List of ecoregions affected by a specific vegetation regime shift
This list describes woody plant encroachment specific to different ecoregions of the world. The list is further subdivided into countries. Although political boundaries usually have limited influence on the occurrence of woody plant encroachment in an ecosystem, this structure provides insight into country-specific scientific research and responses.
Ecoregions.
Northern Europe.
Scandinavia.
Woody encroachment is common in the Alpine tundra of Norway and Sweden Also in the Coastal meadows of Estonia woody plant encroachment is observed, resulting from land abandonment. In Denmark, dry grasslands are affected by woody encroachment.
United Kingdom.
In the United Kingdom, shrub encroachment in heathlands may lead to the loss of ecosystem carbon, as carbon losses from the soil will not be offset by above-ground carbon in the additional biomass.
Ireland.
In the Burren of Ireland, extensive low input farming helps to prevent further encroachment by "Blackthorn" and "Hazel", while high density stands are actively thinned out.
Eurasian Steppe.
Caragana shrubs are the primary contributor to woody encroachment in the Eurasian steppe, among others in the Black Sea-Kazakhstan steppe, the Tibetan Plateau steppe, and the Central Asian steppe. Woody plant encroachment is observed in parts of Ukrainian steppe.
Central Europe and European Alps.
Woody plant encroachment is common in the Alps. Recorded expansion rates range from 0.6% to 16% per year and 5.6% per decade. Areas that formerly were forests require continuous maintenance to avoid woody plant encroachment. When active land cultivation ends, fallow land is the result and gradual spread of shrubs and bushes can follow. Animal species once native to Central Europe effectively countered this natural process. These include herbivores such as European bison, auerochs (extinct), red deer and feral horse. Grassland and heath are considered to require protection due to their biodiversity as well as to preserve cultural landscapes. Woody plant encroachment is therefore frequently countered with selective removal of woody biomass or through the seasonal or year-round introduction of grazing animal species, such as sheep, goats, heck cattle or horses. Woody encroachment occurs in the Alps, where structural change in agriculture leads to the abandonment of land. Alnus viridis is the most widely distributed shrub species in the sub-alpine zone and is found to severely impair species richness and beta diversity when encroaching grassland. Also Bilberry is a common encroaching species in the sub-alpine belt. 
Woody encroachment in the alpine tundra is associated with aboveground carbon storage and a slowdown of the biogeochemical cycle. 70 percent of cultivated land in the Eastern Alps are affected by woody encroachment. Also in Hungary bush encroachment is linked to the abandonment of formerly cultivated land. Moderate encroachment is found to have no negative impact on biodiversity and suppression of woody plants is considered an effective restoration approach.
Mediterranean Basin.
The Mediterranean region is widely reported to be affected by bush encroachment, which is often a transition into the establishment of trees in former grasslands. This is found to have negative effects on biodiversity and to magnify climate and related droughts. Further, it adversely affects soil organic matter. At the same time encroaching shrubs are also found to have a positive effect, reversing the desertification process. Areas experiencing woody encroachment have more extended droughts and higher usage of deep water and this is expected to increase under future climate scenarios. In the Spanish Pyrenees, woody encroachment is connected to land abandonment and affects around 80 percent of cultivated land. It is increasingly observed that the cessation of land use is not the only driver of woody encroachment in the Mediterranean Basin, as the phnomenon also occurs in areas that continue to be used for agriculture.
Spain.
Livestock decline and changes in grazing patterns have favoured the encroachment of various woody species in the Pyrenees. The encroachment was found to have a significant impact on soil properties, but not increased soil organic carbon accumulation. In the Pyrenees, mechanical uprooting of shrubs was found to be effective for the purpose of restorting a productive grass layer.
In the La Rioja region in Spain, systematic shrub clearing was introduced in the 1980, aiming to enhance ecosystem services on abandoned and encorached farmland. Assessments show a positive effect on fire frequency, species diversity, soil health, soil carbon sequestration and hydrological connectivity and water resources.
