Estimating soil turnover rate from tree uprooting during hurricanes in Puerto Rico

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Abstract

Soil turnover by tree uprooting in primary and secondary forests on the island of Puerto Rico was measured in 42 study plots in the months immediately after the passage of a Category 3 hurricane. Trunk basal area explained 61% of the variability of mound volume and 53% of the variability of mound area. The proportion of uprooted trees, the number of uprooted trees, or the proportion of uprooted basal area explained 84–85% of the variation in hurricane-created mound area. These same variables explain 79–85% of the variation in mound volume. The study indicates that the soil turnover period from tree uprooting by Puerto Rican hurricanes is between 1600 and 4800 years. These rates are faster than soil turnover by landslides and background treefall in the same area and provide a useful age constraint on soil profile development and soil carbon sequestration in these dynamic landscapes.

Introduction

The uprooting of trees reallocates soil, biomass, carbon, and nutrients in forested watersheds (Gabet et al., 2003). Uprooting may be the most pervasive form of soil bioturbation (Mitchell, 1988). Uprooted trees bring buried nutrients, clasts and soil organic carbon to the surface, exposing them to atmospheric and surficial processes. Treethrow may increase mineral weathering processes and nutrient availability (Foster, 1988). By exposing material to aeration and erosion, it can influence the storage of carbon in soils, which globally contain 75% of the carbon in the terrestrial organic carbon pool and double the amount of carbon found in the atmosphere (Prentice, 2001). Thus, better quantitative estimates of bioturbation rates are needed to achieve an understanding of long-term terrestrial carbon dynamics (Gabet et al., 2003).

An element of this type of disturbance is mound-and-pit microtopography, which has interested scientists for at least 70 years (Lutz, 1940) because of its potential influence on soil formation, nutrient cycling, soil morphology, sediment movement, drainage patterns and forest ecology (Schaetzl et al., 1989). Mound-and-pit microtopography can influence species distributions (Putz et al., 1983), with some species favoring pits for establishment (Walker, 2000), while others favors mounds (Kabrick et al., 1997).

These processes have implications for forest soil development and forest management. Knowledge of uprooting susceptibility, such as by tree type or species, can yield informed decisions regarding reforestation and afforestation projects, including under the reducing emissions from deforestation in developing nations (REDD) structure of the proposed international climate treaty. Estimates of soil disturbance across a range of sites could complement existing literature on the proportion of trees uprooted by a hurricane or other disturbance event.

Reported mean areas of mounds and pits range from 1.5 m2 for pits in Kentucky (Cremeans and Kalisz, 1988) to 16 m2 for combined mound/pit complexes on Barro Colorado Island in Panama (Putz, 1983), with other estimates including 11.9 m2 for “soil disturbance” from 22 freshly uprooted maple and beech trees in Michigan (Brewer and Merritt, 1978); an average of 2.5 m2 for pits of various ages (n = 73) in a forested subalpine area of Colorado (Osterkamp et al., 2006); 8.8 m2 of “exposed soil and rock” per uprooted tree in the Luquillo Experimental Forest in Puerto Rico (Zimmerman et al., 1994); and 4.7–8 m2, depending on treefall type, for mounds in central New York forests (Beatty and Stone, 1986). These studies of mound formation, however, are applicable only to specific sites and are limited in applications beyond that forest stand.

Establishing the frequency of individual uprooting events, required when assessing soil turnover rate from uprooting, is especially challenging in tropical forests. While tree-ring cores can be used to estimate uprooting dates of many temperate species, tree-ring dating of tropical trees is limited and typically requires isotopic analysis (Evans and Schrag, 2004). However, an understanding of the return rate of catastrophic windthrow events, such as hurricanes, can help fill the knowledge gap about soil turnover processes in both tropical and temperate regions in the hurricane zone (Lugo, 2008). Furthermore, ongoing climate change may increase the frequency of uprooting events and soil turnover in hurricane-prone forests, as warming sea surface temperatures create conditions that increase wind velocity of hurricanes when other atmospheric factors do not intervene (Emanuel, 2005, IPCC, 2007).

This study quantifies the volume and area of soil uplifted by trees disturbed by the passage of Hurricane Georges over the Caribbean island of Puerto Rico, 21–22 September 1998. Our analyses focused on these questions: (1) How do the analyzed variables of individual trees and stands, landforms, and hurricane properties influence tree uprooting at the plot level? (2) How do these variables influence the quantity of soil uplifted by individual trees and at the plot level? (3) How does the rate of hurricane-induced soil turnover in Puerto Rico compare to other types of disturbance? To seek first-order principles that have applications at a variety of sites, more attention was given to finding broad similarities across heterogeneous sites than discerning small differences within or among sites or individual samples.

