Impacts of fire and prospects for recovery in a tropical peat forest ecosystem

Uncontrolled fires place considerable burdens on forest ecosystems, compromising our ability to meet conservation and restoration goals. A poor understanding of the impacts of fire on ecosystems and their biodiversity exacerbates this challenge, particularly in tropical regions where few studies have applied consistent analytical techniques to examine a broad range of ecological impacts over multiyear time frames. We compiled 16 y of data on ecosystem properties (17 variables) and biodiversity (21 variables) from a tropical peatland in Indonesia to assess fire impacts and infer the potential for recovery. Burned forest experienced altered structural and microclimatic conditions, resulting in a proliferation of nonforest vegetation and erosion of forest ecosystem properties and biodiversity. Compared to unburned forest, habitat structure, tree density, and canopy cover deteriorated by 58 to 98%, while declines in species diversity and abundance were most pronounced for trees, damselflies, and butterflies, particularly for forest specialist species. Tracking ecosystem property and biodiversity datasets over time revealed most to be sensitive to recurrent high-intensity fires within the wider landscape. These megafires immediately compromised water quality and tree reproductive phenology, crashing commercially valuable fish populations within 3 mo and driving a gradual decline in threatened vertebrates over 9 mo. Burned forest remained structurally compromised long after a burn event, but vegetation showed some signs of recovery over a 12-y period. Our findings demonstrate that, if left uncontrolled, fire may be a pervasive threat to the ecological functioning of tropical forests, underscoring the importance of fire prevention and long-term restoration efforts, as exemplified in Indonesia

Individual, contextual, and age-related acoustic variation in Simakobu (Simias concolor) loud calls.

Primate loud calls have the potential to encode information about the identity, arousal, age, or physical condition of the caller, even at long distances. In this study, we conducted an analysis of the acoustic features of the loud calls produced by a species of Asian colobine monkey (simakobu, Simias concolor). Adult male simakobu produce loud calls spontaneously and in response to loud sounds and other loud calls, which are audible more than 500 m. Individual differences in calling rates and durations exist, but it is unknown what these differences signal and which other acoustic features vary among individuals. We aimed to describe the structure and usage of calls and to examine acoustic features that vary within and among individuals. We determined the context of 318 loud calls and analyzed 170 loud calls recorded from 10 adult males at an undisturbed site, Pungut, Siberut Island, Indonesia. Most calls (53%) followed the loud call of another male, 31% were spontaneous, and the remaining 16% followed a loud environmental disturbance. The fundamental frequency (F0) decreased while inter-unit intervals (IUI) increased over the course of loud call bouts, possibly indicating caller fatigue. Discriminant function analysis indicated that calls were not well discriminated by context, but spontaneous calls had higher peak frequencies, suggesting a higher level of arousal. Individual calls were distinct and individuals were mainly discriminated by IUI, call duration, and F0. Loud calls of older males had shorter IUI and lower F0, while middle-aged males had the highest peak frequencies. Overall, we found that calls were individually distinct and may provide information about the age, stamina, and arousal of the calling male, and could thus be a way for males and females to assess competitors and mates from long distances

Descriptive statistics of acoustic parameters.

<p>Min = minimum value, Max = maximum value, SD = standard deviation, CV = coefficient of variation.</p

Variation in relation to male age class.

<p>Results based on GLM. <i>N</i> = 68 loud calls recorded from 7 males.</p><p>Significant differences after Hochberg correction indicated in bold.</p

Mean ± 95% confidence interval for peak frequency of huh syllables across contexts.

<p>Mean ± 95% confidence interval for peak frequency of huh syllables across contexts.</p

Changes in call characteristics as a function of unit position: (A) fundamental frequency of the hoo syllable and (B) inter-unit interval.

<p>Best-fit lines for individual males provided for demonstration purposes only.</p

Variation in relation to call unit position within the loud call.

<p>Results based on LMM with loud call recording as a random factor. <i>N</i> = 22 loud calls recorded from four males.</p

Mean ± 95% confidence interval of three parameters that varied significantly across age classes: (A) inter-unit interval, (B) fundamental frequency of hoo syllables, and (C) peak frequency of hoo syllables.

<p>Mean ± 95% confidence interval of three parameters that varied significantly across age classes: (A) inter-unit interval, (B) fundamental frequency of hoo syllables, and (C) peak frequency of hoo syllables.</p

Discriminant scores for loud calls produced by males in different age classes for the first two canonical discriminant functions.

<p>The three age classes are denoted by different symbols. Variables showing loadings with an absolute value >0.4 for each function are indicated along the axes.</p

Sample spectrogram of a simakobu loud call indicating the parameters measured in the acoustic analysis: (a) call unit, (b) huh, (c) hoo, (d) duration, (e) inter-unit interval, (f) fundamental frequency, and (g) peak frequency.

<p>Sample spectrogram of a simakobu loud call indicating the parameters measured in the acoustic analysis: (a) call unit, (b) huh, (c) hoo, (d) duration, (e) inter-unit interval, (f) fundamental frequency, and (g) peak frequency.</p