The differential effects of bracken (Pteridium aquilinum (L.) Kuhn) on germination and seedling performance of tree species in the African tropics

Ssali, Fredrick; Moe, Stein R.; Sheil, Douglas

doi:10.1007/s11258-018-0901-8

Cited by 32 publications

(21 citation statements)

References 37 publications

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“…For example, the disturbance-favouring niche can be occupied by ferns (Kessler, 2010), bamboo (Griscom and Ashton, 2006), shrubs (Jiménez-Castillo et al, 2007), or grasses (Van Nes et al, 2014), particularly at high elevations and latitudes, or in degraded forests. These plant forms can be common and widespread, e.g., bracken fern (Pteridium aquilinum) is found on every continent except Antarctica and inhibits forest succession through soil deterioration and shading, and by facilitating seed predation (Ssali et al, 2018(Ssali et al, , 2019. Grass is widely implicated in thresholds between forest and savanna through fuelling wildfires (Van Nes et al, 2014).…”

Section: Variation Between Forest Recovery Response Classesmentioning

confidence: 99%

Conceptualising the Global Forest Response to Liana Proliferation

Marshall

Platts

Chazdon

et al. 2020

Front. For. Glob. Change

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Lianas are woody vines, rooted in the soil, and supported physically by trees. Lianas contribute to forest ecosystem functioning globally, but especially in the tropics and subtropics. However, prolific liana growth following heavy disturbance frequently affects subsequent recovery of forest tree diversity, biomass, structure, and function. Understanding this forest liana dynamic, and its sensitivity to climate and anthropogenic forces, is essential for worldwide forest restoration and climate change mitigation. Here, we synthesise the evidence for both positive and negative effects of lianas on forests and propose a framework that outlines the expected global response of forests to disturbance-induced liana proliferation. Emerging evidence suggests that lianas play a major role in both facilitating and delaying forest recovery following disturbance. At low levels of disturbance and/or where environmental conditions favour tree growth, lianas can facilitate forest recovery by protecting trees from extreme weather, fire, weed invasion and herbivory. However, under conditions where lianas proliferate beyond critical thresholds, positive feedbacks are expected to induce and sustain liana-dominated forest states that can endure for decades or even longer. We conceptualise alternative classes of forest recovery response to disturbance and describe measurement and modelling of liana thresholds. We identify four essential challenges for global change science relating to lianas: (1) incorporation of lianas and sapling stems into forest monitoring and tree stand measurements worldwide; (2) long-term experiments to determine variation in liana-tree competition, and potential drivers across forest successional gradients; (3) identification and prediction of liana thresholds and other alternative forest recovery response classes; and (4) dynamic mechanistic modelling of forest recovery to determine regional and global variation within and among different recovery response classes, in relation to variation in potential drivers, liana feedbacks and their interactions. Addressing these challenges will determine the importance of lianas in shaping regional and global forest composition, recovery and dynamics.

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Section: Variation Between Forest Recovery Response Classesmentioning

confidence: 99%

Conceptualising the Global Forest Response to Liana Proliferation

Marshall

Platts

Chazdon

et al. 2020

Front. For. Glob. Change

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“…Second, forest regeneration in frequently disturbed areas may be partially inhibited by high frequencies of debris damage and a self‐perpetuating cycle in which disturbed vegetation maintains and attracts further disturbance. Finally, as seen in our studies of bracken‐dominated clearings, seedling densities in these open areas are low (Ssali et al., ), due in part to limited rain, low seed persistence, and shading (Ssali, Moe & Sheil, ,b; Ssali et al., ); thus, an annual 61.3% damage rate is likely to further slow recovery. Exclosure studies would be required to assess this influence.…”

