Abstract
Nutrient cycling in forest ecosystems can be sensitive to disturbances that change the availability of one nutrient relative to others, altering the synchrony in nutrient cycles that is expected to develop in undisturbed systems. We asked whether the relative availabilities of nitrogen (N) and phosphorus (P) differ with forest successional age after harvest, and tested effects of adding one nutrient on availability and recycling of the other, in a factorial nitrogen (N) × phosphorus (P) fertilization study in multiple early- and mid-successional and mature northern hardwood forest stands in central NH, USA. We did not find effects of forest age on resin-available N:P ratios, which varied widely among successional forest stands and were related to net N mineralization potentials in the forest floor of each stand. P addition suppressed resin-N availability by 31 % and lowered litterfall N recycling by 10 %, but we detected no effects on net N mineralization potentials. P addition also increased nitrification potentials in the organic horizon by up to 60 %, mostly in combination with added N. The effects of added N depended on P; lower resin-P in mature stands and lower litterfall P recycling in stands of all ages were detected only when P was added with N. We conclude that P limitation influences N recycling across forest age classes in these northern hardwoods, with some indication of stronger effects in successional stands. However, net N mineralization potentials better predicted the resin-N response to added P than did stand age. Our results suggest that alleviating P limitation promotes N limitation over time, especially in more rapidly growing successional forests, by increasing biotic demand for N, reducing its recycling in litterfall, and potentially by reducing net N mineralization.
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Claims 11
Claim · model-written summary
Forest age did not affect resin available N:P ratios.
- Taxon
- northern hardwood forestst0
- Treatment
- forest agee0
- Outcome
- resin-available N:P ratiose0
- Direction
- did not find effectse0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“We did not find effects of forest age on resin-available N:P ratios”
Claim · model-written summary
Resin available N:P ratios varied widely among stands and related to forest floor net N mineralization potentials.
- Taxon
- northern hardwood forestst0
- Outcome
- resin-available N:P ratiose1
- Setting
- successional forest standse0
Not reportedDirection
Verbatim
t0“northern hardwood forests”
e0“which varied widely among successional forest stands and were related to net N mineralization potentials in the forest floor of each stand”
e1“We did not find effects of forest age on resin-available N:P ratios”
Claim · model-written summary
P addition reduced resin N availability by 31%.
- Taxon
- northern hardwood forestst0
- Treatment
- P additione0
- Outcome
- resin-N availabilitye0
- Direction
- suppressede0
- Value
- 31 %e0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“P addition suppressed resin-N availability by 31 %”
Claim · model-written summary
P addition reduced litterfall N recycling by 10%.
- Taxon
- northern hardwood forestst0
- Treatment
- P additione0
- Outcome
- litterfall N recyclinge0
- Direction
- lowerede0
- Value
- 10 %e0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“P addition suppressed resin-N availability by 31 % and lowered litterfall N recycling by 10 %”
Claim · model-written summary
P addition had no detected effect on net N mineralization potentials.
- Taxon
- northern hardwood forestst0
- Treatment
- P additione1
- Outcome
- net N mineralization potentialse0
- Direction
- no effectse0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“but we detected no effects on net N mineralization potentials”
e1“P addition suppressed resin-N availability by 31 %”
Claim · model-written summary
P addition increased organic horizon nitrification potentials by up to 60%, mostly with added N.
- Taxon
- northern hardwood forestst0
- Treatment
- P additione0
- Outcome
- nitrification potentialse0
- Direction
- increasede0
- Value
- up to 60 %e0
- Qualifier
- mostly in combination with added Ne0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“P addition also increased nitrification potentials in the organic horizon by up to 60 %, mostly in combination with added N”
Claim · model-written summary
Adding N with P lowered resin P in mature stands.
- Taxon
- northern hardwood forestst0
- Treatment
- P was added with Ne0
- Outcome
- resin-Pe0
- Direction
- lowere0
- Qualifier
- mature standse0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“lower resin-P in mature stands and lower litterfall P recycling in stands of all ages were detected only when P was added with N”
Claim · model-written summary
Adding N with P lowered litterfall P recycling across stand ages.
- Taxon
- northern hardwood forestst0
- Treatment
- P was added with Ne0
- Outcome
- litterfall P recyclinge0
- Direction
- lowere0
- Qualifier
- stands of all agese0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“lower resin-P in mature stands and lower litterfall P recycling in stands of all ages were detected only when P was added with N”
Claim · model-written summary
Net N mineralization potential predicted resin N response to P better than stand age.
Verbatim
t0“northern hardwood forests”
e0“net N mineralization potentials better predicted the resin-N response to added P than did stand age”
Claim · model-written summary
The authors infer P limitation influences N recycling across forest ages, possibly more in successional stands.
- Taxon
- northern hardwood forestst0
- Treatment
- P limitatione0
- Outcome
- N recyclinge0
- Qualifier
- some indication of stronger effects in successional standse0
Not reportedDirection
Verbatim
t0“northern hardwood forests”
e0“P limitation influences N recycling across forest age classes in these northern hardwoods, with some indication of stronger effects in successional stands”
Claim · model-written summary
The authors propose that alleviating P limitation promotes N limitation over time through higher biotic N demand and lower litterfall recycling.
- Taxon
- northern hardwood forestst0
- Treatment
- alleviating P limitatione0
- Outcome
- N limitatione0
- Direction
- promotese0
- Qualifier
- especially in more rapidly growing successional forestse0
Not reportedComparator
Verbatim
t0“northern hardwood forests”
e0“alleviating P limitation promotes N limitation over time, especially in more rapidly growing successional forests, by increasing biotic demand for N, reducing its recycling in litterfall, and potentially by reducing net N mineralization”