Arid BioCredit Pilot

KEY DETAILS

Principal Investigator
Dr. Lucy Smyth
Date
11 March 2025
Version
1.0.0
Programme
Arid Biodiversity Programme
Study Site
Eendoorn-Keimas Remainder-Pelgrimsrust (EKP)
Key partners
ORKCA
Contact email
lsmyth@naturalstate.org

1. PREAMBLE

Natural State’s objectives and activities are governed by a set of accepted Design Documents (DDs). These documents describe the context and purpose of all Natural State projects. Each DD documents key project details, the objectives and background of the project, features of the study area, and the general methodological framework. Specific methodological details may be found in the project Standard Operating Procedures (SOP) which is available in the Related Documents section below.

2. GLOSSARY

Natural State Glossary

3. PROJECT OVERVIEW

The Arid Biocredit Pilot Project uses a space for time approach to increase our understanding of how biodiversity and soil carbon change across a gradient of sheep grazing in the arid rangeands of Southern Namibia. This pilot project has been developped to lay the groundwork for a rewilding credit in the landscape.

3.1 PROJECT AIMS

The Arid BioCredit Pilot Project project aims to:

  1. Familiarise the ORKCA team with the data collection and processing protocols which will be used in monitoring change for the rewilding credit.
  2. Refine survey design and data collection methods to the desert biome, ensuring that they are able to detect change with sufficient power.
  3. Gain an increased understanding of how bird and mammal biodiversity varies across the landscape, and what changes can be expected with the proposed intervention.
  4. Gain an increased understanding of how vegetation diversity and cover varies across the landscape, and what changes can be expected with the proposed intervention.
  5. Undertake a preliminary assessment of labile soil organic carbon and mineral associated carbon in the landscape, to understand whether it is affected by land management.

3.2 PROJECT BACKGROUND

ORKCA (Orange River Karoo Conservation Area) is an organisation that describes themselves as a land management support organization, though they are landowners themselves as well. Their long term vision is to bring together a large number of private farms, conservation areas and community conservancies to create a 1 million hectare or larger continuous conservation area, through which wildlife will roam freely and in which ecological process will be re-established. ORKCA will be the management body overseeing the entire protected area.

Together, ORKCA and Natural state have recieved a grant from Rolex to lay the foundations for a rewilding credit in the region. ORKCA will buy a new property with some of the funds from this grant, where sheep farming will be halted, fences will be dropped and wildlife will be allowed to return. The predicted uplift on this piece of land will form the basis of a rewilding credit to provide long-term funding for these conservation efforts through easily and robustly verifiable positive change in biodiversity in the region. Natural State will provide technical support on survey design, monitoring methodologies, data processing and data analysis.

3.3 STUDY AREA

The ORKCA landscape is located at the joining point of the Succulent Karoo, Nama Karoo and Desert biomes, just north of the Orange River. It is a dry landscape, characterised by frequent drought and unreliable rainfall. Mean annual rainfall in the landscape is ~125 mm, mostly falling betweeen February and April, though this number fluctuates substantially. Though anecdotal, landowners in the area have remarked that mean annual rainfall seems to be decreasing.

The Orange River flows west through the region, with the high water mark on the Namibian side of the river delineating the boundary between South Africa and Namibia. The river provides an important water source for local communities in an otherwise arid landscape. Local herders bring cattle, sheep and goats to drink at the river, and the riverbed provides a route for relatively easy movement by locals from both sides of the border. Herders also often build huts just below the high water mark. Smuggling of abalone, drugs and other illegal products is common across the river, unfortunately meaning that the river poses a security threat to properties located along its edge. The land on the South African side of the river is predominantly community owned and open to the river while the land on the Namibian side is predominantly privately owned, with some properties fenced off from the river due to security concerns. The Orange River is severely infested by invasive Prosopis trees, which dominant the riparian zone, though they are interspersed with some native tree species. The Prosopis is thick and runs all the way up the Orange River to its source. Removing Prosopis is challenging as it coppices when cut, meaning that stumps cannot be left once trees are chopped; they need to be removed entirely or poisoned.

