Hurricane disturbance in a temperate deciduous forest: patch dynamics, tree mortality, and coarse woody detritus

Patch dynamics, tree injury and mortality, and coarse woody detritus were quantified to examine the ecological impacts of Hurricane Fran on an oak-hickory-pine forest near Chapel Hill, NC. Data from long-term vegetation plots (1990–1997) and aerial photographs (1998) indicated that this 1996 storm caused patchy disturbance of intermediate severity (10–50% tree mortality; Woods, J Ecol 92:464–476, 2004). The area in large disturbance patches (>0.1 ha) increased from <1% to approximately 4% of the forested landscape. Of the forty-two 0.1-ha plots that were studied, 23 were damaged by the storm and lost 1–66% of their original live basal area. Although the remaining 19 plots gained basal area (1–15% increase), across all 42 stands basal area decreased by 17% because of storm impacts. Overall mortality of trees >10 cm dbh was 18%. The basal area of standing dead trees after the storm was 0.9 m²/ha, which was not substantially different from the original value of 0.7 m²/ha. In contrast, the volume and mass of fallen dead trees after the storm (129 m³/ha; 55 Mg/ha) were 6.1 and 7.9 times greater than the original levels (21 m³/ha; 7 Mg/ha), respectively. Uprooting was the most frequent type of damage, and it increased with tree size. However, two other forms of injury, severe canopy breakage and toppling by other trees, decreased with increasing tree size. Two dominant oak species of intermediate shade-tolerance suffered the largest losses in basal area (30–41% lost). Before the storm they comprised almost half of the total basal area in a forest of 13% shade-tolerant, 69% intermediate, and 18% shade-intolerant trees. Recovery is expected to differ with respect to vegetation (e.g., species composition and diversity) and ecosystem properties (e.g., biomass, detritus mass, and carbon balance). Vegetation may not revert to its former composition; however, reversion of biomass, detritus mass, and carbon balance to pre-storm conditions is projected to occur within a few decades. For example, the net change in ecosystem carbon balance may initially be negative from losses to decomposition, but it is expected to be positive within a decade after the storm. Repeated intermediate-disturbance events of this nature would likely have cumulative effects, particularly on vegetation properties.     

Posthurricane Seedling Structure in a Multi‐aged Tropical Dry Forest: Implications for Community Succession

Hurricane‐caused tree mortality in tropical dry forests occurs predominantly in early successional species. Consequently, hurricanes may accelerate succession in these forests. Forest regeneration, however, must be measured over an extended posthurricane time period to demonstrate this pattern. In this study, we recorded tree seedlings in 19 Florida Keys forests during May–August 1995, 3 years after Hurricane Andrew. For these forests—spanning a chronosequence from 14 to over 100 years since the most recent clearing—we used weighted averaging regression on relative abundances of pre‐hurricane trees to calculate a successional age optimum for each species; and used weighted averaging calibration to calculate inferred successional ages for stands based on pre‐hurricane trees and on posthurricane seedlings. To test the hypothesis that successional stage of seedlings exceeded successional stage of pre‐hurricane trees, we compared inferred stand ages based on posthurricane seedlings with those based on pre‐hurricane trees. Across the study area, inferred stand ages based on posthurricane seedlings were greater than those based on pre‐hurricane trees (P < 0.005); however, more seedlings in the youngest stands were early successional than in older stands. Of 29 species present both as pre‐hurricane trees and posthurricane seedlings, 23 had animal‐dispersed seeds. These results provide evidence that: (1) hurricanes do not ‘reset’ succession, and may accelerate succession; and (2) a strong legacy of stand successional age influences seedling assemblages in these forests.     

Hurricane Gilbert and structural changes in a tropical forest in south-eastern Mexico

This paper describes structural change and damage to the natural tree vegetation in the Dr Alfredo Barrera Marín Botanical Garden, following Hurricane Gilbert in September, 1988. Post-hurricane data were compared with pre-hurricane data from the same plots, focusing mainly on composition and structure. Near complete defoliation of trees and plants of the understorey occurred and average foliage loss was estimated to be 4.5 t/ha. The density of trees decreased by 33%, and the basal area decreased by 12%. Small diameter trees accounted for the great majority of losses and trees in the largest diameter classes survived best. The average height of trees in the lower canopy decreased by 6% and for those in the upper canopy by 9%. The frequency of understorey plants decreased by 51% and their cover decreased by 70%. Floristic richness decreased only slightly after the hurricane.     

