Large terrestrial herbivorous mammals (LTH‐mammals) influence plant community structure by affecting seedling establishment in mature tropical forests. Many of these LTH‐mammals frequent secondary forests, but their effects on seedling establishment in them are understudied, hindering our understanding of how LTH‐mammals influence forest regeneration in human‐modified landscapes. We tested the hypothesis that the strength of LTH‐mammals' effects on seedling establishment depends on landscape protection, forest successional stage and plant species' traits using a manipulative field experiment in six 1‐ha sites with varying successional age and landscape protection. In each site, we established 40 seedling plot‐pairs, with one plot excluding LTH‐mammals and one not, and monitored seedlings of 116 woody species for 26 months. We found significant effects of LTH‐mammal exclusion on seedling survival contingent upon the protection of forests at the landscape level and forest stage. After 26 months, survival differences between LTH‐mammal exclusion and non‐exclusion treatments were greater in protected than unprotected landscapes. Additionally, plant species' traits were related to the LTH‐mammals' differential effects, as LTH‐mammals reduced the survival of seedlings of larger‐seeded species the most. Overall, LTH‐mammals' effects translated into significant shifts in community composition as seedling communities inside and outside the exclosures diverged. Moreover, lower density and higher species diversity were found as early as 12 and 18 months outside than inside exclosures.
Despite numerous studies examining the fitness consequences of animal personalities, predictions concerning the relationship between personality and survival are not consistent with empirical observations. Theory predicts that individuals who are risky (i.e. bold, active and aggressive) should have higher rates of mortality; however, empirical evidence shows high levels of variation in behaviour–survival relationships in wild populations. We suggest that this mismatch between predictions under theory and empirical observations results from environmental contingencies that drive heterogeneity in selection. This uncertainty may constrain any universal directional relationships between personality traits and survival. Specifically, we hypothesize that spatiotemporal fluctuations in perceived risk that arise from variability in refuge abundance and competitor density alter the relationship between personality traits and survival. In a large‐scale manipulative experiment, we trapped four small mammal species in five subsequent years across six forest stands treated with different management practices in Maine, United States. Stands all occur within the same experimental forest but contain varying amounts of refuge and small mammal densities fluctuate over time and space. We quantified the effects of habitat structure and competitor density on the relationship between personality traits and survival to assess whether directional relationships differed depending on environmental contingencies. In the two most abundant species, deer mice and southern red‐backed voles, risky behaviours (i.e. higher aggression and boldness) predicted apparent monthly survival probability. Mice that were more aggressive (less docile) had higher survival. Voles that were bolder (less timid) had higher survival, but in the risky forest stands only. Additionally, traits associated with stress coping and de‐arousal increased survival probability in both species at high small mammal density but decreased survival at low density. In the two less abundant study species, there was no evidence for an effect of personality traits on survival. Our field experiment provides partial support for our hypothesis: that spatiotemporal fluctuations in refuge abundance and competitor density alter the relationship between personality traits and survival. Our findings also suggest that behaviours associated with stress coping and de‐arousal may be subject to density‐dependent selection and should be further assessed and incorporated into theory.
- Award ID(s):
- 1940525
- NSF-PAR ID:
- 10481459
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- Journal of Animal Ecology
- Volume:
- 93
- Issue:
- 2
- ISSN:
- 0021-8790
- Format(s):
- Medium: X Size: p. 196-207
- Size(s):
- ["p. 196-207"]
- Sponsoring Org:
- National Science Foundation
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