Cyclone damage sustained by riparian revegetation sites in the Tully-Murray floodplain, Queensland,...

Cyclone damage sustained by riparian revegetation sites inthe Tully-Murray floodplain, Queensland, Australia

CAROLINE BRUCE,1* FREDERIEKE KROON,1,2 DAMON SYDES2,3 ANDANDREW FORD1

1CSIRO Sustainable Ecosystems,Tropical Forest Research Centre, PO Box 780, Atherton, Qld 4883,Australia (Email: [email protected]), 2FNQ NRM Pty Ltd, Innisfail, and 3Cardwell ShireCouncil,Tully, Queensland, Australia

Abstract Cyclones have been instrumental in shaping the structural and floristic composition of tropical forests,including tropical rainforests of north Queensland, Australia. The response of tropical riparian rehabilitation sitesto cyclonic wind damage, however, is currently unknown. This lack of knowledge may severely hamper long-termsuccess of riparian restoration efforts, particularly in light of predictions that cyclones in north Queensland maybecome less frequent but more severe. In this study, we examined the extent, type and magnitude of damageinflicted on revegetation works in the Tully-Murray floodplain of north Queensland by Severe Tropical CycloneLarry.We compared wind damaged in 20 paired revegetated and associated rainforest remnant sites, using (i) grosscommunity damage scores, (ii) mean weighted damage scores, and (iii) type of damage sustained by individualplants. Overall, wind damage due to Severe Tropical Cyclone Larry was surprisingly similar in revegetated andremnant sites. Both gross community damage scores and mean weighted damage scores did not differ betweenpaired revegetated and remnant sites. In contrast, the type of damage sustained by individual plants was notindependent of site, with a larger proportion in revegetated sites sustaining severe damage compared with remnantsites. This larger proportion of severely damaged individuals in revegetated sites was at least in part due to thesignificantly higher proportion of pioneers at these sites. The pioneer species Homalanthus novoguineensis wasparticularly susceptible to wind damage. The potential effects of spatial differences, such as consistent bias due tosize, shape or exposure between the remnants and revegetated sites, on our results are discussed. In light of ourresults, we recommend that future revegetation sites include fewer pioneer species that are highly susceptible towind damage, more pioneer species that are resistant to wind damage, and alteration of pioneer species distributionwithin planting matrices.

Key words: cyclone, rainforest, rehabilitation, riparian, Wet Tropics, wind damage.

INTRODUCTION

Cyclones have been instrumental in shaping plantpopulation dynamics (e.g. Lugo et al. 1983) withintropical forests over evolutionary timescales of thou-sands of years (Lodge & McDowell 1991). At shortertimescales, cyclones are agents of both short- andlong-term ecological disturbance (e.g. Lodge &McDowell 1991; Franklin et al. 2004; Sinclair &Byrom 2006). For example, cyclonic damage to veg-etation can be influenced by turbulence and distancefrom the cyclonic core (Unwin et al. 1988; Grangeret al. 1999), landscape context (Bellingham 1991),previous site history including cyclone exposure(Ostertag et al. 2005), anthropogenic disturbance(Paine et al. 1998), biogeographic origin (MacDonaldet al. 1991), and community- and species-specific

attributes such as tree size (Lugo et al. 1983; Ostertaget al. 2005).

In the tropical rainforests of north Queensland, Aus-tralia, cyclones have had a significant influence onstructural and floristic composition (Webb 1958) atboth landscape and local scales. Lowland and foothillrainforests have regularly sustained severe or generalcyclone damage, with damage varying spatially due tolocal topographic effects, and frequency and intensityof cyclones (Webb 1958). Regular cyclonic activity hasresulted in compositional changes in the tropical rain-forests, including the development of ‘cyclone scrubs’due to local wind intensification and characterized bya low uneven canopy with scattered emergents denselydraped in vines (Webb 1958).

Severe Tropical Cyclone Larry crossed the northQueensland coast near Innisfail on 20 March 2006(fig. 1 in Turton 2008). At landfall, the cyclone isthought to have been a high Category 4, and main-tained cyclonic strength for several hundred kilometres*Corresponding author.

