## 3 Results
### Upstream and Downstream Gradient Analysis
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{11}{c}{**Land Mean Ecosystem Service Value/CNY \(\times\) km\({}^{-2}\)**} \\ \cline{2-11}
**Type of Land Use** & **Zones along** & **Zones along** & **Zones along** & **Zones along** & **Zones along** & **Zones along** & **Zones along** & **Zones along** & **Zones along** \\  & **River 1** & **River 2** & **River 3** & **River 4** & **River 5** & **River 6** & **River 7** & **River 8** & **River 9** & **River 10** \\ \hline Grassland & 160.43 & 14.27 & 109.34 & 136.28 & 77.70 & 125.11 & 43.11 & 19.94 & 15.25 & 45.99 \\ Scrub & 1,456,599.32 & 1,069,259.79 & 942,599.26 & 925,022.31 & 407,431.00 & 254,341.65 & 565,571.80 & 76,776.66 & 29,088.37 & 122,059.05 \\ Construction & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 & 0.00 \\ Broad-leaved forest & 1,412,518.28 & 1,689,861.50 & 1,845,724.86 & 1,852,688.26 & 1,039,478.70 & 1,129,807.40 & 1,129,002.26 & 259,097.98 & 112,688.96 & 308,193.95 \\ Artificial wetlands & 1020,029.29 & 69,176.82 & 100,334.47 & 1100,405.58 & 204,911.56 & 734,815.99 & 657,037.366 & 741,547.84 & 756,599.16 & 1,298,946.04 \\ Natural wetlands & 0.00 & 48.19 & 322.16 & 187.44 & 159,164 & 32,075.69 & 1,9956.50 & 15,711.19 & 859,292.28 & 8356.26 \\ Paddy fields & 172,730.24 & 172,614.99 & 181,867.54 & 1663,301.84 & 197,302.32 & _266,662.39_ & 367,673.98 & 34,179.32 & 314,950.49 & 305,155.07 \\ Water bodies & 1,139,794.73 & 1,000,800.16 & 845,184.08 & 1,202,578.94 & 980,128.48 & 1,366,028.30 & 1,530,015.71 & 1,852,494.26 & 1,107,438.0 & 1,317,514.74 \\ Coniferous forests & 184,206.05 & 205,281.43 & 217,803.74 & 341,134.29 & 222,510.46 & 199,621.26 & 33,151.70 & 5,262.70 & 13,345.84 & 45.786.33 \\ Total & 4,377,264.34 & 4,387,207.27 & 4,175,202.44 & 4,601,699.36 & 3,065,130.83 & 3,983,477.70 & 2,836,436.72 & 3,333,718.08 & 2,342,339.99 & 3,045,974.33 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: The revised upstream and downstream gradient table for the average ecosystem service value in the land and water interface zone of the Guangdong section of the Xijiang River. As can be seen from Figure 7, the value of the provisioning services of broad-leaved forests within levels 1-4 of the river section dominated all ecosystem types, but from the sixth level of the river section onwards, the value of the ecosystem provisioning services of broad-leaved forests showed a clear downward trend until it reached a lower level. The value of the ecosystem provisioning services of water bodies always occupied an important position at all upstream and downstream gradients, and the value of the ecosystem provisioning services of water bodies gradually increased from the fifth level of the river section onwards, eventually occupying an absolutely dominant position. The ecosystem provisioning services value of artificial wetlands increased continuously from the fifth level of the river section and reached a peak at the ninth level of the river section. As for the regulating services, the ecosystem regulating value of waters had the highest proportion, and within levels 4-10 of the river section, the ecosystem regulating service value of water bodies dominates. Meanwhile, broad-leaved forests, scrub, paddy fields, and artificial wetlands all had high shares; the ecosystem provisioning service value of broad-leaved forests plays a prominent role at the 1-6 level of the river section but falls to a lower level from the seventh level of the river section. The ecosystem regulating service value of scrubland is at a high level in levels 1-4 of the river section but gradually drops to a low level from the fifth level of the river section; the ecosystem regulating service value of artificial wetlands increases significantly from tertile 5 and reaches the highest value in tertile 10.