Follow-up control, revegetation and monitoring - Weeds Australia

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Follow-up control, revegetation and monitoring - Weeds Australia

Section FourFollow-up control,revegetation andmonitoringFollow-up control 44Other weeds invading after boneseed control 45Restoring native vegetation 45Natural regeneration 45Revegetation 46Monitoring your progress 46Photopoints 46Measuring density 47Measuring cover 49Surveying and recording boneseed distriibution 4943


SECTION 4:Follow-up control, revegetation & monitoringFollow-up controlThere are three stages to achieving successfulweed control:• primary treatment – removal of matureboneseed plants and existing seedlings• secondary treatment – intensive controlof the seedlings that emerge after removalof mature boneseed plants, and control ofresprouting mature plants• maintenance weeding – ongoing removalof boneseed seedlings that establish fromthe seedbank or from seeds imported to thearea by birds or other sources.Follow-up control (i.e. secondary treatmentand maintenance weeding) is crucial becauseboneseed seedlings can continue to germinatefrom the long-lived seedbank, possibly for upto 10 years.For effective follow-up control you should:• Inspect treated areas within 6 to 12 monthsof primary control, and remove boneseedseedlings by hand pulling or foliar sprayingbefore they flower and set seed.• Inspect treated areas where boneseed rootshave been left in the ground (i.e. after foliarspraying, cutting-and-swabbing, or cuttingwithout herbicide treatment) for regrowthand control if necessary.• Conduct maintenance inspections at leastevery 12 months and remove any newboneseed seedlings by hand. The extent offollow-up control required will decreaseeach year and inspections can be as simpleas an annual walk and hand pulling day.• Survey regularly for new infestations,especially if there are other infestations ofboneseed nearby.Removing boneseed in the Murray Mallee region, SA.• Pay close attention to areas where seedsmight be dispersed, such as under trees andalong fence lines where birds perch.• Combine yearly progress monitoring withfollow-up control, and record weeds as youremove them.The extent of follow-up control required willdepend on the density of the infestation andhow long it had been established. The largerthe boneseed seedbank, the more resourcesthat will be required for follow-up work.Numerous boneseed seedlings willgerminate after mature plants areremoved. However, many will die duringsummer. As boneseed rarely flowers inthe first year, this first flush of seedlingscan be left to thin out naturally, and theremaining young plants pulled up or cutand-swabbedin autumn. The juvenileplants will also be easier to spot than thesmall seedlings, making control moreefficient.Nicole Zeoli44


CONTENTSI. Background and summary page 3II. Purpose page 6III. Resources page 7IV. Results page 7V. Financial implementation page 12VI. Expression of thanks page 12ANNEXESList of acronyms page 13Cover photo: © UNICEF/ 2011/Salih2


SECTION 4:Follow-up control, revegetation & monitoringRevegetationRevegetation by planting tube-stock or directseeding is useful when:• a site has limited or no potential fornatural regeneration (e.g. if the boneseedinfestation was long established and anative seedbank is no longer present)• key species are missing and cannot benaturally recruited to an area.Use only locally indigenous species in yourrevegetation project, preferably propagatedusing material sourced from the bushlandarea to be planted (local provenance species).This ensures that the plant community youare attempting to establish is appropriate forthe habitat you are working in. For example,you want to ensure that a natural grasslandcommunity is not replanted with trees andshrubs.Timing is important when establishing nativevegetation from direct seeding or tubestock.Include revegetation in your boneseedmanagement plan, and try to schedule yourweed-control activities to coincide with thebest time to revegetate.For detailed information on revegetation seeBush Regeneration: Recovering AustralianLandscapes by Robin Buchanan (1989).Whether through natural regeneration orrevegetation, rehabilitation of bushlandis a long-term process that requires acommitment to extended monitoring andfollow-up.Monitoring your progressYou can monitor your progress using manydifferent methods, including site maps,photopoints, or quantitative measuressuch as density or cover. The most suitablemethod depends on the resources available,the expertise of the people carrying outthe monitoring, the questions you want toanswer, and the intended audience. Forexample, if you wish to demonstrate thenative regeneration following boneseedcontrol at your site to the wider community,photopoints are ideal. Or, if you need topresent quantitative data on the results of yourcontrol activities to your funding body, youcould monitor the numbers of boneseed plantsand native species using plot transects.To make valid comparisons, monitoringneeds to be done at a similar time of year,at least once each year, and in a consistentmanner. Incorporate monitoring into youryearly activity timetable. Monitoring can becombined with follow-up control – pull up anyseedlings as you survey the area.A site diary is useful for documenting activitiesundertaken, as well as observations aboutseasonal conditions or other factors that mayinfluence the results of your control program.Recording the cost of control (both in labourand dollars) is important for evaluating thecost-effectiveness of different methods andhelps you stay within budget.PhotopointsPhotopoints are a photographic record ofchanges occurring over time at your site, takenfrom the same point each time. They are anexcellent tool for demonstrating progress tomembers of community groups, the public,and funding bodies.46


