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Alien plant invasions and gravelly floodplain vegetation of the Kinu River. Ecol. Civil Eng. 4(2), 121-132, 2001
Abstract
Vegetational and substrate features for vascular plants in the gravelly floodplains of the middle reaches of the Kinu River in Kanto Region were studied with the special interest in the present status of the threatened river-endemics and biological invasions by alien plants. Hierarchical clustering analysis of the presence / absence data of 550-1452 quadrats (0.5 m × 0.5 m) for each of seven study sites along the middle reaches revealed two site groups characterized by the occurrence of distinct species. The river endemics, Anaphalis margaritacea subsp. Yedoensis, Artemisia capillaris, and Aster kantoensis predominated the vegetation of the ‘upper’ five sites located in the upper part of the middle reaches, but were almost totally absent from the two ‘lower’ sites in the lower middle reaches. The importance index of the river endemics in the sites was negatively correlated with that of alien species represented by Solidago altissima. The current flooding frequency or substrate could not explain the vegetational difference appreciated between upper and lower site groups. In the ‘upper sites’, an alien, Eragrostis curvula, occurred on the channel shelf together with three river endemics, but hardly coexisted with them within the same quadrat. © 2001, Ecology and Civil Engineering Society. All rights reserved.
... Sediment and nutrient produced in upstream forest and hay fields have been accumulated in the wetland to cause sediment and nutrient excess within the wetland, which likely favors the growth of willow and alder trees. Similar examples were found in the restoration sites in the Kinu and Tama Rivers, where a native herb, Aster kantoensis Kitamura (Asteraceae), has been extirpated by nonnative species (Murakami and Washitani 2001; Washitani 2001). Both rivers are short of cobble-size sediment input but have excessive fine sediment input due in part to flow regulation, which has been inferred to be the cause of alterations in species composition (Inoue et al. 1998; Washitani 2001). ...
... Sediment and nutrient produced in upstream forest and hay fields have been accumulated in the wetland to cause sediment and nutrient excess within the wetland, which likely favors the growth of willow and alder trees. Similar examples were found in the restoration sites in the Kinu and Tama Rivers, where a native herb, Aster kantoensis Kitamura (Asteraceae), has been extirpated by nonnative species (Murakami and Washitani 2001; Washitani 2001). Both rivers are short of cobble-size sediment input but have excessive fine sediment input due in part to flow regulation, which has been inferred to be the cause of alterations in species composition (Inoue et al. 1998; Washitani 2001). ...
... Similar examples were found in the restoration sites in the Kinu and Tama Rivers, where a native herb, Aster kantoensis Kitamura (Asteraceae), has been extirpated by nonnative species (Murakami and Washitani 2001; Washitani 2001). Both rivers are short of cobble-size sediment input but have excessive fine sediment input due in part to flow regulation, which has been inferred to be the cause of alterations in species composition (Inoue et al. 1998; Washitani 2001). Thus, the rehabilitation of material flows at catchment scales are of importance for species conservation and restoration, since otherwise its persistence cannot be realized. ...
A hierarchical approach to restoration planning at the regional, catchment and local scales is proposed and examined. Restoration projects limited to a local scale and focused on habitat improvement for individual species ended in failure, which has led to the recognition that there is a need for ecosystem-based management at the landscape level. The first landscape-level restoration in Japan is under way in the Kushiro and Shibetsu River Basins, in northern Japan. However, public consensus on these large-scale restoration projects has not yet matured and there are very few projects that have progressed even as far as mapping to classify intact and disturbed ecosystems. Classification of habitat quality using physical and biological indicators appears to be the core element of analysis of ecological degradation at the regional scale (100–1,000km2). This mass-screening process is critical to identify areas in potential need of restoration. The causes and mechanisms of ecosystem degradation are then examined at the catchment scale (10–100km2) by linking material flows and habitat conditions. Direct environmental gradient analysis is useful to determine cause and effect relationships between species and habitat quality. Finally, we recommend implementation of field experiments with a clear hypothesis at the local scale (0.01–1km2). At this stage, key variables causing degradation of the target ecosystem are manipulated to verify the hypothesis. Based on the results of local-scale analyses, the possibility of restoration success can be evaluated, which directs us to practical schemes for future restoration projects at larger scales.