In the Saja-Besaya Natural Park, in the province of Cantabria, experiments were conducted with presribed fires as a grassland conservation tool.
Italy.
Resarch in the Italian Alps and Sicily found that woody encroachment, following changes in land use, can lead to decreases in ecosystem carbon storage at wetter sites, while leading to increases at drier sites.
North American grasslands.
North American grasslands have been found to be affected by woody plant encroachment. Documentation of shrub encroachment caused by fire exclusion was documented as early as 1968.
Canada.
Woody plant encroachment contributes to grassland loss in Western Canada, especially in Aspen parkland. Also the creation of wetlands is associated with woody encroachment. A case study of the Cypress Hills Interprovincial Park found an annual increase of shrub cover of 1% between 2011 and 2018.
United States of America.
In the United States up to 330 million hectares of grassland are affected by woody encroachment. Affected ecosystems include the Chihuahuan Desert, the Sonoran Desert, the northern and southern Rocky Mountains, the sagebrush steppe, as well as the Southern and Central Great Plains. Poor grazing management and fire suppression are among the documented causes. In particular, historic livestock overgrazing has contributed to woody plant encroachment. Historically, the displacement of indigenous populations and the simultaneous elimination of fire-based land management are believed to be root causes of the observed regime shift. Also the absence of previously common large browsers, especially elk, is a contributing factor. The Great Plains biome is found to be at the brink of collapse due to woody encroachment, with 62% of Northern American grassland lost to date.
Woody plant expansion is considered one of the greatest contemporary threats to mesic grasslands of the central United States. Woody encroachment is estimated to lead to a loss of 75% of potential grass biomass in the Great Plains. In the western United States, 25% of rangelands experience sustained tree cover expansion, with estimated losses for agricultural producers of $5 billion since 1990. The forage lost annually is estimated to be equal to the consumption of 1.5 million bison or 1.9 million cattle. Woody plants have increased on around 44 million hectares in the western United States since 1999. Among encroaching species is "Piñon-juniper" which mostly encroaches in shrubland adjacent to wooded areas. Up to 350 sagebrush-associated plant and animal species are threatened as a result. In the northern Great Basin piñon-juniper has encroached 0.45 million hectares since 2001 alone. The rate at which grassland is lost to woody encroachment is found to equal the rate of conversion of grassland to agricultural land. Also the tundra ecosystems of Colorado and Alaska are affected by the rapid expansion of woody shrubs. In coastal fen ecosystems, woody plant encroachment leads to the reduction of herbaceous species richness and loss of rare species.
Negative impacts on forage production and an interrelation with carbon sequestration are documented. At the same time in the semiarid karst savanna of Texas, USA, woody plant encroachment has been found to improve soil infiltrability and therewith groundwater recharge. At the same time a conversion of rangelands to redcedar woodland has been modeled to result in a 20-40% reduction in streamflow and therewith the amount of water available. Woody plant encroachment has been found to prevent the effective recharge of aquifers. Experiments showed positive results for increased water savings through woody plant control.
Over a period of 69 years, woody encroachment in Texas has increased aboveground carbon stocks by 32%. 
Bird population decline as a result of woody encroachment has been identified as a critical conservation concern, with bird populations found to have decreased by nearly two-thirds over the last half-century.
Through government funded conservation programmes, shrubs and trees are thinned out systematically in affected ecosystems. This is found to revive habitat for birds and improve other ecosystem services. There is evidence that selective thinning with post-treatment has successfully reversed the effects of conifer encroachment in studied areas. At the same time study areas in Nebraska, where Juniperus virginiana encroachment was treated with fire, showed that woody cover stayed low and stable for 8–10 years after fire treatment, but rapid re-encroachment then followed. In the Loess Canyons community driven partnerships among land owners for the purpose of coordinated prescribed fires, has shown to successfully halt and reverse woody plant encroachment, with positive effects for rangeland productivity and bird species richness. A notable initiative is the Prairie Project, funded by the United States Department of Agriculture, aiming to render the Great Plains more resilient against woody plant encroachment through targeted fire and grazing regimes. USDA conservation programs amount to close to $90 million annually in public and private funds for bush control and rangeland health.
