Simulated forest biofuel harvest decreases soil carbon and nitrogen. Natalie Koncki Jeffrey Corbin Union College

Transcription

1 Simulated forest biofuel harvest decreases soil carbon and nitrogen Natalie Koncki Jeffrey Corbin Union College

2 The promise of biofuel Domestic source Reduced fossil fuels use Higher commodity prices Sustainability?

3 Future Plans for Increased Biofuel Production from Trees 1. Larger forest area cut New England and Pacific Northwest

4 Future Plans for Increased Biofuel Production from Trees 1. Larger forest area cut New England and Pacific Northwest 2. Different tree species Willow, loblolly pine, hybrid poplar

5 Future Plans for Increased Biofuel Production from Trees 1. Larger forest area cut New England and Pacific Northwest 2. Different tree species Willow, loblolly pine, hybrid poplar 3. More intensely harvesting timber lands Frequency and amount removed

6 Harvest Intensity Selective harvest Clear cut

7 Harvest Intensity Selective harvest Clear cut Residue left behind Residue removed

8 Sawlog harvest Mature forest Slash retained Forest regrowth Soil C, N Soil C, N Soil C, N

9 Whole tree harvest Mature forest Whole tree harvest Forest regrowth Soil C, N Soil C, N Soil C, N

10 Whole tree harvest Mature forest Whole tree harvest Forest regrowth Soil C, N Soil C, N Soil C, N More intense harvest could: deplete soil C, N lengthen time to neutrality

11 Hypotheses More intense harvesting will: Decrease total C and N in ecosystem Decrease soil carbon Decrease soil nitrogen

12 The DayCent Model Simulates C and N movement between atmospheric, vegetation and soil pools Can be used to simulate a variety of management regimes Model overview:

13 The DayCent Model Simulates C and N movement between atmospheric, vegetation and soil pools Can be used to simulate a variety of managements Inputs: climate, vegetation characteristics, soil chemistry, and land management techniques Outputs: detailed dynamics of C and N Model overview:

14 Using DayCent Simulates Different Types of Disturbances: Infestation of a type of insect Fire Storm Logging

15 Modeled Ecosystem: Hubbard Brook Mixed northern hardwood forest Logged in early 20 th century, subject of intense ecological research since 1960 s mages/sitemaps/hbrsitemap.gif

16 Modeled Ecosystem: Hubbard Brook Mixed northern hardwood forest Logged in early 20 th century, subject of intense ecological research since 1960 s Model parameterized: daily climate, soil characteristics (bulk density, field capacity, etc), vegetation traits mages/sitemaps/hbrsitemap.gif Model validated: Compared model output to actual soil and tree characteristics

17 Treatments Type of Harvest Description Logs Removed % Debris Removed % Uncut untouched forest 0 0 Sawlog typical timber harvest % Removal 65% cut % Removal 90% cut Forest grew for 1900 years including harvest in 1901 Treatments initiated in 2013

18 Total C in Ecosystem in July vs. Different Harvests harvest at HB Total C in Ecosystem (g/m 2 ) Treatments Time (yrs) time vs uncut time vs sawlog time vs 65% removed time vs 90% removed

19 Total C in Ecosystem in July vs. Different Harvests Total C in Ecosystem (g/m 2 ) yrs to reach precut C levels Time (yrs) time vs uncut time vs sawlog time vs 65% removed time vs 90% removed

20 Total N in Ecosystem in July vs. Different Harvests Total N in Ecosystem (g/m 2 ) Time (yrs) time vs uncut time vs sawlog time vs 65% removed time vs 90% removed

21 Results Less C and N in ecosystem following all 3 treatments Effect is larger with more intense management What about the soil?

22 Total C in Soil in July vs. Different Harvests Total C in Soil (g/m 2 ) Time (yrs) time vs uncut time vs sawlog time vs 65% removed time vs 90% removed

23 Total N in Soil in July vs. Different Harvests Total N in Soil (g/m 2 ) Time (yrs) time vs uncut time vs sawlog time vs 65% removed time vs 90% removed

24 Results Percent Drop Between Uncut Forest vs. Different Treatment Source Sawlog 65% Removed 90% Removed Total C in Ecosystem Total C in Soil Total N in Ecosystem Total N in Soil years after treatment

25 Drop in soil C components of Uncut vs. 65% Removed 1.5%

26 Conclusions Management decreases C and N in ecosystem and soil

27 Conclusions Management decreases C and N in ecosystem and soil Removing debris decreases C and N further (i.e. sawlog vs. 65% removed treatments)

28 Conclusions Management decreases C and N in ecosystem and soil Removing debris decreases C and N further (i.e. sawlog vs. 65% removed treatments) Drop in soil C largest in slow turnover and microbial pools

29 Implications More intense harvest of forest must consider effect on soil C

30 Implications More intense harvest of forest must consider effect on soil C Some biofuel management may not be C neutral in reasonable time span

31 Implications More intense harvest of forest must consider effect on soil C Some biofuel management may not be C neutral in reasonable time span Sustainable biofuel management must consider both percent wood removed and percent debris left behind

32 Acknowledgements DayCent Creators Valerie Barr, Lance Spallholz, and Union College CS Department This research has been supported in part by a grant from the National Science Foundation, IIS CPATH Award #

33 Soil C pools in DayCent