Vegetation in the area is sparse, and strongly dependant on the underlying geology. Rocky hillslopes are home to quiver trees and succulents, while flatter, sandier plains provide growing conditions for more grasses and forbs. Large mammals in the area include Cape Mountain Zebra, Oryx, Kudu, Springbok, Leopard, Caracal, Jackal and Black-footed Cat. Aardvarks have historically been seen in the area but there have been no sightings recorded since a severe 6 year drought which ended in 2018. Namibian laws allow for the private ownership of wildlife, and when a piece of land is purchased the understanding is that it comes with whatever wildlife is present at the time. Sometimes the seller will request more money based on the amount of wildlife on the land. Farmers are allowed to hunt wildlife for consumption on their land. Oryx and Kudu easily jump farm fences and pass between properties, while Zebra and Springbok do not. Predators threaten livestock and thus are hunted prolifically by farmers in the area.

The most common land use in the area is sheep farming, as the naturally occurring vegetation is not sufficient for cattle rearing. Farmers divide their land with internal fences, and move sheep between large camps, based on grass availability. Sheep are left in camps at night and farmers attempt to remove as many predators as possible from their land to limit livestock losses. However, they still accept a lamb loss rate of approximately 30%, including both natural and predator inflicted mortality. Insufficient grass due to irregular rainfall is a big problem for farmers. Some farmers have goats as well as sheep. In the landscape it is generally assumed that 1 sheep requires 10-15 hectares of land. Lamb prices fluctuate, but lamb is currently sold for 81 ZAR/kg, and 1 lamb weighs approximately 16-18 kg. Farmers generally aim to earn ZAR 1 million gross income per 1000 sheep. The land north of the Orange River is also of significant interest to prospectors and miners. Historically, the region has been known for diamonds, however mining interest now is predominantly centered around lithium and tantalite.

The pilot study will take place across three properties: Pelgrimsrust, Keimas Remainder and Eendoorn. The sandy plains in the north of Pelgrimsrust are representative of land that has not been farmed for the last 40 years. Keimas remainder is representative of land that was farmed until 7 years ago, and has been left to rest since then. Eendoorn is representative of an active sheep farm, managed using conventional farming methods.

3.4 PROJECT TIMELINE

Sampling for the Arid BioCredit Pilot Project will begin in September 2024 with the deployment of camera traps and acoustic sensors. These devices will be deployed for four months and collected in January 2025. The vegetation and carbon component of the pilot study will begin in March 2025.

4. SURVEY DESIGN

The survey uses a space-for-time substitution to investigate the effects of sheep farming and recovery on biodiversity in the ORKCA landscape.

4.1 SPATIAL DESIGN

The pilot study will involve sampling across three properties: Pelgrimsrust, Keimas Remainder and Eendoorn. Each farm represents a distinct treatment representing a temporal step along a rewildling gradient from livestock ranch to intact open space. The farms are homogeneous in terms of soil type and sand content, elevation and rainfall. Spatial stratification of each farm was therefore not necessary.

Survey design for this pilot study was non-random in order to maximise our use of roads in the area, while maintaining an inter-site distance within farms of ~2 km. This non-random approach is necessary to keep the project scope within the capacity of ORKCA’s field team. There are 12 sampling sites per property, resulting in a total of 36 sampling sites. For the camera trap and acoustic survey, 24 camera traps and 12 acoustic monitors will be placed on each farm. Sampling will occur in a pseudo-grid-like pattern on each farm, adjusted for road access, with a ~2 km inter-site distance.

4.2 TEMPORAL DESIGN

The ORKCA landscape is highly dependent on rainfall which is unpredictable and patchy in the region. It is therefore important that temporal replicates investigating spatial patterns occur at the same time of year.

The camera trap and acoustic pilot survey will be set up in September 2024. Devices will be left in the field for a period of 4 months from the deployment of the last sensor, after which they will be collected. Devices will be checked every 3 weeks. Devices will be taken down in January 2025. The vegetation and carbon surveys will take place in March and April 2025.

This pilot survey will not be repeated, as its main goal is to build out monitoring capacity and methods. However, it is intended to reflect seasonal monitoring patterns that would be implemented in support of a rewilding credit.

5. SAMPLING DESIGN

At each sampling site, two camera traps and a single acoustic recorder will be deployed as floating detectors, meaning that they can be located anywhere in a radius of up to 50m from the pre-defined sampling site, so as to maximize detections. The acoustic sensor will be deployed at the same station as one of the camera traps. The camera trap station with the least acoustic interference (wind, water, road noise) should be selected for the deployment of the acoustic sensor.

The vegetation survey will consist of 1 plot per site, with the plot mid point located at the mid point of the two camera trap stations. Each plot will be 40 m X 40 m and face north to south. The carbon survey will occur at 6 of the 12 vegetation plots per farm with sampling a 0 - 20 cm depth, a 20 - 40 cm depth and a bulk density sample taken in each subplot.

