For over 140 years, the habitat of Socorro Island in the Mexican Pacific has been altered by the presence of exotic sheep. Overgrazing, jointly with tropical storms, has caused soil erosion, and more than 2000 hectares of native vegetation have been lost. Sheep eradication was conducted from 2009 to 2012. Since then, the vegetation has begun to recover passively, modifying soil properties. The objective of our study was to verify that this island was resilient enough to be recovered and in a relatively short time scale. To confirm our hypothesis, we analyzed changes in the physical-chemical properties of the soil and vegetation cover, the last one in different times and habitats after sheep eradication. The change in vegetation cover was estimated by comparing the normalized difference vegetation index (NDVI) between 2008 and 2013. In sites altered by feral sheep, soil compaction was assessed, and soil samples were taken, analyzing pH, electrical conductivity, organic carbon, total nitrogen, phosphorus, calcium, and magnesium. After a year of total sheep eradication, clear indications in the recovery of vegetation cover and improvement of soil quality parameters were observed and confirmed, specifically compaction and nitrogen, organic carbon, phosphorus, and calcium. The results seem to support our hypothesis.

En los ecosistemas áridos, las costras biológicas de suelo junto con las comunidades de microartrópodosdan lugar a uno de los servicios ambientales más importantes: la descomposición de la materia orgánica. La relaciónentre comunidades de microartrópodos y costras biológicas de suelo, así como la influencia de las propiedades edáficasen la distribución de microartrópodos fueron estudiadas en un matorral desértico en el sur de la península de BajaCalifornia. Se tomaron 25 muestras de suelo de 3 sitios: sin costras (10), con costras (10) y superficies erosionadas (5).Se extrajeron los microartrópodos, que fueron identificados hasta familia y se identificaron hábitos alimenticios. Seencontraron 4 682 microartrópodos en 40 taxa, Prostigmata con la mayor riqueza. La falta de cobertura vegetal en lossitios erosionados parece afectar las condiciones micro-ambientales, por lo que no fueron encontrados microartrópodosen estos sitios y las costras biológicas encontradas fueron simples. En el resto del matorral, las costras biológicas erancomplejas en su estructura y las propiedades edáficas fueron más favorables para el desarrollo de microartrópodos.Se relacionaron las diferencias específicas dentro de la estructura de la comunidad de microartrópodos para cadamicrohábitat con los hábitos alimenticios de cada taxa.

Soil respiration is a critical ecological process and is a hierarchical component of ecosystem respiration that regulates the global carbon cycle. But there is scarce knowledge on respiration dynamics in water-stressed ecosystems and the influence of biocrusts. Soil respiration-values varied from 0.099 to 0.828 µmol s⁻¹ m⁻² after extraordinary rains; after this period, recorded values were null or negative at the most (0.000 to −0.055 µmol s⁻¹ m⁻²). Shrubland soil with and without biocrusts showed the highest net CO₂ exchange values and in disturbed soil with and without biocrusts (0.067; 0.059; 0.048, and 0.023 µmol s⁻¹ m⁻²). The results showed that shrubland soil with BSC absorbed more CO₂ than the rest of the experimental variants. Accordingly, the observed low precipitation combined with high temperatures and evapotranspiration could not activate the BSC respiration process. Such an event seemed to occur under specific temperature and moisture conditions, anyhow related to extraordinary rain events to emit CO₂ to the atmosphere. Reports of negative soil respiration values in drylands are very scarce, so we discuss the possible processes that could cause this phenomenon for our study area.