argentina. We studied vegetation recovery after fire(January 2014) in two different communities: grass-steppes(grasslands) and shrub-steppes(open low shrublands). We measured vegetation cover, species richness and bare ground percentage in burned and unburned areas 1, 4, 8, 11 and 23 months after fire. Vegetation surveys were also performed at the end of the growing season(December) 11 and 23 months after fire. Data were analyzed using regression analysis, ANOVA and multivariate analysis(NMS, PERMANOVA). Both communities increased their vegetation cover at the same rate, without differences between burned and unburned areas after two years. Species richness was higher in shrublands and their recovery was alsofaster than in grasslands. Considering functional composition, besides transient changes during the first year after fire, there were no differences in abundance of different functional vegetation groups two years after fire. At the same time, shrublands showed no differences in species composition, while grasslands had a different species composition in burned and unburned plots. Also, burned grassland showed a higher species richness than unburned grassland. Data shown mountain vegetation in Pampas grassland is adapted to fire, recovering cover and richness rapidly after fire and thus reducing soil erosion risks. Vegetation in mountain Pampas seems to be well adapted to fire, but in grasslands species composition has changed due to fire.

关键词： Amelichloa caudata Forbs Grass Natural grassland Nassella trichotoma Piedmont valleys Shrubs Sierra de la Ventana Vegetation functional groups

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Distribution and effects of tree leaf litter on vegetation composition and biomass in a forest–grassland ecotone

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Journal of Plant Ecology 2014年第3期7卷 264-275页

作者： alejandro loydi Kerstin Lohse Annette Otte Tobias W.Donath R.Lutz Eckstein Institute of Landscape Ecology and Resource Management Research Center for BiosystemsLand Use and Nutrition(IFZ)Justus-Liebig University GiessenHeinrich-Buff-Ring 26-32DE-35392GiessenGermany

Aims After abandonment of grasslands,secondary succession leads to the invasion by woody *** process begins with the accumulation of tree litter in the forest–grassland *** objectives were to determine the relationships between litter amounts and vegetation composition and cover along natural forest–grassland ecotones and to experimentally study the initial effects of tree litter accumulation on grassland vegetation and on microsite *** We established 11 transects varying from 12 to 15 m in length in different forest–grassland ecotones in the Lahn-Dill highlands,Germany,and measured the mass and cover of tree litter and the cover and composition of vegetation at five sequential positions along each transect by using 1 m2 plots with five *** a field experiment,we established plots subjected to different litter amounts(0,200 and 600g m^(−2))and evaluated changes in grassland vegetation,soil temperature and soil nutrient availability below the litter *** Findings Tree litter amounts decrease from 650 to 65g m^(−2) across the forest–grassland *** changed from shrubs and annual species(adapted to more stressful conditions)in the forests edge to grasses,rosettes and hemirosette species(with higher competitive abilities)in the *** anthropogenic forest–grassland ecotones showed abrupt edges,and the two adjacent ecosystems were characterized by different species pools and functional *** the field experiment,the presence of a litter layer reduced vegetation biomass and cover;the species richness was only reduced in the treatment with high litter(600g m^(−2)).Additionally,adding litter on top of vegetation also reduced thermal amplitude and the number of frost days,while increasing the availability of some nutrients,such as nitrogen and aluminium,the latter being an indicator of soil *** a tree litter layer of 600g m^(−2) in grassland areas had strong effects on the compos

关键词： forest edge land abandonment land use change litter oak(Quercus robur) semi-natural grassland tree invasion

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Effects of biological soil crusts and drought on emergence and survival of a Patagonian perennial grass in the Monte of Argentina

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Journal of Arid Land 2014年第6期6卷 735-741页

作者： Flavia Alejra FUNK Alejro loydi Guadalupe PETER Center for Renewable Natural Resources of the Semi-arid Zone National Scientific and Technical Research Council (CONICET)Bahía Blanca 8000Argentina Río Negro National University Viedma 8500Argentina

Biological soil crusts are widely distributed in arid and semiarid regions. They have an important eco- logical role, especially by modifying physical and chemical properties of soils. Biological crusts may also modify seed germination and seedling establishment. The effects vary widely according to the type of crust and the vas- cular plant species. The objective of this study was to determine the effect of moss-dominated biological soil crusts on the emergence, biomass and survival of Poa ligularis Nees ex Steud. under different irrigation regimes. We col- lected seeds of P. ligularis and biological soil crusts composed of two species of mosses： Syntrichia princeps （De Not.） Mitt and Ceratodon purpureus （Hedw.） Brid. from an area in the Monte of Argentina. The result showed that seedling emergence of P. ligularis was higher in treatments with bare soil than in soil covered by crusts, and also in those with watering to field capacity. Mean emergence time was higher in treatments with bare soil and watering to field capacity. Seedling biomass also showed significant differences between treatments. These results suggest that biological soil crusts dominated by mosses do not promote P. ligularis emergence, although they would not affect its survival.

关键词： drought field capacity recruitment microsites mosses semiarid region Poa ligularis

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