Section: Discussionmentioning

confidence: 55%

Damage to artificial seedlings across a disturbed Afromontane forest landscape

2019

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Seedling mortality is an important demographic bottleneck for forest regeneration, yet the factors influencing recruitment are often poorly characterized across space and time. In African highlands, where extensive patches of previously disturbed forests remain in persistent shrub-dominated states, patterns of damage to seedlings have not been examined in detail. We used artificial seedlings to determine how (nonherbivory-related) damage varies across a fragmented forest landscape in the Bwindi Impenetrable National Park, Uganda. A total of 848 artificial seedlings were established in 106 plots, each with 8 seedlings, across a gradient of environmental factors, including habitat type, topographic position, distance to water, and distance to human activity. We divided damage into that due to vertebrates, plant debris, and unknown agents. From our 16,960 monthly stem assessments, 1,289 damage events were recorded. The mean "seedling" damage per year (± 1 SE) was 59.5 ± 2.3%. Damage was significantly more frequent in sites dominated by short herbs (66.1 ± 3.0) than in sites dominated by shrubs (60.1 ± 2.6) and ferns (47.9 ± 2.7). The mean percentage of damage by each class of agents was 45.8 ± 2.1% for vertebrates, 21.4 ± 2.1% for plant debris, and 3.8 ± 0.6% for unknown agents. These rates surpass those reported in other montane forests, likely reflecting the density of large vertebrates in our site.Our results indicate that most damage to artificial seedlings arises from larger vertebrates but that most spatial variation in this damage reflects the impacts of falling plant debris. These damage processes appear sufficient to constrain the regeneration of tree species in areas where forest cover is patchy and fragmented.

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“…Bracken fern Pteridium were also regarded as ecological filters worldwide ( Senyanzobe et al, 2020 ). The seedling establishment of rainforest species in Brazil, Scots pine and Norway spruce in Sweden, and tropical species in Africa can be significantly interfered by Pteridium ( Dolling, 1996 ; Silva Matos and Belinato, 2010 ; Ssali et al, 2019 ). Proanthocyanidin selligueain A is the major secondary compound in the green fronds and litter of Pteridium ( de Jesus Jatoba et al, 2016 ).…”

Section: Recognition Of the Ecosystem Functions Of Dicranopmentioning

confidence: 99%

Rethinking the Ecosystem Functions of Dicranopteris, a Widespread Genus of Ferns

et al. 2021

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Dicranopteris is an ancient and widespread genus of ferns in pantropical regions. Some species of the genus can form dense thickets, and dominate the understory, which are common and key species in tropical and subtropical ecosystems. However, they were mostly cut or burned in forest management because of forming dense thickets which were considered to interfere with forest regeneration and succession. In the current review, we argue that the Dicranopteris species which are able to rapidly colonize barren areas may contribute to ecosystem recovery, resistance to environmental stress, and succession control. Rapid colonization involves prolific spore production, rapid clonal growth, the generation of high surface cover, and the ability to fill gaps; stress resistance includes resistance to abiotic stress, and the ability to reduce soil erosion from rainfall, alien species invasion, and soil contamination and toxicity; and succession facilitation consists of carbon and nutrient sequestration in soil, moderation of the microclimate, alteration of the soil microbial and faunal communities, and determination of which plant species to be established in the next successional stage. All of these ecosystem functions may be beneficial to ecosystem resilience. We expect that the distribution of Dicranopteris will expand in response to global warming, changes in precipitation patterns, increases in soil pollution, deforestation, and land degradation. We recommend that Dicranopteris, as a pioneer fern and a valuable component of tropical and subtropical ecosystems, needs more attention in future research and better management practices to promote forest regeneration and succession.

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The differential effects of bracken (Pteridium aquilinum (L.) Kuhn) on germination and seedling performance of tree species in the African tropics

Cited by 32 publications

References 37 publications

Conceptualising the Global Forest Response to Liana Proliferation

Conceptualising the Global Forest Response to Liana Proliferation

Damage to artificial seedlings across a disturbed Afromontane forest landscape

Rethinking the Ecosystem Functions of Dicranopteris, a Widespread Genus of Ferns

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