... Pilg.), and Japanese lawn grass (Zoysia japonica Steud.) in less disturbed areas at higher elevations along the river bank. Weeping lovegrass forms dense tussocks, mostly in areas of sparse vegetation (Muranaka and Washitani 2001), and occupies habitats suitable for endangered plant species endemic to gravelly floodplains (Muranaka and Washitani 2001;Washitani 2001). The National Censuses on River Environments, which are periodic surveys of fauna and flora conducted by the Ministry of Land, Infrastructure, Transport, and Tourism, Japan (hereafter, ''MLIT''), reported that the weeping lovegrass-dominated vegetation area in the Kinu River floodplains increased [10-fold between 2002 and 2006 (unpublished data). ...
... Pilg.), and Japanese lawn grass (Zoysia japonica Steud.) in less disturbed areas at higher elevations along the river bank. Weeping lovegrass forms dense tussocks, mostly in areas of sparse vegetation (Muranaka and Washitani 2001), and occupies habitats suitable for endangered plant species endemic to gravelly floodplains (Muranaka and Washitani 2001;Washitani 2001). The National Censuses on River Environments, which are periodic surveys of fauna and flora conducted by the Ministry of Land, Infrastructure, Transport, and Tourism, Japan (hereafter, ''MLIT''), reported that the weeping lovegrass-dominated vegetation area in the Kinu River floodplains increased [10-fold between 2002 and 2006 (unpublished data). ...
We investigated invasion impacts of a grass species (Eragrostis curvula) on native grasshoppers by periodic censuses of these insects on gravelly floodplains of the Kinu River, Japan. Our hypothesis
was that there are greater impacts on natives when they are habitat specialists, as opposed to habitat generalists. The study
area comprised two main habitat types: gravelly areas and riparian grasslands. Among 12 grasshopper species identified, five
were more abundant in one of the habitat types and all of them were significantly negatively affected by coverage of weeping
lovegrass, whereas seven occurred at the both habitat types simultaneously and a significantly smaller portion of species
(two of the seven) was negatively affected by the alien plants. The results suggest that habitat specificity is related to
the grasshopper species’ sensitivity to the plant, indicating that habitat specialist herbivores living on open gravelly floodplains
are likely highly vulnerable to this plant invasion.
KeywordsEragrostis-Gravelly floodplain-Grasshoppers-Habitat specialist-Herbivores-Open habitat
... However, the mechanisms by which this variation is maintained in pre-urban environments remain unknown. Red-leaved individuals may have had an advantage in natural habitats with high temperatures and low plant density, such as bare land and riverbanks, as has been reported for red-leaved individuals of Setaria viridis frequently observed in riverside habitats (49). Anthocyanins may be the key secondary metabolite for adaptation to the urban heat island. ...
Prevalence of impervious surface and resulting higher temperatures in urban areas, known as urban heat islands, comprises prominent characteristics in global cities. However, it is not known whether and how urban plants adapt to such heat stress. This study focused on Oxalis corniculata, which has intraspecific poly-morphism in leaf color (green and red) and examined whether the leaf color variation is associated with urban heat stress. Field observations revealed that green-leaved plants were dominant in green habitats, and red-leaved individuals were dominant in urban habitats, at local (<500 meters), landscape (<50 kilometers), and global scales. Growth and photosynthesis experiments demonstrated that red-leaved individuals performed better under heat stress, while green-leaved individuals performed better under nonstressful conditions. Genome-wide SNP analysis suggests that the red leaf may have evolved multiple times from the ancestral green leaf. Overall, the results suggest that the red leaves of O. corniculata observed in cities worldwide are evidence of plant adaptive evolution due to urban heat islands.
... Rivers have a role in the dispersal of plant roots, and water flow may mix alien seeds into natural seed banks (Ito et al. 2003). Moreover, introduced species that have become naturalised along riversides may disturb the existing natural vegetation, particularly if the invading species have extensive seed sources provided from surrounding areas (Muranaka & Washitani 2001Muranaka 2005). Therefore, the distribution area of R. pseudoacacia may be enlarged by root sucker propagation, crowding out the existing riverside vegetation. ...
