For a detailed account of the environmental impacts of P. montana var lobata please read: Pueraria montana (Kudzu) Impacts Information. The information in this document is summarised below.
Kudzu is widely believed to drastically reduce biodiversity because of its ability to smother other vegetation and develop large-scale monocultures (Alderman 1998; Forseth and Innis 2004, in Sun et al. 2006). It can climb overtop and subsequently kill new seedlings or mature trees (Berisford, Bush andand Taylor 2006). Forestry problems associated with aggressive vines such as kudzu include mortality of edge trees, exclusion of native plant species, and potential to increase fire hazard during winter (Putz 1991, in Harrington Rader-Dixon & Taylor 2003).
Kudzu constrains urban, suburban, and rural development in highly infested areas (Blaustein 2001). Eradication and clearing must occur to safeguard open space, parks, structures, and buildings.
Ecosystem Change: Few plants can survive once smothered by kudzu and small ecosystems can be radically altered. Infestations quickly spread in open habitats, rapidly covering the soil and low growing vegetation, and only slowed by adjoining forests. Kudzu can affect indigenous plants and completely modify the structure of the ecosystem (Clabassi et al. 2003, in EPPO 2007). Kudzu may have a disproportionate effect on animals with specific mutualisms or feeding relationships with trees or shrubs suppressed by its growth (Forseth and Innis 2004).
Reduction in Native Biodiversity: Kudzu is invading National Parks in the USA and when it does encroach on natural areas it kills trees and plants by growing over them (EPPO 2007). Pron (2006, in EPPO 2007) found that there was a reduction in the number of species in invaded places: while 20 to 25 species grew in 4 m² of non-invaded meadow or forest, only 6 to 9 species grew in 4 m² invaded by kudzu.
Competition: Key traits of kudzu that contribute to its ability to spread rapidly and dominate natural communities are its high allocation to extension growth and leaf area instead of support structures; frequent rooting of stems at nodes in contact with the soil, rapid leaf movements, high leaf level photosynthetic rates accompanied by high leaf area indices, large hydraulic capacitance in roots and rhizomes, and the ability to fix atmospheric N2 (Forseth and Innis 2004). This unique combination of traits makes P. montana an extremely aggressive competitor in the eastern deciduous and southeastern USA mixed pine forest biomes (Forseth and Innis 2004). ). Kudzu vines can tie trees together and the twining of vines on vines exhort tension to pull trees down (Miller and True 1986).
Disease Transmission: Kudzu is a reservoir for soybean rust and Phytophthora species (EPPO 2007).
Modification of Nutrient Regime: Pueraria montana forms an initial interconnected ground cover of stolons and annually produces a thick leaf litter layer with high leaf nitrogen due to its nitrogen-fixing properties (Forseth and Innis, 2004). Kudzu has a symbiotic relationship with nitrogen-fixing bacteria (Rhizobium spp.) in root nodules and can almost double the concentration of nitrogen compounds in the topsoil (1 to 6 cm deep) (Pron 2006, in EPPO 2007).
As a rapidly growing vine, kudzu can cover and smother orchard and plantation crops, including young forest plantations. Where productive forest land has been overtaken, lost productivity is estimated at about 120 USD per hectare per year (EPPO 2007). Lost productivity in forests has been estimated at anywhere between $100 to 500 million per year (Blaustein 2001, Quimby et al. 2003, in Forseth and Innis 2004).