Long-term resilience, bush encroachment patterns and local knowledge in a Northeast African savanna

Gil‐Romera, Graciela; Lamb, Henry F.; Turton, David; Sevilla-Callejo, Miguel; Umer, Mohammed

doi:10.1016/j.gloenvcha.2010.04.008

Cited by 30 publications

(28 citation statements)

References 78 publications

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“…However, a 2000-year record of vegetation change in the Dara range of the Mago National Park, southwestern Ethiopia proves that the system is resilient, with alternating open and encroached phases, as along as the encroachment is within the thresholds conditioning the system's resilience (Gil-Romera et al 2010). The aggressive invasion of rangelands by alien woody species (e.g.…”

Section: Rangeland Rehabilitationmentioning

confidence: 99%

Rehabilitation of degraded dryland ecosystems – review

Yirdaw¹,

Tigabu²,

Monge³

2017

Silva Fenn.

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Highlights• The prospect of restoring degraded drylands is technically promising.• The forest landscape restoration concept can be used as the overarching rehabilitation framework.• Development of process-based models that forecast rehabilitation outcomes is needed.• Rehabilitation methodologies developed for moist areas are not necessarily suitable for drylands.• More data is needed on cost-benefit analysis of rehabilitation interventions. AbstractLand degradation is widespread and a serious threat affecting the livelihoods of 1.5 billion people worldwide of which one sixth or 250 million people reside in drylands. Globally, it is estimated that 10-20% of drylands are already degraded and about 12 million ha are degraded each year. Driven by unsustainable land use practices, adverse climatic conditions and population increase, land degradation has led to decline in provision of ecosystem services, food insecurity, social and political instability and reduction in the ecosystem's resilience to natural climate variability. Several global initiatives have been launched to combat land degradation, including rehabilitation of degraded drylands. This review aimed at collating the current state-of-knowledge about rehabilitation of degraded drylands. It was found that the prospect of restoring degraded drylands is technically promising using a suite of passive (e.g. area exclosure, assisted natural regeneration, rotational grazing) and active (e.g. mixed-species planting, framework species, maximum diversity, and use of nurse tree) rehabilitation measures. Advances in soil reclamation using biological, chemical and physical measures have been made. Despite technical advances, the scale of rehabilitation intervention is small and lacks holistic approach. Development of processbased models that forecast outcomes of the various rehabilitation activities will be useful tools for researchers and practitioners. The concept of forest landscape restoration approach, which operates at landscape-level, could also be adopted as the overarching framework for rehabilitation of degraded dryland ecosystems. The review identified a data gap in cost-benefit analysis of rehabilitation interventions. However, the cost of rehabilitation and sustainable management of drylands is opined to be lower than the losses that accrue from inaction, depending on the degree of degradation. Thus, local communities' participation, incorporation of traditional ecological knowledge, clear division of tasks and benefits, strengthening local institutions are crucial not only for cost-sharing, but also for the long-term success of rehabilitation activities.

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Section: Rangeland Rehabilitationmentioning

confidence: 99%

Rehabilitation of degraded dryland ecosystems – review

Yirdaw¹,

Tigabu²,

Monge³

2017

Silva Fenn.

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“…For example, savanna seems to be resilient to changes at a centennial timescale, as the vegetation fluctuates between two stable states of grassland and woodland (Gillson, 2004;Gil-Romera et al, 2010). For example, savanna seems to be resilient to changes at a centennial timescale, as the vegetation fluctuates between two stable states of grassland and woodland (Gillson, 2004;Gil-Romera et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Among others, changes in precipitation, atmospheric pCO 2 , vegetation fires, and land use are considered to be triggers and/or drivers (Aleman, Blarquez, & Staver, 2016;Berry & Kulmatiski, 2017;Buitenwerf, Bond, Stevens, & Trollope, 2012;Case & Staver, 2017), which likely interplay at different timescales. For example, while climate shifts are considered the main driver of changes in the grass/woody vegetation ratio on a long timescale (Gil-Romera et al, 2010;Scott et al, 1991), changes in grazing pressure and fire, besides stochastic variations in rainfall, are thought to drive decadal-scale variability (Gillson, 2004;van Rooyen et al, 2018). Interestingly, different studies have shown that precipitation, fire, and herbivory may have different effects on encroacher species, and thus a different effect on savanna stability (Joubert et al, 2008;Joubert, Smit, & Hoffman, 2012.…”

