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 and the Baltic 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.Stafford, R., Chamberlain, B., Clavey, L., Gillingham, P. K., McKain, S., Morecroft, M. D., Morrison-Bell, C. and Watts, O. (Eds.) (2021). Nature-based Solutions for Climate Change in the UK: A Report by the British Ecological Society . London, UK. Available at: www.britishecologicalsociety.org/nature-based-solutions 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 the Ukrainian steppe.Borovyk, Dariia & Dembicz, Iwona & Dengler, Jürgen & Guarino, Riccardo & Kuzemko, Anna & Vynokurov, Denys. (2024). Plant species richness records in Ukrainian steppes. TUEXENIA. 44. in press. 10.14471/2024.44.002. 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. Open land that was formerly forested requires continuous maintenance to prevent 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, aurochs (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. In the Alps, structural change in agriculture leads to the abandonment of land and subsequent encroachment. 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. Seventy percent of cultivated land in the Eastern Alps is 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 phenomenon 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 restoring a productive grass layer. In the La Rioja region in Spain, systematic shrub clearing was introduced in the 1980s, aiming to enhance ecosystem services on abandoned and encroached 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 prescribed fires as a grassland conservation tool. Italy Research 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. Israel Maquis encroachment occurs in Israel. Palestine In Palestinian oak scrub forest, heavy grazing maintained low shrub cover and height, while moderate grazing led to greater encroachment. 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. Further, enroachment occurs in the Canadian Arctic tundra. 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. In Saskatchewan, native grasslands are encroached by wolf willow, western snowberry and trembling aspen, among other native shrub and tree species. United States of America Woody plant expansion is considered one of the greatest contemporary threats to mesic grasslands of the central 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. Various studies quantify the extent of grassland loss for different regions: 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, and a resulting loss in potential grass biomass of 75%. 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. In the Midwest, as little as 1-4% of original native tallgrass prairie is estimated to remain.Merola‑Zwartjes, M. (2004). Biodiversity, functional processes, and the ecological consequences of fragmentation in southwestern grasslands. In D. M. Finch (Ed.), Assessment of grassland ecosystem conditions in the Southwestern United States (Vol. 1, Gen. Tech. Rep. RMRS‑GTR‑135‑vol. 1, pp. 49–85). Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station. 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. Evidence suggests that although about 75 percent of southern New Mexico was covered in grasslands prior to the late 1800s, by the late 1960s only 5 percent grassland coverage remained.York, J. C. & Dick‑Peddie, W. A. (1969). Vegetation changes in southern New Mexico during the past hundred years. In W. G. McGinnies & B. J. Goldman (Eds.), Arid Lands in Perspective (pp. 157–166). Washington, DC: American Association for the Advancement of Science; and Tucson: University of Arizona Press. In the Chihuahuan Desert, an estimated 25 to 50 percent of the area that is currently covered by shrublands was actually grassland less than 200 years ago.Dinerstein, E., Ison, D., Atchley, J., Loucks, C., Contreras‑Balderas, S., Abell, R., Inigo, E., Enkerlin, E., Williams, C. E., & Castilleja, G. (2000). Ecoregion-based conservation of the Chihuahuan Desert: A biological assessment. The Nature Conservancy; World Wildlife Fund; Comisión Nacional para el Conocimiento y Uso de la Biodiversidad (CONBIO); PRONATURA Noreste; Institute Tecnologico y de Estudios Superiores de Monterrey (ITESM). Poor grazing management and fire suppression are among the documented causes.IPCC, 2019: Climate Change and Land: an IPCC special report on climate change, desertification, land degradation, sustainable land management, food security, and greenhouse gas fluxes in terrestrial ecosystems, P.R. Shukla, J. Skea, E. Calvo Buendia, V. Masson-Delmotte, H.-O. Pörtner, D. C. Roberts, P. Zhai, R. Slade, S. Connors, R. van Diemen, M. Ferrat, E. Haughey, S. Luz, S. Neogi, M. Pathak, J. Petzold, J. Portugal Pereira, P. Vyas, E. Huntley, K. Kissick, M. Belkacemi, J. Malley, (eds.). In press. 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. 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.