*3.2. Landscape Pattern with Small Biotopes*

In this study, a landscape map was obtained using the object-based image analysis described in the methodology section. The accuracies of the classifications are listed in Table 1, respectively. The overall accuracy of classifying based on UAS photogrammetric orthoimage is 95% (Table 1). This landscape pattern (land cover map) clearly shows a typical landscape of abandoned land surrounded by pine forest communities, as well as a particular pattern of small biotopes (Figure 5b). Based on the high-resolution orthoimage data of UAS, and under the classification framework proposed by us, the detailed object classification was obtained, which is an essential prerequisite for further detecting the ecotones.

**Table 1.** Accuracy of classification of subtle landscape elements.


### *3.3. Ecotones Detection and Quantification*

A window moving along the edge between abandoned land and forest was used to judge pixels under the above two conditions (height restriction and area ratio). A landscape with ecotones between abandoned land and forest boundaries was delineated (Figure 5c). Subsequently, the corresponding landscape metrics calculation results are also calculated based on the fine resolution landscape map (Table 2). In general, the ecotones between abandoned land and forest in the Baijixun plot was irregular to the west and north of the abandoned land (Figure 5c). The ecotones were expanding from forest interior to bare land or abandoned agricultural land. This landscape pattern indicates the gradient of vegetation spontaneous regeneration between abandoned farmland and forest. To the east, the abandoned farmland boundaries left over from the past prior to degradation remained the boundaries between the ecotones and the forests, and their shapes are quite regular (e.g., ecotones elements in this landscape have lower SI values (Table 2)). It may also be disturbed by a small amount of human activity, as shown in Figure 5, where tracklike bare land was identified, and result in a higher landscape contrast of the eastern boundary. The texture characteristics revealed that the region contained sparse vegetation and large amounts of bare land. From the quantitative results, the ecotone class has the maximum boundary length. It also occupies a large proportion in landscape proportion, almost equal to the type of abandoned land.

**Figure 5.** An orthoimage of the study area (**a**), a landscape patter map derived from OBIC (**b**), and (**c**) a landscape including the ecotones extracted (shadows removed).


Shape Index 1.55 2.39 2.27 1.82 3.27 1.30

**Table 2.** A series of common landscape metrics used to quantify some elements of the landscape.

### *3.4. Transect-Based Analysis*

Separately, our research group conducted a series of studies on ecotones in the agroforestry ecosystem of the Baijixun sample plot. These investigations were mainly carried out through the laying of transect lines. Analyses of plant diversity levels within the community and soil properties were used to determine the dynamic changing characteristics and width range of the ecotones. The results showed that the ecotones in the Baijixun plot were 37.5–57.5 m, 30–42.5 m, and 30–57.5 m width in IV, pH, and OM, respectively (Figure 6 and Table S1). However, when the landscape pattern diagram of the sample plot produced in this study was used as the basis, and distances were measured along the same direction as the transect lines laid previously, the widths of the ecotones were found to be 35.43–55.20 m.

**Figure 6.** The data obtained in situ were analyzed based on transects. Every transect consists of 8 big quadrats (10 × 10 m) and five small quadrats (5 × 5 m). IV, pH, and OM were surveyed in every quadrat. In this figure, the first column (from left) denotes the distribution of IV along a transect, the second denotes pH, and the third is OM. Three color plates reflect the changes of value in each quadrat, and the higher the value of a quadrat, the deeper the color. The fourth column reflects a land cover with ecotones along a transect. The fifth column shows the changes of different indicators along the direction of the transect. The black lines in the first three columns act as scale to indicate the width of the ecotones detected based on the MSW.

IV, pH, and OM values in each quadrat were measured and presented spatial heterogeneity along the transect (Figure 6). In the three transects, the MSW method was used to calculate the changes of three indicators from field survey along the transects. The changes of field data and the changes of ecotones derived from photogrammetric orthoimage were plotted into a coordinate (Figure 6). The method of F-1 measure was used to test the accuracy of our method on the detection of the ecotones. The overall accuracy was greater than 74% in the ecotones scale (width) detection (Table 3). The location of the crest was the location where the ecotones occurred. From the results, in terms of the accuracy of the occurrence location, the detection accuracy was 100% (Figure 6).

**Table 3.** Test the accuracies of ecotones width derived from UAS at corresponding transect in different data. For the meaning of TP, FN, and FP, refer to the accuracy assessment section above.

