Facilitating natural regeneration in Saccharum spontaneum (L.) grasslands within the Panama Canal Watershed: effects of tree species and tree structure on vegetation recruitment patterns

Jones, Elizabeth R.; Wishnie, Mark; Deago, José; Sautu, Adriana; Cerezo, Arturo

doi:10.1016/j.foreco.2003.12.002

Cited by 80 publications

(70 citation statements)

References 45 publications

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“…Trees that attract a spectrum of frugivores are recommended (Martinez-Garza & Howe 2003), especially large-seeded forest species, as they have the highest performance in the Saccharum. Tall tree species with a high crown density should be considered, as they promote bird dispersal (Jones et al 2004); this may increase diversity. Planting shrubs and large monocots would further increase diversity by attracting bats and agoutis.…”

Section: mentioning

confidence: 99%

Barriers to forest regeneration of deforested and abandoned land in Panama

Hooper

Legendre

Condit

2005

Journal of Applied Ecology

258

175

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Summary1. In Panama, abandoned agricultural lands that supported tropical rain forest are invaded by the exotic invasive grass Saccharum spontaneum , which precludes native forest regeneration. This study aimed to evaluate the importance of several barriers to forest regeneration and highlight mitigation opportunities. 2. We examined four barriers to natural regeneration: Saccharum competition, seed dispersal limitation, fire and soil nutrient deficiency. Tree and shrub regeneration was measured in a factorial experiment combining Saccharum cutting treatments, distances from adjacent forest and a prescribed burn to assess the first three barriers, respectively. We compared soil nutrients in Saccharum plots with those from adjacent forest. Additionally, we determined the importance of distance to remnant vegetation (large-leaved monocots, shrubs and isolated trees) on forest regeneration. 3. Fire significantly decreased plant species richness of forest regeneration. Fire inhibited the germination of most species; the effect was exacerbated by cutting the Saccharum . 4. Grass competition significantly decreased seedling growth, while soil nutrient deficiency did not affect forest regeneration. 5. Seed dispersal limitation affected density and species richness. Significantly more species (3 × ) regenerated at 10 m compared with 35 m from the forest. Mean seedling densities were, respectively, four, three and two times higher under large-leaved monocots, isolated trees and shrubs than in open Saccharum . When seed input was experimentally equalized, large-seeded species had the highest establishment rate, suggesting that if their propagules were dispersed to the site they would regenerate in high proportions. However, under natural conditions they regenerated poorly and represented the most dispersal-limited species group. 6. Synthesis and applications . Our results suggest that facilitation of natural regeneration may be a feasible, low-cost management option for restoring native forest cover to large areas. Firebreaks must be established to promote biodiversity of forest regeneration. We do not recommend Saccharum cutting or fertilization as site treatments. Shading effectively eliminates Saccharum . Planting a variety of tree species in clumps throughout the Saccharum may overcome dispersal limitations and catalyse natural regeneration. Trees that attract different frugivores are recommended, especially largeseeded forest species.

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Section: mentioning

confidence: 99%

Barriers to forest regeneration of deforested and abandoned land in Panama

Hooper

Legendre

Condit

2005

Journal of Applied Ecology

258

175

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“…Studies throughout the tropics have found that tree plantations can serve as 'catalysts' for secondary regeneration in these areas, whereby they increase the stem density and species richness of understory plant communities compared to areas without planted trees (Parrotta et al 1997;Lamb et al 2005). The mechanisms responsible for these increases are thought to be trees' ability to attract seed-dispersers (Wunderle 1997), suppress grasses through shading (Kuusipalo et al 1995;Jones et al 2004), and improve soil conditions through litter inputs (Parrotta 1992). However, tree species vary greatly in their effects on understory regeneration (Powers et al 1997;Slocum and Horvitz 2000).…”