We investigated the invasion of Robinia pseudoacacia and subsequently affected riparian vegetation of the Saigawa and Azusagawa Rivers, which are upper tributaries of the Shinano River, the longest river in Japan. Habitats that had been affected by river water disturbance in recent years were located at a height relatively near the river surface and were composed of coarse gravel with numerous annual plants. We found subtrees and shrubs of R. pseudoacacia under willow canopies, but small willow individuals did not occur under the R. pseudoacacia canopies. Furthermore, forest floors in willow communities hosted more wetland and riverside species, including herb species, than those beneath R. pseudoacacia canopies. Mature R. pseudoacacia stands reduced the distribution of wetland and riverside species. Furthermore, the species composition at these sites was not riparian, instead consisting of various forest species. The resulting forest landscape is unlike the natural riparian zone in this area.
... According to the literature and field observations, each plant was classified using the following life-history attributes: (1) origins: alien (species introduced after the 19th century, when Japan abandoned its policy of national isolation) or native species [27]; (2) naturalness: riparian (riverside-endemic and hygrophilous species) or ruderal (synanthropic species and weeds, usually appearing with human activity) [28][29][30]; species richness (SR), as the total number of different species represented in an ecological community or habitat [31] was used to account for the diversity of vegetation in our study. ...
Riparian areas are local hot spots of biodiversity that are vulnerable and easily degraded. Comparing plant communities in habitats with different degrees of urbanization may provide valuable information for the management and restoration of these vulnerable habitats. In this study, we explored the impact of urbanization on vegetation communities between artificial and semi-natural habitats within two rivers with different levels of development. We compared species richness, types of vegetation, and composition patterns of the plants in our study. In artificial habitats, the sites with relatively high levels of urbanization had the highest species richness, while in semi-natural habitats, the highest species richness was recorded in the less urbanized sites. Furthermore, every component of urbanization that contributed to the variation of species richness was examined in the current study. In artificial habitats, the proportion of impervious surface was the strongest predictor of the variation in species richness and was associated with the richness of alien, native, and riparian species. In semi-natural habitats, most of the richness of alien and native species were associated with the distance to the city center, and the number of riparian and ruderal species was significantly related to the proportion of impervious surface. Moreover, we found that a high level of urbanization was always associated with a large abundance of alien and ruderal species in both artificial and in semi-natural habitats. We recommend the methods of pair comparison of multiple rivers to analyze the impact of urbanization on plant species in riparian areas and have suggested various management actions for maintaining biodiversity and sustainability in riparian ecosystems.
... Weeping love grass is originally a grass from southern Africa that was introduced into Japan in 1959 in order to protect soil on dikes and for greening reasons (Muranaka and Washitani, 2001). However, it is now found along several riverbeds in Japan, such as Kinu Riverbed and Yoshino Riverbed (Washitani et al., 2010), and recently the grass has become a problematic plant. ...
Weeping love grass (Eragrostis curvula) has become a well-established invasive species along the Kinu River, Japan and is now considered a problematic invasive weed species. The aim of this study was to map the probability of the establishment of this invasive grass in the shore of the Kinu River using airborne hyperspectral imagery. Binary logistic regression analysis was used to model the probable presence/absence of weeping love grass. This study tried entering two types of input variables, original reflectance bands and MNF (Minimum Noise Fraction) transformed bands, into the regression model. No available variable of original reflectance data was selected, but two bands of MNF were selected in the regression analysis. The final classification, using the selected MNF bands, has distinguished weeping love grass from pseudo-absence pixels with user's and producer's accuracies of 100 and 66.7 respectively. The kappa coefficient was 0.74. These results indicate that the MNF transformed hyperspectral bands are more suitable than the original reflectance data to estimate the distribution of invasive weeping love grass in the shore of the Kinu River.
... Vegetation survey data suggest that river endemics can hardly coexist with E. curvula in the same microsite (0.25 m 2 ) (Muranaka & Washitani, 2001a). Ecophysiological investigation demonstrated that shading by the grass has a significant negative impact on seedling growth of Aster kantoensis (Matsumoto et al., 2000a,b). ...
