Rare Plants of the Sacramento Mountains

Thesis/ Reports Le�-Chadde Rare Plants of the Sacramento Mountains ScottLee-Chadde LauraFoster Huenneke Department of Biology New Mexico State University Las Cruces, NM 88003 Produced as acontribution to the EcosystemsNeeds Assessment for the Sacramento Mountains for the RockyMountain Forest and Range Experiment Station USDA Forest Service RarePlants of the Sacramento Mountains Scott Lee-Chadde LauraFoster Huenneke Departmentof Biology New MexicoState University Las Cruces, NM 88003 Produced as acontribution to the EcosystemsNeeds Assessmentfor the SacramentoMountains for the RockyMountain Forest andRange Experiment Station USDA Forest Service The SacramentoMountains of south-centralNew Mexico constitutes a regionof diverse natural communitiesand complex challenges for environmentalmanagement, because of the number of rare species, noxious weeds, and intense conflicts over natural resource conservationand sustainability. In1994-95, inassociation with the USDA ForestService, we undertookto develop the meansof assessingecosystem status in the Sacramentos. Rare species - their status, wlnerabilityto threats, andman agement needs - canbe used to indicatecertain aspects of ecosystemstatus. Thus w� analyzedthe presence andstatus of rareand en dangeredplants of the SacramentoMountains to assess the degree of biological endangerment to individual plant species, andto assist in determining conservationpriorities and management. In particular, we were interestedin the question of whether "rare" speciesare rare because of intrinsicecological andevolutionary reasons (e.g.,restricted to a rarehabitat type) or because recent historyhas caused actualdeclines inhabitat area, environmentalquality, or population size. The Sacramento Mountainsof south-centralNew Mexicorepresent anarea of highendemism, and.thus we suspectedthat many of its "rare" plants arespecies that have alwaysbeen rare, rather thanthose facing some biological endangermentdue to recent changes of environment or management. The initialstage in this analysiswas to construct adatabase of information on rareplant species of the Sacramentos- this document. Methods TheSacramento Mountains are located in southeasternNew Mexico (long/latitude)and are considered the southernmost extension of the RockyMountain chain. Withinthe Sacramento Mountainsfour distinct ranges arerecognized: the WhiteMountains near Ruidoso, the ncarilla Mountains nearCarrizozo, the CapitanMountains nearCapitan, andthe Sacramento Mountains nearCloudcroft. These fourranges make up three distinctsky islands. Thencarillas and Capitansform isolated mountain regions to thenorth of the largest and highestsky island of the Sacramento andWhite Mountains. For purposesof this study, the lower elevationalboundary of our study areais definedas the Pinyan-Juniper community (Brown's Great Basin Conifer Woodland)within each skyisland. Withinthe studyarea, SO species of vascularplants, mainlyherbs, were identified as rare, threatened,.or endangered. The species list was generated fromfive sources: (1)Invent�ry of rare andendangered plants of NewMexico (Sivinskiand Lightfoot 1994), i.e. the New Mexico "EndangeredSpecies List"; (2)A handbookof the rare and endemic plantsof New Mexico (NM NativePlant Protection AdvisoryCommittee 1984); (3)Endangered andthreatened wildlife and plants(USFWS 1994) SO CFR17.11 & 17.12, i.e. the federal"E ndangeredSpecies List";(4) an unofficiallist of sensitive plantsof the. LincolnNational Forest; and(S) a listof the rareplants located inthe SacramentoMountains generate.d by the NewMexico's NaturalHeritage Program database. Allspecies ever recommended forprotection at either the stateor federal level were included regardless of their currentlegal status.. A-ii For each species infonnationon its current legal status, distribution, habitatrequirements, population biologyand ecology was collected. Infonnationsources were gleanedfor categorical informationthat, if known, would assist in the management and conservationof the species (see references). Availableinfonnation sources included primaryliterature, governmentdocuments (USFWS'sStatus Reports & RecoveryPlans; Forest Service Surveysand Management Plans, NM Endangered Species List, etc.), available florasofNew Mexico(Wooton and Standley 1915; Martinand Hutchins 1980), andherbarium labelsfrom plantcollections deposited atNew Mexico State University Herbarium (NMC). To standardizethe process andimprove the efficiencyof the search, categories of infonnation (database fields)were selected priorto theactual collection of information. Once the categoricalinfonnation was collected andentered into a database, the database was distributed to botanistsand ecologists familiar withthe SacramentoMountains for review. Additionalinformation and commentsprovided by