Temporal clustering of tropical cyclones on the Great Barrier Reef and its ecological importance

Tropical cyclones have been a major cause of reef coral decline during recent decades, including on the Great Barrier Reef (GBR). While cyclones are a natural element of the disturbance regime of coral reefs, the role of temporal clustering has previously been overlooked. Here, we examine the consequences of different types of cyclone temporal distributions (clustered, stochastic or regular) on reef ecosystems. We subdivided the GBR into 14 adjoining regions, each spanning roughly 300 km, and quantified both the rate and clustering of cyclones using dispersion statistics. To interpret the consequences of such cyclone variability for coral reef health, we used a model of observed coral population dynamics. Results showed that clustering occurs on the margins of the cyclone belt, being strongest in the southern reefs and the far northern GBR, which also has the lowest cyclone rate. In the central GBR, where rates were greatest, cyclones had a relatively regular temporal pattern. Modelled dynamics of the dominant coral genus, Acropora, suggest that the long-term average cover might be more than 13 % greater (in absolute cover units) under a clustered cyclone regime compared to stochastic or regular regimes. Thus, not only does cyclone clustering vary significantly along the GBR but such clustering is predicted to have a marked, and management-relevant, impact on the status of coral populations. Additionally, we use our regional clustering and rate results to sample from a library of over 7000 synthetic cyclone tracks for the GBR. This allowed us to provide robust reef-scale maps of annual cyclone frequency and cyclone impacts on Acropora. We conclude that assessments of coral reef vulnerability need to account for both spatial and temporal cyclone distributions.

     

Impact of cyclones on hard coral and metapopulation structure,connectivity and genetic diversity of coral reef fish

Cyclones have one of the greatest effects on the biodiversity of coral reefs and the associated species. But it is unknown how stochastic alterations in habitat structure influence metapopulation structure, connectivity and genetic diversity. From 1993 to 2018, the reefs of the Capricorn Bunker Reef group in the southern part of the Great Barrier Reef were impacted by three tropical cyclones including cyclone Hamish (2009, category 5). This resulted in substantial loss of live habitat-forming coral and coral reef fish communities. Within 6–8 years after cyclones had devastated, live hard corals recovered by 50–60%. We show the relationship between hard coral cover and the abundance of the neon damselfish (Pomacentrus coelestis), the first fish colonizing destroyed reefs. We present the first long-term (2008–2015 years corresponding to 16–24 generations of P. coelestis) population genetic study to understand the impact of cyclones on the meta-population structure, connectivity and genetic diversity of the neon damselfish. After the cyclone, we observed the largest change in the genetic structure at reef populations compared to other years. Simultaneously, allelic richness of genetic microsatellite markers dropped indicating a great loss of genetic diversity, which increased again in subsequent years. Over years, metapopulation dynamics were characterized by high connectivity among fish populations associated with the Capricorn Bunker reefs (2200 km²); however, despite high exchange, genetic patchiness was observed with annual strong genetic divergence between populations among reefs. Some broad similarities in the genetic structure in 2015 could be explained by dispersal from a source reef and the related expansion of local populations. This study has shown that alternating cyclone-driven changes and subsequent recovery phases of coral habitat can greatly influence patterns of reef fish connectivity. The frequency of disturbances determines abundance of fish and genetic diversity within species.

     

Relationship between tropical cyclones and the distribution of sea turtle nesting grounds