The floodplains on the middle reaches of rapid Japanese rivers are characterized by extensive grav-elly areas with sparse vegetation cover. There are a number of plant species endemic to the gravelly floodplain habitats, including two threatened species, Aster kantoensis and Ixeris tamagawaensiss. The Kinu River is a typical rapid river in central Japan, and the river endemics have remained among the vegetation of the middle reaches until recently. These unique habitats, however, are rapidly being altered by an aggressive invasion of the alien grass (Eragrostis curvula), which is supposed to have become established through dispersal from upstream stands formed due to active introduction of the species for soil erosion control. The substrate condition of invaded areas tends to be changed from gravelly to sandy/silty, because tussock of E. curvula trap sand and silt during flooding. Thus, the original condition with sparse vegetation cover principally consisting of riparian endemics adapted to gravelly conditions is being lost. E. curvula exerts a strong negative influence on the performance of riparian endemics. A restoration project aimed at recovering the original condition of the floodplain by adaptive management techniques was started in 2002. As a 'first-aid' minor restoration effort, E. curvula was mechanically removed from a part of the floodplain (1,800 m 2), fine sands were washed out by spray the ground with a jet of water to restore the original gravelly condition, and stocked seeds of A. kantoensis were sown. A local population of A. kantoensis was successfully restored, but more extensive exclusion measures are needed in the next stage of management to prevent further negative impact of the invasive species.
... Alien pasture grasses that have been extensively introduced into various construction work sites throughout Japan for the purpose of erosion prevention such as Eragrostis curvula and Festuca arundinacea have established tremendous seed sources everywhere, especially in mountainous regions (Washitani, 2001). These introduced grasses are highly invasive and if riparian habitats are invaded, the substrate condition of gravelly floodplains can be changed into sandy/silty conditions, because bunches of these grasses tend to trap sand and silt during flooding (Nakatsubo, 1997;Muranaka & Washitani, 2001a). Thusly altered substrate conditions facilitate the establishment and growth of weedy plants including those grasses themselves, which were totally absent from the original gravelly floodplains (Muranaka & Washitani, 2001b). ...
Status of invasive alien species problems in Japan is briefly summarized, with special emphasis on invasions during the period from the 1960s to today, one of the two eras characterizing the modern his- tory of the biological invasion into Japan. A number of cases of invasions are categorized from the viewpoints of route of invasion, i.e., intentional or unintentional introduction, release and escape; and types of impacts of invasive alien species on ecosystems, biodiversity, and human life and health. Examples are given of species and situations exemplifying the individual types of influences. 1. Scope of the Introductory Thesis Aside from the urgent social need for investigation of invasive alien species problems, Japan is an inter- esting country to investigate regarding biological in- vasion, since it is an island country with clear oceanic boundaries, having a somewhat unique biota. The Japanese Archipelago was a part of the Asian Continent until 15 million years ago when the Sea of Japan was a young marginal basin located between Japan and the Asian Continent (Chinzei, 1991). Before that geological age, the Japanese islands were not separated from the Eurasian continent, but formed the east end of the continent. Even after their separation from the continent, intermittent formation of land bridges during the Ace Ages (Nogami et al., 1980) facilitated active migration and colonization events of plants and animals including mammoths and humans from the continent to the islands. Therefore, Japanese flora and fauna are fairly similar to those of continen- tal East Asia, but the endemism is moderately high due to the relatively long history of land isolation. After the long period of national seclusion during the Edo Period corresponding to the period of Euro- pean colonization, the country was reopened and was eager to incorporate not only western cultures and techniques, but also biotic matters. After more than one hundred years of striving, contemporary Japanese society, like an "Asian and Western" cultural chimera, has been formed with its flora and fauna well blended with plants and animals of European and North American origins (Totman, 2000). At present, Japan is clearly losing the battle against biological invaders, and now stands at a critical moment. In this introductory essay heading this special issue, I attempt to present a brief sketch of the present status of the problem of invasive alien species in Japan, focusing on ecological as well as social mechanisms of invasions, and their impacts on biodiversity, eco- systems, and human activities and health.