Section: Introductionmentioning

confidence: 99%

Vegetation state changes in the course of shrub encroachment in an African savanna since about 1850 CE and their potential drivers

Tabares

Zimmermann

Dietze

et al. 2019

Ecology and Evolution

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1. Shrub encroachment has far-reaching ecological and economic consequences in many ecosystems worldwide. Yet, compositional changes associated with shrub encroachment are often overlooked despite having important effects on ecosystem functioning.2. We document the compositional change and potential drivers for a northern Namibian Combretum woodland transitioning into a Terminalia shrubland. We use a multiproxy record (pollen, sedimentary ancient DNA, biomarkers, compoundspecific carbon (δ 13 C) and deuterium (δD) isotopes, bulk carbon isotopes (δ 13 Corg), grain size, geochemical properties) from Lake Otjikoto at high taxonomical and temporal resolution.3. We provide evidence that state changes in semiarid environments may occur on a scale of one century and that transitions between stable states can span around 80 years and are characterized by a unique vegetation composition. We demonstrate that the current grass/woody ratio is exceptional for the last 170 years, as supported by n-alkane distributions and the δ 13 C and δ 13 Corg records. Comparing vegetation records to environmental proxy data and census data, we infer a complex network of global and local drivers of vegetation change. While our δD record suggests physiological adaptations of woody species to higher atmospheric pCO 2 concentration and drought, our vegetation records reflect the impact of broadscale logging for the mining industry, and the macrocharcoal record suggests a decrease in fire activity associated with the intensification of farming. Impact of selective grazing is reflected by changes in abundance and taxonomical composition of grasses and by an increase of nonpalatable and trampling-resistant taxa.In addition, grain-size and spore records suggest changes in the erodibility of soils because of reduced grass cover. | 963TABARES ET Al.

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“…Este equipo de investigadores está centrado en el estudio de la paleoclimatología y la paleoecología, disciplinas que intentan caracterizar los cambios ambientales pasados y entender las respuestas de los ecosistemas a estos cambios, en escalas temporales superiores a décadas o siglos. Con ello se persigue la reconstrucción de la dinámica del clima, la hidrología y las comunidades vegetales esencialmente, centrando la atención, en los cambios I. PARDO, J. ARANBARRI, F. BARREIRO, P. A. BRAVO, H. A. CHAPARRO, F. COMÍN, R. CORRIÁ... abruptos (Valero-Garcés et al, 2000;González-Sampériz et al, 2010;, y en la resiliencia de los sistemas ecológicos (Gil-Romera et al, 2010), tanto en ausencia como en presencia del ser humano. De este modo, los resultados obtenidos son utilizados para evaluar la capacidad de respuesta de los ecosistemas actuales pueden tener ante al Cambio Global.…”

Section: La Variabilidad Climática Terrestre; La Gran Reguladora De Lunclassified

Primeras jornadas Iperinas: presentación de nuevas líneas de investigación del Instituto Pirenaico de Ecología (CSIC)

Pardo¹,

Aranbarri²,

Barreiro³

et al. 2013

Pirineos

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Long-term resilience, bush encroachment patterns and local knowledge in a Northeast African savanna

Cited by 30 publications

References 78 publications

Rehabilitation of degraded dryland ecosystems – review

Rehabilitation of degraded dryland ecosystems – review

Vegetation state changes in the course of shrub encroachment in an African savanna since about 1850 CE and their potential drivers

Primeras jornadas Iperinas: presentación de nuevas líneas de investigación del Instituto Pirenaico de Ecología (CSIC)

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