Aim This study examines the relationship between the distribution of existing sea turtle nesting sites and historical patterns of tropical cyclone events to investigate whether cyclones influence the current distribution of sea turtle nesting sites. The results, together with information on predicted cyclone activity and other key environmental variables, will help in the identification and prediction of future nesting sites for sea turtles as changes to the coastal environment continue. Location Queensland, Australia. Methods We used data on the nesting distribution of seven populations of four species of sea turtles [green (Chelonia mydas), flatback (Natator depressus), hawksbill (Eretmochelys imbricata) and loggerhead (Caretta caretta)] from the eastern Queensland coast, and tropical cyclone track data from 1969 to 2007 to explore the relationship between (1) sea turtle nesting phenology and cyclone season, and (2) sea turtle nesting sites and cyclone distribution. Furthermore, using two green turtle populations as a case study, we investigated the relationship between cyclone disturbance and sea turtle reproductive output, nesting site and season. Bootstrapping was used to explore if current sea turtle nesting sites are located in areas with lower or higher cyclone frequency than areas where turtles are currently not nesting. Results All populations of sea turtles studied here were disturbed by cyclone activity during the study period. The exposure (frequency) of tropical cyclones that crossed each nesting site varied greatly among and within the various sea turtle populations. This was mainly a result of the spatial distribution of each population’s nesting sites. Bootstrapping indicated that nesting sites generally have experienced lower cyclone activity than other areas that are available for nesting. Main conclusions Tropical cyclones might have been sufficiently detrimental to sea turtle hatching success on the eastern Queensland coast that through a natural selection process turtles in this region are now nesting in areas with lower cyclone activity. Therefore, it is important that future studies that predict climate or range shifts for sea turtle nesting distributions consider future cyclone activity as one of the variables in their model.     

Do Tropical Cyclones Shape Shorebird Habitat Patterns? Biogeoclimatology of Snowy Plovers in Florida

Background

The Gulf coastal ecosystems in Florida are foci of the highest species richness of imperiled shoreline dependent birds in the USA. However environmental processes that affect their macroecological patterns, like occupancy and abundance, are not well unraveled. In Florida the Snowy Plover (Charadrius alexandrinus nivosus) is resident along northern and western white sandy estuarine/ocean beaches and is considered a state-threatened species.

Methodology/Principal Findings

Here we show that favorable nesting areas along the Florida Gulf coastline are located in regions impacted relatively more frequently by tropical cyclones. The odds of Snowy Plover nesting in these areas during the spring following a tropical cyclone impact are seven times higher compared to the odds during the spring following a season without a cyclone. The only intensity of a tropical cyclone does not appear to be a significant factor affecting breeding populations.

Conclusions/Significance

Nevertheless a future climate scenario featuring fewer, but more extreme cyclones could result in a decrease in the breeding Snowy Plover population and its breeding range. This is because the spatio-temporal frequency of cyclone events was found to significantly affect nest abundance. Due to the similar geographic range and habitat suitability, and no decrease in nest abundance of other shorebirds in Florida after the cyclone season, our results suggest a common bioclimatic feedback between shorebird abundance and tropical cyclones in breeding areas which are affected by cyclones.     

Tropical Rain Forest Recovery from Cyclone Damage and Fire in Samoa1

In 1990 and 1991, Samoa was struck by two cyclones, Ofa and Val. In the Tafua Rain Forest Preserve on the island of Savai'i, one part of the forest also burned after the first cyclone. Here we report on patterns of regeneration and changes in tree species composition in the Tafua lowland rain forest after five years of recovery from cyclone and fire disturbance. In the unburned area, tree canopy cover increased from 27 percent after the last cyclone to 58 percent, and in the burned area from below 12 to 49 percent. Nine of the ten most common tree species decreased in relative abundance in the entire forest after the last cyclone. One fast growing pioneer species, Macaranga harveyana now makes up 42 percent of the total number of trees (>5 cm DBH) in the unburned area and 86 percent in the burned area. Large interspecific differences occur in size distribution and there are at least four distinguishable regeneration patterns, which may be related to shade tolerance. Mean number of species per plot was generally higher in the unburned area than in the burned area, while the Shannon evenness index was higher in the unburned than in the burned area only for trees above 1 cm DBH. Species with fruits known to be fed upon by birds and/or bats generally made up a larger proportion of all trees in the burned than in the unburned area. In contrast to other studies of post‐cyclone regeneration, in which recovery is often rapid due to resprouting of trees, recovery in the Tafua forest was a slow process with regeneration more dependent on vertebrate seed dispersal than on resprouting.     