Kym SmithDense boneseed infestation before control.Setting up a photopoint• Choose sites that will best represent thework undertaken at your site, such as anarea with significant ecological values, or aheavily infested area.• Place a permanent marker such as a stakeat the point from where you will take thephoto each time.• Label an A4 card with the date andphotopoint location, and attach to anotherstake approximately 10 metres from thecamera position.• Stand at the marker, face the labelling card,and take your photo.Tips• Align markers north to south to avoidexcessive sun or shadow, and to make iteasy to remember which direction to takethe photo if the markers are removed.• Try to include a distinctive object in eachphoto, such as a tree or fence post, that willbe there each time.• Use the same camera and film type (or thesame settings on a digital camera), and takethe photos from the same height (rest thecamera on the stake), with the same zoomsettings.• Take photos as frequently as required toreflect changes at the site, but ensure youhave photos taken at the same time eachyear to make valid comparisons.• Label each photo with the date, location,and the reason for taking the photo (e.g.annual monitoring, before and after weedremoval).Native regeneration after partial and gradual boneseedremoval.Measuring densityDensity is defined as the number of individualplants per unit area – for example 100boneseed plants per hectare. Density is agood measure of boneseed population size,as boneseed populations will respond to mostcontrol treatments by a change in the numberof individuals (of various age classes), ratherthan a change in vigour or plant size.Density is the most appropriate populationmeasure for scattered boneseed infestations.Measuring the density of thick boneseedinfestations is difficult, as it can be timeconsumingto determine how many individualplants are present in a clump. For densethickets it is more appropriate to measurecover (see page 49).Measuring density in age classes will moreaccurately reflect the changes caused bythe control treatments. It is a good idea todetermine the density of juvenile and matureplants separately, as the removal of matureboneseed plants is generally followed by thegermination of many boneseed seedlings.Juvenile plants could be defined as thoseunder 50 cm tall, or, if measured when thepopulation is in flower, juvenile plants couldbe those that are not flowering.For example, before treatment, the density maybe 500 mature plants and 100 juveniles (total600 plants) per hectare. Six months after theinitial treatment, the density may be 50 matureplants and 650 juveniles (total 700 plants)Kym Smith47


SECTION 4:Follow-up control, revegetation & monitoringper hectare. Follow-up control is carriedout 12 months after the initial control. After18 months, the density may have dropped to0 mature plants and 300 juveniles (total 300plants) per hectare. If only total numbers ofboneseed plants were counted, the dramaticeffect of the initial treatment on the boneseedpopulation would not have been captured.Plot countsBoneseed density can be measured simply, bymarking out three or more plots (‘quadrats’)of 10 m x 10 m (100 square metres). Theplots should be randomly located over thesite, and the more plots you have, the moreprecise the results will be. Count the numberof boneseed plants (in each age class) in eachplot, and determine the average. Multiply theaverage number of plants per 10 m x 10 mplot by 100 to get the number per hectare (onehectare is 10,000 square metres). For plantsstraddling the boundaries of the plot, count allindividuals along two contiguous sides, anddo not count the individuals that straddle theother two sides.Plot transectsPlots are often placed along sample linescalled transects. Transects are commonly100 m long, and are placed 10–50 mapart, parallel to each other. Using multipletransects will give you results that are morerepresentative of your entire site. Plot size willdepend on the species being measured. Forshrubs such as boneseed, 2 m x 2 m plots maybe appropriate. Smaller plots (50 cm x 50 cm)would be needed if you were measuring nativeseedling regeneration. Keep the plots the samesize on each subsequent monitoring occasion,so that results are comparable.If you wish to monitor native regeneration,you can count all species in each plot. Or,you may choose one or two key native speciesas the target species to be monitored. Recordthe number of individuals of the target specieswithin each plot. Average the number ofindividuals of each species in each plot (overall transects), and convert to a density measure(i.e. individuals per square metre or individualsper hectare).10 m100 m10 m30 mtransectend pointstakeCalculation4 + 2 + 3 = 9 plants total in 3 plots9/3 = average of 3 plants per 100 m 2 plot3 x 100 = 300 plants per haplots placed at intervals alongthe transectCalculating density using plot transects.Calculating density using plot counts.48


misshitend pointstakePost control monitoring using a 2 m x 2 m plot frame.Measuring coverSample point methodCounting individual boneseed plants is onlypossible for scattered or light infestations, asseparating individual plants is very difficultin dense infestations. An easier method formeasuring dense boneseed populations is todetermine percentage cover using the samplepoint method.Use a tape-measure and a narrow pole tomeasure sample points along a transect. Placethe pole next to the tape at set distances alongeach transect, and record a ‘hit’ if the poletouches a boneseed plant, or a ‘miss’ if thepole does not touch a boneseed plant. Theproportion of sample points with a ‘hit’ is anestimate of the cover. Using more samplingpoints gives you more precise results.Alternatively, walk between two points (e.g.two stakes or other permanent features) andrecord a ‘hit’ if a boneseed plant is presentwithin a metre of you at a given step interval.For example, you start at the gate and walktowards the large gum tree for a total of 400steps, recording ‘hit’ or ‘miss’ every 10 steps.You can vary distances and intervals to suityour site.Rachel Mellandsample points at set intervalsalong the transectCalculation % cover = % of ‘hits’ = 6/10 = 60% coverCalculating percentage cover using the sample pointmethod.Surveying and recording boneseeddistributionThe information you record on the distributionof boneseed at your site may not have beenrecorded before. If you think you haveidentified a new or previously unknownboneseed infestation, report it to your localweeds officer (contactable through your localcouncil or shire). The information can then bepassed on to state agencies, and be added tomaps at state and national levels.Consider surveying for boneseed beyond theboundaries of your site. This will help you toidentify possible threats to your control effortssuch as a large boneseed infestation nearby,and will improve knowledge of the distributionof boneseed in the region. Recording theabsence of boneseed in an area is alsoimportant, so the area is known to be surveyedand free of boneseed. Be sure to pass theresults of your survey on to the relevant weedcontacts.A field manual has been developed by theBureau of Rural Sciences to standardise themapping of Weeds of National Significance.A field manual for surveying and mappingnationally significant weeds (McNaught etal. 2006) lists the attributes that should berecorded when surveying for weeds, anddescribes various methods of determiningweed density. Copies of the manual areavailable from the Weeds Australia website.49

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