Defining a regional approach for invasive plant research and management - Invasive Plants: Ecological and Agricultural Aspects - page 132

Table 3. Example transition matrix for P. recta in northeastern Oregon, yielding a population growth
rate (λ) of λ = 1.2144. The population is increasing by about 21% annually.

Year 2 Year 1

Seed Seedling Rosette Small adult Large adult

Seed 0 0 0 1211 3528

Seedling 0.001 0 0 0 0

Rosette 0.001 0.05 0.55 0.16 0.02

Small adult 0.0001 0.01 0.21 0.43 0.35

Large adult 0 0 0.01 0.11 0.46

survive and remain within that size class for a year, 2) the probability that an
individual will survive and grow into another stage and 3) reproductive output
or fecundity [61]. The model (Tab. 3) describes a variety of population param-
eters including the population growth rate (λ). Initial analyses indicate that P.
recta populations in old fields expand at about 21% per year.

Relative growth rate and competitive ability
Growth analysis is a methodology to determine plant carbon allocation pat-
terns over time, which may influence competitive ability with other plants in a
community. Relative growth rate (RGR) is a measure of dry matter accumula-
tion in relation to size of the individual over time; it is the efficiency of plant
growth through time [62, 63]. Tuitele-Lewis [64] determined RGR for P. recta
over a range of disturbed and undisturbed conditions on three old-field sites in
the Blue Mountains Ecoregion. He found that P. recta ranged from
0.52-1.01 g g -1 week -1 for the three sites in 2002, and 0.13-0.2 g g -1 week -1
in 2003. These values were not unusual when compared to those of other com-
mon plant species in the area that were obtained from the literature (Tab. 4). It
appears that RGR, as a measure of individual plant resource acquisition, is not

Table 4. R max for certain plant species found in the Blue Mountains of northeast Oregon [64]

Species R max Author

0.51 g g -1 d -1 Bromus tectorum Arredondo et al. [98]

0.43 g g -1 d -1 Taeniatherumcaput-medusae Arredondo et al. [98]

0.36 g g -1 d -1

Pseudoroegneria spicata Arredondo et al. [98]

0.41 g g -1 d -1 Elymus elymoides Arredondo et al. [98]

0.23 g g -1 d -1 Phleum pratense Poorter and Remkes [99]

1.96 g g -1 week -1

Achillea millenifolia Grime and Hunt [100]

1.18 g g -1 week -1

Festuca rubra Grime and Hunt [100]

0.83 g g -1 week -1 Potentilla recta Grime and Hunt [100]