Pat L. Shaver USDA-NRCS-WNTSC Portland, OR

Transcription

1 Pat L. Shaver USDA-NRCS-WNTSC Portland, OR

2 Process to collect and document professional knowledge and observations on selected indicators and attributes of rangeland health.

3 How Ecological Processes are Functioning? Soil/Site Stability Water Cycle and Hydrology Nutrient Cycle Energy Flow Plant Species Functional Diversity

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5 Elements of an ecosystem used to assess processes that are too difficult or expensive to measure. Bare ground Due to the complexity of ecological processes a suite of indicators are recommended. Flow Pattern Compaction Layer

6 1. Rills 2. Water Flow Patterns 3. Pedestals/ Terrecettes 4. Bare Ground 5. Gullies 6. Wind Scour Areas 7. Litter Movement 8. Resistance to Erosion 9. Loss of Soil Surface 10. Plant/Infiltration Effects 11. Compaction Layer 12. Functional/Structural Groups 13. Plant Mortality/ Decadence 14. Litter Amount 15. Annual Production 16. Invasive Plants 17. Reproductive Capability

7 Sliding scale of five categories based on agreement with the reference sheet: -- reference = none to slight -- departure from reference = slight-to-moderate moderate moderate-to-extreme extreme-to-total

8 Soil and site Hydrologic Biotic stability function integrity

9 Rangeland Health is the collective understanding of the indicators and attributes that provide us knowledge on how well ecological processes are functioning on an area. Rangeland health provides us an early warning that lands may be in a deteriorated condition or at risk of deterioration (communication, monitoring).

10 What s the reference?

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14 What s possible?

15 What s possible depends on soils and climate (= ecological site) Ecological site: a distinctive kind of land based on recurring soil, landform, geological, and climate characteristics that differs from other kinds of land in its ability to produce distinctive kinds and amounts of vegetation and in its ability to respond similarly to management actions and natural disturbances

16 The rangeland health reference is based on what is possible (long-term ecological potential) for a particular soil and climate combination (i.e. ecological site) S&T models indicate both what is possible and realistic (based on shortterm potential and limited resource availability) (i.e. communities in an ecological state)

17 State & Transitions: eference State hrub Native Perennial Grass Threshold Invasive-dominated State Invasive Annual Grass Community A Community D Community B Community C Community Pathway Community E Relatively Irreversible Transition (Invasion & Fire) After Stringham et al JRM

18 Knowing what s possible provides: - consistent standards for inventory, assessment & monitoring - complete range of management options

19 Knowing what s realistic provides: - realistic management options - rationale for focusing limited resources on specific areas

20 STATES STATE - a recognizable, resistant and resilient complex of two ecosystem components, the soil base and the vegetation structure soil - developed through time from specific parent material, climate, landscape position and interaction with biota - determine the site s capability - interaction between soil and vegetation determines functional status of site and inherent resistance to change Stringham, et al., 2003

21 Reference state the set of plant communities where ecological processes relating to soil and site stability, hydrologic function and biotic integrity are performing at an optimum level under a natural disturbance regime IIRH uses this state (communities within the state defined by the natural disturbance regime) as the reference for the rangeland health evaluation

22 State & Transitions: eference State hrub Native Perennial Grass Threshold Invasive-dominated State Invasive Annual Grass Community A Community D Community B Community C Community Pathway Community E Relatively Irreversible Transition (Invasion & Fire) After Stringham et al JRM

23 Each Ecological Site must have Reference Sheet that describes each indicator in the Reference State Provides the range of variability (both temporal and spatial) for each indicator in the Reference State

24 Community A Community C Community B

25 Reference State Shrub Native Perennial Grass Threshold Invasive-dominated State Invasive Annual Grass Community A Community D Community C Community B Community E 1. Number and extent of rills: Minimal on slopes less than 5% and increasing slightly as slopes increase up to 15%. Rills spaced ft. apart when present on slopes of >15%. After fire, extended drought, or combinations of these disturbances, rills may double in numbers on slopes from >15% after high intensity summer thunderstorms.

