Response of primary and secondary rainforest flowers and fruits to a cyclone, and implications for plant‐servicing bats

Abstract

The response of primary (PF) and secondary (SF) rainforests to cyclones has broad implications for servicing fauna and the resilience of forest functions. We collected fine-scale data on the reproductive phenology of plant communities in Fijian PF and SF in 12 monthly surveys before and after Cyclone Tomas (2010). We generated a resource index from the reproductive loads of 2218 trees and 1150 non-trees (>190 species) and trunk and stem diameter to assess patterns in resource abundance for nectarivores and frugivores (hereafter NF resources). We aimed to determine (i) whether species richness of NF resources differed between forests; (ii) the patterns of resilience of NF resources at community level in both forests after a cyclone; and (iii) the effect of response on NF resources for plant-servicing bats (Pteropodidae). In 12 months preceding the cyclone, NF resources were greater in PF trees; non-tree resources fluctuated and were greater in SF. Lower species richness of NF resources in SF indicated that fewer opportunities exist there for exploitation by a diverse fauna. More resources were available for bats in PF. In 12 months following the cyclone, PF flowers and fruits, and SF fruits specifically used by pteropodid bats decreased for trees. Non-tree resources were especially susceptible to the cyclone. No universal pattern of decline was associated with the cyclone; instead, some NF resources declined and others were resilient or responded rapidly to a post-cyclone environment. Both PF and SF demonstrated resilience at the community level via increased flower survival (PF) and rapid flower production (SF). Reduced species richness of NF resources in SF will compromise future resilience and response to disturbance, including for threatened pteropodid bat species. These findings are critical for long-term management of forests, given predicted increases in cyclone frequency and intensity associated with anthropogenic climate change.

Globally consistent impact of tropical cyclones on the structure of tropical and subtropical forests

“…The latter would imply TCs to have important evolutionary influences. Alternatively lower canopy heights may be due to resprouting, which is commonly observed in trees surviving TC damages (Bellingham, Tanner, & Healey, ; Scanlon, Petit, Tuiwawa, & Naikatini, ; Van Bloem et al., ; Zimmerman et al., ) and produces multistemmed trees that tend to be lower in height than single‐stemmed trees (Givnish, ; Kruger, Midgley, & Cowling, ).…”

“…The latter would imply TCs to have important evolutionary influences. Alternatively lower canopy heights may be due to resprouting, which is commonly observed in trees surviving TC damages (Bellingham, Tanner, & Healey, 1994;Scanlon, Petit, Tuiwawa, & Naikatini, 2018;Van Bloem et al, 2007;Zimmerman et al, 1994) and…”

A review of the major threats and challenges to global bat conservation

“…An increase in extreme weather events, such as unusually hot or dry conditions, or an increase in the frequency of natural disasters caused by typhoons and hurricanes, can cause rapid population declines that further decrease the resiliency of populations already threatened by small population sizes due to anthropogenic degradation or loss of natural habitats . Bats on tropical islands are particularly vulnerable to cyclones, and drastic declines (80–90% of some Pteropus populations) arising from direct mortality and loss of forest resources have been observed throughout the Pacific Islands . Extreme heat events on continents are increasing in intensity and frequency.…”

The Critical Importance of Old World Fruit Bats for Healthy Ecosystems and Economies

“…Cyclones are known to have an impact on endemic Pteropus spp. on Indian Ocean and Pacific islands, drastically reducing populations (e.g., 80-90% for some island Pteropus) and their food sources, and leaving bats vulnerable to increased hunting pressure from humans, conflict due to greater foraging in anthropogenic landscapes, or predation from domestic animals (Craig et al, 1994;Grant et al, 1997;McConkey et al, 2004;Esselstyn et al, 2006;O'Shea et al, 2016;Scanlon et al, 2018). Again, the negative impacts on island ecosystems are likely to be disproportionately high, particularly since the ecological roles of island Pteropus cannot be replaced by other animals (McConkey and Drake, 2015;Duron et al, 2017).…”