Forest Ecosystems

Table 1 Summary of parameter settings used in the 3-PG simulations for ponderosa pine

From: Does overshoot in leaf development of ponderosa pine in wet years leads to bark beetle outbreaks on fine-textured soils in drier years?

3-PG Parameter	Units	Ponderosa pine
Biomass partitioning and turnover
Allometric relationships & partitioning
Foliage: stem partitioning ratio @ D = 2 cm	–	1.328
Foliage: stem partitioning ratio @ D = 20 cm	–	0.75
Constant in the stem mass v. diam. relationship	–	0.0046
Power in the stem mass v. diam. relationship	–	2.97
Maximum fraction of NPP to roots	–	0.8
Minimum fraction of NPP to roots	–	0.25
Litterfall & root turnover
Maximum litterfall rate	1·month⁻¹	0.021
Litterfall rate at t = 0	1·month⁻¹	0.001
Age at which litterfall rate has median value	months	36
Average monthly root turnover rate	1·month⁻¹	0.015
NPP & conductance modifiers
Temperature modifier (fT)
Minimum temperature for growth	°C	−7
Optimum temperature for growth	°C	18
Maximum temperature for growth	°C	40
Frost modifier (fFRost)
Days production lost per frost day	Days	1
Soil water modifier (fSW)
Moisture ratio deficit for f _q = 0.5	–	0.7
Power of moisture ratio deficit	–	9
Canopy structure and processes
Specific leaf area
Specific leaf area at age 0	m²·kg⁻¹	3.1
Specific leaf area for mature leaves	m²·kg⁻¹	3.1
Age at which specific leaf area = (SLA₀ + SLA₁)/2	Years	2.5
Light interception
Extinction coefficient for absorption of PAR by canopy	–	0.5
Age at canopy cover	Years	15
Maximum proportion of rainfall evaporated from canopy	–	0.1
LAI for maximum rainfall interception	–	5
Production and respiration
Canopy photosynthetic capacity	mol C·mol PAR⁻¹	0.05
Ratio NPP/GPP	–	0.47
Conductance
Minimum canopy conductance	m·s⁻¹	0
Maximum canopy conductance	m·s⁻¹	0.016
LAI for maximum canopy conductance	–	5
Defines stomatal response to VPD	1·mBar⁻¹	0.05
Canopy boundary layer conductance	m·s⁻¹	0.14

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