Austral Ecology (2008) 33, 516–524

© 2008 CSIRO doi:10.1111/j.1442-9993.2008.01906.xJournal compilation © 2008 Ecological Society of Australia

mailto:[email protected]

inland (Bureau of Meteorology 2007). Damage fromsome areas suggests the generation of tornadoes andwind flows influenced by the steep terrain of thecoastal range (Davidson 2006; Bureau of Meteorology2007). Heavy, sustained coastal rainfall betweenIngham and Cairns accompanied the cyclone, causingflooding within several catchments and river systems(Bureau of Meteorology 2007).

Major damage from the cyclone occurred along thecoast between Cairns and Cardwell (fig. 1 in Turton2008) and continued about 70 km inland to the townof Ravenshoe.This included severe damage to tropicalrainforest (Catterall et al. 2008; Metcalfe et al. 2008;Turton 2008) as well as to forest rehabilitation areason the Atherton Tablelands (Kanowski et al. 2008).While the structural and floristic composition of tropi-cal rainforests in north Queensland may reflectcyclonic disturbance (Webb 1958), the response ofriparian rehabilitation sites to cyclonic wind damage iscurrently unknown. Given the prediction that cyclonesin the region may become less frequent but moresevere (J. Nott, James Cook University, pers. comm.2007), this lack of knowledge may severely hamper thelong-term success of riparian restoration efforts.

In this study, we compared the damage of SevereTropical Cyclone Larry between riparian rehabilita-tion works and geographically close, associated rain-forest remnant sites. As trees native to the region wereused in the rehabilitation works assessed, we predictedthat the damage sustained in paired riparian/remnantsites would be similar.To test this prediction, we exam-ined the extent, type and magnitude of damageinflicted by Severe Tropical Cyclone Larry on twentypaired sites in the Tully-Murray floodplain, Queen-sland, Australia.

METHODS

Restoration programmes inthe Wet Tropics region

The Wet Tropics region in north Queensland (hereaf-ter referred to as the ‘Wet Tropics’) experienced sig-nificant tree-clearing, particularly for agriculturaldevelopment, during the past 150 years (Catterall et al.2004). Since the declaration of the Wet Tropics WorldHeritage Area in 1988, forests have been conservedand/or restored through protection of existing rem-nants, improvement of existing remnant vegetationand reforestation (Catterall & Harrison 2006). Refor-estation programmes have been implemented tosupport the timber industry (Harrison & Harrison2004) and/or to restore strips and corridors ofrainforest. These latter plantings are mainly high-density, diverse plantings of native trees and shrubs

(Catterall et al. 2004) of typically less than 5 ha(Catterall et al. 2004; Catterall & Harrison 2006), andoften less than 1 ha (Catterall & Harrison 2006).

Description of study area

The Tully-Murray floodplain

TheTully-Murray basin is located in the Cardwell Shire(Fig. 1), and comprises the Hull River and coastaltributaries, the Tully and Murray Rivers, Dallachy,Meunga and Kennedy Creeks, and coastal creeksrunning into Hinchinbrook Channel (Johnson 1998).The higher elevations and upper reaches of the riversand creeks are primarily occupied by tropical rainforest,while the coastal floodplain has been largely cleared anddrained for agricultural purposes (Johnson 1998).Remnant patches of rainforest are found on the alluvialplains and in wetlands and estuaries near the coast.

Severe Tropical Cyclone Larry inthe Tully-Murray floodplain

Severe Tropical Cyclone Larry passed approximately30–40 km north of the northern boundary of theTully-Murray floodplain (Fig. 1). As such, the flood-plain escaped the cyclone’s maximum winds (radius of20–30 km around the eye: Bureau of Meteorology,2007). However, the northern parts of the floodplainwere subjected to very destructive winds (radius40–50 km), while the remainder of the floodplainexperienced destructive winds (radius 120 km). Thecyclone therefore inflicted considerable damage tovegetation within the floodplain, with damage particu-larly severe north of Tully.

Revegetation works in the Tully-Murray floodplain

River and wetland rehabilitation works on the Tully-Murray floodplain have been conducted by the Card-well Shire Council’s Revegetation Unit during the last12 years. Objectives of rehabilitation works haveranged from stabilizing river banks and establishingwildlife corridors to protecting and enhancingremnant areas, improving water quality and biodiver-sity, and protecting and maintaining cultural and heri-tage values.

