Diversify ground vegetation and canopy structure in the habitat around woody crops

Overall effectiveness category Awaiting assessment
Number of studies: 2
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Background information and definitions

Agricultural intensification methods of large area woody crops (e.g. olives, almonds, coffee) has led to an increase in bare ground (through increased tilling or herbicide) and lack of overstorey surrounding the crop trees. This loss of soil, herbaceous covering and canopy layers has been implicated in losses of wildlife diversity in agricultural systems.

For example, coffee is a small tree or shrub that naturally grows in the forest understory and may be grown commercially under trees that provide shade. In the 1970s, sun-tolerant coffee plants were developed in response to fungal diseases and many plantations removed all canopy trees. These high-yield cultivation practices are considered unsustainable and many coffee plantations, are switching to shade-grown varieties.

Diversifying the habitats where woody crops are grown with respect to both ground and canopy vegetation may increase available habitat for reptile communities within these agricultural systems.

Study locations

Key messages

Two studies evaluated the effects of diversifying ground vegetation and canopy structure in the habitat around woody crops on reptile populations. One study was in Puerto Rico and the other was in Spain.

COMMUNITY RESPONSE (1 STUDY)

Richness/diversity (1 study): One replicated, paired, site comparison study in Spain found that olive groves with natural ground cover had higher reptile species richness and diversity than those with bare ground, but groves planted with a single species as ground cover had similar richness and diversity as those with bare ground.

POPULATION RESPONSE (2 STUDIES)

Abundance (2 studies): One replicated, site comparison study in Puerto Rico found that two of three lizard species were less abundant in shade-grown coffee plantations than in sun-grown plantations. One replicated, paired, site comparison study in Spain found that olive groves with ground cover had more reptiles than groves with bare ground.

BEHAVIOUR (0 STUDIES)

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

A replicated, site comparison study in 2000 in six coffee plantations in north-central Puerto Rico (Borkhataria et al. 2012) found that two of three lizard species were less abundant in shade-grown than sun-grown coffee plantations. Puerto Rican crested anole Anolis cristatellus and barred anole Anolis stratulus were less abundant in shade-grown (crested: 1,642 individuals/m²; barred: 294) than sun-grown coffee plantations (2,034; 631). Upland grass anoles Anolis krugi abundance was similar in shade-grown and sun-grown coffee plantations (shade: 411 individuals/m²; sun: 384). Four further species were observed, but in too low numbers to assess population differences between plantation types. Yellow-chinned anole Anolis. gundlachi and emerald anole Anolis evermanni were mostly observed in shade-grown (yellow: 525 individuals observed; emerald: 241) rather than sun-grown coffee plantations (2; 6), whereas common grass anole Anolis puchellus tended to be less frequently observed in shade-grown compared to sun-grown coffee plantations (shade: 2 individuals observed; sun: 28). Puerto Rican giant anole A. cuvieri observations were the same in shade-grown and sun-grown coffee plantations (5 individuals observed in both). Lizard abundance was estimated using mark-resightings in 4–6 circular 400m² plots in three sun-grown (closely-spaced 2–3 m high sun tolerant coffee trees with dense foliage) and three shade-grown coffee plantations (irregularly-spaced 2–4 m high coffee (or banana or citrus) trees under a canopy of medium and tall shade trees) in March–May 2000. Each plot was sampled for four consecutive days in spring. Lizards were marked at a distance using tree-marking spray paint guns and latex house paint.
Study and other actions tested
Referenced paper
Borkhataria R.R., Collazo J.A. & Groom M.J. (2012) Species abundance and potential biological control services in shade vs. sun coffee in Puerto Rico. Agriculture, Ecosystems & Environment, 151.
A replicated, paired, site comparison study in 2014–2015 in seven olive groves in Andalusia, Spain (Carpio et al. 2017) found that olive groves with natural ground crop cover had greater reptile species richness, diversity and higher reptile counts than groves with bare ground, whereas planted crop ground cover had more reptile observations, but not richness or diversity than bare ground. Reptile observations were higher in olive groves with ground cover (natural cover: 10 individuals/site; planted cover: 8) than groves with bare ground (5). Species richness was highest in olive groves with natural ground cover (2 species/site) compared to planted ground cover (1) or bare ground (1). Species diversity was higher in natural cover crop (Shannon Index: 2) than bare ground (1), but similar to planted cover crops (1). Species diversity in planted cover crops was similar to bare ground. Reptiles were monitored in paired sites in seven olive groves: one site with ground cover (either natural herbaceous cover: 3 sites or planted single-species ground crops: 4 sites), and the other with bare ground (7 sites). Study plots were located within an olive-dominated landscape with almost no natural vegetation, either irrigated or unirrigated, and 10–100 years old. In May and July 2014–2015 reptiles were surveyed using two 1–2 km line transect censuses/site repeated on three warm sunny days. Each transect was surveyed for 30 minutes (336 total transects; 168/year).
Study and other actions tested
Referenced paper
Carpio A.J., Castro J., Mingo V. & Tortosa F.S. (2017) Herbaceous cover enhances the squamate reptile community in woody crops. Journal for Nature Conservation, 37, 31-38.

Please cite as:

Sainsbury K.A., Morgan W.H., Watson M., Rotem G., Bouskila A., Smith R.K. & Sutherland W.J. (2021) Reptile Conservation: Global Evidence for the Effects of Interventions for reptiles. Conservation Evidence Series Synopsis. University of Cambridge, Cambridge, UK.

Where has this evidence come from?

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This Action forms part of the Action Synopsis:

Reptile Conservation

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