A Habitat-Based Framework for Communicating Natural Resource Condition

Table 3

Summary of Rock Creek Park habitat-based condition assessment.

Metric (by habitat)	Units	Grand mean	Standard error	Percentage of threshold attainment
				Metric	Habitat	Park
Forest: 575 ha (81%)					67
Exotic tree/shrub density	% total basal area	16.7	10.9	70
Presence of forest pest species	% of trees infested	0	—	100
Presence of forest interior dwelling species (FIDS) of birds	“highly sensitive” FIDS; “sensitive” FIDS	2.4; 7.8	1.4; 1.1	100
Deer density	deer km^−2	26.4	2.1	0
Native seedling regeneration	seedlings ha^−1	6,000	3,221	0
Critical connectivity (Dcrit; within Park)	m	340	—	100
Proportion of impervious surface (within Park)	—	0.05	—	100
Wetland (inland): 14 ha (2%)					49
Total phosphorus	𝜇g𝐿^−1	929	60	0
Salinity	g L^−1	0.4	0.0	30
Aqueous nitrate	mg L^−1	2.6	0.1	46
Dissolved oxygen	mg L^−1	7.5	0.2	87		60
Benthic index biological integrity (IBI)	—	1.5	0.2	0
Area occupied (PAO) by amphibians	% area occupied.	53.4	8.4	78
Physical habitat index (PHI)	—	56.8	2.5	100
Artificial-terrestrial: 121 ha (17%)					26
Deer density	deer km^−2	26.4	2.1	12
Proportion of impervious surface (within Park)	—	0.05	—	100
PM2.5 concentration	mg m^3	14.4	0.6	27
Ozone	ppm	0.09	0.00	0
Wet SO4 deposition	kg ha^−1 yr^−1	18.2	0.6	0
Total NO3 deposition (cultivated)	kg ha^−1 yr^−1	10.8	0.5	40
Hg deposition	ng L^−1	13.5	0.3	0

Park percentage of attainment condition assessment is area-weighted by habitat type.