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An Application of Rural Landscape Information System for Assessment of Alien Plant Species in Paddy Landscape in Japan
Shori Yamamoto and Yoshinobu Kusumoto
National Institute for Agro-Environmental Sciences (NIAES)
3-1-3 Kan-nondai, Tsukuba, Ibaraki 305-8604, Japan, 2010-04-27

Abstract

Many invasive alien plant species are already distributed in paddy landscape in Japan, and they affect agricultural production and ecosystem. New management systems, which are socially and environmentally acceptable, are necessary. This study analyzed distribution patterns and impacts of alien plant species around paddy fields by using RuLIS. Findings showed three major distribution patterns of alien plants: (1) strong species, which appeared in large area coverage; (2) generalist species, which appeared in many habitats; and (2) specialist species, which appeared in specific and major habitat. A new method for post border impact assessment of alien plant species in paddy landscape (PBAApaddy) was developed based on these distribution patterns, and the method was applied to 50 species. Results suggested that PBAApaddy is an effective tool for the assessment, and Alternanthera philoxeroides was evaluated as the most invasive alien plant in Japanese paddy landscape.

Key words: RuLIS, alien plant species, paddy fields, Japan

Introduction

Invasive alien species is one of the major crises facing biodiversity in Japan (Ministry of Environment 2007). Reducing their impact on ecosystem and biodiversity becomes a big problem at the government or national level. The invasion occurs not only in natural ecosystem but also in agricultural ecosystem. Many alien plant species already occupied agricultural lands such as old fields, paddy levees, irrigation and drainage facilities, and these plants affect the agricultural production and ecosystem around agricultural land. The kind of major alien species in agricultural ecosystem differ depending on the local natural environments and agricultural production system. Therefore, farmers who have to reduce or control alien plants in their own land need to prioritize species for effective management. For this prioritization, a new method for post border impact assessment of alien plant species is necessary to evaluate each species based on their characteristic and land condition.

This study analyzed the distribution patterns and impacts of alien plant species around paddy fields in Japan using Rural Landscape Information System or RuLIS (Ide et al. 2005, Kusumoto et al. 2007) at NIAES. RuLIS is an information system that intends to comprehensively survey and analyze biodiversity in rural areas. Also, a new method for post border impact assessment of alien plant species in paddy landscape was developed.

What Is Rulis (Rural Landscape Information System)

NIAES' RuLIS focuses on the "landscape level" of biodiversity, because the rural landscape is a mosaic of many types of semi-natural ecosystems, such as agricultural fields, irrigation canals, semi-grasslands, and woodlands. RuLIS corresponds to the Countryside Information System (Bunce et al. 1996) and the Countryside Survey (Hallam et al. 1993) in the UK, which include classifications of agro-ecosystems and standardized monitoring surveys. RuLIS has a hierarchical and objective classification of the agro-ecosystems in Japan ( Fig. 1(1194)). Japanese land was divided into 46 agricultural ecosystem classes on a 1-km grid area by using national GIS data such as climate, topography, and vegetation. For example, in the Tone River basin, the paddy-dominated landscapes were classified into four classes: (1) paddies at the base of mountains (class 64); (2) paddies on alluvial plains (class 66); (3) Yatsu paddies (located in gentle valley bottoms surrounded by sloping woodlands, class 67); and (4) mosaic of upland fields and paddy fields on urban fringes (class 68). In each of these four classes, eight monitoring sites were selected to collect ecosystem data from gene to landscape level. These data included land cover and the plant species composition in abandoned paddies, on paddy levees, and in forests and grasslands around the paddies.

RuLIS can be used in analyzing biodiversity changes, quantitative evaluation of ecosystems, and in developing biodiversity indicators.

As a practical application of RuLIS, this study tried to evaluate habitat potential value for butterfly species in class 67 (Yatsu paddy landscape). Evaluation of habitat needs both field surveys data and national GIS data. Field surveys of butterfly distribution around Yatsu paddy show the important habitats in detail scale. On the contrary, national GIS data shows only land use in macro scales. Two different scale data were combined by using land cover data at RuLIS monitoring sites. A model was done to estimate edge length between paddy field and forest, which indicates potential value of butterfly habitat. Comparison estimates in 1976 and 1997 showed that habitat potential value for butterfly species in class 67 has been deteriorating for 21 years because of urbanization in forests and increased abandoned paddy fields (Yamamoto et al. 2006).

Distribution Patterns of Alien Plant Species around Paddy Fields in Japan National Scale Analysis

Japan has few data, which investigate distribution of wild plants, especially alien plants in rural area. This project used data set of the nationwide ecosystem survey carried out by Ministry of Agriculture, Forestry and Fisheries. This data set has lists of the plant species, which appeared at 389 spots of 26 areas around agriculture irrigation canals.

