Abstract
Biological soil crusts (BSC) are associations among cyanobacteria, green algae, lichens, mosses and soil particles, which contribute to multiple ecosystem functions such as nitrogen fixation and soil stabilization. The present work aims to evaluate propagation conditions of different functional types of BSC (dominated by cyanobacteria, cyanolichens, phycolichens and mosses) potentially useful for the recovery of degraded soils. In the greenhouse, different functional types of BSC were cultivated, combining sowing treatments (crushed BSC, discrete fragments) and fertilization (substrate with or without goat manure). Response variables, indicating BSC development and functionality, were total BSC cover, each functional type cover, depth of BSC, soil stability, and ammonium and phosphate concentrations. Total BSC cover increased during the 19 months experimental period. Crushing BSC favored the development and functionality of BSC in pots dominated by cyanolichens, phycolichens and mosses. The addition of fertilizer decreased total BSC cover in pots dominated by phycolichens and mosses. BSC depth and soil stability increased in lichens and moss dominated pots, and were benefited by crushing before sowing. Nutrient concentrations were lower in soils under BSC than in bare soils. We conclude that crushing BSC before sowing and without fertilization favored BSC cover and depth and increased soil stability. These results are useful to plan restoration strategies of degraded drylands.
Highlights
La costra biológica del suelo (CBS) es una asociación entre cianobacterias, algas verdes, líquenes, musgos y partículas de suelo; está presente en lugares con abundante luz y baja productividad como suelos de zonas áridas (Belnap and Lange 2001)
La funcionalidad y la importancia ecológica de las costras biológicas del suelo (CBS) dependen tanto del tipo de organismo fotosintético dominante —ya sean líquenes, musgos o cianobacterias— como de la morfología y la estructura tridimensional que forman las comunidades (Bowker et al 2011; Pietrasiak et al 2013)
Las costras dominadas por cianobacterias con heterocistos y cianolíquenes gelatinosos, como el género Collema, son capaces de fijar nitrógeno atmosférico (Belnap 2002)
Summary
Con el fin de minimizar el impacto negativo sobre las comunidades de CBS, los fragmentos de CBS y el sustrato a utilizar fueron colectados de los bordes de caminos que atraviesan la reserva de la Biosfera de Ñacuñán, Mendoza, Argentina. La recolección de material se realizó durante los años 2015 y 2016, seleccionando muestras claramente dominadas por un tipo funcional (que alcanzaran una cobertura cercana al 90-100%, estimada visualmente) y posteriormente en el laboratorio se realizó la clasificación de las CBS en los distintos tipos funcionales dominantes en cada muestra: cianobacterias, cianolíquenes gelatinosos, ficolíquenes escamulosos y musgos. Se seleccionaron estos tipos funcionales para representar distintos grupos biológicos (cianobacterias, musgos, líquenes), simbiontes (ficolíquenes y cianolíquenes, potencialmente fijadores de N) y morfología (plana, tridimensional), que se espera tengan distintos efectos en los ciclos de agua, C y N, y en la retención de partículas de suelo y su estabilización. Se observaron las cianobacterias Scytonema y Microcoleus, cianolíquenes Enchylium, ficolíquenes Placidium y musgos Tortula, Bryum y Pseudocrossidium
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