Effects of land use history on hurricane damage and recovery in a neotropical forest

Prior land-use history might influence damage and recovery of plant communities from natural disturbance. We examined effects of previous agricultural land use on damage and recovery of plant communities affected by Hurricane Georges. The study was conducted in the karst region of Los Haitises National Park, Dominican Republic. We compared pre- and post-hurricane stem density, basal area and diversity of woody vegetation in sites within the park that had been subject to different land use histories. The type of land uses included a wide range of histories, ranging from abandoned pastures and conucos (mixed plantings) to cacao plantations, intact forests and mogotes (hilltop communities) with no recent history of land use. Previous land use and the amount of basal area present prior to the hurricane determined effects of, and recovery from hurricane disturbance. Systems with high pre-hurricane basal area lost many large trees, whereas the basal area hardly changed in systems without large trees. Thus, basal area decreased at forested sites, mogotes, and cacao plantations and remained comparable to pre-hurricane figures in all other land uses. Shifts in species diversity paralleled to some degree reductions in basal area. Species diversity increased in mogotes and cacao plantations, perhaps as a result of hurricane damage to the forest canopy, which facilitated regeneration of heliophilic species. Finally, regeneration of cacao seedlings in former cacao plantations, and growth of pioneer species in young conucos (mixed plantings) more than doubled post-hurricane stem densities for these two types of land use. Previous agricultural land use left a lasting impression on the structure and composition on plant communities, which persisted even after hurricane damage. This revised version was published online in June 2006 with corrections to the Cover Date.     

The Influence of Hurricane Winds on Caribbean Dry Forest Structure and Nutrient Pools1

In 1998, we measured the effects of Hurricane Georges after it passed over long‐term research sites in Puerto Rican dry forest. Our primary objectives were to quantify hurricane effects on forest structure, to compare effects in a large tract of forest versus a series of nearby forest fragments, to evaluate short‐term response to hurricane disturbance in terms of mortality and sprouting, and to assess the ability of hurricanes to maintain forest structure. We sampled damage from 33 plots (1.3 ha) across a 3000‐ha tract of forest as well as in 19 fragments. For stems with 2.5‐cm minimum diameter, 1004 stems/ha (12.4%) suffered structural damage, while 69 percent of the undamaged stems were at least 50 percent defoliated. Basal area lost to structural damage equaled 4.0 m²/ha (22%) in south‐facing native forests. Structural damage and defoliation increased with stem diameter and were more common in certain dry forest species. South‐facing forests and those on ridgetops incurred more damage than north‐facing forests or those comprised primarily of introduced species. Stem mortality was only 2 percent of all stems after 9 mo. Structural damage did not necessarily result in stem mortality. Hurricane‐induced mortality was not associated with stem height or diameter, but was ten times greater than background mortality. Basal sprouting was proportional to the amount of structural damage incurred in a stand. Forest fragments experienced the same patterns of hurricane effects as the reference forest. The low, dense structure of Caribbean dry forest can be maintained by hurricane damage to larger stems and induction of basal sprouting to generate multistemmed trees.     

Factors Affecting Mortality and Resistance to Damage Following Hurricanes in a Rehabilitated Subtropical Moist Forest1

