Patterns and Determinants of Woody Plant Growth in Savannas

Swemmer, Anthony; Ward, David

doi:10.1002/9781119081111.ch12

Cited by 5 publications

(14 citation statements)

References 189 publications

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“…Our results corroborated the findings of other studies of savanna woody plant responses to browsing that have shown that compensatory or over-compensatory shoot production is a common response to various intensities of browsing (Scogings & Gowda 2020). However, because reduced stem diameter can be indicative of C exhaustion (Hester et al 2006;Palacio et al 2014), this study suggested that extreme intensities of browsing early in the growing season, that may cause exhaustion of stored C during the same season, would retard saplings' long-term growth, and delay recruitment into the seed-producing adult stage (Swemmer & Ward 2020). If repeated frequently, then severe browsing could be fatal for the saplings (Teague 1989).…”

Section: Discussionmentioning

confidence: 78%

“…2006; Palacio et al . 2014), this study suggested that extreme intensities of browsing early in the growing season, that may cause exhaustion of stored C during the same season, would retard saplings’ long‐term growth, and delay recruitment into the seed‐producing adult stage (Swemmer & Ward 2020). If repeated frequently, then severe browsing could be fatal for the saplings (Teague 1989).…”

Section: Discussionmentioning

confidence: 99%

“…Resource availability and browsing by large mammal herbivores are important determinants of woody plant abundance in African savannas (Sankaran et al 2008;Anderson et al 2015;Staver et al 2017;Scogings & Sankaran 2020). Both factors are especially critical at the seedling and sapling stages of woody plants (Vadigi & Ward 2014;Churski et al 2017;Ib añez et al 2017;Swemmer & Ward 2020), yet their combined effects have been poorly studied in savannas (Scogings et al 2017). The effects of resource availability and browsing on growth and nutritional value of saplings are relevant for the transition to seed-producing adults in populations.…”

Section: Introductionmentioning

confidence: 99%

“…The effects of resource availability and browsing on growth and nutritional value of saplings are relevant for the transition to seed-producing adults in populations. If either factor reduces growth, then that transition is delayed (Swemmer & Ward 2020). If either factor should increase nutritional value of saplings, then rebrowsing is likely (Makhabu et al 2006;Fornara & du Toit 2007), which would limit their ability to escape the browser trap (Staver & Bond 2014;Hempson et al 2020).…”

Section: Introductionmentioning

confidence: 99%

“…2017; Ibáñez et al . 2017; Swemmer & Ward 2020), yet their combined effects have been poorly studied in savannas (Scogings et al . 2017).…”

Section: Introductionmentioning

confidence: 99%

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Severe simulated herbivory constrains Sclerocarya birrea saplings regardless of resource availability

Scogings¹,

Fortier

2020

Austral Ecology

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Allocation of carbon to growth and defences in plants is affected by resource availability and herbivory, two determinants of woody plant abundance in savannas. Both factors are critical at the sapling stage of woody plants, yet their combined effects on sapling growth and defence have been poorly studied in savannas. Sclerocarya birrea is an iconic keystone species in southern African savannas, widely used by herbivores and humans. We hypothesised that low resource availability or high herbivory intensity would reduce growth and nutritional value for herbivores, but high resource availability or low herbivory intensity would increase growth and nutritional value. Support for our hypothesis would imply that any level of browsing intensity (relative to unbrowsed plants), regardless of resource availability, would potentially hold saplings in a browser trap because of reduced growth or improved nutritional value. We explored responses of S. birrea saplings to five levels of nutrient fertiliser and six levels of simulated browsing intensity. Low fertiliser application rates did not affect growth, but the highest fertiliser rate increased canopy growth. The most severe intensities of simulated browsing negatively affected growth and nutritional value. Our results suggested that either resource limitation throughout the growing season, or extremely intense browsing early in the growing season, is potentially able to retard long‐term growth of saplings and delay recruitment of adults. Although saplings that are severely browsed early in the growing season might not be re‐browsed later in the same season because of their reduced nutritional value, their weakened nitrogen status would be an additional limitation to regrowth. No significant interactions between resource availability and herbivory intensity were detected, which we suggest resulted from responses to resource availability and herbivory operating at different temporal scales. We recommend that future experiments of this type include carefully timed measurements to detect transient responses.

