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Sobrevila C. 2008. The role of indigenouspeoples in biodiversity conservation:the natural but often forgotten partners.Washington, DC: The World Bank.

doi:10.1890/13.WB.008

Land sparing or landsharing: context dependentWe were indeed limited by space inour editorial, and now, thanks toScariot’s letter, we have an opportu-nity to clarify some issues. Wereceived several email responsesfrom colleagues who expressed dis-may at our simplistic suggestion thatthe tropics are better suited for landsparing whereas temperate regionsare better suited for land sharing. Amore accurate characterization ofour idea would be that land sparingor sharing is not an either/or choice,but is highly context dependent, andshould consider a whole suite of eco-logical, economic, sociocultural, andhistorical conditions. In our editor-ial, we alluded to a few importantconditions, including the history ofland use in the region, the currentextent of intact forest, and theregion’s need for more food. Ourtropics versus temperate regionaldichotomy could be consideredshorthand for deciding on land spar-ing versus sharing based on socioeco-logical context. And we accept thatboth may coexist in some regions.The case of Brazil as elucidated byScariot, with a mixture of land spar-ing and sharing, certainly makessense to us.

Moreover, land sparing does notnecessarily require that people be“fenced out” of forests. The greatestbiodiversity loss occurs when a sys-tem is first converted from forest toagriculture, and even if forests areleft to regrow this loss may neverfully recover, depending on thedegree and type of previous land useand the quality of the surroundingmatrix. As such, preventing initialclearing is more important than pre-venting any use of forests. Sparedland could thus be used (the 11.1%designated as “sustainable use” in

Brazil being a good example), as longas the native ecosystem is stillmainly intact, with the caveat thatinhabited forests are often at risk oflosing highly valued species to bush-meat and other practices.

Finally, although there are manysuccessful examples of land-sharingsystems, these typically involve agro-forestry systems like shade-growncoffee. What is often forgotten in sucharguments is that rice, wheat, andmaize alone supply half of the world’scalories. Can we grow these crops insufficient quantities using land-shar-ing systems? The bottom line is this:to produce more food, we need toeither clear intact habitat or intensifyproduction on existing agriculturalland (of course, whether we need toproduce more food is the subject of anentirely different editorial…).Navin Ramankutty1*

and Jeanine Rhemtulla2

1Department of Geography, McGillUniversity, Montreal, Canada*(navin.ramankutty@mcgill.ca);2Department of Geography and McGillSchool of Environment, McGillUniversity, Montreal, Canada

doi:10.1890/13.WB.009

Is accurate locationinformation necessary forrepeatability in field-basedecology?Peer-reviewed letter

Repeatability of observations andexperiments is necessary to formu-late and test theories and to explainvariation in ecological phenomena.Shapiro and Báldi (Front EcolEnviron 2012; 10[5]: 235–236) scru-tinized the repeatability of ecologicalfield studies and found that ~27% ofarticles recently published in Ecologyand Oecologia did not provide geo-graphic coordinates and 16% of theremaining articles supplied incorrectgeographic coordinates. Concludingthat such inaccuracy hindersrepeatability in ecology, the authorsthus advocated the use of opengeospatial and location standards

(www.opengeospatial.org) as part ofmetadata requirements for publishedfield studies. These standards facili-tate more accurate representation ofspatial study design as comparedwith a text-only site description or asingle geographic coordinate.

The challenge of ecological studydesign is to obtain an unbiased sam-ple of the target population sufficientfor strong inference, given theunavoidable logistical constraints(eg cost and accessibility) that fre-quently accompany field sampling.An ecological sampling design canoften be best described by the spe-cific locations of sampling points.We therefore commend Shapiro andBáldi for their proposal to improverepeatability and agree that geospa-tial standards could enhancerepeatability in some experimentaldesigns. However, we argue that (1)providing accurate location informa-tion is not critical for ensuringrepeatability in all field studies and(2) in some cases, releasing accuratelocation information can actuallyundermine experimental design.

To illustrate this point, we providea hypothetical example followingthe sampling design of Kovács-Hostyánszki et al. (2011), whichcompared insect and plant diversityin crops, set-aside fields, and semi-natural grasslands. The alternativehypothesis is that diversity in set-aside fields is higher than that incrops. Crop and set-aside samples arepaired, effectively accounting forconfounding factors. The variable ofinterest is the effect size between set-asides (treatment) and crops (con-trols). The optimal design wouldseek a sample size that has adequatestatistical power to detect a trueeffect against the null hypothesis (iediversity in set-asides and crops isequal). The selected point locationsare ideally a random, representative,and unbiased sample of the popula-tion, which consists of the crops andset-aside fields in the study area.

Now consider that we wish torepeat the experiment after 5 yearsand that our original findings hadconvinced farmers that set-aside