Species selection is determined from adjoiningremnant vegetation, soil type, revegetation guidelines(Goosem & Tucker 1995; Gleed, pers. comm., 2001),experience and local knowledge. The species plantedare determined both on their ability to provide aframework of native plants to control invasive weeds by

CYCLONE DAMAGE TO RIPARIAN REVEGETATION SITES 517


shading within 2 years, and to draw in new speciesthrough inclusion of bird and mammal food plants.Species used are sourced from local seed stocks werepossible, most being collected and propagated by theCouncil’s nursery. Species diversity ranges from 14species to over one hundred species at any given site.

Description of study sites and survey methods

A total of 40 sites were surveyed for wind damage,including 20 revegetation sites and 20 associatedrainforest remnant sites (Fig. 1). The remnant siteswere paired with individual revegetated sites, and each

Fig. 1. Location of Tully/Murray floodplain and paired study sites relative to track of Severe Tropical Cyclone Larry. Zones ofwind damage (average distance) are also included (zone 1, maximum winds (radius 20–30 km); zone 2, very destructive winds(radius 40–50 km); zone 3, destructive winds (radius 120 km)). Numbers refer to paired study sites: 1, Banyan Creek Dallachy;2, Bribe Creek; 3, Jarra Creek Cremas; 4, Kyambul Warrami; 5, Moongera Creek Gabiola; 6, Moongera Creek O’Kanes; 7,Murray Annabranch Dores; 8, Murray River Cliffords; 9, Murray River Dore; 10, Murray River Finlayson; 11, Murray RiverSmith; 12, Porters Creek; 13, Sellars; 14, Silky Oak Creek Sorbellos; 15, Tully River Crema; 16, Tully River Harneys; 17, TullyRiver Mackays; 18,Warrami; 19,Woolcoo Creek Jacksons; 20,Woolcoo Creek Siani McKinnon Road. Inset map indicates studyarea location in Australia.

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© 2008 CSIROdoi:10.1111/j.1442-9993.2008.01906.xJournal compilation © 2008 Ecological Society of Australia

was as geographically close to the revegetated site aspossible – generally abutting or within 200 m. Allrevegetated sites were of similar age (5–8 years), whilethe age of the remnant sites could not be ascertained.Although classified as ‘remnant’ by the QueenslandEnvironmental Protection Agency (Regional Ecosys-tem mapping, version 5, 2003: Queensland Govern-ment Environmental Protection Agency (2007)), someof these should be considered as old regrowth as theycontain, for example, canopy trees of Mangifera indicaL. (Mango). The remnant rainforest communitieswere all mesophyll rainforest/vine forests with varyingfloristic assemblages attributable mostly to the heightabove sea level, substrate, proximity to a creek systemor depth of the water table (Tracey 1982). All remnantsites had previously been impacted by human distur-bance such as selective logging or partial clearing andmost were riparian.

All sites were assessed between July and early August2006, i.e., approximately 4 months after Severe Tropi-cal Cyclone Larry. None of the sites had undergoneany maintenance, thus still allowing accurate assess-ment of individual plants for damage. To account forvariations in size and shape of each revegetated/remnant site, we used plotless sampling by establishingeither a linear or non-linear transect at each sitedepending on the shape and size of each site, and usingthe ‘ten nearest neighbour’ method of sampling at fivecentral, random points along this transect of varyinglength (as modified from Kanowski & Catterall 2006who suggest sampling instead at 10 m intervals along a50 m transect). Only woody shrubs and trees higherthan 2 m were assessed. The distance between centralpoints varied with the density of individuals in eachsampling site. Plots were typically located only in areasof each site which were not too narrow (i.e. not lessthan two tree widths in remnant, and three tree widthsin revegetation).

