Ecological Sites on Rangeland

Ecological Siteson Rangeland

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 ConceptsIn 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

35

43B

3

42 133A

8

5

30136

54

72

58A

40

25

48A

52

73

29

47

28A

23

6534A

133B103

98

36

56

38

17

143

43A

116A

140

27

131A

112

53B

41

28B 147

77C

125

105

7

58B

153A

67B

78C

127

55B

22A

69

80A

126

2

78B

109

21

31

24

55A

86A

102A

104

7175

90A

74

70C

139

55C

85

95B

119130B

106107B

121

63A32

79

53A

12143

81B

94A

43A

77A

102C

113

150A

Non-native grass invasion,increased fire frequency,loss of native woody plants

Drought-triggeredforest 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 andgrass loss: vulnerable/restorable

Clayey soil (basin floor)Receives water and sediment: low risk

Limestone Grass protected byrocks, 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

The LRU (local climate, soils and geology) refines and supports MLRA concepts

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 severalsimilar soil map unit components

Map unit/components Ecological siteST: Stellar association 40% Stellar clay loam, 0-3% slopes = Clayey40% Stellar clay loam, 0-3% slopes, flooded = Bottomland20% other inclusions

BK: Berino-Dona Ana association50% Berino fine sandy loam, 1-5 % slopes = Sandy30% Dona Ana fine sandy loam, 1-5% slopes = Sandy20% other inclusions

OP: Onite-Pajarito association40% Onite loamy sand, 1-4% slopes = Sandy30% Pajarito fine sandy loam, 0-5% slopes = Sandy15% Pintura fine sand, 0-5% slopes = Deep sandy15% 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 triggersChronic heavy defoliation coupled to multi-year drought events

ThresholdBlack 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

PROVISIONINGfood, fibre

SUPPORTINGwater cycling, nutrient cycling, primary production

CULTURALeducational, recreation, heritage

REGULATINGclimate, waste control, pollinationHI

STO

RICA

L AN

D CU

RREN

T M

ANAG

EMEN

T

PRIO

R EC

OSY

STEM

SER

VICE

S

FUTU

RE E

COSY

STEM

SER

VICE

S

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

http://www.youtube.com/watch?v=Eh96zARD-Io