Temporal Changes in Tree Species and Trait Composition in a Cyclone-prone Pacific Dipterocarp Forest

Our understanding of the effects of tropical cyclones on species composition and dynamics of forest communities is mainly derived from studies that have considered single cyclonic events. Here we examined changes in the tree species and functional trait composition in an 8-ha Dipterocarp forest at Palanan in the northeastern Philippines that is subject to a high frequency of cyclonic disturbance (1–4 cyclones annually). The plot has been censused four times over a 16-year interval allowing us to consider the medium-term forest dynamics in response to repeated cyclones. We hypothesized that as the forest community in Palanan has been selected under frequent disturbance by cyclones, it should show little functional change across the census intervals. We analyzed changes in demography, species composition, and community-weighted functional traits (specific leaf area, leaf area, wood density, and specific growth rate) across the censuses and compared these against cyclone intensities during the census intervals. Demographic changes across census years suggest that the community responded to cyclonic disturbances through substantial turnover in the small- and medium-size individuals, and that there has been an increase in plot-level stem density and basal area across the measured period. Trait compositional changes from 1994 to 2010 were mostly small, but indicate a shift towards species with larger leaves and faster growth rates—traits that are associated with fast recovery after disturbance. These changes all coincide with a large intense cyclone between the second and third censuses, suggesting that cyclone strength, more than cyclone frequency, affects this forest.     

Impacts of Different Grades of Tropical Cyclones on Infectious Diarrhea in Guangdong, 2005-2011

Objective

Guangdong province is one of the most vulnerable provinces to tropical cyclones in China. Most prior studies concentrated on the relationship between tropical cyclones and injuries and mortality. This study aimed to explore the impacts of different grades of tropical cyclones on infectious diarrhea incidence in Guangdong province, from 2005 to 2011.

Methods

Mann-Whitney U test was firstly used to examine if infectious diarrhea were sensitive to tropical cyclone. Then unidirectional 1:1 case-crossover design was performed to quantitatively evaluate the relationship between daily number of infectious diarrhea and tropical cyclone from 2005 to 2011 in Guangdong, China. Principal component analysis (PCA) was applied to eliminate multicollinearity. Multivariate logistic regression model was used to estimate the hazard ratios (HRs) and the 95% confidence intervals (CI).

Results

There were no significant relationships between tropical cyclone and bacillary dysentery, amebic dysentery, typhoid, and paratyphoid cases. Infectious diarrhea other than cholera, dysentery, typhoid and paratyphoid significantly increased after tropical cyclones. The strongest effect were shown on lag 1 day (HRs = 1.95, 95%CI = 1.22, 3.12) and no lagged effect was detected for tropical depression, tropical storm, severe tropical storm and typhoon, with the largest HRs (95%CI) of 2.16 (95%CI = 1.69, 2.76), 2.43 (95%CI = 1.65, 3.58) and 2.21 (95%CI = 1.65, 2.69), respectively. Among children below 5 years old, the impacts of all grades of tropical cyclones were strongest at lag 0 day. And HRs were 2.67 (95%CI = 1.10, 6.48), 2.49 (95%CI = 1.80, 3.44), 4.89 (95%CI = 2.37, 7.37) and 3.18 (95%CI = 2.10, 4.81), respectively.

Conclusion

All grades of tropical cyclones could increase risk of other infectious diarrhea. Severe tropical storm has the strongest influence on other infectious diarrhea. The impacts of tropical cyclones on children under 5 years old were higher than total population.     