The ability to resist hurricane damage is a property of both individuals and communities, and can have strong effects on the structure and function of many tropical forests. We examined the relative importance of tree size, species, biogeographic origin, local topography, and damage from previous storms in long‐term permanent plots in a rehabilitated subtropical moist forest in Puerto Rico following Hurricane Georges in order to better predict patterns of resistance. Severe damage included uprooted trees, snapped stems, or crowns with greater than 50 percent branch loss. Hurricane induced mortality after 21 mo was 5.2 percent/yr, more than seven times higher than background mortality levels during the nonhurricane periods. Species differed greatly in their mortality and damage patterns, but there was no relationship between damage and wood density or biogeographic origin. Rather, damage for a given species was correlated with mean annual increment, with faster growing species experiencing greater damage, suggesting that growth rate may reflect a variety of life history tradeoffs. Size was also predictive of damage, with larger trees suffering more damage. Trees on ridges and in valleys received greater damage than trees on slopes. A strong relationship was noted between previous hurricane damage and present structural damage, which could not solely be explained by the patterns with size and species. We suggest that resistance of trees to hurricane damage is therefore not only correlated with individual and species characteristics but also with past disturbance history, which suggests that in interpreting the effects of hurricanes on forest structure, individual storms cannot be treated as discrete, independent events.     

Tree diversity in primary forest and different land use systems in Central Sulawesi,Indonesia

We studied the tree communities in primary forest and three different land use systems (forest gardens, ca. 5-year-old secondary forests, cacao plantations) at 900–1200 m elevation in the environs of Lore Lindu National Park, Central Sulawesi. The primary forests had ca. 150 tree species 10 cm diameter at breast height (dbh) per hectare, which is unusually high for forests at this elevation in southeast Asia. Basal area in the primary forest was 140 m² ha^–1, one of the highest values ever recorded in tropical forests worldwide. Tree species richness declined gradually from primary forest to forest gardens, secondary forests, and cacao plantations. This decline was paralleled by shifts in tree family composition, with Lauraceae, Meliaceae, and Euphorbiaceae being predominant in primary forests, Euphorbiaceae, Rubiaceae and Myristicaeae dominating in the forest gardens and Euphorbiaceae, Urticaceae, and Ulmaceae in the secondary forests. Cacao plantations were composed almost exclusively of cacao trees and two species of legume shade trees. Forest gardens further differed from primary forests by a much lower density of understorey trees, while secondary forests had fewer species of commercial interest. Comparative studies of birds and butterflies demonstrated parallel declines of species richness, showing the importance of trees in structuring tropical forest habitats and in providing resources.     

Dynamics of a dry forest fragment after the exclusion of human disturbance in southeastern Brazil

Changes in the structure and composition of a dry forest fragment were described for a 4-yr period (1994–1998) in the southeastern Brazil (19°12′05″ S and 47°08′02″ W). This is the first dynamic study of a vanishing type of dry forest, which grows on base-rich soils originating from the basalt bedrock of western Minas Gerais State. A survey of trees ≥ 3.2 cm dbh (diameter at breast height, or 1.30 m) was conducted in 26 transects of 50 m × 6 m (0.78 ha). The species were classified into three regeneration guilds – pioneer, light-demanding and shade-tolerant – on the basis of others studies and personal observation. There was a decrease of 10.1% in the number of trees between 1994 and 1998. However, the basal area had an increase of 1.5% in the same period. Size class distributions in 1994 and 1998 were significantly different. The smallest trees (diameter < 10 cm) had the highest mortality rates. Although stand composition showed little change, a few species showed significant imbalance between recruitment and mortality. The studied fragment had mortality (2.3% yr^–1) and recruitment (1.6% yr^–1) rates similar to other tropical rain forests for trees ≥ 10 cm dbh. The present fragment of forest (turnover time = 39.5 yr, at cut level 10 cm dbh) lies among the most dynamic tropical forests. The main compositional changes were the increase of shade-tolerant trees and decline of pioneer species. The changes in composition and structure over the survey period may reflect the recovery of the forest after 4 yr of conservation. This revised version was published online in June 2006 with corrections to the Cover Date.     

Vulnerability to strong winds for major tree species in a northern Japanese mixed forest: analyses of historical data

This study examined historical census data to evaluate the vulnerability of major tall-tree species in northern Japan to strong winds. Intensive data, which measured more than 20,000 damaged trees (defined as trees that were killed or lost their major crown) in >500 ha of a natural mixed forest, were collected immediately after a severe typhoon in 1954. More than half of the damaged trees had been uprooted, and the negative size-dependency was found for the proportion of uprooting throughout species. Simple correlation analyses with respect to the averaged species-specific characteristics suggested that tree species with a high crown-depth/height tended to uproot (against to stem breakage) in a size-class with diameter at breast height 30–50 cm. Although the census data had yielded no information about non-damaged trees, the estimation of pre-disturbed stand (based on 63 1-ha plot data together with aerial photographs and GIS) revealed that the observed damage reached ca. 25% in terms of basal area. The proportion of damaged trees seemed to be doubled among species (15–42% in basal area). A higher proportion of uprooting, which indicates a large supply of tip-up mounds, and mixture of less vulnerable species, might contribute to recovery process after a wind disturbance in this type of mixed forests.     