Gravel riverbeds in the middle reaches of Japanese rivers are essential habitats for various plants and animals. Disturbance from flooding is necessary for the formation of gravel riverbeds, but human control of rivers, such as dams and channelization, has altered flow and sediment regimes, thereby reducing disturbance. The flooding generates a mosaic pattern characterized by varying frequencies and intensities of disturbance in gravel riverbeds. Understanding the disturbance regimes that form mosaic patterns is important for the conservation of biodiversity in rivers. In this study, we proposed a method to extract mosaic patterns from flow velocity regimes obtained by planar two‐dimensional analysis by classifying them with time‐series clustering. Based on the distribution of Anaphalis margaritacea var. yedoensis on gravel riverbanks, we compared several past flooding events to identify mosaic patterns that are important for A. margaritacea var. yedoensis. The study site is the Echi River, which flows through Shiga Prefecture in Japan and into Lake Biwa. Using a unmanned aerial vehicle (UAV), orthomosaic images with an average ground resolution of 3.3 mm/pixel were created, and colony polygons of A. margaritacea var. yedoensis were created using image detection and visual correction. Hydraulic analysis was performed using iRIC ver2.3 (Nays2DH ver1.0). Time‐series clustering was used to classify the flow velocity regimes for each computed mesh into 30 clusters. The relationship between the clusters of each flooding event and the distribution of A. margaritacea var. yedoensis was evaluated. Mosaic patterns were created by classifying the flow velocity regimes of each computational mesh calculated by planar 2D analysis into clusters using time‐series clustering. After analyzing the relationship between each cluster and the area of distribution of A. margaritacea var. yedoensis, the first flooding event was determined to be the mosaic pattern that best explained the distribution of A. margaritacea var. yedoensis. Cluster 1, the “low peak, short duration type,” was considered the growth center of A. margaritacea var. yedoensis. The method used in this study is an innovative approach for obtaining mosaic patterns that quantifies these five elements of the disturbance regime.
The effect of self- and multiparental pollination on the seed set of endangered Aster kantoensis (Asteraceae) was examined in a hand pollination experiment. The seed set of A. kantoensis increased with the number of pollen donors, which should increase the genetic diversity of the pollen load. Based on the results of the experiment and existing information on the reproductive ecology of the species, we suggest an effective hand pollination method to aid population restoration programs using seeds and seedlings of A. kantoensis.
Recently, in the mid-upper reach of Japanese rivers, due to artificial impacts such as dam construction, original gravel bar environments and endemic plants have been disappearing, meanwhile alien plant communities have been expanding. As a countermeasure against these issues, gravel bar restoration project started in Kinugawa River. In the present study, vegetation transition was investigated from 2012 to 2014 on a large-gravel bar with two lane meandering in Kinugawa River, where the restoration had just been implemented. It is shown that U-shaped vegetation zone, open to the upstream side, was formed along the main channel and the second channel. This U-shaped zone was mainly composed of Poaceae. The endemic species for gravel bar, such as Aster kantoensis Kitam and Anaphalis margaritacea subsp. yedoensis, and the alien species, such as Eragrostis curvula, inhabited according to the sediment size deposited in/around the U-shaped zone. In 2015, we had a large flood. This gravel bar was greatly deformed and almost all vegetation was flushed away. A field investigation with UAV in 2018 revealed that the U-shaped zone reappeared and the endemic plant communities were widely enlarged in the similar range of relative height through these seven years. Based on the field investigation, laboratory experiments were performed which examined the effect of the U-shaped zone on flow field and coarse sediment movement. It is suggested that fine sand for Eragrostis curvula can be deposited on the internal or downstream area of the U-shaped zone, and that gravel for the endemic species can appear in the outer edge of the U-shaped zone.
The population of Ligustrum lucidum Ait., a horticultural plant originating from China, has recently been increasing in urban river environments in Japan. This study sought to clarify how flood disturbances affect the expansion of the L. lucidum population in urban riparian environments. We investigated the number of individuals, size, fructification, and the condition of fallen L. lucidum before and after a flood in the Inagawa River, Hyogo Prefecture, western Japan. One-third of the adult trees were washed away in the flood, but the number of seedlings increased the year after the flood. The flood felled one-third of the trees whose trunks were over one meter long. The percentage of fruit-bearing individuals decreased from 46.8 to 24.5% in the year following the flood. The year following the flood, 37.5% of the standing trees and 4.5% of the flood-felled trees produced berries. These results suggest that flooding has a weak negative effect on the expansion of the L. lucidum population in urban river environments.
We clarified the relationship between species composition and vegetation environment for the rocky Azusa River, in the city of Matsumoto, central Japan, and the sandy Chikuma River. Two endangered species, Ixeris tamagawaensis and Orostachys japonicus, occurred in the rocky riverside habitat of the Azusa River. Several species occurred in the sandy riverside habitat of the Chikuma River, including Phalaris arundinacea and Miscanthus sacchariflorus, which usually grow in wet lowlands, and Cyperus microiria and Portulaca oleracea, which are distributed in crop fields. The dominance of species at all sites was analyzed using the ordination technique of detrended correspondence analysis. The first axis was significantly positively correlated with a short distance from the river, low relative height above the water level, small particle diameter of sand, an increase in therophytes, and a decrease in trees and alien plants. Riverside vegetation was influenced by river flow disturbance, as indicated by the distance from water and relative height above water level. Furthermore, the particle diameters of sand and rocks affected the soil water content at the sites. Consequently, various site factors resulted in differences in the species composition of riverside vegetation.