Resilience of arboreal folivores to habitat damage by a severe tropical cyclone

Abstract Severe tropical cyclones greatly modify habitat of arboreal folivores by destroying forest canopy, reducing structure and complexity and defoliating remaining trees. We hypothesized that forest modification following severe Cyclone Larry would stress arboreal folivores of the Family Pseudocheiridae and be reflected in increased home ranges and a decrease in body condition. We conducted 19 pre‐cyclone and 24 post‐cyclone spotlighting surveys at a site with severe cyclone damage, and 18 post‐cyclone surveys at a site with minor damage. We detected a greater number of lemuroid, Hemibelideus lemuroides and green, Pseudochirops archeri, ringtail possums as these possums remained in the severely damaged canopy and forest edge. In contrast, Herbert River ringtail possums, Pseudochirulus herbertensis, were detected in smaller numbers. We radio‐tracked eight P. herbertensis before the cyclone, following two of these and nine new animals after the category 4 cyclone. No significant post‐cyclone alteration in home range area or span was recorded in data pooled across the two sites or in limited post‐cyclone data at the severely disturbed site, but a greater variability in home range was observed after cyclone (pooled across sites: 1.72 ± 0.77 ha; 197 ± 47 m) than before the cyclone (1.35 ± 0.30 ha; 196 ± 23 m). In contrast, pooled pre‐ and post‐cyclone home range areas and spans were larger at the severely‐disturbed site (2.08 ± 0.56 ha; 231 ± 32 m) than at the site with minor damage (0.68 ± 0.11 ha; 114 ± 25 m), suggesting resources were more widely spread at the former site. Post‐cyclone home ranges were also larger at the severely damaged site (severe: 3.33 ± 1.36 ha, n = 3; minor: 0.52 ± 0.07 ha, n = 4). Condition of P. herbertensis (mass/tail length) did not differ significantly pre‐ and post‐cyclone or between less and severely disturbed sites. These results and observations of breeding after cyclone suggest that possum populations may be resilient to severe cyclone damage under the relatively wet conditions experienced post‐Cyclone Larry.     

Impacts of Cyclone Larry on arboreal folivorous marsupials endemic to upland rainforests of the Atherton Tableland,Australia

Abstract Intense cyclones might be expected to adversely affect populations of arboreal mammals, either directly or as a consequence of the destruction of food resources and other key habitat elements. However, such impacts have rarely been quantified. The present study examined the response of five species of arboreal folivorous marsupials to Severe Cyclone Larry at nine sites in upland rainforests of the Atherton Tableland, north‐east Australia. Sites were originally surveyed for folivores in 1995–1997, and then resurveyed in 2006, 6–8 months after Cyclone Larry had traversed the region. All sites showed evidence of structural damage to vegetation, but overall damage levels (assessed in terms of canopy cover, damage to trees, basal area of dead trees and volume of woody debris) decreased from east to west across the study region. The detectability of rainforest possums increased after the cyclone. For the most commonly observed species, the proportion of individuals observed >5 m from survey transects was correlated with the amount of structural damage to vegetation. To avoid confounding changes in detectability with changes in abundance, only observations close (<5 m) to transects were used to estimate folivore abundance before and after the cyclone. On this basis, there were no significant differences between pre‐ and post‐cyclone abundance estimates for any folivore species. Further, changes in folivore abundance after the cyclone were not correlated with damage to vegetation across sites. Cyclone Larry does not appear to have caused a catastrophic loss of key habitat resources for marsupial folivores at the sites surveyed. The high degree of folivory practiced by marsupial folivores may help make them resilient to cyclone impacts. These conclusions are more robust for three commonly observed folivore species (Hemibelideus lemuroides, Pseudochirulus herbertensis and Trichosurus vulpecula johnstonii) than for two less frequently encountered species (Pseudochirops archeri and Dendrolagus lumholtzi).     