reviewers wasthen incorporated into the database. Two methods are used to detenninethe threat to each species: a linearranking systemand a multivariate approach. Linearranking involved a three step process. First,species arescored according to a number of criteria. Scores within categoriesrepresent the species threatand/or wlnerability based on that character. For example;using population size as acategory, a species with only 10 individualsis more at risk than a species witha 10,000 individuals. Using a discrete scale from 1 (least wlnerable)to S (most wlnerable),the specieswith only 10 individualswould be assigneda score of 5, while the specieswith 10,000 individuals would be assigneda score of 1. Second, scores are averagedor summed to produce a singlescore. Finally,species areranked according to their single score. While linearranking systemsare relatively straightforwardto use, theydo have a numberof problems. First, the use of a single score to rankspecies conceals the factors thatendanger a species. Species with a similar rankingcould be threatened forentirely differentreasons. Second, criteria used in ranking speciesare likely to be correlatedand not of equal weigh� soscores may �e artifactsof the criteriaused. Additionally, differentcriteria may provide differentrankings. Third, manyspecies tend to rank together,making it difficultto separatethem. However,despite these problems, linearranking systems do provide valuable informationas they forceusers to gather infonnation,identify infonnation gaps, and articulateassumptions about whatthreatens a species, andthey can be updated as more infonnationbecomes available. Moreover, the data usedto generatethe linear ranking also generates a species' threatprofile that can be used in a multivariateanalysis. The linearranking systemprovides a sampleof n species, each of which has a score onp variables(criteria). Thesedata can then be used to groupspecies with similarwlnerability profiles togetherand may allow patternsundetectable by the linear ranking systemto emerge. Additionally, a similar set of speciesmay have similarmanagement problems and a multivariate analysismay help in identifyingmanagement strategies that be can applied to a suite of species, rather than managementbased on a species by speciesapproach. In the database; we note preliminaryassignments of speciesto groups, basedon similarityof scores for the 9 criteria. A-iii In our analysis, 42 species were scored for each of9 criteria. Eight species were excluded from the analysis. Seven were excluded because informationis lacking on the presence of thesespecies in the Sacramento Mountains. Of the seven species, 3 aremembers of the cactus family (Mammi/ariawrightii var. wrightii, Opuntia c/avata, andPediocactus papyracanthus) which are foundin the lower elevation grasslandssurrounding the skyislands, andtwo areorchids (Cypripediumpubescens and Hexa/ectris nitida), both ofwhich areon the outer edge of their rangein New Mexico. Cypripediumpubescens has been collected once in 1966 in the Sacramentos nearCloudcroft. Hexalectrisnitida has been collected to the south of the Sacramentos in the Guadalupe Mountains. Most likely, these species areincluded in lists because of their high cultural valueand the difficulty to say withcertainty a species doesn't occurin an area. Lupinus sierrae-blancae ssp. aquilinuswas excluded becausecurrent taxonomic work (Flora ofNorth Americanpro ject) considers it to be synonymous withLupinussierrae-h/ancae. Criteriawere selected that would (1) provide informationon the threat facing a species andbe answerablewith available informationand (2 ) address the issue of scaleand perspective in assessingthreat. For instance, the geographicrange ofa species canbe looked at froma localor global perspective. Two range criteria-globalrange and range withinthe Sacramento Mountains--areused in assessing a species wlnerability so that a distinction canbe madebetween species that areglobally rare, but locallyabundant and species that areglobally abundant, but locallyrare. Similarly, two criteriaare used to describea species habitat, population biology, and its threat. The two habitat criteriadistinguish between a measureof the availability of habitatand a species use of that habitat. The two population biology criteriadistinguish between number of populations andsize of populations to allow distinction between speciesthat have only one large population, andspecies that have severalsmall populations. Finally, the two threatcriteria look at the threatfrom the species perspective, i.e. is the species sensitive to logging or grazing, andin a general sense, i.e., is the habitat itselfdeclining or threatened asis the caseof old-growth Ponderosapine forestin the Sacramentos. To keep the scoringprocess

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