Implementing forest thinning \ insect mortality - RHESSys/RHESSys GitHub Wiki

Redefines the worldfile to incorporate Forest Thinning and Insect Mortality

There are a few options that can be used as tec events to force biomass pool changes that mimic forest thinning or insect mortality. Use the commands below in your TECfile at a specified date similar to the way you implement a redefine, so you will need a corresponding Redefine Worldfile at the same specified date.

redefine_world_multiplier

Whatever value you put in the redefine file will be multiplied to the existing worldfile value. So, for example, if you have a 0.75 in the cs_leafc slot in the redefine file, the leaf carbon value in the worldfile will be multiplied by 0.75.

redefine_world_thin_remain

Only cover fraction, gap fraction, and the main carbon pool variables (cs_pool, cs_leafc, cs_dead_leafc, cs_live_stemc, cs_dead_stemc, cs_live_crootc, cs_dead_crootc, cs_frootc) will be read in from the redefine file (all other values will be ignored). For cover fraction and gap fraction, the value in the redefine file will become the value in the new worldfile (i.e., how the main "redefine_world" routine works... if you put a 0.3 in the redefine file the new worldfile value will be 0.3). For the C-pool values, the values in the redefine file should be the fraction of those pools you want "thinned", or removed from the live biomass pools. The corresponding N-pool values will be automatically removed and both the C and N removed fractions will be distributed to the appropriate litter and CWD pools. So, for example, you might want to run a thinning routine that "thins" all biomass by 0.25 and changes the gap fraction to 0.25. Your redefine file would have 0.25 for all the above listed variables except cover fraction, and the resulting new worldfile will show 75% of the pre-redefine C and N pools, with the missing 25% C and N moved to the litter and CWD pools. Of course, you can also vary what fraction of leaf versus stem versus root C (and corresponding N) you want to remove, and can change these fractions across space.

redefine_world_thin_harvest

Works the same as above, but the aboveground C and N fractions are "harvested" (e.g., removed from the live biomass pools but not added into the litter and CWD pools) while the belowground C and N fractions are removed and added to the litter and CWD pools as in the redefine_world_thin_remain option. The user sets the redefine file exactly as they would for the previous case.

redefine_world_thin_snags

This option should be used when you want to remove biomass but leave standing dead (snags), for example to mimic mortality from insect defoliation or drought. Biomass C and N pools are reduced based on the fractions specified (as in the thin_remain option above) except livestem C and N pools are transferred to deadwood C and N instead of CWD.

Example tec event:

1997 7 2 1 redefine_world_thin_harvest

Example stratum section of a template file used to create a (spatially varying) thinning redefine world. The cfrac and gap maps contain the values you want to set as your cover and gap fractions, respectively, and the thin map contains the values you want to set as your thinning fractions. You can use multiple thin maps to change pools by different fractions.

_stratum patch.fullveg 1
      veg_default_ID value -9999
      cover_fraction mode cfrac
      gap_fraction mode gap
      root_depth value -9999
      snow_stored value -9999
      rain_stored value -9999
       cs_pool mode thin
      cs_leafc mode thin
      cs_dead_leafc mode thin
      cs_leafc_store value -9999
      cs_leafc_transfer value -9999
      cs_live_stemc mode thin
      cs_livestemc_store value -9999
      cs_livestemc_transfer value -9999
      cs_dead_stemc mode thin
      cs_deadstemc_store value -9999
      cs_deadstemc_transfer value -9999
      cs_live_crootc mode thin
      cs_livecrootc_store value -9999
      cs_livecrootc_transfer value -9999
      cs_dead_crootc mode thin
      cs_deadcrootc_store value -9999
      cs_deadcrootc_transfer value -9999
      cs_frootc mode thin
      cs_frootc_store value -9999
      cs_frootc_transfer value -9999
      cs_cwdc value -9999
      epv.prev_leafcalloc value -9999
      ns_pool value -9999
      ns_leafn value -9999
      ns_dead_leafn value -9999
      ns_leafn_store value -9999
      ns_leafn_transfer value -9999
      ns_live_stemn value -9999
      ns_livestemn_store value -9999
      ns_livestemn_transfer value -9999
      ns_dead_stemn value -9999
      ns_deadstemn_store value -9999
      ns_deadstemn_transfer value -9999
      ns_live_crootn value -9999
      ns_livecrootn_store value -9999
      ns_livecrootn_transfer value -9999
      ns_dead_crootn value -9999
      ns_deadcrootn_store value -9999
      ns_deadcrootn_transfer value -9999
      ns_frootn value -9999
      ns_frootn_store value -9999
      ns_frootn_transfer value -9999
      ns_cwdn value -9999
      ns_retransn value -9999
      epv_wstress_days value -9999
      epv_max_fparabs value -9999
      epv_min_vwc value -9999
       n_basestations value -9999