From 77429f43f282a72f5d5c28a0929f59fae2ecdad7 Mon Sep 17 00:00:00 2001
From: Adrianna Foster <afoster@ucar.edu>
Date: Fri, 24 Apr 2026 10:49:10 -0600
Subject: [PATCH 1/4] build namelist update

---
 bld/CLMBuildNamelist.pm | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/bld/CLMBuildNamelist.pm b/bld/CLMBuildNamelist.pm
index 15d92057ee..3e22a39c29 100755
--- a/bld/CLMBuildNamelist.pm
+++ b/bld/CLMBuildNamelist.pm
@@ -1246,7 +1246,14 @@ sub setup_cmdl_spinup {
      }
   }
   $log->verbose_message("CLM accelerated spinup mode is $val");
-  if ( &value_is_true($nl_flags->{'use_cn'}) ) {
+  
+  # is this a BGC-capable mode that supports spinup?
+  # spinup is valid if using CN, or using FATES in non-SP mode.
+  my $use_fates_spinup_ok = &value_is_true($nl_flags->{'use_fates'}) &&
+                            ! &value_is_true($nl_flags->{'use_fates_sp'});
+  my $bgc_spinup_capable = &value_is_true($nl_flags->{'use_cn'}) || $use_fates_spinup_ok;
+  
+  if ( $bgc_spinup_capable ) {
     add_default($opts, $nl_flags->{'inputdata_rootdir'}, $definition,
                 $defaults, $nl, "spinup_state", clm_accelerated_spinup=>$nl_flags->{'clm_accelerated_spinup'},
                 use_cn=>$nl_flags->{'use_cn'}, use_fates=>$nl_flags->{'use_fates'},

From 1af0a00d6b20e283b7f668c0fa214d43cbf634e2 Mon Sep 17 00:00:00 2001
From: Adrianna Foster <afoster@ucar.edu>
Date: Fri, 24 Apr 2026 10:59:41 -0600
Subject: [PATCH 2/4] don't turn on reseed_dead_plants if using FATES

---
 bld/CLMBuildNamelist.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bld/CLMBuildNamelist.pm b/bld/CLMBuildNamelist.pm
index 31b9edb95e..88ba6255b4 100755
--- a/bld/CLMBuildNamelist.pm
+++ b/bld/CLMBuildNamelist.pm
@@ -1270,7 +1270,7 @@ sub setup_cmdl_spinup {
        $nl_flags->{'bgc_spinup'} = "off";
     }
     # For AD spinup mode by default reseed dead plants
-    if ( $nl_flags->{$var} ne "off" ) {
+    if ( $nl_flags->{$var} ne "off" && &value_is_true($nl_flags->{'use_cn'}) ) {
         add_default($opts, $nl_flags->{'inputdata_rootdir'}, $definition,
                     $defaults, $nl, "reseed_dead_plants", clm_accelerated_spinup=>$nl_flags->{$var},
                     use_cn=>$nl_flags->{'use_cn'} );

From ca723c841b88578e1af8c79e87f684743e29b647 Mon Sep 17 00:00:00 2001
From: adrifoster <adrifost@ucar.edu>
Date: Wed, 20 May 2026 15:18:14 -0600
Subject: [PATCH 3/4] add comment for reseed dead plants

---
 bld/CLMBuildNamelist.pm | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/bld/CLMBuildNamelist.pm b/bld/CLMBuildNamelist.pm
index 88ba6255b4..6c90f161e4 100755
--- a/bld/CLMBuildNamelist.pm
+++ b/bld/CLMBuildNamelist.pm
@@ -1269,7 +1269,7 @@ sub setup_cmdl_spinup {
     } else {
        $nl_flags->{'bgc_spinup'} = "off";
     }
-    # For AD spinup mode by default reseed dead plants
+    # For BGC and AD spinup mode by default reseed dead plants
     if ( $nl_flags->{$var} ne "off" && &value_is_true($nl_flags->{'use_cn'}) ) {
         add_default($opts, $nl_flags->{'inputdata_rootdir'}, $definition,
                     $defaults, $nl, "reseed_dead_plants", clm_accelerated_spinup=>$nl_flags->{$var},

