Limits...
Understanding litter decomposition in semiarid ecosystems: linking leaf traits, UV exposure and rainfall variability.

Gaxiola A, Armesto JJ - Front Plant Sci (2015)

Bottom Line: Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria.Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment.Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ecología y Biodiversidad Santiago, Chile ; Departamento de Ecología, Pontificia Universidad Católica de Chile Santiago, Chile.

ABSTRACT
Differences in litter quality, microbial activity or abiotic conditions cannot fully account for the variability in decomposition rates observed in semiarid ecosystems. Here we tested the role of variation in litter quality, water supply, and UV radiation as drivers of litter decomposition in arid lands. And show that carry-over effects of litter photodegradation during dry periods can regulate decomposition during subsequent wet periods. We present data from a two-phase experiment, where we first exposed litter from a drought-deciduous and an evergreen shrub to natural UV levels during five, rainless summer months and, subsequently, in the laboratory, we assessed the carry-over effects of photodegradation on biomass loss under different irrigation treatments representing the observed range of local rainfall variation among years (15-240 mm). Photodegradation of litter in the field produced average carbon losses of 12%, but deciduous Proustia pungens lost >25%, while evergreen Porlieria chilensis less than 5%. Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria. During the subsequent wet phase, remaining litter biomass was lower in Proustia than in Porlieria. Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment. Consequently, for deciduous Proustia carry-over effects of UV exposure were negligible under high irrigation. Litter decomposition of the evergreen Porlieria depended solely on levels of rainfall that promote microbial decomposers. Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

No MeSH data available.


Related in: MedlinePlus

Remaining litter biomass (%) at the end of a 6-month decomposition experiment, preceded by photodegradation in the field. Samples from the field experiment are shown by open (UV+) or filled symbols (UV-). The laboratory experiment included irrigation treatments representing years with contrasting annual rainfall. Irrigation treatments represented the equivalent rainfall of a dry year (˜15 mm), an average year (140 mm) and wet (El Niño) year (240 mm) in semiarid Chile. The experiment was conducted under constant temperature (23°C). (A) Remaining litter biomass Proustia and (B)Porlieria. Data are means ± 1 SE.
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Figure 2: Remaining litter biomass (%) at the end of a 6-month decomposition experiment, preceded by photodegradation in the field. Samples from the field experiment are shown by open (UV+) or filled symbols (UV-). The laboratory experiment included irrigation treatments representing years with contrasting annual rainfall. Irrigation treatments represented the equivalent rainfall of a dry year (˜15 mm), an average year (140 mm) and wet (El Niño) year (240 mm) in semiarid Chile. The experiment was conducted under constant temperature (23°C). (A) Remaining litter biomass Proustia and (B)Porlieria. Data are means ± 1 SE.

Mentions: Between 2 and 65% of initial litter mass was lost during the subsequent 6-months of decomposition in the laboratory after water addition. Variation in biomass loss among litter samples was associated primarily with differences among irrigation treatments (i.e., simulated rainfall), but we also detected the carry-over effects from the process of litter photodegradation in the previous field experiment, and effects of species identity (Figure 2).


Understanding litter decomposition in semiarid ecosystems: linking leaf traits, UV exposure and rainfall variability.

Gaxiola A, Armesto JJ - Front Plant Sci (2015)

Remaining litter biomass (%) at the end of a 6-month decomposition experiment, preceded by photodegradation in the field. Samples from the field experiment are shown by open (UV+) or filled symbols (UV-). The laboratory experiment included irrigation treatments representing years with contrasting annual rainfall. Irrigation treatments represented the equivalent rainfall of a dry year (˜15 mm), an average year (140 mm) and wet (El Niño) year (240 mm) in semiarid Chile. The experiment was conducted under constant temperature (23°C). (A) Remaining litter biomass Proustia and (B)Porlieria. Data are means ± 1 SE.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4362295&req=5

Figure 2: Remaining litter biomass (%) at the end of a 6-month decomposition experiment, preceded by photodegradation in the field. Samples from the field experiment are shown by open (UV+) or filled symbols (UV-). The laboratory experiment included irrigation treatments representing years with contrasting annual rainfall. Irrigation treatments represented the equivalent rainfall of a dry year (˜15 mm), an average year (140 mm) and wet (El Niño) year (240 mm) in semiarid Chile. The experiment was conducted under constant temperature (23°C). (A) Remaining litter biomass Proustia and (B)Porlieria. Data are means ± 1 SE.
Mentions: Between 2 and 65% of initial litter mass was lost during the subsequent 6-months of decomposition in the laboratory after water addition. Variation in biomass loss among litter samples was associated primarily with differences among irrigation treatments (i.e., simulated rainfall), but we also detected the carry-over effects from the process of litter photodegradation in the previous field experiment, and effects of species identity (Figure 2).

Bottom Line: Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria.Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment.Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Ecología y Biodiversidad Santiago, Chile ; Departamento de Ecología, Pontificia Universidad Católica de Chile Santiago, Chile.

ABSTRACT
Differences in litter quality, microbial activity or abiotic conditions cannot fully account for the variability in decomposition rates observed in semiarid ecosystems. Here we tested the role of variation in litter quality, water supply, and UV radiation as drivers of litter decomposition in arid lands. And show that carry-over effects of litter photodegradation during dry periods can regulate decomposition during subsequent wet periods. We present data from a two-phase experiment, where we first exposed litter from a drought-deciduous and an evergreen shrub to natural UV levels during five, rainless summer months and, subsequently, in the laboratory, we assessed the carry-over effects of photodegradation on biomass loss under different irrigation treatments representing the observed range of local rainfall variation among years (15-240 mm). Photodegradation of litter in the field produced average carbon losses of 12%, but deciduous Proustia pungens lost >25%, while evergreen Porlieria chilensis less than 5%. Natural exposure to UV significantly reduced carbon-to-nitrogen and lignin:N ratios in Proustia litter but not in Porlieria. During the subsequent wet phase, remaining litter biomass was lower in Proustia than in Porlieria. Indeed UV exposure increased litter decomposition of Proustia under low and medium rainfall treatments, whereas no carry-over effects were detected under high rainfall treatment. Consequently, for deciduous Proustia carry-over effects of UV exposure were negligible under high irrigation. Litter decomposition of the evergreen Porlieria depended solely on levels of rainfall that promote microbial decomposers. Our two-phase experiment revealed that both the carry-over effects of photodegradation and litter quality, modulated by inter-annual variability in rainfall, can explain the marked differences in decomposition rates and the frequent decoupling between rainfall and litter decomposition observed in semiarid ecosystems.

No MeSH data available.


Related in: MedlinePlus