Fallopia japonica

Japanese knotweed

Fallopia japonica, often referred to as Japanese knotweed, is a vigorous perennial that can grow up to 3 meters tall. Its leaves are broad, pointed and heart-shaped, reach a length of up to 12 cm and are light green. The stems are hollow and resemble bamboo stalks and are speckled with reddish-brown spots. The plant produces dense, hanging clusters of small white flowers from August through October. The plant's nuts are flat and black. Fallopia japonica reproduces vegetatively through rhizome pieces and can quickly colonize new areas through this mechanism. It is highly adaptable and can tolerate a wide range of environmental conditions, including different soil and light conditions, contributing to its spread and invasive potential.

Types of damage

Ecological damage

Fallopia japonica can grow rapidly and dominate large areas, displacing native plants and decreasing biodiversity, particularly along stream banks. Additionally, it can alter soil chemistry and affect nutrient availability to other plants.

Economical damage

Just like Fallopia bohemica, Japanese knotweed forms thick rhizomes that can damage railway tracks or bank reinforcements through their root growth. Larger stocks can cause high costs due to necessary management measures.
Region of origin

China, Japan, East Asia

Introduction vectors

Horticulture

Fallopia japonica was used as an ornamental plant in gardens and parks and spread from there.
Current distribution

Based on the FlorKart Database of the Federal Agency for Nature Conservation, as of 2013

Miscellaneous

Family

The knotweed family (Polygonaceae) includes around 50 genera with around 1,200 species. They are distributed worldwide, with a concentration in the temperate zones of the northern hemisphere. The family mostly includes herbaceous plants, but occasionally also shrubs and small trees. Many species are characterized by the knotty stems and the often three-part flowers. The fruits are usually triangular nuts. Some species, such as buckwheat (Fagopyrum esculentum), are economically important as crops. Rhubarb (Rheum rhabarbarum) is also a member of this family.

Climate change

Fallopia japonica has already filled its potentially suitable habitat under current climate conditions. It does not benefit from climate change because its potentially suitable habitat will become smaller in the future. The environmental factors that most influence their spread are soil type, road infrastructure, altitude, rail infrastructure and the availability of waterways.

Dispersion forecast

Indicates the proportion of land suitable for habitat under current and future climate conditions (2060-2080) under three emission scenarios (RCP26, RCP45 & RCP85).

Habitat suitability maps

Instructions for use: Click here

Habitat suitability under current climate conditions

These habitat suitability maps show for Fallopia japonica where suitable habitat conditions exist.

The map on the left shows this for current climate conditions. Below this are maps for the time classes 2040-2060 and 2061-2080, in which three different emission scenarios can be selected.

The slider at the top left allows you to adjust the opacity of the map to make orientation easier.

By clicking on the respective quadrant, information on the environmental conditions present in it can be called up.

The methodology is explained here beschrieben.

Habitat suitability 2040 - 2060

2040-2060: In the RCP2.6 scenario, GHG emissions are expected to peak by 2040 through comprehensive mitigation measures and to decline rapidly thereafter. By 2060, global warming would stabilise at about 1.5°C above pre-industrial levels. Subtle changes in precipitation patterns could vary regionally, with some areas facing increased drought and others increased precipitation.

2040-2060: Under RCP4.5, GHG emissions would continue to increase until 2040, but stabilise at a high level thereafter. By 2060, there could be a global temperature increase of about 2°C above pre-industrial levels. This scenario would likely cause moderate changes in precipitation patterns, with potential regional differences.

2040-2060: Under RCP8.5, which assumes continued intensive use of fossil fuels, greenhouse gas emissions would rise sharply by 2060. The global temperature increase could be around 2.5-3°C. In this scenario, significant changes in precipitation patterns could occur, with an increased likelihood of extreme weather events.

Habitat suitability 2061 - 2080

2060-2080: By 2080, global warming could be limited to below 2°C in the RCP2.6 scenario, provided emission reductions are consistently pursued. Impacts on precipitation patterns would likely stabilise, although regional variance would remain significant.

2060-2080: In the RCP4.5 scenario, global temperatures would continue to increase and could be around 2.5°C above pre-industrial levels by 2080. Changes in precipitation patterns would likely increase and regional differences could become more pronounced.

2060-2080: Under RCP8.5, global temperatures could rise by more than 4°C above pre-industrial levels by 2080. Precipitation patterns would be expected to change significantly, with further increases in the frequency and intensity of extreme weather events. This would have far-reaching impacts on ecological and socio-economic systems.