From 4b1a933f25d6c52bb18d1f8d8f159cb362c146f8 Mon Sep 17 00:00:00 2001
From: Adrianna Foster <afoster@ucar.edu>
Date: Thu, 23 Jul 2026 06:37:30 -0600
Subject: [PATCH 4/4] update variable names and hist_ndens

---
 bld/namelist_files/namelist_defaults_ctsm.xml      | 4 ++--
 cime_config/usermods_dirs/clm/fates_sp/user_nl_clm | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/bld/namelist_files/namelist_defaults_ctsm.xml b/bld/namelist_files/namelist_defaults_ctsm.xml
index e011258f41..491e3a4e41 100644
--- a/bld/namelist_files/namelist_defaults_ctsm.xml
+++ b/bld/namelist_files/namelist_defaults_ctsm.xml
@@ -74,7 +74,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <hist_fincl1 clm_accelerated_spinup="on" use_cn=".true."
 >'TOTECOSYSC','TOTECOSYSN','TOTSOMC','TOTSOMN','TOTVEGC','TOTVEGN','TLAI','GPP','CPOOL','NPP','TWS','H2OSNO'</hist_fincl1>
 <hist_fincl1 clm_accelerated_spinup="on" use_fates=".true."
->'TOTSOMC','TOTSOMN','TLAI','GPP','NPP','TWS','H2OSNO'</hist_fincl1>
+>'TOTSOMC','TOTSOMN','FATES_LAI','FATES_GPP','FATES_NPP','FATES_VEGC','TWS','H2OSNO'</hist_fincl1>
 <hist_fincl1 clm_accelerated_spinup="on" use_cn=".false."
 >'TLAI','TWS','H2OSNO'</hist_fincl1>
 <hist_fincl1 clm_accelerated_spinup="sasu" use_cn=".true." use_cndv=".true."
@@ -82,7 +82,7 @@ attributes from the config_cache.xml file (with keys converted to upper-case).
 <hist_fincl1 clm_accelerated_spinup="sasu" use_cn=".true."
 >'TOTECOSYSC','TOTECOSYSN','TOTSOMC','TOTSOMN','TOTVEGC','TOTVEGN','TLAI','GPP','CPOOL','NPP','TWS','H2OSNO'</hist_fincl1>
 <hist_fincl1 clm_accelerated_spinup="sasu" use_fates=".true."
->'TOTSOMC','TOTSOMN','TLAI','GPP','NPP','TWS','H2OSNO'</hist_fincl1>
+>'TOTSOMC','TOTSOMN','FATES_LAI','FATES_GPP','FATES_NPP','FATES_VEGC','TWS','H2OSNO'</hist_fincl1>
 <hist_nhtfrq clm_accelerated_spinup="on"  >-8760</hist_nhtfrq>
 <hist_nhtfrq clm_accelerated_spinup="sasu">-8760</hist_nhtfrq>
 <hist_mfilt  clm_accelerated_spinup="on"  >20</hist_mfilt>
diff --git a/cime_config/usermods_dirs/clm/fates_sp/user_nl_clm b/cime_config/usermods_dirs/clm/fates_sp/user_nl_clm
index bd7a93f857..458e60ac84 100644
--- a/cime_config/usermods_dirs/clm/fates_sp/user_nl_clm
+++ b/cime_config/usermods_dirs/clm/fates_sp/user_nl_clm
@@ -6,4 +6,4 @@ use_lch4 = .false.
 fates_spitfire_mode = 0
 use_fates_fixed_biogeog = .true.
 use_fates_nocomp = .true.
-hist_ndens = 1
+hist_ndens = 2