Ecological Sites on Rangeland

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Ecological Site definition:  Ecological site = kind of land with: specific physical characteristics (soil, topography, climate) which differs from other kinds of land in its ability to produce distinctive kinds and amounts of vegetation  In other words, a kind of land with similar natural potential.  Other stratification systems can be an have been used to described rangelands.

Ecological sites vary in kind and amount of vegetation (Example 1)

(Example 2)

(Example 3)

(Example 4)

Ecological Sites – Based on Soil  Soil affects the type of plants that grow on the land.  Therefore, soil maps usually form the basis for maps of ecological sites.  Ecological Site Descriptions – can be found by starting with soil maps in the Web Soil Survey

Ecological Site Descriptions  Ecological Site Descriptions (ESD) are reports that describe the: Biophysical properties of ecological sites  Physical, Climatic, Soil and Vegetation Vegetation and surface soil properties of reference conditions  a) Pre-European vegetation and historical range of variation (in the United States) b) Proper functioning condition or potential natural vegetation Ecosystem services provided by the ecological site and other interpretations

Important Concepts In Dividing the Landscape Spatial scale – what is a site? Temporal scale- how does change occur?

Geographic areas with similar soils Similar landscape patterns Groups of Ecological Sites that share landscapes Intermingled ecological sites or single site Individual representative of the site An observation of plant-soil relationships Regions with similar climate, land use

LAND RESOURCE REGIONS

Non-native grass invasion, increased fire frequency, loss of native woody plants Drought-triggered forest dieback Non-native grass invasion, altered surface hydrology, reduced productivity Perennial grass loss, soil erosion, native woody plant dominance Nonnative woody plant invasion Native woody plant thickening, reduced fire frequency MLRAs distinguish broad differences in potential and types of ecological dynamics Major Land Resource Areas USDA NRCS

Loamy soil (active piedmont) Susceptible to water erosion and grass loss: vulnerable/restorable Clayey soil (basin floor) Receives water and sediment: low risk Limestone Grass protected by rocks, higher rainfall, good water capture: low risk Soil mapping units of the Jornada Basin (15 km) Gravelly soil (shallow, relict piedmont) Surface soil water limited, high risk for grass loss and erosion: vulnerable/restorable Sandy soil (relict basin floor) Erodible surface soils once grasses removed: vulnerable/hard to restore From Bestelmeyer et al 2010

Within LRUs are clusters of sites with similar parent material, but differing in landscape position Each site has a typical soil profile

An ecological site groups several similar soil map unit components Map unit/components Ecological site ST: Stellar association 40% Stellar clay loam, 0-3% slopes = Clayey 40% Stellar clay loam, 0-3% slopes, flooded = Bottomland 20% other inclusions BK: Berino-Dona Ana association 50% Berino fine sandy loam, 1-5 % slopes = Sandy 30% Dona Ana fine sandy loam, 1-5% slopes = Sandy 20% other inclusions OP: Onite-Pajarito association 40% Onite loamy sand, 1-4% slopes = Sandy 30% Pajarito fine sandy loam, 0-5% slopes = Sandy 15% Pintura fine sand, 0-5% slopes = Deep sandy 15% other inclusions A soil map unit can contain more than one ecological site because map units may contain components

The utility of Ecological Sites is based on the ability to systematically stratify the landscape according to varying ecological potential Applications of Ecological Sites and Ecological Site Descriptions

Assess the risk of persistent degradation (undesirable change) and take proactive measures to avoid it Uses of Ecological Sites and Ecological Site Descriptions Transition (T) Slow variables and triggers Chronic heavy defoliation coupled to multi-year drought events Threshold Black grama grass cover loss to < 3% and inability to recover continuity via vegetative growth

Uses of Ecological Sites and Ecological Site Descriptions Specify constraints to desired ecosystem change, estimate their probability of occurrence and devise contingencies

Design and interpret monitoring based on expected responses to management or climatic changes. Uses of Ecological Sites and Ecological Site Descriptions

Ecological Site Information Applications at Larger (LRU, MLRA and LRR) Scales  Narratives for states and communities contain indicator values and management  strategies to promote resilience. Knowledge of the amounts and spatial distribution  of these requirements can inform policies and programs

ECOLOGICAL STATE ECOLOGICAL SITE CLIMATE SOIL PROPERTIES LANDSCAPE POSITION GEOMORPHOLOGY ECOSYSTEM SERVICES PROVISIONING food, fibre SUPPORTING water cycling, nutrient cycling, primary production CULTURAL educational, recreation, heritage REGULATING climate, waste control, pollination HISTORICAL AND CURRENT MANAGEMENT PRIOR ECOSYSTEM SERVICESFUTURE ECOSYSTEM SERVICES From Brown and MacLeod 2011 Land Use and Land Management Changes Can Alter Ecosystem Services Regardless of Land Use

Land cover/use classifications are increasingly useless in making policy decisions people change land use frequently ecological processes are much more complex and variable than a land use category resistance and resilience are vital to predicting ecosystem behavior landscape scale models require ecological process information to allow sites to interact

Some terminology:  Map Units  Lime  Alluvium  Loess

Web Soil Survey  ARD-Io ARD-Io