Here is a summary of the provided article:

## Litterfall Fluxes Merged to the Column Level

The article discusses how CLM (Community Land Model) handles the distribution of litterfall fluxes into three litter pools: labile (LIT1), cellulose/hemicellulose (LIT2), and lignin (LIT3). These litter pools receive inputs from the leaf and fine root litter of multiple plant functional types (PFTs) that can coexist on a single soil column.

The key points are:

1. Litterfall fluxes are calculated as a weighted average of the fluxes originating from the different PFTs on the column.
2. Carbon fluxes to the litter pools are distributed based on the labile, cellulose/hemicellulose, and lignin fractions of the leaf and fine root litter for each PFT.
3. Nitrogen fluxes to the litter pools are assumed to follow the C:N ratio of the senescent tissue and are distributed using the same fractions as the carbon fluxes.
4. The equations provided show the mathematical formulas used to calculate the carbon and nitrogen fluxes to the three litter pools.

Overall, the article describes how CLM merges the litterfall fluxes from multiple PFTs on a soil column into the three litter pools, accounting for the different chemical fractions of the litter.