Weeping love grass (Eragrostis curvula) has become a well-established invasive species along the Kinu River, Japan and is now considered a problematic invasive weed species. The aim of this study was to map the probability of the establishment of this invasive grass in the Shore of the Kinu River using airborne hyperspectral imagery. Binary logistic regression analysis was used to model the probable presence/absence of weeping love grass. This study tried entering two types of input variables, original reflectance bands and MNF (Minimum Noise Fraction) transformed bands, into the regression model. No available variable of original reflectance data was selected, but two bands of MNF were selected in the regression analysis. The final classification, using the selected MNF bands, has distinguished weeping love grass from pseudo-absence pixels with user's and producer's accuracies of 100% and 66.7% respectively. The kappa coefficient was 0.74. These results indicate that the MNF transformed hyperspectral bands are more suitable than the original reflectance data to estimate the distribution of invasive weeping love grass in the Shore of the Kinu River.
To assess the vegetation status and substrate condition on seedling survival and flowery of an endangered plant species Aster kantoensis, I carried out an in situ seed-sowing experiment in the gravelly/sandy floodplain of the Kinu River, central Japan. The coverage
of plant species, especially that of an alien species Eragrostis curvula, increased, and the subsequent reduction in the relative photosynthetically active photon flux density (PPFD) (%) after the
large-scale flood in 1998 caused a decline in the percentage of seedling survival and flowery of A. kantoensis. Performances of A. kantoensis were compared under four types of seminatural conditions, i.e., combinations of existence or absence of E. curvula combined with gravelly or sandy substrates. The highest percentage of survival and flowery were observed on the gravelly
substrate under the E. curvula,-free conditions, but values were low in areas invaded by E. curvula. Aggressive invasion of E. curvula was the principal cause of loss of safe sites for colonization of river-endemic plants.
Asterkantoensis, an endangered and monocarpic perennial plant species, is endemic to the gravelly floodplain of a few rapid flowing rivers
in eastern central Japan. In recent years, an extreme declining trend in the species has been accelerated due to the strong
negative influence by invasion of an alien grass, Eragrostiscurvula. A restoration project aimed at recovering the original condition of the floodplain in the Kinu River, central Japan, has
been started. To determine the possibility of successful restoration as well as its habitat preferences, I carried out some
seed sowing experiments. In April 2003, seeds collected from a seminatural habitat were sown (54,000 seeds) in the restoration
site (1.2ha), where flood frequency, substrate condition, and control of alien plants are combined to form different habitat
conditions. Seedling survival, flowery, and seed production were subsequently monitored from 2003 to 2005. Seed cohorts completed
their life cycles within 3years, and mean fitness of 927 was achieved. Performance of A.kantoensis seedlings was generally greater for environmental variables of sandy-type substrate and/or with control of alien plants.
In addition, there were significant negative correlations between percentage survival, percentage flowery, and seed production
with vegetation cover and coverage of E.curvula. The results confirm that, if safe sites with sparse vegetation exist, irrespective of their substrate condition, as well
as seed sources of river endemics in natural habitats, restoration of riparian vegetation including river endemics is possible.
The aggressive alien species E.curvula should be taken into consideration.
To examine the relative importance and interactions of trophic and non-trophic effects of plant invasions on herbivores, we investigated how the invasion of weeping lovegrass Eragrostis curvula impacted Eusphingonotus japonicus, a food generalist grasshopper endemic to gravelly floodplains with sparse vegetation in Japan. Field observations and laboratory experiments showed that the grasshopper fed mainly on herbs endemic to the gravelly floodplains, which were negatively impacted by the alien grass. The alien grass was not consumed as food. Field censuses also showed that the abundance of the grasshopper was positively correlated with the coverage of endemic herbs in a plot where weeping lovegrass was not dominant. Dominance of the grass (i.e., habitat modification for E. japonicus) negatively impacted the grasshopper and weakened the positive relationship between the grasshopper and endemic herbs. These results suggest that an understanding of the relationship between non-trophic and trophic effects is essential to predict the impacts of plant invasions on herbivores.
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