Responses of the mangrove fern <Emphasis Type="Italic">Acrostichum danaeifolium</Emphasis> Langsd. &; Fisch. (Pteridaceae,Pteridophyta) to disturbances resulting from increased soil salinity and Hurricane Georges at the Jobos Bay National Estuarine Research Reserve,Puerto Rico

Mortality of plants in a mangrove forest dominated by the tree Avicennia germinans began to appear at the southern coastal edge of the forest in the central watershed of the Jobos Bay National Estuarine Research Reserve in Puerto Rico in 1977. The dieback was attributed to salinities in excess of 70 ppt and gradually continued north until some tree mortality was observed in 1995 at the forest’s landward interface with agricultural land. Mortality of the common understory mangrove fern Acrostichum danaeifolium occurred at a much slower rate than tree mortality. Remediation at the forest’s edge was recommended in 1997 and a study to monitor A. danaeifolium at 4-month intervals was begun in January 1998 to determine how the ferns would respond to hydrologic change. Hurricane Georges passed over the reserve in September 1998, so the effects of this disturbance were assessed as well. In May 1998, 4 months after tagging individual plants, the mean number of leaves plant⁻¹ at the impact site was only half that for plants in a control area in the nearby undisturbed eastern watershed. Fertile (spore-bearing) leaf production in both watersheds was very low accounting for plant fertility of 7% or less. Short leaf lengths in the impact site combined with smaller plant leaf counts and much lower leaf production rates in one area of the impact site had resulted in biomass production at the control site that was 18 times greater than in the impact site. After Hurricane Georges plant mortality in the impact area increased with individuals of A. danaeifolium found dead on every monitoring date except September 1999. However, when means for all variables measured in both sections of the forest were compared within 8 months after the hurricane there was an increase in all growth characteristics except sterile leaf length. Relative plant fertility increased from 10% before the hurricane to over 50% by May 2000. The fertile leaf production rate of these plants increased nine-fold by May 1999, and though it declined slowly thereafter it was still almost three time pre-hurricane levels at the end of the study almost 2 years later. Biomass production rates, though very low in the 4 months after the hurricane, had increased to five times pre-hurricane levels by the end of the study in January 2001. Efforts at remediation of the hypersaline conditions that were completed in May 1999 at the landward edge of the impact area appeared to have little effect on the ferns. For A. danaeifolium, plant mortality and decreases in plant size characteristics were the most notable responses to high salinity levels. In contrast, increases in fertile leaf and biomass production rates were the most significant response to hurricane disturbance.     

Effects of a Hurricane Disturbance on Aboveground Forest Structure, Arbuscular Mycorrhizae and Belowground Carbon in a Restored Tropical Forest

To better understand how management and restoration practices influence the response of terrestrial ecosystems to large-scale disturbances, it is critical to study above- and belowground effects. In this study, we examined the immediate effect of a major hurricane on aboveground forest structure, arbuscular mycorrhizae (AM) and belowground carbon pools in experimentally thinned plots in a tropical forest. The hurricane occurred five years after a thinning treatment, when thinned plots had similar aboveground carbon stocks but different forest structure compared to control plots. Thinned plots had more large diameter (>10 cm) trees compared to the control plots, which were characterized by a higher density of small diameter (<10 cm) trees. Despite pre-hurricane differences in forest structure, there were no significant differences between treatments in changes of canopy openness or number of affected trees following the hurricane. Thinned plots had larger belowground carbon pools than the controls plots before the hurricane, and these differences remained after the hurricane despite rapid decomposition of organic matter rich in nitrogen. There were no pre-hurricane differences in AM fungal spores or total AM root colonization. The hurricane reduced AM sporulation by nearly 50% in both treatments, yet we observed a significant increase in AM root colonization after the hurricane with greater AM colonization in the thinned plots. Hurricanes have well-known visible aboveground effects, but here we showed that less visible belowground effects are influenced by forest management and may play an important role in forest recovery.     

