## 4 Discussion
Our findings suggested that we need to strengthen ecological monitoring to find highly suitable habitats for IAPS in protected areas. Hence, our method could provide conservation suggestions for the assessment scales of invasive species used by biological conservativationists and land managers. Can we evaluate the risk of IAPS on finer scales, such as the grid of protected areas? We need to solve the problem of how spatial scales affect habitat quality. Modeling the habitat quality of species was influenced by the spatial scale of climate change. We aimed to determine the scale units to model the habitat quality of species--a fine resolution or coarse resolution [46]. This led us to question of whether SDM results obtained using different scales were accurate. The results obtained from Maxent for all scales were positively related to the regions' species richness, indicating that the habitat quality of species at different scales was useful for long-term management [18]. [PERSON] et al. (2013) studied the impact of the use of various scales on plant species' distributions and proposed that it is necessary to balance fine and coarse scales [17]. Some studies have found that there is an important relationship between habitat quality when using fine scales or coarse scales, and this indicates that scale selection might overestimate or underestimate SDM outcomes [12; 17; 18; 46]. We also found that the extent of the difference in the results of Maxent--namely, the invasion risk--of different scales suggested this pattern in our study. This problem can be solved by applying a scale balance to the SDM results of Maxent based on the relationship between habitat quality using fine scales or coarse scales [17; 47]. PCA is the most commonly used multivariate statistical analysis tool to select the appropriate variables accounting for the total variation [20; 21]. Hence, we could balance the biases of IAPS risk that occurred when fine or coarse scales were used in the estimates. Recent studies have shown that fine scales can reduce uncertainty when modeling regional habitat quality [9; 17; 18]. The finding that the invasion inequality of IAPS for protected areasat the finest scales could account for all scales was consistent with the findings of previous studies [17]. It is necessary to conduct long-term monitoring of protected areas, particularly grids with highly suitable habitats for IAPS to prevent the invasive spread of IAPS that is due to climate change [46]. However, we used 5.0 arcminutes to predict the ability of IAPS to invade protected areas because 5.0 arcminutes had a significant relationship with each spatial scale and represented the results of all scales [48; 49]. We invented a simple and convenient method to balance the various results of modeling at different spatial scales to prevent the overestimation or underestimation of SDM results caused by the selection of the spatial scale and to consider the impact of different scales on SDM results. In China, between the west and the east there is a substantial difference of almost 3000 km, as well as a latitudinal gradient of around 2000 km, making it difficult to use the same eight variables for all species. Perhaps this is possible when using a coarse spatial resolution, but it minimizes environmental variation in large areas of the country according to the resolution used. Hence, 5.0 arcminutes were relatively coarse for SDM applications in predictions of the distributions of IAPS compared to previous studies. We should emphasize that conservation measures cannot afford to wait until there is enough information available on IAPS [46]. Our study provides a great example of the use of SDMs: for instance, the application of Maxent to biological conservation and ecological risk assessment.