5.1 Camera Traps

Camera trapping will follow the standard arid rangelands camera-trapping protocols. Cameras should be set on a pole or tree. Cameras should be placed such that the motion detector is 45 cm above the ground. When placing float cameras, each camera should be placed along a distinct feature. Two cameras should not be placed along the same game trail, road, or drainage line. All cameras must be at least 50 m apart from each other and not more than 100 m apart from each other. Vegetation can be trimmed in front of cameras, especially tufts of grass directly beneath the camera that could grow and obscure the motion detector or lens. Cameras should operate with a full complement of batteries and a clean sd card.

5.2 Acoustic Sensors

Passive acoustic monitoring will follow the standard arid rangelands PAM protocols. One AudioMoth should be placed on the same pole as one of the camera-traps per sampling site. Audio Moths should not be placed in depressions or against cliff faces, but on the edge at the top of a cliff is suitable. They should also not be placed near ambient noise. This means avoid placing them near running water, busy roads, or construction. AudioMoths should operate with a full complement of batteries and a clean sd card.

5.3 Vegetation Survey

Vegetation monitoring will follow the standard arid rangelands vegetation monitoring protocols. The midpoint of each vegetation plot should be placed at the midpoint between the two camera trap stations at each site. Measuring tapes should be laid out to mark the plot, running north to south and east to west, and dividing the plot into 4 subplots. Each subplot should be photographed from the plot centroid. Eight 1 m X 1 m quadrats should then be established within the plot, each one surrounded by two larger quadrats (3.16 m X 3.16 m and 10 m X 10 m). All trees located within each subplot should be identified, and their basal diameter should be recorded. Within each 1 m X 1 m quadrat all shrub, grass and forb species need to be recorded (per category). Additionally, the 5 most dominant species need to be identified and the percentage cover of the 5 most dominant species needs to be estimated as well as the percentage of bare ground. Then, a photograph needs to be taken from directly above the quadrat, capturing an aerial view of what lies within the quadrat. Lastly any new species present within the 10 m² quadrat should be recorded, followed by any new species present within the 100 m² quadrat.

5.4 Carbon Survey

Carbon monitoring will follow the standard arid rangelands carbon monitoring protocols. Vegetation plots will be used as the basis for the carbon survey, though soil carbon sampling will only occur at 6 predetermined vegetation plots per property. Carbon sampling will occur in the centre of each of the four subplots that make up a vegetation plot, resulting in 4 carbon sampling stations per subplot. At each carbon sampling station, sampling will occur at 4 separate points, and 2 depths at each point. Each point will lie 1 m out radially from the centre of the subplot. At each point, a carbon sample from a depth of 0-20 cm and a carbon sample from 20-40 cm will be taken. Samples from the same depth within the same subplot will be pooled, resulting in 2 soil carbon samples per subplot, and 8 soil carbon samples per plot. This will produce 144 soil samples in total. Additionally, one bulk density sample will be taken in the centre of each subplot, producing 72 bulk density samples in total.

6. ANALYTICAL FRAMEWORK

The primary goal of the pilot project described here is do develop the field methodologies for the region, and to produce training data for a camera trap image classifier and audio clips for the development of species-specific confidence thresholds for bird call identification. However if the data collected are of sufficient quality it will be used to look at species richness and diversity. It is also possible that camera trap and audio data could be used in single species single season occupancy models.

7. EXPECTED OUTPUTS

  1. Camera trap training data.
  2. Audio data for manual validation.
  3. Tree, shrub, grass and forb species list.
  4. Data on tree sizes from basal area measurements.
  5. Data on aerial percentage cover of bare ground, shrubs, grasses and forbs.

No publications are expected from this pilot survey.

8.1 STANDARD OPERATING PROCEDURES

8.2 OUTPUTS

None.

8.3 DATA ELEMENTS

Data Collection

8.4 ADMINISTRATIVE DOCUMENTS

9. REVISION AND VERSION HISTORY AND DESCRIPTION

v0.1.0 Initial design document created in September 2024. v0.2.0 Updates to include vegetation and carbon components in November 2024. v0.2.1 Updates according to comments from Matt in January 2025. v1.0.0 Updates according to new template structure and also major revisions to vegetation and carbon sampling design in March 2025.

10. BIBLIOGRAPHY

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