Carbon storage of Mediterranean grasslands

Abstract

Secondary grasslands are one of the most common vegetation types worldwide. In Europe, and in the Mediterranean basin, human activities have transformed many woodlands into secondary grasslands. Despite their recognized role in the global carbon cycle, very few data are available for estimating the biomass of Mediterranean grasslands. We developed linear regression models in order to predict the biomass of two native Mediterranean grasses (Ampelodesmos mauritanicus and Hyparrhenia hirta) and an invasive alien grass (Pennisetum setaceum). Ampelodesmos mauritanicus is very common throughout the Mediterranean basin, mostly on north-facing slopes, H. hirta characterizes thermo-xeric grasslands, while P. setaceum is an alien species that is rapidly spreading along coastal areas. The measured morphometric attributes of individual plants as potential predictors were considered. The validation results corroborate the ability of the established models to predict above ground and total biomass of A. mauritanicus and P. setaceum. We also evaluated the total biomass per hectare for each species. The highest biomass per hectare was found for A. mauritanicus, whereas biomass was higher for H. hirta than for P. setaceum. The replacement of H. hirta by P. setaceum may reduce the total carbon storage in the ecosystem; however, P. setaceum allocates more resources to the roots, thus increasing the more stable and durable pool of carbon in grasslands. Los pastizales secundarios son uno de los tipos de vegetación más comunes en todo el mundo. En Europa y en la cuenca mediterránea, las actividades humanas han transformado muchos bosques en pastizales secundarios. A pesar de su reconocido papel en el ciclo global del carbono, hay muy pocos datos disponibles para la estimación de la biomasa de los pastizales mediterráneos. Hemos desarrollado modelos de regresión lineal con el fin de predecir la biomasa de dos gramíneas nativas del Mediterráneo (Ampelodesmos mauritanicus e Hyparrhenia hirta) y otra exótica e invasora (Pennisetum setaceum). Ampelodesmos mauritanicus es muy común en toda la cuenca mediterránea, sobre todo en pendientes orientadas al norte, Hyparrhenia hirta es característica de pastizales termo-xerófilos, mientras que Pennisetum setaceum es una especie exótica que se está extendiendo rápidamente a lo largo de las zonas costeras. Se consideraron los caracteres morfométricos de plantas individuales como factores de predicción potenciales. Los resultados han corroborado la capacidad de los modelos establecidos para predecir la biomasa aérea total de A. mauritanicus y P. setaceum. También se ha medido y evaluado la biomasa total por hectárea de cada especie: la mayor fue la que correspondía a A. mauritanicus, mientras que la H. hirta fue mayor que la de P. setaceum. Así pues, la substitución de H. hirta por P. setaceum puede reducir el carbono almacenado en el ecosistema, sin embargo, P. setaceum asigna más recursos a las raíces, lo que implica un almacenaje de carbono más estable y duradero.

Seedling growth of a native ( Ampelodesmos mauritanicus ) and an exotic ( Pennisetum setaceum ) grass

“…after fire, Vilà et al, 2001). This finding is particularly interesting because at the same study site from where the seeds were collected, adult Amp individuals are much taller and larger than Penn (Corona et al, 2016;Pasta et al, 2010). Because large-size individuals are known to be strongly competitive against neighboring plants in herbaceous communities (Grime, 1973), the ability of Penn to enter mature and close Amp grassland is likely to be quite low.…”

Water and Carbon Dynamics, Ecosystem Stability of Forest and Grassland in Response to Climate Change

“…Information on the spatiotemporal variability of SOCD is critical for understanding the global carbon budget and adjusting land-use management policies, around CO 2 emission reduction and global warming mitigation . Grasslands store approximately 34% of the total soil carbon and 10% of SOC in global terrestrial ecosystems (Scurlock et al, 2002;Corona et al, 2016;Yuan et al, 2021). With a mean SOCD of 7.6-14.1 kg C m −2 and SOCS of 278.9-591.5 Pg, global grasslands have strong carbon sequestration potential and play a critical role in regulating the global carbon cycle and climate (King et al, 1997;Prentice et al, 2001;Piao et al, 2009;Wei and Fang, 2009;.…”

Graminoid Invasion in an Insular Endemism Hotspot and Its Protected Areas

“…The closed canopy of the forest prevents P. setaceum invasion and this forest type additionally contains lower species numbers compared to other ecosystems on the Canary Islands [72]. P. setaceum derives from arid areas of the Middle East and northern Africa where lush evergreen forest is scarce which can explain this pattern [42]. Additionally, P. canariensis forests historically have a high fire frequency of dominant pine species being fire-tolerant and having the ability to resprout after fire [73].…”

“…Seeds stay viable for up to 10 years (Acevedo Rodríguez, personal observation) and germinate without light [49]. Pennisetum setaceum ( Figure 2) originates from northern Africa and the Middle East but is now present on most continents and many oceanic islands in the Pacific and Atlantic Ocean [30,42]. The invader is suspected to have arrived in La Palma during the construction of the new airport in the 1970s [43,44].…”