It’s certainly feeling like mid summer around here, the temperature has increased, the rains have paused and there are more fruits than you can shake a fruit laden stick at. This week we started a series of observational surveys and tests looking at habitat, garden wildlife (specifically invertebrates) and soil health.
So here’s what we’ve been up to in more detail.
Habitat Types – Aponia
Our project mission is to develop and promote practices that can produce food while enhancing biodiversity. In order to encourage biodiversity in our gardens we include a variety of habitat into the landscape design, some wild (at various stages of succession) and some cultivated. The gardens are, essentially, a mosaic of habitat.
The map below shows the various habitat types within our 8 year old Market Garden, Aponia. (Aquatic habitat not labelled). I’ll be writing a detailed report of these habitat types at a later date including the typical flora and fauna species, how to develop, maintain and manage them, and what is the productive potential of each habitat.
For now we wanted to take a closer look at the biodiversity value that each of these habitats provide, specifically to see how they compare with each other and how our cultivated habitat types i.e annual and perennial polyculture, compare to the wild habitat types. This week we devised some simple invertebrate surveys within the habitat types using pitfall traps and canopy observations to measure the number of unique species found in each habitat. The habitats we surveyed included:
- Perennial Polyculture
- Annual Polyculture
- Mixed Species Hedgerow
- Late Scrub
- Early Scrub
- Mixed Species Meadow
This will be a 3 year study with the surveys carried out at the same time every Monday and Tuesday for a 3 week period in the months of August and April. Weather conditions – Cloud Cover, Temperature, Wind – are recorded with each survey.
The Pitfall Traps
Two pitfall traps are set within each habitat type. Each trap is labelled for recording purposes. The traps are set on Monday morning, left overnight and emptied onto white trays on Tuesday morning. The number of unique species are counted within each trap and an average of the two traps per habitat is taken to provide the average number of unique species found within each habitat type. After emptying the traps, lids are placed on the jars and the survey is repeated the week after. The below image shows the locations of the traps within each habitat type.
Shahara made some great videos that show the habitat types and how we undertake the pitfall traps surveys. Here’s part one
50m trails within each habitat are determined as shown by red dotted lines in the below image.
The Results – Week 1
For what it is worth, here are the results from last weeks surveys . I’m looking forward to getting more data in the future and hope, at least, to gain a glimpse of how invertebrate diversity compares within these habitats.
Shortcomings of the Surveys
We’d like to keep the surveys as simple and replicable as possible without sacrificing the validity of the data. We’ve identified the following shortcomings so far.
- Because we are not using ethanol in the pitfall traps (commonly used to kill what falls in the traps), it’s possible that predators may fall in and eat prey species before we can count them.
- As we are not identifying the species and have limited knowledge of entomology we may be counting unique species when in fact they are male or female, larvae/adult or at different instar stages.
- The canopy observations do not account for nocturnal invertebrates
- The canopy observations from the habitat types with tall shrubs and trees do not account for invertebrates in the higher canopy. We could use a “beating tray” observation for this but for some of the habitat such as early scrub and hedgerow it will be difficult to set this up.
- Doing these surveys each month from April – October would provide a more accurate picture.
If you have any suggestions on how we can improve the survey please do let us know and if you would like to try the survey yourself, send me an email and I’ll send you the record sheets and protocols.
The Biomass Belt – Aponia
The belt is growing well, although not all of the original hedgerow species have survived, we added Miscanthus x giganteus – Giant Miscanthus into the hedgerow to fill the gaps. Elaeagnus umbellata – Autumn Olive has grown well as a hedge plant and is fruiting this year (even after trimming in the spring). The Symphytum x uplandicum – Comfrey ‘Bocking 14’ beds have done well and you can find some details of how much biomass we harvested from these beds here. I’m really pleased with the Trifolium repens – White Clover pathways.
Here is the original layout and planting scheme…
Aponia – Market Garden
Climbing Beans, Cucumbers and Melothria scabra – Cucamelon. The Beans and cucamelon are doing great but I’ve rarely had great results with cucumbers. They always seem to be misshapen, small with bitter skin, although tasty enough when peeled.
The Paulownia tomentosa – Foxglove Tree rows that we are growing to shade the annual vegetable beds are ready for another thin. We tried 1.5 m spacing between the trees in the bed on the left and 1 m spacing in the bed on the right. I’d say the 1.5 m spacing is sufficient, providing plenty of shade and as you can see in the below image the trees appear to grow faster at this spacing.
The fallow patches in the market garden are in full flower now attracting an abundance of insects. Viper’s-bugloss – Echium vulgare is a great wildlife plants and its deep roots (down to 70 cm) probably serve well as a mineral repositor fixing nutrients that would otherwise wash through the soil into biomass.
The team chilling :)