出现，PA_Spe_accum和PA_Spe2_accum是列表而不是数字向量，这导致了错误。您可以尝试在使用黄土函数之前将它们转换为数字向量。以下是如何修改代码以实现所需的平滑。

PA_Spe_accum_vec <- unlist(PA_Spe_accum)
PA_Spe2_accum_vec <- unlist(PA_Spe2_accum)
smooth_PA_Spe_accum <- loess(PA_Spe_accum_vec ~ seq_along(PA_Spe_accum_vec))
smooth_PA_Spe2_accum <- loess(PA_Spe2_accum_vec ~ seq_along(PA_Spe2_accum_vec))

smoothed_PA_Spe_accum <- predict(smooth_PA_Spe_accum)
smoothed_PA_Spe2_accum <- predict(smooth_PA_Spe2_accum)
plot(smoothed_PA_Spe_accum, ci = 1.96, ci.type = "bar", las=1, col = "green3", lty = 1, lwd=2, ci.col = "green3", ci.lty = 1, xlim=c(0,60), ylim=c(0,70))
lines(smoothed_PA_Spe2_accum, lwd=2, col = 'royalblue4', add = TRUE)

请让我知道这是否有帮助。