Responses of Soil Labile Organic Carbon to a Simulated Hurricane Disturbance in a Tropical Wet Forest

Abstract

Abstract:Hurricanes are an important disturbance in the tropics that can alter forest ecosystem properties and processes. To understand the immediate influence of hurricane disturbance on carbon cycling, we examined soil labile organic carbon (LOC) in a Canopy Trimming Experiment (CTE) located in the Luquillo Experimental Forest of Puerto Rico. We trimmed tree canopy and deposited debris (CTDD) on the forest ground of the treatment plots in December 2014, and collected floor mass samples and 0-10 cm soil samples three weeks before the treatment, as well as at scheduled intervals for 120 weeks after the treatment. Within the first week following the CTDD treatment, the mean soil microbial biomass carbon (MBC) and soil LOC in the CTDD plots were significantly greater than in the control plots (soil MBC: 2.56 g/kg versus 1.98 g/kg, soil LOC: 9.16 g/kg versus 6.44 g/kg, respectively), and the mean turnover rates of soil LOC in the CTDD plots were significantly faster than in the control plots. The measured indices fluctuated temporally more in the CTDD plots than in the control plots, especially between the 12th and 84th week after the CTDD treatment. The treatment effect on soil LOC and its turnover rate gradually disappeared after the 84th week following the treatment, while higher levels of soil MBC in the CTDD plots than in the control plots remained high, even at the 120th week. Our data suggest that hurricane disturbance can accelerate the cycling of soil LOC on a short temporal scale of less than two years, but might have a longer lasting effect on soil MBC in a tropical wet forest.

On the Shoulders of Giants: Continuing the Legacy of Large-Scale Ecosystem Manipulation Experiments in Puerto Rico

“…Debris addition temporarily increased tree basal area [49]. Data also suggest that hurricane disturbance can accelerate the cycling of soil labile organic carbon on a short temporal scale of less than two years [82]. In addition, scientists found that both surface-(0-10 cm) and subsoils (50-80 cm) have the potential to significantly increase carbon and nutrient storage a decade after the sudden deposition of disturbance-related organic debris, suggesting Luquillo Experimental Forest soils can serve as sinks of carbon and nutrients derived from disturbance-induced pulses of organic matter [83].…”

The effects of Hurricane Otto on the soil ecosystems of three forest types in the Northern Zone of Costa Rica

“…Tropical forest hurricanes rapidly deposit large amounts of leaf litter and woody debris from the canopy to the forest floor [4] , [5], [6], [7], which then results in short to long-term changes to the forest structure and forest ecological processes [4] associated with the rapid increase in the C and N nutrients [8], [9], [10], [11]. This increase in nutrients and enhancement of the ecological processes are thought to influence the soil microbial communities [12], [13], yet, very little is known about how hurricanes influence these communities.…”

“…In field experiments in which canopy material was cut and dropped to the forest floor to simulate the effects of a hurricane, nutrient pulses of more labile forms of C, N and phosphorus derived from the younger leaf litter from the canopy were processed in the first year post deposition of material [4][6] [9] [10] [16] [17]. Following this, Liu et al ( [10]) showed the initial pulse of labile organic C and nutrient turnover rate in the forest soil lasted from about the first week to about 2 years. They also showed there was an elevation of the soil microbial biomass that lasted from week 1 until at least 120 weeks after deposition of the canopy material.…”

“…Others have shown an increases in soil C, microbial biomass C and N between sites with experimentally deposited leaf litter and CWD, also between these sites by season, and beneath and in close proximity to the larger CWD from the experimental vegetation deposition as compared to the soil more distant to the CWD [9] [15]. Another study showed there was an initial (1 week post experimental deposition of leaf litter and CWD) to longer-term (120 weeks post-deposition) increase in microbial biomass C occurring in the leaf litter of the forest floor during the experiment [10]. In a review by Lugo [8], the idea that the extensive defoliation of young leaf material and its deposition on the forest floor also is thought to enhance early N cycle activity, and perhaps results in changes in the associated soil microbial communities.…”

“…Based on the previous literature [4][5][6][7][8][9][10][11], we predicted that the likely deposition of fresh leaf litter and excessive woody debris deposited on the forest floor during Hurricane Otto would result in increased levels of inorganic N and C biomass, as indicators of enhanced microbial activity involved in the decomposition and incorporation of the extra C and N material into the forest biota, and would be associated with an increase in the abundance of the microbes associated with these activities.…”