Tree species composition and diversity of tropical mountain cloud forest in the Yunnan, southwestern China

Species composition, physiognomy, and plant diversity of the less known cloud forests in Yunnan were studied based on data collected from 35 sample plots at seven sites. In floristic composition, the cloud forests are mainly comprised of Fagaceae, Ericaceae, Vacciniaceae, Aceraceae, Magnoliaceae, Theaceae, Aquifoliaceae, Illiciaceae, Lauraceae, and Rosaceae. Physiognomically, the forests are dominated by tree and shrub species. Lianas are rare in the forests. The plants with microphyllous or nanophyllous leaves comprise 44.32–63.46% of the total species, and plants with an entire leaf margin account for more than 50% of the tree and shrub species. There are few tree and shrub species with a drip tip leaf apex and papery leaves. Evergreen species make up more than 75% of the total tree and shrub species. In a 2,500 m² sampling area, the number of vascular species ranged between 57 and 110; Simpson’s diversity index ranged from 0.7719 to 0.9544, Shannon–Winner’s diversity index from 1.8251 to 3.2905, and Pielou’s evenness index from 0.5836 to 0.8982 for trees. The cloud forests in Yunnan are physiognomically similar to the tropical cloud forests in America and Southeast Asia. They very much resemble the mountain dwarf mossy forest in Hainan Island, southeastern China, and the Mountain ericaceous forests in the Malay Peninsula. The cloud forests in Yunnan are considered to be developed, as are the tropical upper montane cloud forests in Asia.     

Spatio‐temporal Analysis of the Effects of Hurricane Ivan on Two Contrasting Epiphytic Orchid Species in Guanahacabibes,Cuba

Hurricanes represent the dominant type of disturbance in many tropical coastal forests. Here, we focus on mortality of epiphytic orchids caused by hurricane Ivan in the Guanahacabibes National Park (Cuba) and subsequent population recovery. We analyzed different aspects of hurricane damage on two contrasting epiphytic orchids, Broughtonia cubensis and Dendrophylax lindenii, as observed in three plots of coastal vegetation and in three plots of semi‐deciduous forest, respectively. First, we quantified the damage to host trees and orchids and explored if hurricane damage depended on height, size, or identity of the host tree. Second, we used mark connection and mark correlation functions to conduct a detailed analysis of small‐scale spatial patterns in hurricane damage for host trees and orchids. Finally, we analyzed the degree of recovery after Ivan during the 6 yr following the storm. Damage of B. cubensis host trees was independent of height and size, but Ivan severely affected larger and higher host trees of D. lindenii. Spatial analysis revealed non‐random structure in damage that differed between species. Broughtonia cubensis exhibited small‐scale spatial correlation in the proportion of damaged orchids, whereas D. lindenii did not. Dendrophylax lindenii showed ‘patchy’ damage patterns, correlated with height, but B. cubensis did not. The relative growth rate of B. cubensis for the 5–17 mo following Ivan was only moderately reduced and fully recovered in subsequent years, whereas that of D. lindenii was severely reduced the first year and did not fully recover thereafter. We hypothesize that differences in the host, vegetation type, and the traits of the two orchids contribute to the different responses to the hurricane.     