The relationship between the appearance ratio of alien plants and RuLIS' ecosystem classes was first analyzed. The ecosystem classes of RuLIS reflect natural environments condition such as climate, topography and so on. Also, the ecosystem classes reflect land use and landscape structure in each 1-km grid. Results of analysis showed the following tendencies ( Table 1(1101)): (1) Many alien species, such as Bidens frondosa, Stenactis annuus, Trifolium pretense and so on, were distributed over the whole country; (2) Some alien species, such as Solidago altissima, Conyza sumatrensis, Elodea nuttallii and so on, were not distributed in specific classes, especially in the cold districts as class 2; (3) Most of IAS (Invasive Alien Species listed based on The Invasive Alien Species Act in Japan) had low appearance ratio. The lack of some invasive species, such as Solidago altissima, in cold districts shows that the distributions of alien species were strongly affected by climate and other natural conditions.

Tokuoka et al. (2007) analyzed the correlation between ratio of naturalized alien species of each survey stand and land usearea ratio in each 1-km grid of 389 spots by using RuLIS database ( Table 2(1158)). Results show that forest cover ratio was negatively correlated with the ratio of naturalized species and the ratio of annual alien plants. On the contrary, paddy field cover ratio and built up or paved area ratio were positively correlated with each other. These results indicate that the distributions of alien plants were strongly affected by landscape structure of each spot.

Regional Scale Analysis

Database of plant distribution around paddy fields was built in two ways. First is the RuLIS' monitoring data of 761 plots (1-km gird) around paddy fields in Tone river watershed including cultivated paddy fields, abandoned paddy fields, paddy levees and developing places. Second is survey data of 265 plots (1-km grid) around drainage channels including water surface, water's edge, banks of channel, abandoned paddies and paddy levees adjacent to channels, carried out by MAFF in Watarase District and Inba-numa District (Kusumoto et al. 2007). Survey plots were divided into several types according to geographical conditions (land element types); around paddy field plots into six types and around channel plots into five types.

Then, the relationship between distribution of alien plant species and land element types was analyzed by using average cover ratio, stand specializing index (SSI). Distributions of alien plants into agricultural ecosystem showed several characteristic patterns ( Table 3(1191)). The first pattern was strong species appearing with large coverage; maximum coverage was over 75% and average was over 25%, represented by Solidago altissima, Alternanthera philoxeroides, Elodea nuttallii and Eichhornia crassipes. These alien species were very strong in ecological competition and they occupied the habitat resulting in the decrease of other plant species. The second pattern was generalist species, which appeared in many land element types with middle degree in SSI over 75% of lend element types, represented by Solidago altissima, Alternanthera philoxeroides, Bidens pilosa, Erigeron canadensis, Lindernia dubia, Bidens frondosa and Eclipta alba. These alien plants had adaptability against land element type of wide range.

The third pattern was specialist species, which appeared in specific and major land element type with very high degree in SSI over 3.0, represented by Elodea nuttallii, Bidens pilosa, Erigeron canadensis, Potentilla amurensis, Ludwigia decurrens, Veronica persica, Trifolium pratense, Erigeron phiadephicus and Stenactis annuus. These alien species were mainly distributed in xeric site such as paddy levee or in stream.

These results suggest scheme for selection of invasive alien plants. Three focal points are: (1) the strong species appearing in large area coverage; (2) the generalist species, which appear in many habitats; and (3) the specialist species which appear in specific and major habitat.

Post Border Impact Assessment of Alien Plant Species in Paddy Landscape

A new method for post border impact assessment of alien plant species in paddy landscape (PBAApaddy) was developed based on the distribution patterns of alien plants which was mentioned above. The PBAApaddy can evaluate the impact of each alien plant species on rice production and ecosystem around paddy fields in the following three viewpoints or perspectives:

  • (1) Distribution pattern - shows behavior of species after its invasion into paddy landscape. The patterns were mentioned above.
  • (2) Physiological and ecological characteristics - shows species faculty such as the range of distribution, competitiveness with similar species or other species, and so on. Check points of characteristics were selected by referring to Australian Weed Risk Assessment (AWRA; Groves et al. 2001; Nishida 2007) assuming that the species has already invaded Japan.
  • (3) Adaptability to environment in the agriculture drainage channels - shows species fitness for land condition of assessment target area. The fitness for land condition is very important in post border assessment (Standards Australia 2006). Therefore, PBAApaddy evaluates four sides of fitness to the agriculture drainage channels, the structure of the channel, running water, materials at the bottom, and the materials of channel wall.

Evaluation score of each alien species is calculated by summing up default scores of check point about tree view points of PBAApaddy according to the judgment result whether species characteristics agree with each check point. The check points are shown

in Table 4(1197). Each check point is judged based on existing knowledge or field survey data. The perfect score is 50 points. The species which get high score is that which has the wide range of habitation including climate and land condition, and has heavy impact on both ecosystem and maintenance activities in paddy fields and channels.

