Laboratory Analysis of Northern Hardwoods Soil Physical, Chemical, & Biological Properties

1. Laboratory Analysis of Northern Hardwoods Soil Physical, Chemical, & Biological Properties Katherine Foo, Jennifer Heller, Lucas Langstaff, Chia-jin Wu, Derek Robinson

2. Goals • Summarize laboratory findings • Integrate field and lab components • Link results to factors influencing soil • formation Katherine Foo, Jennifer Heller, Lucas Langstaff, Chia-jin Wu, Derek Robinson

3. Outline • Introduction • Site summary • Physical characteristics & their effects • Texture, H2O, Bulk Density (Chia-jin) • Chemical characteristics & their effects • Soil pH & organic matter content (Derek) • CEC & Base Saturation (Jennifer) • Biological characteristics & their effects • Soil microbial biomass & N mineralization (immobilization) (Katherine) • Ecosystem Level processes • Ecosystem biomass & nutrient pools (Lucas) • Conclusion

4. Soil Water Content ( mL/ cm3) Available Water Content • AWC= FC- PWP • AWC, Texture and OM • AWC and Sand

5. AWC Among 4 Ecosystems

6. AWC Among 4 Sites in NH • Soil texture  AWC • Exception: De La Solum

7. Db Among 4 Ecosystems

8. Db Among 4 Sites in NH

9. Soil pH • Chemical: • pH = -log[H] • rate of weathering, solubility of minerals • Physical: • Influences the rate of weathering • Controls the solubility of minerals and microbial activity. • Indirectly influences aggregate stability, air and water movement • Organic Material influences pH dependent charges • Fertilizer • Atmospheric additions

10. Site A Site B Mixed-Oak Northern Hardwoods Deionized Water pH 6.1 5.3 CaCl pH 6.3 3.7 2 Organic Carbon (%) 2.0 1.51 Organic Matter (%) 4.0 3.02 CEC (cmol(+)/kg) 10.30 4.03 Base Saturation (%) 99.59 93.0 Soil pH • Biological: • Affects rate of microbial respiration • Suitability for plant colonization and growth • Field values were validated in the lab using an electrode submersed in our deionized water, and CaCl solutions.

11. Soil O.M. Content • Physical: • alters H2O holding capacity • alters soil colour • alters soil structure which indirectly affects air & H2O holding capacity of soil • Biological: • controls microbial growth in soil through microbial respiration (which decomposes O.M. and releases CO2) • Supplies nutrients to plants • Chemical: • O.M. makes up 30-50% of total cation exchange capacity • Involved in anion exchange capacity • Effects pH and acidity of soil

12. Site A Site B Mixed-Oak Northern Hardwoods Deionized Water pH 6.1 5.3 CaCl pH 6.3 3.7 2 Organic Carbon (%) 2.0 1.51 Organic Matter (%) 4.0 3.02 CEC (cmol(+)/kg) 10.30 4.03 Base Saturation (%) 99.59 93.0 O.M. cont.

13. CEC & Base Saturation CEC: The total sum of cations a soil can absorb via electrostatic attraction Base Saturation: the percentage of the CEC which is occupied by base cations (such as Ca2+, Mg2+, K+, Na+) * Data is a mean of all Monday lab group findings

14. Cation Exchange Capacity • Relatively small CEC at 4.03 cmol+/kg • Due to specific characteristics of the Northern Hardwoods ecosystem… - Low organic matter content of 3.02% - Mineralogy of sand has a low potential to attract and adsorb cations - Loamy sand texture

15. Base Saturation • High base saturation (93%) is due to… - An abundance of base cations in soil - which supports the high productivity of the ecosystem - young (~9,000 yr old), relatively unweathered soil • Implications - relatively large supply of nutrients available to plants in soil solution

16. Total Acidity • A mean of .409 cmol(+)/kg was found • Relatively high, which supports the pH findings in relation to the other ecosystems studied Question: How does this number support the pH finding on its own, without looking at a relationship between the sites?