Each individual plant was identified to species level(where possible). Individual plants which had beensmashed, uprooted or snapped, and did not have anysubsequent coppicing or epicormic growth, or whichcould not be identified for other reasons, wererecorded as ‘unknown’. Each individual was measured(six stem diameter classes at diameter at breast height(d.b.h.); 1 =< 2 cm, 2 = 2–4.9 cm, 3 = 5–7.9 cm,4 = 8–11.9 cm, 5 = 12–19.9 cm and 6 => 20 cm), andrated for cyclone damage as per the following catego-ries: i (no damage), ii (minimal damage), iii (leavesshredded), iv (leaves lost), v (small branches), vi (largebranches), vii (snapped), viii (leaning), ix (uproot) andx (smashed) (see Metcalfe et al. (2008) for furtherdetails). The damage scored was a result of wind andwas the worst damage that a stem/plant sustained. Forexample, if a tree had lost most of its leaves and had alarge branch broken off, the damage was recorded as‘large branches’. Post-cyclone flush was relatively

easily identifiable, allowing us to confidently deter-mine the damage as it had been immediately after thecyclone.

At each site, the following attributes were recorded:(i) average canopy height of the assessed area; (ii)direction of wind damage if obvious (from uprootedstems); (iii) any current or potential for future bankor creek-side erosion; and (iv) gross communitydamage. For the latter, we considered damage to thewhole site. The gross community damage score was ameasure of scale and intensity of tree injury asderived by Unwin et al. (1988) and modified by Met-calfe et al. (2008) to better suit the specific damageresponses to Severe Tropical Cyclone Larry. Domi-nant species were recorded for the entire assessedtransect.

Finally, each species was allocated a life historyclass based on the assumed light requirements for aseedling/sapling to reach 1 m in height. Class 1 =pioneers (species which require high light and canregenerate in non-forest environments); class2 = gap-demanding species (species which regenerateonly in forest, and need the higher light environmentprovided by a tree fall gap or other disturbance);class 3 = shade tolerators (species which can regen-erate in the closed understorey environment under afull canopy).

Data analyses

We used three different analyses to assess whethercyclone damage between revegetated and remnantsites differed. In these analyses, we did not control forfactors such as location, exposure, etc., as we used anexperimental design with pairs of rehabilitated andremnants sites. That is, we assumed that each pair ofrehabilitated and remnant sites would have been simi-larly exposed to cyclonic wind damage, given theirlocation in relation to the cyclone path.

First, we compared gross community damagebetween revegetated and associated remnant sitesusing Wilcoxon matched pairs test. For the followingtwo analyses, we combined the nine damage scoresfor individual plants into four damage categories:no damage = (i), minimal damage = (ii) + (iii) +(iv), medium damage = (v) + (vi) and severedamage = (vii) + (viii) + (ix). Plants that sustained sec-ondary damage (i.e. smashed) were not included inthese analyses. We compared mean weighted damagescores between revegetated and associated remnantsites using Wilcoxon matched pairs test. A meanweighted damage score was calculated for each site bymultiplying each individual damage category (1–4) bythe number of plants that had sustained that particulardamage, summing all four weighted damage catego-ries, and dividing this by the number of plants



assessed. Finally, we examined whether the type ofdamage sustained by individual plants was indepen-dent of site (remnant and revegetated) using the G-testfor a 2 ¥ 4 contingency table (Zar 1984).

In subsequent analyses, we focussed on determin-ing which life history classes, d.b.h. classes and indi-vidual species contributed to differences in damagebetween revegetated and remnant sites. Two-tailedtests were used for all analyses, and non-parametrictests were used when assumptions of normality andhomoscedasticity were not met (Zar 1984); a was setat 0.05.

RESULTS

General

At our 40 sites, we identified a total of 159 taxa (96 inrevegetated sites and 124 in remnant sites) and 1877individual plants (973 in revegetated and 904 inremnant sites, respectively) (data available for down-load from http://www.ecolsoc.org.au/What%20we%20do/Publications/Austral%20Ecology/AE.html). Theremainder of the 2000 individual plants assessed (123individuals; 27 in revegetated sites and 96 in remnantsites) could not be identified in the field. Revegetationand remnant sites had a total of 61 taxa in common; 35taxa were recorded only in revegetated sites, while 63taxa were recorded only in remnant sites.

Most of the 2000 individual plants assessed weregap-demanding species (720), followed by shade tol-erators (665), pioneers (492) and unknowns (123).The proportion of individuals within each life historyclass was not independent of site (revegetation vs.remnant) in the population sampled (G = 414.4, d.f.= 3, P < 0.001; Fig. 2a), with a higher proportion ofpioneers and gap-demanding species in revegetationsites, and a higher proportion of shade tolerators andunknowns in remnant sites.

