Predicting leaf litter decomposability: an exploratory assessment of leaf traits, litter traits and spectral properties in six Mediterranean herbaceous species

Abstract

Algunos trabajos han explorado métodos fáciles y rápidos de evaluar la decomponibilidad de la broza de grandes conjuntos de especies. Aquí evaluamos tres de los más utilizados en seis especies mediterráneas herbáceas de diferentes familias y formas de vida: (1) 'caracteres de hojas verdes': caracteres de hojas vivas relacionadas a las estrategias de vida de las plantas; (2) 'caracteres de la broza': respiración de la broza durante incubaciones in vitro y propiedades iniciales de la broza; (3) 'propiedades espectrales de las hojas y de la broza': características espectrales (NIR) de las hojas verdes y de la broza. Analizamos las relaciones entre estos métodos y su consistencia para evaluar la tasa de descomposición de la broza en el campo. Las propiedades espectrales de hojas verdes fueron las más precisas para predecir la descomponibilidad a campo, seguidas por el contenido de materia seca de las hojas (LDMC) y el contenido inicial de compuestos no lábiles de la broza. La descomponibilidad in vitro se correlacionó marginalmente con la descomponibilidad a campo. La selección entre los predictores puede depender, entonces, de los instrumentos disponibles. LDMC es el método más económico y fácil de medir para grandes conjuntos de especies que, a su vez, fue constante dentro de las especies analizadas. Alternativamente, en el caso de tener el equipamiento y las calibraciones disponibles, los espectros NIR de las hojas verdes y de la broza inicial representan un método rápido para estimar la descomponibilidad y calidad de la broza al mismo tiempo. Nuestros resultados confirman evidencias previas que para las especies de sistemas semiáridos caracteres estructurales como LDMC y el contenido de compuestos no lábiles son propiedades importantes en el control de la descomponibilidad de la broza. La validez de nuestras conclusiones para un rango mayor de especies debería probarse en futuros estudios.

Several studies attempted to find quick and easy methods to assess litter decomposability. We tested three frequently used methods on 6 Mediterranean herbaceous species from different plant families and life forms: (1) ‘green leaves traits’: traits of living leaves related to the strategies of living plants; (2) ‘litter traits’: litter respiration during in vitro incubation and initial litter properties; and (3) ‘leaf and litter spectral properties’: the spectral characteristics (NIR) of green leaves and litter. We analyzed the relationship between these methods and their consistency to assess litter decomposability in the field. Green leaves spectral properties were the most accurate to predict Several studies attempted to find quick and easy methods to assess litter decomposability. We tested three frequently used methods on 6 Mediterranean herbaceous species from different plant families and life forms: (1) ‘green leaves traits’: traits of living leaves related to the strategies of living plants; (2) ‘litter traits’: litter respiration during in vitro incubation and initial litter properties; and (3) ‘leaf and litter spectral properties’: the spectral characteristics (NIR) of green leaves and litter. We analyzed the relationship between these methods and their consistency to assess litter decomposability in the field. Green leaves spectral properties were the most accurate to predict field decomposability, followed by leaf dry matter content (LDMC) and initial content of non-labile compounds. In vitro decomposability marginally correlated with field decomposability. The selection among these predictors may then depend on the instruments available. LDMC is the easiest and least expensive, and is also a constant trait within species. Alternatively, if available, NIR spectra of green leaves and initial litter represent the quickest method for estimating decomposability and litter quality at the same time. Our findings confirm previous evidence that for species from semi-arid systems structural traits like LDMC and non-labile compounds content are important properties controlling species litter decomposability. The validity of our conclusions when a wider range of species is included remains to be tested. decomposability, followed by leaf dry matter content (LDMC) and initial content of non-labile compounds. In vitro decomposability marginally correlated with field decomposability. The selection among these predictors may then depend on the instruments available. LDMC is the easiest and least expensive, and is also a constant trait within species. Alternatively, if available, NIR spectra of green leaves and initial litter represent the quickest method for estimating decomposability and litter quality at the same time. Our findings confirm previous evidence that for species from semi-arid systems structural traits like LDMC and non-labile compounds content are important properties controlling species litter decomposability. The validity of our conclusions when a wider range of species is included remains to be tested.