Sea turtle species vary in their susceptibility to tropical cyclones

Severe climatic events affect all species, but there is little quantitative knowledge of how sympatric species react to such situations. We compared the reproductive seasonality of sea turtles that nest sympatrically with their vulnerability to tropical cyclones (in this study, “tropical cyclone” refers to tropical storms and hurricanes), which are increasing in severity due to changes in global climate. Storm surges significantly decreased reproductive output by lowering the number of nests that hatched and the number of hatchlings that emerged from nests, but the severity of this effect varied by species. Leatherback turtles (Dermochelys coriacea) began nesting earliest and most offspring hatched before the tropical cyclone season arrived, resulting in little negative effect. Loggerhead turtles (Caretta caretta) nested intermediately, and only nests laid late in the season were inundated with seawater during storm surges. Green turtles (Chelonia mydas) nested last, and their entire nesting season occurred during the tropical cyclone season; this resulted in a majority (79%) of green turtle nests incubating in September, when tropical cyclones are most likely to occur. Since this timing overlaps considerably with the tropical cyclone season, the developing eggs and nests are extremely vulnerable to storm surges. Increases in the severity of tropical cyclones may cause green turtle nesting success to worsen in the future. However, published literature suggests that loggerhead turtles are nesting earlier in the season and shortening their nesting seasons in response to increasing sea surface temperatures caused by global climate change. This may cause loggerhead reproductive success to improve in the future because more nests will hatch before the onset of tropical cyclones. Our data clearly indicate that sympatric species using the same resources are affected differently by tropical cyclones due to slight variations in the seasonal timing of nesting, a key life history process.     

Effects of a tropical cyclone on the distribution of hatchery‐reared black‐spot tuskfish Choerodon schoenleinii determined by acoustic telemetry

The effects of a tropical cyclone on the distribution of hatchery‐reared black‐spot tuskfish Choerodon schoenleinii were examined using acoustic telemetry. Nine fish were released in Urasoko Bay, Ishigaki Island, Japan, in September 2006, and another nine were released in June to July 2007, before a cyclone's passing through the area in September 2007. Data for the fish released in 2006 were used as the cyclone‐inexperienced group to compare their distribution pattern to that of the 2007 cyclone‐experienced group. Both groups of fish were monitored for up to 150 days. Of the nine fish in each group, four (44%) and two (22%) were monitored for over 150 days in the cyclone‐inexperienced and the cyclone‐experienced groups, respectively. Three of the five fish that had settled in the monitoring area left the area within a few days of the cyclone event. To estimate the time of disappearance of the fish, maximum wind speed during a period of 7 days (indicating the occurrence and intensity of the tropical cyclone), fish size and release year were evaluated as explanatory variables using a Cox proportional hazards model with Akaike's information criterion. The best predictive model included the effect of maximum wind speed. One fish that left the monitoring area displayed movement patterns related to strong winds, suggesting that wind‐associated strong currents swept the fish away. No relationships were found between the movement patterns of the other two fish and any physical environmental data. The daily detection periods of one of the two fish gradually decreased after the cyclone hit, and this fish eventually left the monitoring area within 3 days, suggesting that it shifted to a habitat outside the monitoring area. These results indicate that tropical cyclones have both direct and indirect effects on the distribution of hatchery‐reared C. schoenleinii.     

Cyclone tolerance in new world arecaceae: biogeographic variation and abiotic natural selection

Background and Aims

Consistent abiotic factors can affect directional selection; cyclones are abiotic phenomena with near-discrete geographic limits. The current study investigates selective pressure of cyclones on plants at the species level, testing for possible natural selection.

Methods

New World Arecaceae (palms) are used as a model system, as plants with monopodial, unbranched arborescent form are most directly affected by the selective pressure of wind load. Living specimens of known provenance grown at a common site were affected by the same cyclone. Data on percentage mortality were compiled and analysed in biogeographic and phylogenetic contexts.

Key Results

Palms of cyclone-prone provenance exhibited a much lower (one order of magnitude) range in cyclone tolerance, and significantly lower (P < 0·001) mean percentage mortality than collections from cyclone-free areas. Palms of cyclone-free provenance had much greater variation in tolerance, and significantly greater mean percentage mortality. A test for serial independence recovered no significant phylogenetic autocorrelation of percentage mortality.