High litterfall in old-growth and secondary upper montane forest of Costa Rica

Tropical upper montane forests usually comprise trees of small stature with a relatively low aboveground productivity. In contrast to this rule, in the Cordillera de Talamanca (Costa Rica), tall trees (>35 m in height and more than 60 cm in diameter) are characteristic for the upper montane old-growth oak forests which are growing at an altitude of almost 3,000 m close to the alpine timberline. For these exceptional forests, productivity data are not yet available. In this study, we analyzed litterfall and its components (tree leaves, litter of epiphytic vascular and non-vascular plants, mistletoes, twigs and other canopy debris) in three forest stands belonging to different successional stages and related seasonal changes in litterfall to micrometeorological variables. The studied stands were early-successional forest (10–15-year-old), mid-successional forest (40-year-old), and old-growth forest. The stands are dominated by Quercus copeyensis and are located at 2,900-m altitude. Total litterfall was highest in the mid-successional forest (1,720 g m⁻² y⁻¹), and reached 1,288 g m⁻² y⁻¹ in the old-growth forest and 934 g m⁻² y⁻¹ in the early-successional forest. Litter mass was dominated by leaves in all stages (56–84% of total litterfall). In the old-growth forest, however, twigs and small canopy debris particles (33%), epiphytes (6%), and mistletoes (5%) also contributed substantially to litter mass. Leaf litterfall showed a clear seasonal pattern with a negative correlation to monthly precipitation and highest values in the dry season (January–April). However, the strongest correlation existed with minimum air temperature (negative), probably because temperatures already dropped at the end of the rainy season, when precipitation had not yet declined and leaf shedding already increased. In contrast, litterfall of epiphyte mass, and twigs and other debris was mostly dependent on occasional strong winds. We conclude that the upper montane oak forests of the Cordillera de Talamanca are exceptional with respect to the large tree size and the relatively high productivity as indicated by litterfall. Litter mass was especially high in the mid-successional and old-growth forests, where the observed annual totals are among the highest recorded for tropical forests so far.     

Effects of Hurricane Andrew on stands of slash pine (Pinus elliottii var. densa) in the everglades region of south Florida (USA)

Few hurricanes affect intact stands of subtropical pines. We examined effects of winds in the eyewalls of Hurricane Andrew, where wind speeds were >200 km h^–1, on all remaining large mainland stands of Pinus elliottii var. densa (south Florida slash pine) on limestone outcroppings (rocklands) in the everglades region of southern Florida. We measured densities and sizes of trees and assessed damage and mortality in plots in old-growth stands in the Lostman's Pines (LOP) region of Big Cypress National Preserve and in second-growth stands in the Pines West (PIW) and Long Pine Key (LPK) regions of Everglades National Park. We also examined age-size relationships using sections from trees killed by the hurricane in LOP and LPK. We used the data to predict effects of recurrent hurricanes on the structure and dynamics of the old-growth stand and to compare effects of hurricanes on old- and second-growth stands.Slash pine was resistant to hurricane winds. Most trees in stands (68–76%) were not severely damaged; mortality in the three regions averaged 17–25% shortly after the hurricane and 3–7% during the following year. Mortality was positively associated with tree size; mean tree sizes decreased and size-selective thinning occurred in all stands. Nonetheless, local mortality ranged from 3–4% to 50–60% among plots in all stands. Such local variation in mortality resulted from clustering of large trees, especially in old-growth stands, and from microbursts during the hurricane, which affected all stands. Recurrent, intense hurricanes are predicted to kill larger trees, slowly opening new patches and increasing sizes of extant patches, thus resulting in almost continual presence of openings suitable for recruitment in old-growth stands. Age-size relationships also indicated that large trees in old-growth stands may survive 2–3 centuries. The combination of frequent openings and wind resistance of large trees is predicted to result in old-growth stands that are highly uneven aged, with trees locally distributed in similar-aged patches. The extent to which such stands deviate from demographic equilibrium, as well as turnover rates within stands, are likely to increase as the frequency of recurrent, intense hurricanes increases.Damage and mortality differed in old- and second-growth stands. Large trees were more, but small trees less likely to be damaged in old- than second-growth stands. In contrast, mortality was significantly lower in old- (LOP: 16.9% ± 3.1 [mean ± s.e.]) than second-growth stands (PIW: 22.5% ± 2.0; LPK: 25.2% ± 2.7). Total hurricane-related mortality was 30–60% higher in second- than old-growth stands. Size class structure, more uneven in old- than second growth stands prior to the hurricane, diverged even more afterwards. Hurricane Andrew removed     

A Flood Plain Palm Forest in the Luquillo Mountains of Puerto Rico Five Years After Hurricane Hugo1

