Rangeland Baseline Survey

KEY DETAILS

Principal Investigator: Dr. Matthew Rogan
Date; 6 July 2023
Version; 0.2.0
Programme; Rangelands Biodiversity Project (RBP)
Study Site; Lewa-Lolldaiga-Borana-Ngare Ndare (LLBN)
Key partners; K. Lisa Yang Center for Conservation Bioacoustics
Contact email; mrogan@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 objective 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.

1.1 DD PURPOSE

To provide a clear understanding of the purpose of each Natural State project and its contribution to Natural State’s mission of facilitating nature restoration at scale by using the latest technology and methods to revolutionise impact monitoring for carbon, biodiversity and human well-being.

1.2 DD SCOPE

This document details how this project fits within Natural State’s Impact Monitoring strategy and the principal team members overseeing the project. It explains why the project was conceived and how it will be implemented. It further directs readers to where they can find additional information relevant to the project.

2. GLOSSARY

Camera-trap: A remote camera with a defined automatic trigger (e.g., motion, time-lapse)
Camera-height: The height in cm from the ground to the motion detector. Standard NS protocols stipulate that cameras should be placed ~45 cm above the ground but rare exceptions can be made if the camera needs to be higher to avoid an object obstructing its field of view; in such cases that camera should be placed at a slight downward angle.
Centroid: A point at the center of a corresponding sampling grid cell denoted by a geohash, a longitude coordinate, and a latitude.
Centroid cameras: A camera placed at the centroid of each grid cell. When the centroid has a reasonably good field of view, the camera should be placed within 5 m of the centroid, facing the centroid. If there are obstructing factors, the camera can be placed up to 30 m from the centroid. All centroid cameras should be interpreted as following a randomized sampling design.
Closed Woodland: Habitat patches with plentiful trees and interconnected canopies over most of the patch or immediate vicinity.
Deployment: The defined period of continuous time a single remote sensor is active within the environment at a single, defined station as part of a survey.
Dominant Woody Vegetation: The primary species that provides structure to the habitat within or around a sampling unit. Must stand taller than the height of the grass. The dominant woody vegetation might not be the most abundant type but is rather the one that consistently provides maximum vertical structure within the grid cell.
Exclosure: A defined area fenced intended to prevent some species of wild animals from accessing the area to reduce browsing and prevent unsafe human-wildlife encounters or facilitate tree growth and recruitment. Exclosures have a variety of fencing types that restrict the movement of either elephants and giraffe or all medium-large herbivores. In actuality, excosures reduce access but do not prevent access to excluded animals.
Extension: An exclosure or portion of exclosure erected in 2022 or later.
Features, Sampling: Physical fine-scale characteristics of the landscape that correlate with animal movement and space use such that detection within a used habitat patch is assumed to be greater on or near such features than away from them.
Float detectors: Deployments of sampling devices that are placed at locations largely at the discretion of the field team to maximize detection probabilities for animals that use the surrounding habitat.
Grid Cell: A geohash or other rectangular area within which one or more sensors may be deployed as semi-independent sampling units.
Habitat type: Coarse, subjective classifications of the amount of woody cover in a heterogeneous savanna typically measured within a ~100m radius of the sampling location (see open grassland, open woodland, and closed woodland).
LLBN: The Lewa-Lolldaiga-Borana-Ngare Ndare landscape (See study site description for details).
Open Grassland: Habitat patches with few or no trees, or a small clump of trees highly localized within the patch or immediate vicinity.
Open Woodland: Habitat patches that are covered primarily by grass but trees or bushes are spaced somewhat regularly throughout most of the patch or immediate vicinity.
Project: A concerted, data-driven effort to robustly measure variation in Biodiversity, Carbon, or Human-wellbeing in response to one or more sources of heterogeneity in a designated landscape.
RBS: The Rangelands Biodiversity Survey; A concerted effort to assess the impact of various rangeland management practices on the bird and medium-large mammal populations of the LLBN landscape.
Remote Sensor: An electronic sensor with automated data collecting capabilities that operate independently of a human handler.
Rough, Hilly Terrain: Areas with a Terrain Ruggedness Index (Riley et al 1999) of 40 or greater or above 2100 m elevation, calculated from SRTM ~90m DEM data.
Sampling Design: The set of field methods employed in a survey and the manner of their use.
Sampling Protocol: Explicit survey methodology that describes the design, effort, duration, configuration, and operation of a camera-trap survey.
Site, Sampling: A distinct, discrete spatial unit defined in at least two dimensions where sampling occurs.
Station, Sampling: A point location where sampling occurs in space.
Study Area: A defined geographic region of interest within which one or more surveys investigate ecological patterns at one or more sites.
Survey: A set of simultaneous deployments of remote sensors over a defined period of time at a coordinated set of stations for the purposes of collecting data on the environment and its communities.
Survey Design: The theoretical and practical methods for choosing the spatiotemporal distribution of sampling units in a survey.
Vegetation structure: Variation in height and woodiness of vegetation that extends above the grass.