26 Soil and site Hydrologic Biotic stability function integrity

27 IIRH and S&T are used together: To determine departure from the reference state None to Slight expected for the ecological site and falls within the range of variation for the indicator (no threshold crossed) SM, M, ME - indicates that a threshold is being approached or has already been crossed Extreme to Total Up to and including maximum possible departure for the indicator To identify specific issues of concern (erosion, hydrology, biotic integrity) To help identify and communicate management options

28 TRANSITIONS TRANSITION - the trajectory of a change - change is precipitated by natural events, management actions, or both - degrades the integrity of one or more of the state s primary ecological processes beyond the point of self repair THRESHOLD- boundary in space and time between two states - irreversible for practical purposes without input of outside energy Stringham, et al., 2003

29 Process function (% of capacity) Disturbance Low resistance and high resilience Time (years) High resistance Low resistance and low resilience (Modified from Seybold, et al, 1999)

30 Example: comparison of production and resilience for 3 ecological sites Gravelly Sandy Hills New Mexico, USA (Chihuahuan Desert)

31 Ecological Sites affect potential grass production 100% 75% 50% 25% Grass dynamics in 123 trend plots: ca % Hills Gravelly Sandy NRCS Data

32 Ecological Sites also affect grass resilience 100% 75% Grass dynamics Eliminated (non-resilient) % of Plots 50% 25% Grass dynamics in 123 trend plots: ca Resilient 0% Stable Hills Gravelly Sandy B. Bestelmeyer/BLM data, 123 plots ( )

33 Ecological Sites affect grass resilience 100% Grass dynamics 75% Eliminated (non-resilient) % of Plots 50% 25% Grass dynamics in 123 trend plots: ca Resilient 0% Stable Hills Gravelly Sandy NRCS + B. Bestelmeyer/BLM data, 123 plots ( )

34 1.0 Reference State Warm season tall and mid grasses Surface Soil Stability >4.3 Subsurface Soil Stability >2.7 Canopy Gaps <8% Basal Gaps <15% Basal Cover >7% Juniper Foliar Cover <8% 1.1a 1.2a Warm season mid and tall grasses and one-seed juniper < 4 tall Surface Soil Stability Subsurface Soil Stability Canopy Gaps 12-27% Basal Gaps 15-36% Basal Cover 7-9% Juniper Foliar Cover 11-24% Legend Community pathway 1.0 State Number and Name Transition Restoration 1.1 Community Phase T1a R1a R3b 2.0 Juniper State 3.0 Eroded State One-seed juniper active wind and water erosion Surface Soil Stability <2.1 Subsurface Soil Stability <1.5 Canopy Gaps >29% Basal Gaps >30% Basal Cover <4% Juniper Foliar Cover >29% R3a T2a One-seed juniper > 4 tall Warm season mid grasses Surface Soil Stability Subsurface Soil Stability Canopy Gaps 7-13% Basal Gaps 12-25% Basal Cover 5-10% Juniper Foliar Cover 18-28% 2.2a 2.1a One-seed juniper and warm season mid grasses Surface Soil Stability Subsurface Soil Stability Canopy Gaps 18-33% Basal Gaps 29-55% Basal Cover <4% Juniper Foliar Cover 16-32%