PBAApaddy was applied to 50 major alien species including Invasive Alien Species (IAS in the law), waterweed species from those listed by Japanese' Ministry of Environment (MOE), and species actually damaged as reported in a questionnaire survey (Kusumoto et al. 2007). The result of evaluation suggested that PBAApaddy is effective for the assessment evaluation of alien plant species in paddy landscape, because the waterweeds reported damages were evaluated highly, regardless of a list in the law ( Table 5(1332)).

The species, which was evaluated as the most invasive with 45 point is Alternanthera philoxeroides. This species compete strongly with other species when it appeared. Also the species has very wide range of habitation from water surface to non-water fields. In addition, according to the Chinese report (Yu 2006), Alternanthera philoxeroides can distribute under a very wide climate condition, from subtropical region to cool temperature zoon. It was suggested that these characteristics of Alternanthera philoxeroides were the reason for its highest score even though it was discovered in only two districts in Japan. This result suggested that Alternanthera philoxeroides was expected to widely spread through Japanese paddy landscape in the future.

Conclusion

To manage or control invasive alien species, the relationships between invasive alien plants species and biodiversity or agricultural production must be comprehensively understood. The NIAES' RuLIS is a very useful tool to understand such relationships. Efficient and effective management of invasive alien species, which already spread in the country must be prioritized. The method for post border impact assessment of alien plant species, such as PBAApaddy, is expected to clarify which alien species must be given priority.

Many invasive alien plants species are already distributed in paddy landscape in Japan. Management systems, which are socially and environmentally acceptable must be developed immediately and this can be done by using RuLIS and PBAApaddy methods.

References

  • Bunce, R.G.H., Barr C.J., Clarke R.T., Howard D.C. and A.M.J. Lane. 1996. Land classification for strategic ecological survey. Journal of Environmental Management. 47:37-60.
  • Groves, R.H., Panetta, F.D. and J.G. Virtue. eds. 2001. Weed Risk assessment. CSIRO publishing, Collingwood. 246pp.
  • Hallam C.J., Hornung M., Howard D.C. and M.J. Ness. 1993. Countryside Survey 1990 Main Report. Department of the Environment. 174pp.
  • Ide M., Ohkuro T. and Y. Kusumoto. 2005. Rural Landscape Information System for Conserving Biological Diversity. Inventory. 5: 20-23. (In Japanese)
  • Kusumoto, Y., Yamamoto, S. and Y. Tokuoka. 2007. Development of RuLIS and its Application for Survey of Invasive Alien Plants. Proceedings of NIAES International Symposium 2007 _ Invasive Alien Species in Monsoon Asia: Status and Control. O5.
  • Ministry of Environment. 2007. Alien Species. http://www.env.go.jp/nature/intro/
  • (in Japanese)
  • Nishida, T. 2007. Weed Risk Assessment-Case of Australia and New Zealand-, Edited by The Society for the study of Species Biology, Weed Ecology and Agroecosystems, 121-136. Bun-ichi Sogo Shuppan Co. Tokyo. (in Japanese)
  • Standards Australia. 2006. National Post-Border Weed Risk Management Protocol. Standards Australia. 76pp.
  • Tokuoka, Y., Kusumoto, Y. and S. Yamamoto. 2007. Analysis of factors affecting distribution patterns of alien plants around irrigation and drainage facilities in Japan. Journal of Rural Planning, 26: 227-232. (in Japanese)
  • Yamamoto, S., Kusumoto, Y., Shiina, M., Ide, M. and S. Okushima. 2006. Biotope Evaluation in Yatsu Area based on Plant Communities, Butterflies and Landscape Structure. J.JASS, 23,1: 1-10. (in Japanese)
  • Yu, L. 2006. Response of Exotic Invasive Weed Alternantheara philoxeroides to Environmental Factors. NIAES InternationalSymposium 2006: 47-50.

Index of Images

Figure 1 Classification of Ecosystem by Rural Landscape Information System (Kusumoto Et Al. 2007).

Figure 1 Classification of Ecosystem by Rural Landscape Information System (Kusumoto Et Al. 2007).

Table 1 Appearance Ratio of Major Alien Species in Classes of Rulis

Table 1 Appearance Ratio of Major Alien Species in Classes of Rulis

Table 2 Correlation between the Ratio of Alien Species and Environment (after Tokuoka Et Al. 2007)

Table 2 Correlation between the Ratio of Alien Species and Environment (after Tokuoka Et Al. 2007)

Table 3 Distribution Patterns of Alien Plant Species in Paddy Landscape in Japan

Table 3 Distribution Patterns of Alien Plant Species in Paddy Landscape in Japan

Table 4 Check Points for Pbaa Paddy (Post Border Impact Assessment in Paddy Landscape)

Table 4 Check Points for Pbaa Paddy (Post Border Impact Assessment in Paddy Landscape)

Table 5 Pbaa Paddy Scores of 50 Major Alien Plant Species in Japan

Table 5 Pbaa Paddy Scores of 50 Major Alien Plant Species in Japan

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