The main advantage of this protocol is it allows researchers to capture both flying and crawling arthropods from the foliage. Although we use this technique on trees it can also be used on bushes and shrubs. Be careful to practice bagging branches quickly without disturbing the foliage so active arthropods do not escape capture.
To begin this procedure, use bolt cutters, large wire cutters, or an electric grinding disc to remove the bottom third of a 30 centimeter wire tomato cage so that it is approximately 55 centimeters in length. Then, cut two 50 centimeter braces from aluminum tubing or a similarly semi-rigid material to use as attachment rods and braces on each side of the largest end of the tomato cage. At 38 centimeters from the end use a tabletop vice or larger grasping tools such as channel locks to bend the brace to an approximately 30 degree angle.
Attach the long end of each attachment rod to opposite ends of the tomato cage with zip ties. Use either duct tape or electrical tape to support this attachment making sure that the tape is wrapped around at least six centimeters of the cage and rod. Attach the other end of each rod on opposites sides of the end of an extendable pole with zip ties.
Use either duct tape or electrical tape to support this attachment making sure to wrap the tape around multiple times and that it overlaps the pole and rods by at least six centimeters. Make sure that the opening of the cage is contact with the end of the telescoping pole when the cage is attached. Then attach the cage directly onto the end of the pole using tape.
Attach hook and loop fastener strips at two points to the opening of the cage 90 degrees from the previously attached pole. First, attach two pieces of hook and loop fastener to the outside opening of the bag so that they align with the hook and loop fastener attached to the opening of the cage. Be certain that the hook and loop fastener is aligned so when the bag is inserted and attached the opening to the pull strings of the bag run parallel to the telescoping pole.
Insert a 49 liter kitchen garbage bag into the wire tomato cage. Place three gator clips evenly dispersed on each respective side of the bottom of the bag and attach the clips to both the bag and the wire cage so that the bag is held against the cage. Orient the gator clip on the bag opening so that it is attached to the drawstring parallel to the telescoping pole opposite of the location of the pole attachment.
Attach paracord to the bag's drawstring closest to the pole. Cut four pieces of plastic or hard rubber tubing in four centimeter sections and attach them at four locations with duct tape or electrical tape. First should be placed on the extending part of the pole about 0.5 meters from the end of the pole nearest the tomato cage.
The remaining three should be placed equidistance along the bottom section of extending pole starting about five centimeters from the top of the bottom section. Thread the end of the paracord that is not attached to the bag through the plastic tubing. After this run both paracord strings together through the plastic tubing inserts to hold it in place.
For each sample tree, use a random number generator to select a sample height that is within the height of the extension pole when extended at maximum length. Use the random number generator to select a sample distance from the tree trunk and identify a branch that will fit in the bag with minimal disturbance to the foliage. And is the proper height and distance from the trunk based on the numbers generated.
Raise the sampling pole to a height parallel with the desired branch. Quickly slide the bag over the branch and then quickly pull the paracord strings that are attached to the drawstrings to seal the bag. Have a second person use the extension pole pruner to clip the branch at the location adjacent to the bag's opening.
Then carefully bring the sample bag to the ground and rapidly tie the bag's drawstrings closed. Store the bagged branch in a freezer until ready to conduct the laboratory arthropod analysis. Hold the frozen bag and branch upright and shake the sample branch while it is in the bag to dislodge the arthropods into the bag.
Carefully remove the branch from the bag and rinse it in large collection pan to remove any remaining arthropods. Next, empty the material remaining in the bag into the collection pan and remove an non-arthropod debris. Separate the arthropods into the desired taxonomic groups.
Noting differences between larvae and adults. Quantify the arthropods as desired. If biomass is of interest either measure the length of arthropods and use published length mass table to estimate biomass.
Replace arthropods in small drying pans. Dry in drying oven for 24 hours at 45 degrees Celsius and weigh on an electronic balance. Dry the leaves in a drying oven for 48 hours at 45 degrees Celsius and weigh them on an electronic balance.
Or measure the length of all woody branches within the sample. In a representative study, 626 samples are collected from 323 individual trees that composed five tree groups. For estimates of total arthropod biomass per meter of branch sampled the standard error ranges from 12%to 18%of the mean for the five tree groups.
This level of precision is adequate to detect variation among tree groups in a quadratic change in biomass by date. This technique provides more precision when estimating guild diversity as demonstrated by the standard error of arthropod guild diversity ranging from 3%to 7%of the mean diversity across the five tree groups. Precision at this level is adequate to detect variation across the five tree groups.
Precision of estimates of richness are also very precise as demonstrated by standard errors that ranged from 3%to 7%of the mean richness among the five tree groups. This level of precision is adequate to identify variation among tree groups. A quadratic association with date, decrease in richness with height on the tree, and a positive relationship between arthropod richness and distance from the tree trunk.
Be certain that you enclose the branch quickly without disturbing the foliage to ensure active arthropods do not escape capture.