3. PROJECT OVERVIEW

3.1 PROJECT AIMS

The primary objective of the Rangelands Baseline Survey is to assess the impact of various rangeland management practices on the bird and medium-large mammal. This survey focuses on three specific management practices that the survey is designed to measure:

The use of browsing exclosures to manage herbivory and tree growth
The presence of livestock in addition to wildlife communities
Restorative grazing rangeland management.

3.2 PROJECT BACKGROUND

Natural State’s mission is to restore African landscapes with benefits for carbon, biodiversity and human wellbeing. To do so, we must demonstrate an ability to measure variation in all three streams. The Rangeland Baseline Survey demonstrates Natural State’s capabilities to survey medium-large mammals and birds using passive sensors.

3.3 STUDY AREA

The Lewa-Lolldaiga-Borana-Ngare Ndare (LLBN) study site is a savanna rangeland landscape in the central highlands of Kenya that extends north from the lower slopes of Mt. Kenya, straddling the boundary between Meru and Laikipia counties. The four main properties are located at 0.11 = 0.34° latitude and 37.07-37.53° longitude. The study site-centered ecosystem (SCE) exhibits three main “arms” with on extending south around the western edge of Mt. Kenya, one extending east along the southern side of the B9 highway to the northeastern edge of Meru County, and the longest and largest arm extending 130 km northwest to Maralal with some isolated islands of similar ecosystem to the north and west. The entire SCE is located between -0.3° and 2.3° latitude, and between 36.3° and 38.1° longitude.

Rainfall is highly variable, but is typically between 400 and 600 mm annually. During droughts, total annual rainfall can drop below 200 mm. Rainfall generally follows a north-south gradient with more rainfall at higher elevations in the south. The landscape sits at 1400-2370 m with higher elevations in Ngare-Ndare forest and south-central Lolldaiga and the lowest elevations in Lewa and northeast Borana. Soil types are highly variable throughout the landscape but consist primarily of Luvisols (Haplic and Vertic) and Dystric Regosols. Vegetation communities are predominantly Acacia-Commiphora bushlands and thickets with montane forests at higher elevations (Dinerstein et al. 2017).

Each of the four core properties are subject to divergent management practices. Lewa Wildlife Conservancy is mostly owned by The Nature Conservancy but has a number of small, privately owned enclaves. The reserve is almost exclusively used for photographic tourism but does have some livestock grazing, especially along the community road and in a section nicknamed ‘Bosnia’ where the community have grazing rights. Over the last 30 years, the conservancy has increasingly adopted elephant and large-mammal exclosures as a major management practice aimed at increasing tree cover on the conservancy.

Lolldaiga ranch is principally a livestock ranch but is also used by free ranging wildlife. Historically, the ranch was intensively grazed but recently new management has implemented a regenerative grazing regime based on intensive grazing by a few large, fast-moving herds. The grazing regime is intended to stimulate grass productivity and prevent selective grazing by livestock herds.

Borana Conservancy is a dual use wildlife and livestock ranch that also includes privately owned enclaves. In addition to photographic tourism, the conservancy produces cattle and has a partnership with a local community that extends limiting grazing rights to community herders. Borana has a few large-mammal exclosures, especially along the river that runs between Lewa and Borana.

Ngare-Ndare forest is a state forest reserve but is managed by the Ngare-Ndare Forest Trust on behalf of six villages. The Trust administers sustainable use of the forest by the six communities, predominantly for firewood collection and grazing. The forest also has small-scale tourism operations. The forest is predominantly populated with wild olives and junipers.

North of Lewa, Borana, and Lolldaiga are several community conservancies that practice predominatly pastoral lifestyles as well as the Mukogodo Forest, which is a forest conservancy managed on behalf of four neighboring communities. On the western boundary of Lolldaiga Ranch is Kupona, a small experiemental plot for testing restoration interventions.

The RBS was conducted across three properties: Lewa Wildlife Conservancy, Borana Conservancy, and Lolldaiga Ranch. The survey will be restricted to the areas most subject to these management practices: flat, low-lying areas with the largest, oldest exclosures and the primary areas of livestock grazing. To that end, rough, hilly terrain is excluded from sampling areas (see definition above).

3.4 PROJECT TIMELINE

Grid 1 deployements occurred from early April 2023 until mid May 2023. Grid 2 deployments occurred June-July 2023. Data processing for the complete dataset began in November 2023 and is planned to finish in January 2024. Analysis is planned for January 2024 through March 2024.

4. SURVEY DESIGN

4.1 SPATIAL DESIGN

The Rangelands Biodiversity Survey was a stratified random sampling that paired Audio Moth acoustic detectors with motion-triggered camera traps. Sampling sites for the Rangelands Biodiversity Survey were randomly sampled from two strata: 1) one site per large (> 0.5 km2) exclosure, and 2) non-exclosure sites with at least 2000 m distance between these sites. The minimum distance was not maintained for exclosure sites due to an assumption of semi-independence between exclosures resulting from fences and hard habitat edges.

