The role of lemur seed dispersal in restoring degraded forest ecosystems in Madagascar

Abstract

Anthropogenic disturbances lead to the degradation or destruction of tropical forests, with negative consequences for flora, fauna, and local people. Restoration plantings may compensate these impacts, but time and financial expenditures are high. Thus, priority is often given to plantations of a few introduced species that have little value for conservation. Animal seed dispersal may diversify and accelerate regeneration of restoration plantings, thereby lowering their costs. We studied seed dispersal quantity and quality of crowned lemurs (Eulemur coronatus) in a highly degraded forest in northern Madagascar, conducting behavioural observations and germination experiments and describing dispersed plant species’ characteristics. Crowned lemurs were highly frugivorous, dispersing a large number of seeds and plant species. While there were negative effects of gut passage on germination, the positive effects of pulp removal outweighed these, resulting in an overall positive effect on regeneration. Our study confirmed that effects of gut passage are dependent on the dispersed plant species. We found 20 plant species, including three threatened with extinction, whose only dispersers in Oronjia seem to be crowned lemurs. We conclude that lemurs play important roles in protecting plant species and maintaining healthy ecosystems through seed dispersal, and that E. coronatus is a key species in this respect. In addition, if lemurs were included in restoration, they would disperse a diversity of plant species that cannot be matched by conventional restoration plantings. Their influence would facilitate the regeneration of some, but not all plant species. Negative effects, like the spread of invasive species through seed dispersal by lemurs, must also be considered.

Ground‐based vegetation descriptions and remote sensing as complementary methods describing habitat requirements of a frugivorous primate in northern Madagascar: implications for forest restoration

“…On each transect, we marked 20 points at 25 m intervals, totalling 40 points. During our lemur behaviour study (Steffens et al ., 2022), we marked lemur defecation points of two groups of lemurs (group ‘A’ with 5–7 individuals and group ‘B’ with 8–14 individuals) by use of a handheld GPS (Garmin GPSMAP 64 s) and red tissue flags. To ensure independency of data, we marked only points with at least 25 m distance.…”

“…For this, we follow the same methods as described above, but here we did not restrict the analysis to the indices values at lemur defecation points, but rather used all lemur occurrence points georeferenced during our behavioural observations. To gain these, we followed the two lemur groups through the forest and took a GPS point every 5 minutes if at least one individual of the observation group was in sight (Steffens et al ., 2022). This approach allowed us to investigate a much larger sample size compared to the analyses where we combined classical vegetation descriptions and remote sensing information.…”

“…Among lemurs, the genus Eulemur includes highly frugivorous species that are spread over large parts of the country dispersing a variety of plant species. In northern Madagascar, the crowned lemur ( Eulemur coronatus ) is a key species in this aspect (Steffens, 2022; Steffens, Sanamo, & Razafitsalama, 2022). The importance of lemurs for seed dispersal implies that loss of their populations or species may have detrimental effects on recruitment and thus survival of plant species (Ganzhorn et al ., 1999; Crowley, Godfrey, & Irwin, 2011; Federman et al ., 2016; Albert‐Daviaud et al ., 2020).…”

Significance of seed dispersal by the largest frugivore for large-diaspore trees

“…In Madagascan forest ecosystems, the largest frugivorous taxon, Lemuridae (body mass: 1.6-3.6 kg 45 ), has proven to be a highly effective seed disperser, i.e. they are capable of dispersing large quantities of intact seeds from a variety of plant species over large areas [46][47][48][49][50] . In addition, they are thought to be the sole seed dispersers for large-seeded plants 43,45,48 .…”