Disentangling the long‐term effects of disturbance on soil biogeochemistry in a wet tropical forest ecosystem

Abstract

Climate change is increasing the intensity of severe tropical storms and cyclones (also referred to as hurricanes or typhoons), with major implications for tropical forest structure and function. These changes in disturbance regime are likely to play an important role in regulating ecosystem carbon (C) and nutrient dynamics in tropical and subtropical forests. Canopy opening and debris deposition resulting from severe storms have complex and interacting effects on ecosystem biogeochemistry. Disentangling these complex effects will be critical to better understand the long-term implications of climate change on ecosystem C and nutrient dynamics. In this study, we used a well-replicated, long-term (10 years) canopy and debris manipulation experiment in a wet tropical forest to determine the separate and combined effects of canopy opening and debris deposition on soil C and nutrients throughout the soil profile (1 m). Debris deposition alone resulted in higher soil C and N concentrations, both at the surface (0-10 cm) and at depth (50-80 cm). Concentrations of NaOH-organic P also increased significantly in the debris deposition only treatment (20-90 cm depth), as did NaOH-total P (20-50 cm depth). Canopy opening, both with and without debris deposition, significantly increased NaOH-inorganic P concentrations from 70 to 90 cm depth. Soil iron concentrations were a strong predictor of both C and P patterns throughout the soil profile. Our results demonstrate that both surface- and subsoils have the potential to significantly increase C and nutrient storage a decade after the sudden deposition of disturbance-related organic debris. Our results also show that these effects may be partially offset by rapid decomposition and decreases in litterfall associated with canopy opening. The significant effects of debris deposition on soil C and nutrient concentrations at depth (>50 cm), suggest that deep soils are more dynamic than previously believed, and can serve as sinks of C and nutrients derived from disturbance-induced pulses of organic matter inputs.

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

“…Chev., and Prestoea acuminata (Wildenow) H.E. Moore (=Prestoea montana (Graham) A. Henderson and G. Galeano) [31]. Mean air temperature was 24 °C [31], and mean annual precipitation was 3500 mm [32].…”

“…Moore (=Prestoea montana (Graham) A. Henderson and G. Galeano) [31]. Mean air temperature was 24 °C [31], and mean annual precipitation was 3500 mm [32]. Although this is a non-seasonal forest, there is typically a weak dry season from December to March [14].…”

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

“…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. The hurricaneinduced deposition of course woody debris (CWD) from the canopy caused an increased immobilization of the nutrients, resulting in a decreased availability of these for the food web [11] [18] [19] [17] [20], a slowing down decomposition activities in the forest soils [9].…”

“…There have been experimental studies that have shown the deposition of canopy material to the tropical forest floor, in a manner simulating the effects of a hurricane, result in nutrient pulses of more labile forms of C, N and phosphorus derived from the younger leaf litter from the canopy for about the first two years[4] [10] [14] [15] [16] [17]. This material is quickly processed within the first year [7] [11] [19], and is followed by utilization of the CWD deposited on the forest floor, resulting in a slower rate of processing activities [9] [11] [17] [18] [19][20].All these processes would be associated with the types of increases in inorganic N and Biomass C, and changes in the microbial communities that we observed in the forest soils after the…”

Characterization of Phosphorus in Subtropical Coastal Sand Dune Forest Soils

“…Several studies have characterized the P dynamics and distributions through either chemical sequential extraction or 31 P-NMR spectroscopy in tropical forests [24][25][26], subtropical forests [27,28], and temperate forests [4,23]. Negassa and Leinweber [29] indicated that only a few studies have characterized P in soils by comparing 31 P-NMR and sequential chemical extraction.…”