Regeneration patterns of key pine species in a mixed-pine forest indicate a positive effect of variable retention harvesting and an increase in recruitment with time

Forest Ecosystems

Table 1 Mean (± 1SE) seedling density (seedlings·ha^− 1) by retention treatment for tree species documented in a mixed-pine forest ecosystem in the eastern Upper Peninsula of Michigan, USA

Species common name	Species scientific name	Mean seedling density (± 1SE) (seedlings·ha^− 1)
Species common name	Species scientific name	Aggregated	Dispersed	Control
2 years since treatment
Red pine	Pinus resinosa L.	0 a	104 ± 76 a	0 a
Eastern white pine	Pinus strobus L.	659 ± 185 ab	763 ± 229 a	138 ± 95 b
Jack pine	Pinus banksiana Lamb.	0 a	0 a	0 a
Red maple	Acer rubrum L.	6840 ± 1895 a	2395 ± 420 b	1979 ± 515 b
Northern red oak	Quercus rubra L.	1076 ± 230 a	1631 ± 375 a	659 ± 274 a
Aspen (quaking & bigtooth)	Populus spp.	1215 ± 430 a	3715 ± 941 b	69 ± 69 a
Balsam fir	Abies balsamea (L.) Mill.	243 ± 430 a	0 a	486 ± 450 a
Black spruce	Picea mariana (Mill.)	0 a	0 a	381 ± 203 a
6 years since treatment
Red pine	Pinus resinosa L.	312 ± 91 a	208 ± 91 ab	0 b
Eastern white pine	Pinus strobus L.	1180 ± 298 a	868 ± 290 ab	104 ± 56 b
Jack pine	Pinus banksiana Lamb.	138 ± 80 a	138 ± 80 a	0 a
Red maple	Acer rubrum L.	10,833 ± 2452 a	5381 ± 1600 ab	3541 ± 954 b
Northern red oak	Quercus rubra L.	2569 ± 410 a	2638 ± 636 a	1388 ± 557 a
Aspen (quaking & bigtooth)	Populus spp.	5590 ± 1372 a	4756 ± 1151 a	2222 ± 753 a
Balsam fir	Abies balsamea (L.) Mill.	833 ± 429 a	0 a	416 ± 350 a
Black spruce	Picea mariana (Mill.)	0 a	69 ± 47 a	798 ± 306 b