Most of the 2000 individual plants measured were inthe d.b.h. class 2 (608 individuals), followed by class 3(363), class 1 (298), class 4 (281), and class 5 (258).The largest d.b.h. class contained the fewest individualplants (192). The proportion of individuals withineach d.b.h. class was not independent of site (reveg-etation vs. remnant) in the population sampled(G = 142.9, d.f. = 5, P < 0.001; Fig. 2b), with a higherproportion of larger plants in remnant sites.

Of the 2000 individual plants assessed, 46 (2.3%)were smashed, with similar numbers of smashed plantsin revegetated (21) and remnant sites (25). Individualplants were smashed at nine revegetated sites andeleven remnant sites. These plants were not furtherincluded in the analyses.

Differences in cyclone damage betweenrevegetation and remnant sites

Gross community damage did not differ significantlybetween revegetated and associated remnant sites(median = 0.00, Z = 0.00, n = 20, P = 1.00). More-over, mean weighted damage did also not differ sig-nificantly between revegetated and associated remnantsites (median = -0.2, Z = 0.45, n = 20, P = 0.65). Incontrast, the type of damage sustained by individualplants was not independent of site (revegetation vs.remnant) in the population sampled (G = 25.9, d.f.= 2, P < 0.001; Fig. 3), with a larger proportion inrevegetated sites (14.2%, 139 plants) sustaining severedamage compared with remnant sites (7.9%, 77plants). In both revegetated and remnant sites,however, both the number and proportion of severelydamaged plants was relatively small.

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Life history

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Diameter at Breast Height

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G = 142.9P < 0.001

Fig. 2. Number of individual plants surveyed in (a) threelife history categories (plus unknown category), and (b) sixd.b.h. categories, in revegetation and remnant sites,respectively. The G-values for log-likelihood ratio for (a)2 ¥ 4, and (b) 2 ¥ 6 contingency tables and associatedP-values are given.

520 C. BRUCE ET AL.


http://www.ecolsoc.org.au/What%20we%20

Characteristics of plants sustainingsevere damage

To assess whether different life history classes contrib-uted to the larger proportion of individual plants inrevegetated sites sustaining severe damage comparedwith remnant sites, we compared the absolute andrelative contribution of the three life history classes.At revegetated sites the majority of individual plantsseverely damaged were pioneers (54.8%, 74 plants),whereas at remnant sites the number of severelydamaged plants were distributed approximatelyequally across the three life history classes (Fig. 4a).Moreover, when correcting for the total number ofindividual plants assessed per life history class, pio-neers contributed disproportionately more to thesevere damage category in both revegetated (G = 14.9,d.f. = 2, P < 0.001) and remnant sites (G = 14.8, d.f.= 2, P < 0.001).Thus, the larger proportion of severelydamaged individuals in revegetated sites is at least inpart due to the significantly higher proportion of pio-neers at these sites and the relative tendency for pio-neers to be severely damaged.

To assess whether different d.b.h. classes contributedto the larger proportion of individual plants in reveg-etated sites sustaining severe damage compared withremnant sites, we compared the absolute and relativecontribution of the six d.b.h. classes. Most of the indi-vidual plants severely damaged at revegetated sites werein d.b.h. classes 2, 3 and 4, whereas at remnant sitesmost were in d.b.h. classes 5 and 6 (Fig. 4b). However,when correcting for the total number of individualplants assessed per d.b.h. class, the larger d.b.h. classescontributed disproportionately more to the severe

damage category in both revegetated (d.b.h. classes 3–5;G = 35.2, d.f. = 5, P < 0.001) and remnant sites (d.b.h.classes 4–6; G = 34.9, d.f. = 5, P < 0.001). Thus, thelarger proportion of severely damaged individuals inrevegetated sites does not appear to be due to the initialdifferences in proportions across the six d.b.h. classesbetween revegetated and remnant sites.

To identify those species that are more likely tosustain severe damage due to cyclonic winds, we cal-culated the proportional contribution of individualspecies to the severe damage category in revegetatedsites. The proportional contribution was highest forHomalanthus novoguineensis (46%), followed by Mallo-tus paniculatus (43%) and Rhus taitensis (38%)(Table 1). Severe damage was sustained by H. novogu-ineensis at 80% of the ten sites where the species wasassessed.