Long-term studies are needed to understand the dynamics of tropical forests, particularly those subject to periodic disturbances such as hurricanes. We studied a flood plain Prestoea montana palm forest in the Luquillo Mountains of Puerto Rico over a 15-yr period (1980–1995), which included the passage of Hurricane Hugo in September 1989. The passage of the hurricane caused the dominant species to become more dominant and created low instantaneous tree mortality (1% of stems) and reductions in tree biomass (-16 Mg/ha/yr) and density, although not in basal area. Five years after the hurricane, the palm flood plain forest had exceeded its prehurricane aboveground tree biomass, tree density, and basal area. Aboveground tree biomass accumulated at a rate of 9.2 Mg/ha/yr, 76 percent of which was due to palms. Before the hurricane this rate was on the order of 3 Mg/ha/yr. Forest floor litter decreased to prehurricane levels (6.7 Mg/ha), within 5 yr, mostly due to the disappearance of woody litter. Thirteen tree species not represented in the canopy entered the forest by regeneration, and 2 species suffered almost 20 percent/yr mortality over a 5-yr period after the storm (floodplain average of 2%/yr). Delayed tree mortality was twice as high as instantaneous tree mortality after the storm and affected dicotyledonous trees more than it did palms. Regencration of dicotyledonous trees, palms, and tree ferns was influenced by a combination of factors including hydroperiod, light, and space. Redundancy Data Analysis showed that the area near the river channel was the most favorable for plant regeneration. Palm regeneration was higher in locations with longer hydroperiods, while regeneration of dicotyledonous trees was higher in areas with low risk of flooding. This study shows how a periodic disturbance provides long-term opportunities for species invasions and long-term ecosystem response at the patch scale of < 1 ha.     

Belowground nitrogen dynamics in relation to hurricane damage along a tropical dry forest chronosequence

Understanding and predicting the responses of plant communities to multiple overlapping disturbances remains a challenging task. Hurricane Wilma represents a large, yet infrequent type of disturbance that was superimposed on an existing disturbance gradient of time since fire. We examined disturbance and recovery patterns in response to these overlapping disturbances by measuring how canopy structure, fine roots, mycorrhizae, and soil nitrogen dynamics, varied along a fire chronosequence in the 2 years after Hurricane Wilma. Hurricane damage increased canopy openness in all seral stages. In the early-seral stage, canopy openness returned to pre-hurricane conditions within 2 years, whereas canopy openness in the late-seral stage remained significantly higher throughout the study. We observed no significant change in root length density in the early- and mid-seral stages. However, in the late-seral stage, root length density was significantly reduced immediately after the hurricane and remained so 2 years after the hurricane. In the late-seral stage, we also observed a significant reduction in percent soil nitrogen and a significant increase in soil nitrogen isotopic composition (δ¹⁵N) values, indicating a loss of soil nitrogen. In contrast, in the early- and mid-seral stages, there were no significant changes in percent nitrogen or soil δ¹⁵N values. Results from this study suggest that forest fire disturbance history influences responses to hurricane damage. Moreover, feedbacks between aboveground and belowground processes have the potential to influence forest recovery.     

Invertebrate communities in a tropical rain forest canopy in Puerto Rico following Hurricane Hugo

1. Canopy invertebrate responses to Hurricane Hugo, tree species, and recovery time were examined at the Luquillo Experimental Forest in Puerto Rico during 1991–92 and 1994–95. Six tree species representing early and late successional stages were examined in paired plots representing severe hurricane disturbance (most trees toppled) and light hurricane disturbance (all trees standing and most branches intact). 2. Hurricane disturbance affected invertebrate abundances significantly. Sap-suckers and molluscs were more abundant, and defoliators, detritivores, and emergent aquatic insects were less abundant in recovering tree-fall gaps than in intact forest during this 5-year period. These changes in functional organisation are consistent with comparable studies of arthropod responses to canopy removal during harvest in temperate forests. 3. Tree species also affected invertebrate abundances significantly, but invertebrate communities did not differ significantly between the three early successional and three later successional tree species. 4. Most taxa showed significant annual variation in abundances, but only two Homoptera species showed a significant linear decline in abundance through time, perhaps reflecting long-term trends during recovery. 5. Leaf area missing, an indicator of herbivore effect on canopy processes, showed significant seasonal and annual trends, as well as differences among tree species and hurricane treatments. Generally, leaf area missing peaked during the wet season each year, but reached its highest levels during an extended drought in 1994. Leaf area missing also tended to be higher on the more abundant tree species in each disturbance treatment. 6. Herbivore abundances and leaf area missing were not related to concentrations of nitrogen, phosphorous, potassium, or calcium in the foliage. 7. This study demonstrated that invertebrate community structure and herbivory are dynamic processes that reflect the influences of host species and variable environmental conditions.     

