## 4 Discussion
### Influence of Environmental Factors
#### 4.2.2 Vegetation and Landscape Fragmentation  
While the importance of vegetation in tick ecology studies is widely acknowledged, the role of NDVI is controversial because it indicates a variety of vegetation-related features [55] from the abundance or density of vegetation [77], to plant water content [78], and to relative humidity around the vegetation layer [79]. Despite this, NDVI is typically strongly correlated with black-legged tick populations and their host-seeking behavior, which is also supported by our alternative negative binomial regression model. In general, areas with higher NDVI are covered by thriving vegetation (with higher water content) or denser tree canopies, which create a microclimate conducive to black-legged ticks. The NDVI values in a specific area may also show seasonal patterns due to the presence of deciduous vegetation [77].  
Our regression models also indicate that specific vegetation land-cover types, such as hardwood forests and dwarf shrubs, are more significant for tick ecology studies than the general NDVI. This has practical implications as a more detailed land cover and vegetation classification should be considered in addition to NDVI. Hardwood forests, characterized by large tree canopies, can capture snowmelt, maintain moisture with leaf litter, and provide a favorable habitat for black-legged ticks [80]. The calibrated regression model clearly shows the significant and positive effect of hardwood forests on the number of questing black-legged ticks. In contrast, pine forests, with needle-leaved tree canopies, do not create a cool and humid microenvironment as effectively as broad-leaved hardwood forests [81]. Tick sampling conducted by [36] in New Jersey showed that questing tick populations observed in hardwood forests (4.3 \(\pm\) 1.1 across 8 sites) were approximately twice the questing tick populations in pine forests (2.1 \(\pm\) 0.5 across 14 sites). Our study also showed a similar pattern, with mixed hardwood having a higher coefficient than pine forests or grassland in the calibrated regression model. We also found that dwarf shrubs tended to have more questing ticks than both, as black-legged ticks usually move to shrubs to attach to passing hosts.  
In addition to hardwood forests, questing tick populations are often positively correlated with the total length of ecotone boundaries within each sampling site, as ticks usually reside and quest along forest boundaries. [PERSON] et al. [82] found that black-legged ticks are unlikely to appear in no-shade or totally shaded areas but are frequently observed along forest edges with 30% to 80% mixed shade. Therefore, totally forested areas, compared with forest ecotones, may have a lower tick population [83]. Additionally, ecotones in suburban areas usually create a more fragmented landscape, which supports larger black-legged tick populations because these areas usually have large and diverse populations of tick host species, including the white-tailed deer, white-footed mice, and chipmunks [84; 85]. Furthermore, the effects of landscape fragmentation on deer populations are found to be especially striking in suburban areas due to the preferred forage provided by abundant ecotonal vegetation and the absence of predator species [77]. In our full and alternative regression models, the ecotone boundary length variable has a positive coefficient, which is in line with the existing theories. However, in the presence of other factors, such as the NDVI and percentages of vegetation land cover, the variable was not statistically significant. Therefore, while ecotone boundary length and vegetation fragmentation may have a significant impact on the number of question black-legged ticks at a macro scale, their effect is less pronounced at the local level.