17. Soil Microbial Biomass & Respiration Controls the release of Nitrogen from organic into inorganic forms (NH4+, NO3-), which are directly available to plants Has important implications because Nitrogen is the limiting nutrient in temperate terrestrial ecosystems • Microbial Respiration serves as a general indicator of microbial efficiency within the soil • Specific Microbial Respiration measures the respiration per gram of microbe; indicator of microbial efficiency and organic matter quality

18. Microbial Results Microbial Biomass Microbial Respiration Specific Mic. Resp. (gC/m2) (microg/g/d) (mg/g/d) Soil Coughing 23.14 19.43 79.09 Fine Young Ent. 13.00 25.05 199.65 Mottley Hue 13.09 23.28 208.18 Duripan Duripan 27.01 27.99 126.42 Bt Boys 15.15 20.83 163.10 High microbial biomass can be explained by: (a) Types and properties of the microbes in the soil. (b) High litter quality, relatively low respiration & specific respiration rate Low Specific Microbial Respiration indicates that: (a) Microbes efficiently assimilate carbon to biomass

19. Mineralization & Nitrification • Mineralization describes the microbial release of organic Nitrogen into the inorganic form of ammonium, able to be taken up by plants • Nitrification describes the transformation of ammonium into nitrate through autochemotrophic microbes • The processes together show the amount of nitrogen available to plants within a soil • Carbon Respired to Nitrogen Mineralized Ratio measures the amount of energy consumed by microbes as it relates to the amount of Nitrogen produced; a direct indicator of soil organic matter quality

20. Mineralization & Nitrification Results • Net Mineralization Net Nitification C Resp. / N Min. • (g N/m2/d) (g N/m2/d) Soil Coughing 0.35 0.03 5.20Fine Young Ent. 0.36 0.19 7.17Mottley Hue 0.42 0.20 6.50Duripan Duripan 0.22 0.11 15.72Bt Boys 0.47 0.22 5.21High nitrogen mineralization is due to: • High microbial biomass, and an associated high efficiency of carbon • assimilation by the microbial community • Low nitrification is due to: • Low pH, as microbes that aid the nitrification process are habitat specific • and are intolerant to low pH. • Low Carbon Respired to Nitrogen Mineralized Ratio means that: • Microbes efficiently assimilate carbon to biomass. They expend very little • energy in the assimilation of carbon to biomass.

21. Biomass (Carbon) • Why? • High nutrient availability - base saturation (93%) • Moderate CEC (4.03 cmol+/kg) • Low disturbance regime due to complex topography (e.g. excluding of fire), preserves nutrient supply • High decomposition rates • High microbial biomass (23.14 g C/m2) with high net N mineralization (.364 g N/m2/d) • Low evaporation and transpiration due to cool climate/high altitude. Total NH biomass was higher than NO and OH, but lower than MO, 359.7 Mg/ha

22. Biomass (Carbon) Pools • Compared to other ecosystems, we had high aboveground and forest floor carbon pools. The soil carbon pool was relatively low. • The aboveground pool was high due to many large trees with a high basal area. • The forest floor pool was high due to the microtopography of the area, consisting of many pits and mounds that collected litter. • The soil carbon was relatively low due to low OM content, low bulk density, and the microbes here have a high rate of substrate utilization for biomass.

23. Biomass (Carbon)

24. Nitrogen Pools • Total Nitrogen content was high, 3468 kg N/ha • The aboveground pool was high (794 kg N/ha), because of the large aboveground biomass with high basal area • The forest floor pool was comparatively high (165 kg N/ha) because of the moderately large amount of litter production and collection, due to the pit and mound topography and high productivity. • The soil Nitrogen pool was very high (2509 kg N/ha) because of the large microorganism biomass (~25 g C/m2), which in turn has a high net nitrogen mineralization (.364 g N/m2/d). • This nitrogen mineralization is higher than all other ecosystems sampled, except for Mixed Oak.

25. Nitrogen Pools

26. THANK YOU Katherine Foo, Jennifer Heller, Lucas Langstaff, Chia-jin Wu, Derek Robinson