Latin American grasslands.
Argentina.
A total of approximately 5.7 million hectares of land are affected by woody encroachment in Argentinia. In the Gran Chaco intense shrub encroachment has detrimental impact on livestock economies, especially in the Formosa Province. Livestock pressure and the lack of wildfires have been main causes. Woody encroachment ist also observed in the savanna ecosystems of the central Argentine Espinal as well as the lower Argentine Monte. Among the encroaching species is Geoffroea decorticans. In Patagonia's drylands, successful trials of rehabilitation through mechanical shrub cutting and enhancing patch connectivity were conducted.
Bolivia.
In Bolivia, different stages of woody plant encroachment threaten the habitat of the Guacano.
Brazil.
Wide-ranging woody encroachment is found in the Cerrado, a savannah ecosystem in central Brazil. Studies found that 19% of its area, approximately 17 million hectares, show significant woody encroachment. A 40% increase in wood cover reduced the diversity of plants by about 30%.
Among the researched causes are fire suppression and land use abandonment. Fire suppression is linked to Brazil's conservation policy that aims at deforestation in the Amazon, but achieves the limitation of fires also in the Cerrado. This ecological change is linked to the disturbance of ecohydrological processes. In some areas of the Cerrado, open grassland and wetlands has largely disappeared. 
A contributing factor to the loss of the natural Cerrado savanna ecosystem is the planting of monocultures, such as pine, for wood production. When pine is removed and plantations abandoned, areas turn into low-diversity forests lacking savanna species. A 20-year study found that woody encroachment led to reduced species diversity and richness. Also in the highland grassland of Southern Brazil, bush encroachment caused by land management changes is seen as a significant threat biodiversity, human wellbeing and cultural heritage in grassland ecosystems.
Studies show that woody encroachment in the Cerrado has a significant impact on rodent species abundance, with positive effects for forest specialists and negative effects for grassland specialists.
Research has been conducted on the effectiveness of controlled fires as a means to control woody encroachment.
Nicaragua.
In Nicaragua "Vachellia pennatula" is known to encroach due to land intensification as well as land abandonment.
Caribbean Islands.
Cuba.
The Republic of Cuba experiences woody plant encroachment, mainly by "Dichrostachys cinerea" (locally called "marabú"). Encroacher wood is actively harvested and used for charcoal production and considered for electricity production.
Asian temperate savanna and steppe.
China.
Temperate savanna-like ecosystems in Northern China are found to be affected by shrub encroachment, linked to unsustainable grazing and climate change. In Inner Mongolia, shrub encroaches steppe. Woody plant encroachment is found to lead to the reduction of biodiversity and decreased forage quality. Rare herbaceous plants and those with lower stature are at risk of extinction. In Yunnan Province in Southwest China, the loss and fragmentation of savanna due to woody encroachment is found to be larger than the loss of forests. In marsh areas of the Sanjiang Plain, woody encroachment was found to significantly reduce soil moisture, organic carbon, and total nitrogen. Shrub encroachment has led to the decline of soil quality of up to 40% in Northwest China. 
In the Tibetan Plateau, woody encroachment is found to be one of the main grassland disturbance factors. Among the encroaching species is "Potentilla fruticose." 
The determination of an optimal vegetation cover of tree and shrub species in China's drylands, is a subject of research. 
Bhutan
The encroachment observed in the Chinese Tibetan Plateau and Himalayas, extends into Bhutan.
India
Semi-arid Banni grasslands of western India are found to be affected by bush encroachment, with affects both species composition and behaviour of nocturnal rodents.
Australian lowland woodlands.
In Australia woody encroachment is observed