Conclusions

Variation in cyclone tolerance in New World Arecaceae correlates with biogeography, and is not confounded with phylogeny. These results suggest natural selection of cyclone tolerance in cyclone-prone areas.Key words: Abiotic selection, Arecaceae, biogeography, cyclone, hurricane, phylogenetic independence     

Landscape‐scale redistribution of a highly mobile threatened species,Pteropus conspicillatus (Chiroptera,Pteropodidae), in response to Tropical Cyclone Larry

Abstract Severe category 4 Tropical Cyclone Larry, which crossed north‐east Queensland on 20 March 2006, provided a unique opportunity to examine the short‐term impacts of a major disturbance event on the population of a highly mobile threatened species, Pteropus conspicillatus. As we had recorded, the species’ population distribution in colonial roosts (camps) across the region each month for almost 2 years prior to Cyclone Larry, we continued monthly surveying of P. conspicillatus camp‐sites for a year post‐cyclone. Here we report on how P. conspicillatus responded and redistributed immediately after the cyclone, and over the subsequent year. Post‐cyclone, P. conspicillatus typically roosted in smaller camps than pre‐cyclone, suggesting that these animals had largely dispersed to locate available blossoms and fruit. For 6 months after Cyclone Larry, up to 90% of the pre‐cyclone P. conspicillatus population (ca. 250 000) was unaccounted for across the region. Information provided by the general public assisted us in locating six small camps of P. conspicillatus at ‘new’ locations, but contributed little to increase our overall population estimate for the species at this time. After November 2006, the number of P. conspicillatus built up at located camp‐sites until a post‐cyclone peak of 209 000 at the end of the study in March 2007, comparable with the population estimates in March 2005 and 2006. There is no evidence that the cyclone caused significant direct mortality among P. conspicillatus, although there may yet be longer‐term and indirect effects on population size. We suggest that redistribution by P. conspicillatus makes sense ecologically in the face of major habitat disturbance and short‐ to long‐term food resource limitation, and is not unlike the response of other Australian mainland Pteropus species to seasonal changes in food availability.     

Stand structure of the emergent conifer Araucaria laubenfelsii) in maquis and rainforest,Mont Do,New Caledonia

Abstract Despite its small size, New Caledonia has a flora which includes 43 endemic species of conifer. This study examines the stand structure of the New Caledonian conifer, Araucaria laubenfelsii Corbasson, a species which occurs on ukramafic soils as an emergent tree in rainforest and in an unusual structural association with maquis vegetation. Fire and cyclone blow-down are the primary disturbances in the maquis, but fire is infrequent in the rainforests which is evident from the low proportion of fire scarred trees. Preliminary results show abundant seedlings and saplings of A. laubenfelsii both in maquis and forest. Size class distributions of individuals suggest that the species is continuously regenerating in the maquis and immature forests. Variability in the stand structure in maquis communities reflects the probable patchy nature of disturbance from small-scale fires and blow-down from tropical cyclones. In mature forests, Nothofagus codonandra (Baillon) Steenis is the dominant canopy species and ‘other tree species’ are continuously regenerating, while the size class distributions and basal area of A. laubenfelsii suggest that there is, at present, limited regeneration of this species. Tree ring counts indicate that individuals in forest areas grow at a slower rate than those in maquis, but attain greater age, probably as a result of greater protection from fire.     