Section snippets

Study area

Puerto Rico is a 890,000-ha tropical island in the Greater Antilles chain of the West Indies, centered on approximately 18.5° North and 67° West. Approximately 60% of island area is classified (by Holdridge, 1967) as moist forest (1000–2000 mm rainfall annually), 25% as wet forest (2000–4000 mm), and 14% as dry forest (<1000 mm, Ewel and Whitmore, 1973). Extensive clearing for agriculture had reduced the island's forest cover to a low of about 12% by the late 1940s (Koenig, 1953). Since then,

Results

Of 42 study plots, approximately 40% did not include uprooted trees, two included landslides, and one showed evidence of recent surface fire. No pattern was discernable to explain why no trees uprooted in some plots, most of which were adjacent to plots in similar forest types with uproots. The eye of Hurricane Georges passed over about 40% of the plots, generally bringing higher rainfall (Fig. 1). About 64% of the plots were in subtropical wet forest and 64% contained predominantly broadleaf

Uprooting proportion

The proportion of uprooting was highly variable among the plots and supported other studies that indicate complex non-linear relationships between hurricane wind velocity and damage (Everham and Brokaw, 1996, Scatena et al., 2004). In general the proportion of uproots was greater in plots exposed to the hurricane eye than in plots away from the storm center.

Palms have a well-documented tendency to shed fronds early in a hurricane, which may help account for relatively low uprooting rates

Acknowledgements

The authors thank Ariel E. Lugo, D. Jean Lodge, Carlos Estrada and others at the International Institute of Tropical Forestry, the Long-Term Ecological Research program the Sabana Research Station for logistical support. Robert Segal provided valuable technical assistance in the field. Alex Arizpe provided assistance in the preparation of figures. Colleagues at the University of Arizona, including Steven Leavitt and Malcolm Hughes of the Laboratory of Tree-Ring Research and Phil Guertin of the

References (55)

  • S.P. Bennett et al.

    Hurricane Georges Preliminary Storm Report

    (1998)
  • R. Brewer et al.

    Wind throw and tree replacement in a climax beech-maple forest

    Oikos

    (1978)
  • Brown, S., Lugo, A.E., Silander, S., Liegel, L., 1983. Research History and Opportunities in the Luquillo Experimental...
  • D.W. Cremeans et al.

    Distribution and characteristics of windthrow microtopography on the Cumberland Plateau of Kentucky

    Soil Sci. Soc. Am. J.

    (1988)
  • Crow, T.R., Weaver, P.L., 1977. Tree growth in a moist tropical forest of Puerto Rico. Río Piedras, Puerto Rico. USDA...
  • J.B. Elsner et al.

    Hurricanes of the North Atlantic

    (1999)
  • K. Emanuel

    Increasing destructiveness of tropical cyclones over the past 30 years

    Nature

    (2005)
  • B.J. Enquist et al.

    Global allocation rules for patterns of biomass partitioning in seed plants

    Science

    (2002)
  • E.M. Everham et al.

    Forest damage and recovery from catastrophic wind

    Botan. Rev.

    (1996)
  • Ewel, J.J., Whitmore, J.L., 1973. The ecological life zones of Puerto Rico and the U.S. Virgin Islands. Rio Piedras,...
  • D.A. Falk et al.

    Cross-scale analysis of fire regimes

    Ecosystems

    (2007)
  • D.R. Foster

    Disturbance history, community organization and vegetation dynamics of the old-growth Pisgah Forest, southwestern New Hampshire, USA

    J. Ecol.

    (1988)
  • Franco, P.A., Weaver, P.L., Eggen-McIntosh, S., 1997. Forest Resources of Puerto Rico, 1990. USDA For. Serv. Resour....
  • J.L. Frangi et al.

    Hurricane damage to a flood plain forest in the Luquillo Mountains of Puerto Rico

    Biotropica

    (1991)
  • E.J. Gabet et al.

    The effects of bioturbation on soil processes and sediment transport

    Annu. Rev. Earth Planet. Sci.

    (2003)
  • M.R. Guariguata

    Landslide disturbance and forest regeneration in the upper Luquillo Mountains of Puerto Rico

    J. Ecol.

    (1990)
  • E.H. Helmer et al.

    Mapping the forest type and land cover of Puerto Rico, a component of the Caribbean biodiversity hotspot

    Caribbean J. Sci.

    (2002)
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    Present address: School of Natural Resources and the Environment, Biological Sciences East, University of Arizona, Tucson, AZ 85721, USA.

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