35 1.0 Warm season bunchgrass Warm season tall and mid grasses Canopy Gaps <8% Basal Cover >7% Juniper Foliar Cover <8% 1.2a 1.1a Warm season mid and tall grasses and one-seed juniper <4 tall Canopy Gaps 12-27% Basal Cover 7-9% Juniper Foliar Cover 11-24% R2a T1a 1.0 Warm season bunchgrass (reference state): Two community phases Diagnosis & Indicators: High perennial grass cover and production. Surface soil stability >3.4, one-seed juniper less than 4 tall. Feedbacks & Ecological Processes: Organic matter inputs allows for increased soil moisture, herbaceous production, root turnover and litter increasing soil surface stability, infiltration and nutrient cycling. 1.1 Warm season tall and mid grasses (reference phase): Canopy gaps <8%, basal cover >7% and juniper foliar cover <8%, surface soil stability >4.3, subsurface soil stability >2.7, bare ground <32%. 1.2 Warm season mid & tall grasses and one-seed juniper <4 tall (at-risk phase): Canopy gaps 12-27%, basal cover 7-9%, juniper foliar cover 11-24%, juniper <4 tall, surface soil stability , subsurface soil stability , bare ground 24-42%. Management: Management actions focus on activities that maintain herbaceous production and organic matter inputs. Prescribed burning or other actions to limit juniper establishment and growth are necessary. Transition-1a: Slow variables and triggers: Elimination of fire and overgrazing causing increase juniper establishment and growth. Thresholds: Surface soil stability <3.4, basal cover <7%, juniper foliar cover >24%, juniper >4 tall. Restoration Pathway-R2a: Decrease juniper canopy cover and height, increase organic matter inputs. R3a 2.0 Juniper State One-seed junipershrubs-warm season mid grasses Canopy Gaps 7-13% Basal Cover 5-10% Juniper Foliar Cover 18-28% 2.2a 2.1a One-seed juniper and warm season mid grasses Canopy Gaps 18-33% Basal Cover <4% Juniper Foliar Cover 16-32% 3.0 Eroded State T2a 2.0 Juniper State (alternative state 2): Two community phases Diagnosis & Indicators: Juniper canopy cover controls the soil moisture, herbaceous production and organic matter inputs. Juniper >4 tall, Surface Soil Stability Feedbacks & Ecological Processes : Juniper use of moisture, decreasing herbaceous production, decreasing organic matter inputs, and nutrient cycle, decreasing infiltration and surface soil stability. 2.1 One-seed juniper-shrubs-warm season mid grasses: Juniper >4 tall, with foliar cover 18-28%, understory shrubs common, canopy gaps 7-13%, basal cover 5-10%, surface soil stability , subsurface soil stability , bare ground 27-37%. 2.2 One-seed juniper warm season mid grasses (at-risk phase): Juniper >4 tall, with foliar cover 16-32%, understory shrubs missing, canopy gaps 18-33%, basal cover <4%, surface soil stability , subsurface soil stability , bare ground 33-47%. Management: Management actions focus maintaining understory shrub and herbaceous production and ground cover. Manipulation of brush species, prescribed burning and other management focused to maintain or improve herbaceous production and shrub cover. Transition-2a: Slow variables and triggers: Juniper canopy increase causing decrease in shrubs understory and herbaceous production and cover causing decrease in organic matter inputs. Thresholds: Surface soil stability <2.4, bare ground >40%, canopy gaps >30%, basal cover <4% One-seed juniper active wind and water erosion Canopy Gaps >29% Basal Cover <4% Juniper Foliar Cover >29% 3.0 Eroded State (alternative state 3) one community phase-3.1: Active wind & water erosion. Diagnosis & Indicators: Juniper foliar cover >29%, surface soil stability <2.1, subsurface soil stability <1.5, canopy gaps >29%, basal cover <4%, bare ground >39%. Feedbacks & Ecological Processes: Juniper use of all available moisture, eliminates organic matter inputs, decreases soil surface stability, increases wind and water erosion. Restoration Pathway-R3a: Restoration practices planned must decrease juniper canopy with little or no surface disturbance, increase herbaceous production and allow for litter accumulation to improve organic matter inputs to stabilize soil surface.

36 1.0 Warm season bunchgrass Warm season tall and mid grasses Canopy Gaps <8% Basal Cover >7% Juniper Foliar Cover <8% 1.2a 1.1a Warm season mid and tall grasses and one-seed juniper < 4 tall Canopy Gaps 12-27% Basal Cover 7-9% Juniper Foliar Cover 11-24% 1.1a: time since last fire or by a series of dry years followed by wet years. opportunity for juniper seedling establishment increases. decreases herbaceous production, crown cover and organic matter input into the soil, allow juniper seed germination and establishment 1.2a: fire frequency allows for ground fires that remove juniper seedlings and established plants less than 1.5 meters tall T1a: slow variables and triggers for this transition are the elimination of fire due to decrease in fine fuels allowing juniper canopy. The threshold values surface soil stability < 3.4, basal cover <7%, juniper foliar cover >24%, juniper >4 tall Juniper State R2a T1a R2a: removal of juniper canopy cover to < 5% with minimal soil surface disturbance management actions that increases herbaceous production and favors the establishment and growth of warm season tall and mid grasses One-seed juniper-shrubs warm season mid grasses Canopy Gaps 7-13% Basal Cover 5-10% Juniper Foliar Cover 18-28% 2.2a 2.1a One-seed juniper and warm season mid grasses Canopy Gaps 18-33% Basal Cover <4% Juniper Foliar Cover 16-32% 2.1a: juniper canopy increases with time since last fire...other management action to reduce juniper canopy increase in juniper canopy decreases shrub and herbaceous production and cover shrubs and tall grasses decrease or are eliminated drought years followed by wet years will allow for increase in juniper establishment a: management actions that decrease juniper canopy and increase herbaceous and shrub production can include prescribed burning, chemical or mechanical brush management, while other management actions are aimed at increasing herbaceous production R3a 3.0 Eroded State One-seed juniper active wind and water erosion T2a T2a: slow variables and trigger for this transition are increase in juniper seedling establishment and juniper cover caused by management actions that lead to decreased herbaceous production and decreased organic matter inputs by lack of management actions that actively reduce juniper canopy cover threshold values...surface soil stability <2.4, bare ground >40%, canopy gaps >30%, basal cover <4%. R3a: management and restoration planned must decrease juniper canopy to <5%...little or no surface disturbance, management actions must increase herbaceous production allow for litter accumulation improve organic matter inputs to stabilize soil surface

37 THANK YOU!