Contrasting effects of tropical cyclones on the annual survival of a pelagic seabird in the Indian Ocean

Tropical cyclones are renowned for their destructive nature and are an important feature of marine and coastal tropical ecosystems. Over the last 40 years, their intensity, frequency and tracks have changed, partly in response to ocean warming, and future predictions indicate that these trends are likely to continue with potential consequences for human populations and coastal ecosystems. However, our understanding of how tropical cyclones currently affect marine biodiversity, and pelagic species in particular, is limited. For seabirds, the impacts of cyclones are known to be detrimental at breeding colonies, but impacts on the annual survival of pelagic adults and juveniles remain largely unexplored and no study has simultaneously explored the direct impacts of cyclones on different life‐history stages across the annual life cycle. We used a 20‐year data set on tropical cyclones in the Indian Ocean, tracking data from 122 Round Island petrels and long‐term capture–mark–recapture data to explore the impacts of tropical cyclones on the survival of adult and juvenile (first year) petrels during both the breeding and migration periods. The tracking data showed that juvenile and adult Round Island petrels utilize the three cyclone regions of the Indian Ocean and were potentially exposed to cyclones for a substantial part of their annual cycle. However, only juvenile petrel survival was affected by cyclone activity; negatively by a strong cyclone in the vicinity of the breeding colony and positively by increasing cyclone activity in the Northern Indian Ocean where they spend the majority of their first year at sea. These contrasting effects raise the intriguing prospect that the projected changes in cyclones under current climate change scenarios may have positive as well as the more commonly perceived negative impacts on marine biodiversity.     

Wood density predicts plant damage and vegetative recovery rates caused by cyclone disturbance in tropical rainforest tree species of North Queensland,Australia

Abstract The ability to withstand disturbance (resistance) and the ability to recover biomass following disturbance (resilience) were investigated in Australian wet tropical rainforest tree species. These two attributes are expected to be negatively correlated, because investment of biomass in structural support (conferring resistance) results in trees exhibiting high wood densities and slow growth rates, and vice versa. We examined species’ responses to disturbance caused by a severe tropical cyclone to test this hypothesized trade‐off. We assessed cyclone damage in six species in three Mabi rainforest fragments on the Atherton Tablelands. Species differed in the proportion of individuals within four damage categories (minor damage, severe branch damage, snapped, uprooted). Resistance was positively related to wood density. We found a positive correlation between the proportion of trees experiencing minor damage only and wood density, supporting the hypothesized association between resistance and mechanical strength. Among the subset of trees in which stems snapped, rates of resprouting differed between species and were highest in low wood density species and lowest in species with highest wood density. Resilience, characterized as the ability to recover biomass following disturbance and estimated as growth rate standardized for stem diameter at breast height (g day^?1 · mm^?1), was negatively related to wood density. Thus, species with low wood densities were more likely to suffer stem and branch damage owing to cyclonic winds, but also demonstrated highest resprouting and fastest responses in terms of redeveloping biomass in the 8 months following disturbance. This suggests that a species’ position along the resistance–resilience spectrum can be predicted by mean wood density, which may allow managers to predict species’ responses to future cyclones. Our findings also provide mechanistic evidence for the ‘direct regeneration’ model of post‐cyclone succession, where response is characterized by resprouting and species composition is unchanged.     

Towards modelling the future risk of cyclone wave damage to the world's coral reefs

Tropical cyclones generate extreme waves that can damage coral reef communities. Recovery typically requires up to a decade, driving the trajectory of coral community structure. Coral reefs have evolved over millennia with cyclones. Increasingly, however, processes of recovery are interrupted and compromised by additional pressures (thermal stress, pollution, diseases, predators). Understanding how cyclones interact with other pressures to threaten coral reefs underpins spatial prioritization of conservation and management interventions. Models that simulate coral responses to cumulative pressures often assume that the worst cyclone wave damage occurs within ~100 km of the track. However, we show major coral loss at exposed sites up to 800 km from a cyclone that was both strong (high sustained wind speeds >=33 m/s) and big (widespread circulation >~300 km), using numerical wave models and field data from northwest Australia. We then calculate the return time of big and strong cyclones, big cyclones of any strength and strong cyclones of any size, for each of 150 coral reef ecoregions using a global data set of past cyclones from 1985 to 2015. For the coral ecoregions that regularly were exposed to cyclones during that time, we find that 75% of them were exposed to at least one cyclone that was both big and strong. Return intervals of big and strong cyclones are already less than 5 years for 13 ecoregions, primarily in the cyclone‐prone NW Pacific, and less than 10 years for an additional 14 ecoregions. We identify ecoregions likely at higher risk in future given projected changes in cyclone activity. Robust quantification of the spatial distribution of likely cyclone wave damage is vital not only for understanding past coral response to pressures, but also for predicting how this may change as the climate continues to warm and the relative frequency of the strongest cyclones rises.     

