Fig 1.
The measurement of possum fur on an image taken under a microscopy at ×200 magnification by using (a) the DGI method–a grid layer (12 × 9, grid size 0.05 × 0.05 mm) was placed on the top of the image and the horizontal and vertical intersections of possum fur that crossed the edges of each square were counted and recorded (e.g., C = 14, the possum fur length calculated using the Tenant equation was 0.550 mm), and (b) the PIP method–the possum fur in the same image was traced (yellow line) manually and measured by the ImageJ software (e.g., L = 0.503 mm).
Fig 2.
AMF hyphae on an image taken under a microscopy at ×100 magnification measured by using (a) the DGI method—a grid layer (12 × 9, grid size 0.05 × 0.05 mm) was placed on the image, and the horizontal and vertical intersections of hyphae that crossed the edges of each square were counted and recorded (e.g., C = 23, the hyphal length calculated using the Tenant equation was 0.904 mm); and (b) the PIP method—the hyphae in the same image were traced (pink line) and measured by the ImageJ software with NeuronJ plugin (e.g., L = 0.931 mm).
Fig 3.
A scatterplot matrix with linear regressions among the lengths of possum fur measured by both the DGI (LDGI) and PIP (LPIP) methods and the known lengths of possum fur (Lknown).
Fig 4.
The distribution of the 95% confidence limits (dashed lines) of the mean lengths (solid lines) of possum fur measured by both the DGI (LDGI) and PIP (LPIP) methods and the known lengths of possum fur (Lknown).
Fig 5.
The lengths (means ± 95% confidence intervals) of hyphae in soils with low P fertility (solid circles) and high P fertility (open circles) measured by the digital gridline–intersection (DGI) method plotted against measurements by the photomicrography–ImageJ processing (PIP) method.
The 1:1 line is shown as a dashed line.
Fig 6.
Ilustration of the intersection of gridlines with a stained hypha and the different number of counts that can be obtained with different random arrangements of the structure.
A given length of 0.35 mm hypha if distributed as (a) intersection count recorded C = 7, then a estimated legnth of 0.28 mm was calculated using Tennant equation, and as (b) intersection count as C = 11, its corresponding estimated length was 0.43 mm.