4.2 TEMPORAL DESIGN

The survey was divided into 2 grids such that detectors cacould be rotated between the two grids. Each sampling location was intended to be active for at least 30 days however acoustic sampling was highly variable due to memory-card limits and sensor failures.

5. SAMPLING DESIGN

5.1 SITE CONFIGURATION

Each site is defined as a 500 m X 500 m cell with an associated centroid. Centroids were located at least 50 m from documented roads and at least 250 m from exclosure or property boundaries. They were also excluded from areas that would result in more than 25% rough, hilly terrain within the cell, or from areas with elevations above 2100 m.

Each site consists of three camera traps and one Audio Moth. At a few sites, only two cameras are deployed due to limited camera availability. One camera is placed at the cell centroid, hereafter referred to as the “centroid camera”. In all cases, the centroid camera must be placed within 30 m of the centroid. If that is not feasible, then the centroid must be moved (see below). If the centroid has a clear field of view, then the camera should be placed ~5 m from the centroid facing towards the centroid point. In open habitat, the camera should generally be placed to the north or south of the centroid point to avoid glare from the rising and setting sun but the field team should disregard this if there is a good justification for facing the camera east or west. The camera should be positioned to maximize the field of view at and around the centroid point. This camera should be recorded in Survey 123 as type “centroid”.

If the centroid point falls in dense vegetation without a viable field of view, or on bare rocks or other features unsuitable for camera trapping, the camera may be placed anywhere within the 30 m radius of the centroid point that maximizes its field of view. If there is a game trail or other camera feature within 5m of the centroid (or within 30 m in cases where there is no field of view within 5 m), it is appropriate to position the camera such that its field of view encompasses the feature. The second and third cameras placed at the discretion of the field team at least 50 m from the cell boundary and at least 100 m from the other two cameras along a feature such as roads, game trails, and water points that are likely to maximize detection rates of mammals. Cameras placed at the discretion of the field team are hereafter referred to as “float cameras”. Each Audio Moth is assumed to have a maximum detection radius for most bird species of 100 m. Therefore, each Audio Moth is placed at least 100 m within the cell boundary in an area with the greatest structural diversity.

5.2 Camera-trapping

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 cameras along tourist roads, emphasis should be put on using trees. If no tree is available, cameras along tourist roads can be placed on wooden poles, but not on metal poles.

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 at least 50 m from the edge of the sampling cell. This can be interpreted as meaning no more than 50 m outside the Audio Moth bounding box (see below).

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. Cameras should be set to medium sensitivity and images should be recorded at the lowest resolution possible (see table 1). Cameras should be programmed to record a single photo of each trigger event.

Table 1: Camera trap settings per the specific Camera types

Settings	SPARTAN	BROWNING
Sensitivity	Normal	Normal
Resolution	Lowest (3M)	Lowest (4MP)
Trigger event	1 Photo	1 Photo

5.2 AudioMoths

Audio Moths should generally be placed in vegetation at a height of 1.5 - 2 m. Audio Moths should NOT BE PLACED IN DEPRESSIONS OR AGAINST TO 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. Audio Moths should be programmed to run for 20 hrs per day from 00:00 – 11:00 and from 15:00 – 24:00. Audiomoths should be programmed with a sampling rate of 32 khz. In addition to the coordinates of each centroid, the field team is provided with a bounding box for each sampling location that represents the area within which an Audio Moth can be placed to ensure its coverage is within the sampling cell. This Audio Moth bounding box is 300 m X 300 m.

5.3 Field Metadata

The following site characteristics were recorded in SMART:

The sampling location ID (e.g. RBS059).
The centroid longitude and latitude to at least four decimal places. If the centroid has to be moved for any reason, this should record the updated longitude and latitude.
The treatment (control or exclosure).
The dominant vegetation type: Open grassland, Open woodland, or Closed woodland, or other in exceptional circumstances.
The dominant woody plant species.

For each detector, the following information should be recorded:

The detector ID
The detector model
The detector coordinates as placed in the field, reported to 4 decimal places (NB: the coordinates of the centroid camera should also be recorded even if the coordinates are indistinguishable from the centroid coordinates.)
All features the detector is placed along. For Audio Moths, this should include only features likely to affect bird species or the ambient noises and should not include mammal game trails but should include roads do to the sound of passing vehicles.

6. ANALYTICAL FRAMEWORK

Data will be classified using machine learning algorithms and verified manually. Analyses will consist of a suite of hierarchical modeling approaches (e.g., occupancy, N-mixture models) to account for distinct detection and occurence processes. These models will be used to estimate species richness and relative intensity of use of birds and medium-large mammals across management regimes.

9. REVISION AND VERSION HISTORY AND DESCRIPTION

v0.1.x were used during field collection.

v0.2.0 is updated to meet NS’s design document standards.