0

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None Minimal Medium Severe

Damage

Fig. 3. Number of individual plants that sustained nodamage, minimal damage, medium damage and severe damage,for revegetation and remnant sites, respectively.The G-valuefor log-likelihood ratio for 2 ¥ 4 contingency table and asso-ciated P-value are given. Note: total number of plants doesnot add up to 2000, because smashed plants are excluded.

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4.7%

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14.8%

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22.5%

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19.2%

8.7%

3.4%

20.4%

16.3%

9.8%

6.5%

Fig. 4. Number of individual plants that sustained severedamage by (a) life history category, and (b) d.b.h. category, inrevegetation and remnant sites, respectively. Proportions arebased on the total number of plants assessed in each lifehistory and d.b.h. class, respectively. The G-values for log-likelihood ratio for (a) 2 ¥ 4, and (b) 2 ¥ 6 contingency tablesand associated P-values are given.



Characteristics of plants sustaining no damage

Of the 2000 individual plants assessed, 948 (47.4%)did not sustain obvious wind damage, with similarnumbers of non-damaged plants in revegetated (467)and remnant sites (481).When correcting for the totalnumber of individual plants assessed per life historyclass, the three life history classes contributed insimilar proportions to the no damage category in reveg-etated sites (G = 1.7, d.f. = 2, P > 0.05), whereas inremnant sites pioneers contributed disproportionatelyless to the non-damage category (G = 18.8, d.f. = 2,P < 0.001). The six d.b.h. classes contributed dispro-portionately to the non-damage category in bothrevegetated (G = 48.4, d.f. = 5, P < 0.001) andremnant sites (G = 77.1, d.f. = 5, P < 0.001), with theproportion of non-damaged plants generally decreas-ing with increasing d.b.h.

To identify those species that are more likely tosustain no damage due to cyclonic winds, we calculatedthe proportional contribution of individual species tothe no damage category in revegetated sites. The pro-portional contribution was highest for Carallia bra-chiata and Callistemon viminalis (both 85%), followedby Melaleuca quinquinervia (74%) and Ficus racemosavar. racemosa (71%) (Table 2). No damage was sus-tained by C. brachiata at 83% of the twelve sites wherethe species was assessed.

DISCUSSION

Our study showed that overall wind damage fromSevere Tropical Cyclone Larry was similar in pairedrevegetated and remnant sites in the Tully-Murrayfloodplain. Gross community damage scores and

Table 1. Total number and proportion of individuals per species in revegetated sites sustaining severe damage

Species Life history class

Number assessed Severely damaged

Plants Sites % of plants % of sites

Homalanthus novoguineensis 1 37 10 46 80Mallotus paniculatus 1 14 6 43 33Rhus taitensis 1 13 3 38 67Rhysotoechia robertsonii 3 31 7 26 29Acacia mangium 1 29 8 24 38Macaranga tanarius 1 38 12 24 75Melicope elleryana 2 26 9 23 44Aleurites rockinghamensis 2 22 5 23 40Elaeocarpus grandis 2 55 13 22 46Chionanthus ramiflora 3 10 4 20 50

Life history class of each species, number of sites where species were assessed, and proportion of sites where species sustainedsevere damage, are given. Highest ranking proportions are given for first ten species (where number of individuals per speciesassessed � 10).

Table 2. Total number and proportion of individuals per species in revegetated sites sustaining no damage

Species Life history class

Number assessed No damage

Plants Sites % of plants % of sites

Carallia brachiata 3 27 12 85 83Callistemon viminalis 2 13 3 85 100Melaleuca quinquinervia 1 19 5 74 100Ficus racemosa var. racemosa 2 14 7 71 71Glochidion sumatranum 1 19 6 68 83Syzygium tierneyanum 2 35 13 66 69Nauclea orientalis 1 69 16 64 75Glochidion benthamianum 1 16 4 63 50Millettia pinnata 2 40 13 63 85Acmena hemilampra ssp. hemilampra 2 31 9 61 100

Life history class of each species, number of sites where species were assessed, and proportion of sites where species sustainedsevere damage, are given. Highest ranking proportions are given for first ten species (where number of individuals per speciesassessed � 10).