Structural response of Caribbean dry forests to hurricane winds: a case study from Guánica Forest, Puerto Rico

Aim Tropical dry forests in the Caribbean have an uniquely short, shrubby structure with a high proportion of multiple‐stemmed trees compared to dry forests elsewhere in the Neotropics. Previous studies have shown that this structure can arise without the loss of main stems from cutting, grazing, or other human intervention. The Caribbean has a high frequency of hurricanes, so wind may also influence forest stature. Furthermore, these forests also tend to grow on soils with low amounts of available phosphorus, which may also influence structure. The objective of this study was to assess the role of high winds in structuring dry forest, and to determine whether soil nutrient pools influence forest response following hurricane disturbance. Location Guánica Forest, Puerto Rico. Methods Over 2000 stems in five plots were sampled for hurricane effects within 1 week after Hurricane Georges impacted field sites in 1998. Sprout initiation, growth, and mortality were analysed for 1407 stems for 2 years after the hurricane. Soil nutrient pools were measured at the base of 456 stems to assess association between nutrients and sprout dynamics. Results Direct effects of the hurricane were minimal, with stem mortality at < 2% and structural damage to stems at 13%, although damage was biased toward stems of larger diameter. Sprouting response was high – over 10 times as many trees had sprouts after the hurricane as before. The number of sprouts on a stem also increased significantly. Sprouting was common on stems that only suffered defoliation or had no visible effects from the hurricane. Sprout survival after 2 years was also high (> 86%). Soil nutrient pools had little effect on forest response as a whole, but phosphorus supply did influence sprout dynamics on four of the more common tree species. Main conclusions Hurricanes are able to influence Caribbean tropical dry forest structure by reducing average stem diameter and basal area and generating significant sprouting responses. New sprouts, with ongoing survival, will maintain the high frequency of multi‐stemmed trees found in this region. Sprouting is not limited to damaged stems, indicating that trees are responding to other aspects of high winds, such as short‐term gravitational displacement or sway. Soil nutrients play a secondary role in sprouting dynamics of a subset of species. The short, shrubby forest structure common to the Caribbean can arise naturally as a response to hurricane winds.     

High Mortality for Rare Species Following Hurricane Disturbance in the Southern Yucatán

Hurricanes are an important part of the natural disturbance regime of the Yucatán Peninsula with the potential to alter forest structure and composition, yet investigations of species‐level responses to severe winds are limited in this region. The effect of a category 5 hurricane (Hurricane Dean, 21 August 2007) on dry tropical forests across the southern Yucatán was examined with respect to tree damage, mortality, and sprouting. Damage was assessed 9–11 mo following the hurricane in 92 (500 m²) plots stratified by wind speed and normalized difference vegetation index (NDVI) change classes over a 25,000 km² study area. We investigated the relative importance of biotic (i.e., species, size, and wood density) and abiotic (i.e., wind speed) factors to better explain patterns of damage. Overall mortality was low (3.9%), however, mortality of less common species (8.5%) was elevated more than fourfold above that of 28 common species (1.8%), indicating immediate selective consequences for community composition. Species varied in the degree and type of damage experienced, with susceptibility increasing with tree diameter and height. Wood density influenced damage patterns only in areas where a critical threshold in storm intensity was exceeded (wind speeds ≥210 km/h). Although overall, damage severity increased with wind speed, common coastal species were more resistant to damage than species distributed farther inland. Our findings suggest that selective pressure exerted by frequent hurricane disturbance has, and will, continue to impact the floristic composition of forests on the Yucatán Peninsula, favoring certain wind‐resistant species. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .