Challenge of weed risk assessment (WRA) for ecological restoration in China: The case ofRhus typhinaL. and the new officially released weed risk assessment system

Abstract

Challenge of weed risk assessment (WRA) for ecological restoration in China: The case of Rhus typhina L. and the new officially released weed risk assessment system, AbstractChina has conducted many ecological restoration projects to alleviate environmental degradation, with numerous alien species having good adaptability widely used for fast effect. However, unsuitable plant selection may bring negative impacts and even cause biological invasion. Weed risk assessment (WRA) is therefore indispensable, yet it is often contentious especially concerning those species that has been widely utilized before weedy attributes were noted. In this paper, we take Rhus typhina L. as an example to illustrate how scientific researches and social factors can influence the evaluation of alien species and cause challenge to WRA. The evaluation of this species is not only a pure scientific issue but also influenced by many factors such as the introduction history, current utilization status in afforestation, and divergent underlying values varying through persons and sectors. These factors determined the kind of data to be assessed, which lead to different evaluations, therefore, causing challenge to its WRA. We further examined newly officially released WRA system in China from the invasion biology viewpoint, arguing that it had some major flaws in design and validation and need much improvement. Considering the human dimension and biological characters together, we suggest that the "black list" and "green list" approaches with rigorous expert assessment should be adopted simultaneously in alien species management in China.

Dominance of an alien shrub Rhus typhina over a native shrub Vitex negundo var. heterophylla under variable water supply patterns

“…heterophylla will be more appropriate for revegetation. Similarly to the proposal of Wang et al (2013) [ 19 ], ceasing the utilization of R . typhina in afforestation and finding an alternative native species may be a better choice.…”

“…R . typhina had a growth strategy with a large crown area and stem basal diameter ( Fig 4 ), and the leaf lateral expansion (higher crown area and total leaf area) were always fast, which is beneficial to its competition for sunlight [ 19 ]. Plant height growth was not the main factor to determine competition success in our study, although height is usually the key factor in determining the success of light competition between individuals in other species [ 9 ].…”

“…Species invasion and management are important issues in the study of plant ecology. Alien species should be evaluated more comprehensively, using both scientific and social factors [ 19 ]. Our results highlighted the strong competitive ability of R .…”

“…typhina , a deciduous member of Anacardiaceae, is a large shrub or a small tree native to eastern North America [ 8 , 18 , 19 ], which is highly invasive in Europe [ 20 , 21 ]. However, there has been controversy about whether it should be identified as an invader species in China since its introduction in 1959 [ 3 , 19 ]. R .…”

“…The growth of two other native species ( Cotinus coggygria and Platycladus orientalis ) has also been suppressed by the presence of R . typhina [ 19 ]. In this research, both plant species are early-successional species, and now coexist in many areas on hills (personal observation) in northern China, which provides a good model to study species interactions as the plants overlap more and the competition is more intense in early successional plant communities [ 23 ].…”