Ecological Archives A017-019-A2

Julia A. Klein, John Harte, and Xin-Quan Zhao. 2007. Experimental warming, not grazing, decreases rangeland quality on the Tibetan Plateau. Ecological Applications 17:541–557.

Appendix B. Method for estimating aboveground net primary productivity.

Additional details on nondestructive ANPP estimates. When vegetation such as tall grasses or shrubs formed a canopy over another layer of vegetation, we first recorded the dominant vegetation when viewed from above (in all 400 squares) and then pushed aside the top canopy layer and recorded the vegetation present underneath the top canopy. We then added these together and divided by 400. For example, if forbs comprised the dominant vegetation in 40 squares when viewed down onto the top of the canopy, and comprised the dominant vegetation of five additional squares under the shrub canopy, we counted forbs as comprising a total of 45/400*100 = 11.25% coverage in that plot.

TABLE B1. Regression equations between non-destructive multi-layered cover estimate and dry-weight, harvested biomass as described in the Methods section of the text.

 
Adj R2
Coeff.
SE
Std.
coeff.
t
P
n
Vegetation Groups              
Shrub ( live foliage ) 0.99 1.05 0.05 0.99 21.90 <0.0005 8
Shrub ( wood ) 0.95 6.75 0.51 0.98 13.23 <0.0005 10
Grass ( at meadows ) 0.98 1.75 0.07 0.99 25.06 <0.0005 11
Grass ( at shrublands ) 0.94 1.20 0.11 0.98 10.67 <0.0005 8
Sedge 0.90 0.64 0.05 0.95 12.76 <0.0005 20
Forb Species               
Gentiana straminea 0.98 0.72 0.04 0.99 19.29 <0.0005 7
Saussurea superba 0.98 0.68 0.04 0.99 19.38 <0.0005 8
Morina chinensis 0.98 0.84 0.05 0.99 18.45 <0.0005 8
Oxytropis spp. 0.97 1.32 0.09 0.99 14.99 <0.0005 7
Aster faccidus 0.93 0.58 0.05 0.96 10.62 <0.0005 10
Stellera chamaejasme 1.00 0.73 0.01 1.00 67.81 <0.0005 6
Polygonum viviparum 0.96 0.46 0.06 0.98 8.11 0.004 4
All other forbs 0.91 0.69 0.06 0.96 11.12 <0.0005 13


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