Seedling bank dynamics of Fagus grandifolia var. mexicana before and after a mast year in a Mexican cloud forest

Abstract. Fagus grandifolia var. mexicana seedling dynamics were studied in a relict forest inside the crater of a volcano where it is the only canopy tree species. The objectives of the study were (1) to determine changes in seedling density before and after a mast year, as well as to monitor seedling recruitment, mortality and growth rate in relation to the micro‐environment, and (2) to discuss the impact of masting on seedling dynamics of the population. Before masting, seedling density was 8.8 seedlings m^–2, afterwards seedling density peaked at 51.5 seedlings m^–2, then decreased by 50% in 3 months and by 85% after 8 months, down to levels of before the mast year (9.9 seedlings m^–2) after 16 months. Seedlings in the forest floor before the mast‐seeding event showed a low relative growth rate – 0.14 mm mm^–1 mo^–1 against 1.27 mm mm^–1 mo^–1 for seedlings that emerged immediately after masting. Seed germination was high (83%) and rapid (L₅₀= 7 days) following masting. Seedling growth was positively correlated with soil water content but not with temperatures and relative humidity. Data suggested that seed production in mast years is important in maintaining the seedling bank, and thus the viability of relict Fagus populations.     

Landscape‐scale impacts of Cyclone Larry on the forests of northeast Australia,including comparisons with previous cyclones impacting the region between 1858 and 2006

Abstract Cyclone Larry (category 4) was the most severe cyclone to impact on the Wet Tropics bioregion since the devastating 1918 Innisfail cyclone. Based on an analysis of earlier cyclones impacting on this region over the period 1856–2006, it was determined that Larry was a ‘1 in 50 year’ event. This paper provides an overview of the landscape‐scale impacts of Larry on the forest ecosystems of the Wet Tropics region, based on low‐level helicopter surveys 2 weeks after the event. Cyclone Larry has been described as a ‘midget’ cyclone. Severe forest damage only extended about 30 km from the central track of the cyclone while moderate to severe damage extended some 50 km. Moderate to slight canopy disturbance was rarely identified more than 75 km from the centre of the cyclone's track. Beyond 75 km, forest damage was restricted to exposed areas of elevated terrain and in places exposed to strong lee (gravity) waves from the west. The ecological role of cyclones as important disturbance agents affecting the structure and function of forest ecosystems in the region is discussed, followed by an evaluation of likely effects of climate change on cyclone frequency and intensity.     

Foraging activity and population estimation of Microtermes mycophagus Desneux (Isoptera: Termitidae: Macrotermitinae) in Multan,Punjab, Pakistan

The knowledge of the seasonal foraging activity and the numbers of foragers in a colony would be helpful for designing effective termite baiting programs. The current study presents the seasonal activity of Microtermes mycophagus Desneux in a tree plantation in Multan, Punjab, Pakistan, using silk cotton tree wood traps during 2011–2013. The population of M. mycophagus was also estimated using the constant removal method. The number of workers in the underground traps showed a seasonal trend with the highest capture rate occurring during summer and the lowest during winter. The peak in the population (1139 workers/trap) was observed in October after the rainy season. Positive and significant correlation was found between the mean air temperature and the numbers of M. mycophagus workers captured. The constant removal population estimates revealed 16 499–40 265 individuals in the colony of M. mycophagus. Our results suggest that for cost–effective management of the termite species, baiting programs should be started immediately after August when rapid increases in activity of M. mycophagus have been recorded.