Section: Introductionmentioning

confidence: 99%

Forest regeneration under Tectona grandis and Terminalia amazonia plantation stands managed for biodiversity conservation in western Panama

et al. 2014

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Plantations of Tectona grandis in Central America are widely perceived to suppress forest regeneration in their understories, yet few studies have tested this assumption. We surveyed the understory woody vegetation growing in 7-year-old stands of T. grandis and the native tree species Terminalia amazonia in a plantation in western Panama that was managed with both commercial timber and biodiversity conservation objectives. We predicted that if T. grandis suppressed forest regeneration then the understories of T. grandis stands would have a lower density of woody stems, smaller stems, and fewer species than stands of T. amazonia. None of our predictions were supported. Densities of woody stems were 0.56 ± 0.21 m -2 (mean ± SE) and 0.64 ± 0.10 m -2 in T. grandis and T. amazonia understories, respectively. Stem height structure was similar under both species, where stems \1 m height dominated. Understory species richness did not differ between the two species; in total, 27 and 30 woody species were sampled in T. grandis and T. amazonia stands, respectively. However, understory species composition differed between the two crop species. Overall, our results are inconsistent with the idea that T. grandis plantations suppress forest regeneration and suggest that the lack of woody vegetation in other T. grandis plantation understories may be attributable to management actions, such as understory thinning, rather than species effects of T. grandis. 123New Forests (2015) 46:157-165 DOI 10.1007 research is needed to compare T. grandis and native species for their effects on forest regeneration.

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“…Canopy cover influences woody recruitment through a number of mechanisms including: enhancing bird activity and thereby dispersal of zoochorous seeds (Howe 1990;Jones et al 2004;Fink et al 2009); reducing cover of light-demanding pasture grasses (Holl 2002a;Hooper et al 2002); providing intermediate light conditions favorable for tree growth (Loik and Holl 2001); and enhancing nutrient availability (Siddique et al 2008;Celentano et al 2011). These mechanisms are all likely operating at our sites, but it is impossible to evaluate their relative importance without manipulating them independently.…”

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confidence: 99%

Testing heterogeneity–diversity relationships in tropical forest restoration

et al. 2013

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Restoring small-scale habitat heterogeneity in highly diverse systems, like tropical forests, is a conservation challenge and offers an excellent opportunity to test factors affecting community assembly. We investigated whether (1) the applied nucleation restoration strategy (planting tree islands) resulted in higher habitat heterogeneity than more homogeneous forest restoration approaches, (2) increased heterogeneity resulted in more diverse tree recruitment, and (3) the mean or coefficient of variation of habitat variables best explained tree recruitment. We measured soil nutrients, overstory and understory vegetation structure, and tree recruitment at six sites with three 5-to 7-year-old restoration treatments: control (no planting), planted tree islands, and conventional, mixedspecies tree plantations. Canopy openness and soil base saturation were more variable in island treatments than in controls and plantations, whereas most soil nutrients had similar coefficients of variation across treatments, and bare ground was more variable in control plots. Seedling and sapling species density were equivalent in plantations and islands, and were substantially higher than in controls. Species spatial turnover, diversity, and richness were similar in island and plantation treatments. Mean canopy openness, rather than heterogeneity, explained the largest proportion of variance in species density. Our results show that, whereas canopy openness and soil base saturation are more heterogeneous with the applied nucleation restoration strategy, this pattern does not translate into greater tree diversity. The lack of a heterogeneity-diversity relationship is likely due to the fact that recruits respond more strongly to mean resource gradients than variability at this early stage in succession, and that seed dispersal limitation likely reduces the available species pool. Results show that planting tree islands facilitates tree recruitment to a similar degree as intensive plantation-style restoration strategies.

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Facilitating natural regeneration in Saccharum spontaneum (L.) grasslands within the Panama Canal Watershed: effects of tree species and tree structure on vegetation recruitment patterns

Cited by 80 publications

References 45 publications

Barriers to forest regeneration of deforested and abandoned land in Panama

Barriers to forest regeneration of deforested and abandoned land in Panama

Forest regeneration under Tectona grandis and Terminalia amazonia plantation stands managed for biodiversity conservation in western Panama

Testing heterogeneity–diversity relationships in tropical forest restoration

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