Long-term effects of selective logging on dipterocarp populations in the Pasoh Forest Reserve, Malaysia

Abstract

Background: Selective logging alters tree growth, mortality and recruitment, and the subsequent population dynamics of trees. However, little information is available on how tree populations reduce local extinction in logged forests. Aims: We evaluated the effects of selective logging on tree performance and population dynamics of five dominant dipterocarp species in the Pasoh Forest Reserve, Malaysia. Methods: We used demographic data derived from a forest that was selectively logged in 1958 as well as those from an unlogged primary forest and constructed population transition matrix models to project the population dynamics. Results: The dipterocarp species studied showed minor differences in mortality and diameter growth, but there was a large difference in recruitment between logged and unlogged forest; populations in the logged forest had 10 times slower recruitment rates into the smallest size class than those in the primary forest. Population size structures differed between the two forest types but, despite a large difference in the recruitment rates, there were only minor differences in both asymptotic-and matrix-projected population growth rates. Conclusions: A single selective logging event had only minor impacts on the growth rates of dipterocarp trees in the Pasoh forest. But at the same time it had a large impact on the size structure of the dipterocarp populations through a reduction in recruitment showing that the impacts of selective logging are still seen on dipterocarp population after 50 years.

Demographic strategies of a dominant tree species in response to logging in a degraded subtropical forest in Southeast China

“…However, we observed a population declined during the study period. That is to say, if forests are exposed to under continuous logging management practices, pioneer species with a similar demography to P. massoniana may experience a population decline and even disapperar altogether due to low seedling recruitment (Hastings 2001;Yamada et al 2016). On the other hand, previous studies have shown that it can take years or even decades for the influence of logging to be seen on long-lived tree populations (Bonnell et al 2011;Egnell and Valinger 2003).…”

“…It has been shown that the successful regeneration of pioneer species has a positive correlation to canopy gaps (Arets et al 2003). However, for shade-tolerant species, logging could have a significant impact on population dynamics through a reduction in recruitment, which could even cause extinction if exposed to periodic regime (Yamada et al 2016).…”

The ecology of the Asian dipterocarps

“…Numerous studies noted above addressed some aspects of forest disturbance or fragmentation. Ang et al (2016) showed how logging had minimal impacts on seedling genetic diversity and Yamada et al (2016) also found that logging did not impact tree growth rates or mortality but did influence recruitment. A number of studies used the small Bukit Timah Nature Reserve and surrounding secondary forest as examples of fragmented forest within an urbanised matrix (Corlett 1992) that may represent an extreme fate of dipterocarp forests in the future.…”

“…Timber extraction has been extensive in the past, and long-lived taxa, such as the dipterocarps, may have a 'disturbance memory' of such perturbations, transcending generations and lasting decades or hundreds of years (e.g. Yamada et al 2016).…”

“…The Asian dipterocarps are found in India (Antin et al 2016), Bangladesh, Nepal, Sri Lanka and the Andaman Islands, in the seasonal forests of Thailand (Disyatat et al 2016), Cambodia (Kenzo et al 2016b), Vietnam (Dong et al 2016 Dipterocarps are found across Malesia, throughout the Malay peninsula (Chong et al 2016;Kenzo et al 2016a;Ng et al 2016;Yamada et al 2016), Sumatra, Java, and in Borneo (Ang et al 2016;Brearley et al 2016;Dent and Burslem 2016;Nutt et al 2016;Saner et al 2016) they reach their highest species diversity ( Figure 2). East of Wallace's line, in neighbouring Sulawesi, diversity decreases markedly and although dipterocarp ranges extend to New Guinea (Figure 2), dipterocarp species constitute a much smaller component of the forest canopy.…”