522 C. BRUCE ET AL.


mean weighted damage scores did not differ betweenpaired sites, whereas a larger proportion of plants sus-tained severe damage in revegetated sites comparedwith remnant sites. However, the proportion of indi-viduals that sustained severe damage was relativelysmall. In both revegetated and remnant sites, severelydamaged plants were more likely to be pioneers.

The higher incidence of severe damage observed inrevegetated sites was mostly due to the higher propor-tion of pioneers in these sites and their susceptibility tosevere damage. Pioneers tend to be fast-growing, brittleemergents above the canopy, with low wood density,making them more susceptible to wind damage (Webb1958; Zimmerman et al. 1994; Franklin et al. 2004;Ostertag et al. 2005). Moreover, pioneers tend to havea more aggressive stem system than root system, withlarge leaves and longer branches, thus providing agreater surface area susceptible to wind damage (e.g.Herbert et al. 1999). Our results show that, overall, theproportion of non-damaged plants generally decreasedwith increasing d.b.h. corroborate previous studies(e.g. Gresham et al. 1991; Walker 1991; Franklin et al.2004). An increase in damage with size is probably dueto larger girths equating to taller trees with largercanopies and therefore resulting in higher exposure todamaging winds above the canopy.

Spatial differences, such as consistent bias due tosize, shape or exposure between the remnants andrevegetated sites, may have affected our results. Forexample, a consistently larger or less complex shape ofremnant versus revegetated sites may result in adecreased edge ratio. Consequently, remnant sites mayprovide more sheltering of individual plants resultingin lower overall susceptibility to wind damage (Lau-rance 1997). Further, differences in distribution ofpioneers relative to gap-demanding and shade-tolerantspecies within the vegetation matrix may have affectedthe amount of wind damage sustained at remnantversus revegetated sites. Within revegetated sites thedistribution of all life history class individuals is rela-tively even, whereas in remnant sites pioneers tend tooccur around the edges due to availability of light(Laurance 1997). Finally, differences in revegetationregimes used across the floodplain landscape, due tosoil and other site-specific differences, may have con-tributed to varied susceptibilities of species to winddamage. While soil and site-specific differences aremost likely also reflected in species composition of thepaired remnant sites, it is unknown whether these dif-ferences are consistent across the 20 paired reveg-etated and remnant sites.

Wind damage from Severe Tropical Cyclone Larrywas surprisingly similar in revegetated and remnantsites. This indicates that the current species mix andmatrix used in revegetation plantings in the Tully-Murray basin are well designed to withstand cyclonicwind damage. The higher incidence of severe damage

in revegetated sites, however, suggests that someimprovements can be made to strengthen resistance tosevere cyclones. Our results indicate that replacingpioneer species that were more vulnerable to sustain-ing severe damage, in particular H. novoguineensis,with those that did not sustain a high incidence ofdamage, such as Melaleuca quinquinervia or Glochidionsumatranum, would contribute to minimizing winddamage to revegetation sites in cyclonic conditions.Moreover, alteration of pioneer species distributionwithin planting matrices, with resistant species placedon and near edges and less resistant species withinplantings, could further reduce severe wind damage toindividual plantings. These recommendations need tobe viewed in light of the relative infrequency of intensecyclones, the uncertainty of the longer-term post-cyclone condition of damaged revegetation sites, andthe value of both a species-rich planting matrix and asuitable framework which, combined, allow forachievement of the planting objectives.

ACKNOWLEDGEMENTS

We thank landholders for access to their properties,Dan Metcalfe for determination of life history classes,Dean Jones for initial database creation, and AdamMcKeown for assistance with GIS and databasefinalization. Comments by Dan Metcalfe,Tim Curranand two anonymous reviewers improved themanuscript. We acknowledge the Tropical LandscapesJoint Venture (TLJV) and Rainforest Foundation forpart-funding this project through the ‘Skyrail Rainfor-est Foundation Cyclone Larry Project’.

REFERENCES

Bellingham P. J. (1991) Landforms influence patterns of hurri-cane damage: evidence from Jamaican montane forests. Bio-tropica 23, 427–33.

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