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Section: Discussionmentioning

confidence: 78%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…2017; Ibáñez et al . 2017; Swemmer & Ward 2020), yet their combined effects have been poorly studied in savannas (Scogings et al . 2017).…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Severe simulated herbivory constrains Sclerocarya birrea saplings regardless of resource availability

Scogings¹,

Fortier

2020

Austral Ecology

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Landscape heterogeneity increases survival of Pinus caribaea var. hondurensis juveniles in a frequently burned, humid savanna

et al. 2022

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We characterized Caribbean pine (Pinus caribaea var. hondurensis) seedling and juvenile survival in lowland Belizean savannas with respect to environment and fire regimes. Plants in open and densely wooded environments had lower survival after fire. We hypothesize that facilitative or correlative mechanisms might promote positive relationships between shrubs and pine survival. Abstract in Spanish is available with online material.

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Multispecies allometric equations for shrubs and trees biomass prediction in a Guinean savanna (West Africa)

Kouamé¹,

Millan²,

N’Dri³

et al. 2022

Silva Fenn.

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Currently, tools to predict the aboveground and belowground biomass (AGB and BGB) of woody species in Guinean savannas (and the data to calibrate them) are still lacking. Multispecies allometric equations calibrated from direct measurements can provide accurate estimates of plant biomass in local ecosystems and can be used to extrapolate local estimates of carbon stocks to the biome scale. We developed multispecies models to estimate AGB and BGB of trees and multi-stemmed shrubs in a Guinean savanna of CÃ´te dâIvoire. The five dominant species of the area were included in the study. We sampled a total of 100 trees and 90 shrubs destructively by harvesting their biometric data (basal stem diameter , total stem height , stump area , as well as total number of stems for shrubs), and then measured their dry AGB and BGB. We fitted log-log linear models to predict AGB and BGB from the biometric measurements. The most relevant model for predicting AGB in trees was fitted as follows: AGB = 0.0471 () (with AGB in kg and in g cm m). This model had a bias of 19%, while a reference model for comparison (fitted from tree measurements in a similar savanna ecosystem, Ifo et al. 2018) overestimated the AGB of trees of our test savannas by 132%. The BGB of trees was also better predicted from ÏDb2H as follows: BGB = 0.0125 () (BGB in kg and in g cm m), with 6% bias, while the reference model had about 3% bias. In shrubs, AGB and BGB were better predicted from together with the total number of stems (). The best fitted allometric equation for predicting AGB in shrubs was as follows: AGB = 0.0191 () . This model had about 1.5% bias, while the reference model overestimated the AGB of shrubs of Lamto savannas by about 79%. The equation for predicting BGB of shrubs is: BGB = 0.0228 () that overestimated the BGB of the shrubs of Lamto savannas with about 3% bias, while the reference model underestimated the BGB by about 14%. The reference model misses an important feature of fire-prone savannas, namely the strong imbalance of the BGB/AGB ratio between trees and multi-stemmed shrubs, which our models predict. The allometric equations we developed here are therefore relevant for C stocks inventories in trees and shrubs communities of Guinean savannas.DbHSSnÏDb2H0.915ÏDb2Hâ1ÏDb2H0.6899ÏDb2Hâ1ÏDb2HnÏDb2H0.6227n0.9271ÏDb2H0.7205n0.992

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Patterns and Determinants of Woody Plant Growth in Savannas

Cited by 5 publications

References 189 publications

Severe simulated herbivory constrains Sclerocarya birrea saplings regardless of resource availability

Severe simulated herbivory constrains Sclerocarya birrea saplings regardless of resource availability

Landscape heterogeneity increases survival of Pinus caribaea var. hondurensis juveniles in a frequently burned, humid savanna

Multispecies allometric equations for shrubs and trees biomass prediction in a Guinean savanna (West Africa)

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