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Abstract Microclimatic conditions change dramatically as forests age and impose strong filters on community assembly during succession. Light availability is the most limiting environmental factor in tropical wet forest succession; by contrast, water availability is predicted to strongly influence tropical dry forest (TDF) successional dynamics. While mechanisms underlying TDF successional trajectories are not well understood, observational studies have demonstrated that TDF communities transition from being dominated by species with conservative traits to species with acquisitive traits, the opposite of tropical wet forest. Determining how functional traits predict TDF tree species’ responses to changing environmental conditions could elucidate mechanisms underlying tree performance during TDF succession. We implemented a 6‐ha restoration experiment on a degraded Vertisol in Costa Rica to determine (1) how TDF tree species with different resource‐use strategies performed along a successional gradient and (2) how ecophysiological functional traits correlated with tree performance in simulated successional stages. We used two management treatments to simulate distinct successional stages including: clearing all remnant vegetation (early‐succession), or interplanting seedlings with no clearing (mid‐succession). We crossed these two management treatments (cleared/interplanted) with two species mixes with different resource‐use strategies (acquisitive/conservative) to examine their interaction. Overall seedling survival after 2 yr was low, 15.1–26.4% in the four resource‐use‐strategy × management‐treatment combinations, and did not differ between the management treatments or resource‐use‐strategy groups. However, seedling growth rates were dramatically higher for all species in the cleared treatment (year 1, 69.1% higher; year 2, 143.3% higher) and defined resource‐use strategies had some capacity to explain seedling performance. Overall, ecophysiological traits were better predictors of species’ growth and survival than resource‐use strategies defined by leaf and stem traits such as specific leaf area. Moreover, ecophysiological traits related to water use had a stronger influence on seedling performance in the cleared, early‐successional treatment, indicating that the influence of microclimatic conditions on tree survival and growth shifts predictably during TDF succession. Our findings suggest that ecophysiological traits should be explicitly considered to understand shifts in TDF functional composition during succession and that using these traits to design species mixes could greatly improve TDF restoration outcomes.
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Functional traits provide new insight into recovery and succession at deep‐sea hydrothermal vents
Abstract Investigation of communities in extreme environments with unique conditions has the potential to broaden or challenge existing theory as to how biological communities assemble and change through succession. Deep‐sea hydrothermal vent ecosystems have strong, parallel gradients of nutrients and environmental stress, and present unusual conditions in early succession, in that both nutrient availability and stressors are high. We analyzed the succession of the invertebrate community at 9°50′ N on the East Pacific Rise for 11 yr following an eruption in 2006 in order to test successional theories developed in other ecosystems. We focused on functional traits including body size, external protection, provision of habitat (foundation species), and trophic mode to understand how the unique nutritional and stress conditions influence community composition. In contrast to established theory, large, fast‐growing, structure‐forming organisms colonized rapidly at vents, while small, asexually reproducing organisms were not abundant until later in succession. Species in early succession had high external protection, as expected in the harsh thermal and chemical conditions after the eruption. Changes in traits related to feeding ecology and dispersal potential over succession agreed with expectations from other ecosystems. We also tracked functional diversity metrics over time to see how they compared to species diversity. While species diversity peaked at 8 yr post‐eruption, functional diversity was continuing to increase at 11 yr. Our results indicate that deep‐sea hydrothermal vents have distinct successional dynamics due to the high stress and high nutrient conditions in early succession. These findings highlight the importance of extending theory to new systems and considering function to allow comparison between ecosystems with different species and environmental conditions.
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- Award ID(s):
- 1829773
- PAR ID:
- 10450148
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Ecology
- Volume:
- 102
- Issue:
- 8
- ISSN:
- 0012-9658
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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