Cascading biodiversity and functional consequences of a global change–induced biome switch

  title={Cascading biodiversity and functional consequences of a global change–induced biome switch},
  author={Catherine L. Parr and Emma Gray and William J. Bond},
  journal={Diversity and Distributions},
Aim  At a regional scale, across southern Africa, woody thickening of savannas is becoming increasingly widespread. Using coupled vegetation and faunal responses (ants), we explore whether major changes in woody cover in savannas represent an increase in the density of savanna trees (C4 grass layer remains intact) or a ‘regime shift’ in system state from savanna to thicket (=dry forest) where broad‐leaved, forest‐associated trees shade out C4 grasses. 

Legacy effects of top–down disturbances on woody plant species composition in semi-arid systems

Savanna vegetation is controlled by bottom-up (e.g. soil and rainfall) and top–down (e.g. fire and herbivory) factors, all of which have an effect on biodiversity. Little is known about the relative

Savanna woody encroachment is widespread across three continents

It is argued that the functional traits of each woody flora, specifically the N-fixing ability and architecture of woody plants, are critical to predicting encroachment over the next century and that African savannas are at high risk of widespread vegetation change.

Plant functional groups and species contribute to ecological resilience a decade after woodland expansion treatments

Woody plant expansions are altering ecosystem structure and function, as well as fire regimes, around the globe. Tree-reduction treatments are widely implemented in expanding woodlands to reduce fuel

Quantifying Woody Plant Encroachment in Grasslands: A Review on Remote Sensing Approaches

Abstract Grasslands are an important global ecosystem, providing essential ecological and economic ecosystem services. Over the last couple decades, as a result of climate change and human

Fire refugia facilitate forest and savanna co‐existence as alternative stable states

Does complex topography facilitate the establishment and persistence of fire‐sensitive (forest) vegetation in a fire‐prone landscape? We test the prediction that fire‐sensitive vegetation will

Woody encroachment slows decomposition and termite activity in an African savanna

The first quantification of woody encroachment altering the functioning of African savanna ecosystems through the slowing of aboveground plant decomposition is provided, suggesting that substantial changes to the carbon balance and biodiversity of grassy biomes could occur.

Woody plant encroachment intensifies under climate change across tundra and savanna biomes

Biomes worldwide are shifting under global change. Biomes whose extents are limited by temperature or precipitation, such as the tundra and savanna, may be particularly strongly affected by climate



The impact of shrub encroachment on savanna bird diversity from local to regional scale

Aim  Evidence is accumulating of a general increase in woody cover of many savanna regions of the world. Little is known about the consequences of this widespread and fundamental ecosystem structural

A proposed CO2‐controlled mechanism of woody plant invasion in grasslands and savannas

It is proposed that elevated CO2 will tend to favour regrowth of juvenile trees trapped (sometimes for decades) in the ‘topkill’ zone, thus allowing them to escape more readily from periodic fires as CO2 continues to rise.

Thicket expansion in a South African savanna under divergent land use: local vs. global drivers?

Woody plant increase in grassy biomes has been widely reported over the last century. Increases have been attributed to local drivers associated with land use change, such as heavy grazing or fire

Changes in woody community structure and composition under constrasting landuse systems in a semi‐arid savanna, South Africa

We aimed to explore the farm scale effects of three landuse types, communal grazing, wildlife management and commercial cattle farming, on the woody vegetation of a semiarid savanna.

Catastrophic shifts in ecosystems

Recent studies show that a loss of resilience usually paves the way for a switch to an alternative state, which suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

The origin of the savanna biome

Savannas are a major terrestrial biome, comprising of grasses with the C4 photosynthetic pathway and trees with the C3 type. This mixed grass–tree biome rapidly appeared on the ecological stage 8

Growth responses of African savanna trees implicate atmospheric [CO2] as a driver of past and current changes in savanna tree cover.

CO2 has significant direct effects on tree recruitment in grassy ecosystems, influencing the ability of trees to recover from fire damage and herbivory in savanna systems, but field-based tests are needed to confirm this suggestion.

What Limits Trees in C4 Grasslands and Savannas

The extent of this climate mismatch has been revealed by physiologically based global vegetation simulations and by large empirical data sets, and the implication is that ecosystem structure and function depend on demographic transitions.

The effect of different fire regimes on plant diversity in southern African grasslands