Land Use Change and Mountain Biodiversity - Chapter 11 ppt

Diversity, and Rangeland Conditions in the Southeastern Andes of Peru Palccoyo, Cusco Jorge Alberto Bustamante Becerra INTRODUCTION In the high-elevation 3900 to 4800 m grass-lands of t

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Diversity, and Rangeland Conditions in the

Southeastern Andes of Peru (Palccoyo, Cusco)

Jorge Alberto Bustamante Becerra

INTRODUCTION

In the high-elevation (3900 to 4800 m) grass-lands of the Andes, known as the puna, exten-sive grazing land areas have been utilized by rural farmers (campesinos) for over 10,000 years (Burger, 1992; Burns, 1994) Troll (1968) classified the puna into three provinces: the moist puna, the dry puna, and the desert puna

Precipitation in the puna is concentrated in a single wet season (between October and April),

is of variable length, and ranges from 150 in the desert puna to 1200 mm.a–1, in the moist puna belt (Molina and Little, 1981) Evaluation

of puna grassland characteristics requires infor-mation on both soil and vegetation These grass-lands are characterized by large variations in time and space Classification of grasslands into range sites, habitat types, or some other unit of landscape is an attempt to deal with spatial vari-ation (Pamo et al., 1991)

The puna has a distinct vegetation type that

is found predominantly in Andean Peru, but also extends into adjacent areas such as Bolivia, north

of Chile, and northwestern Argentina Weber-bauer (1936) distinguished four major vegetation formations in the moist puna: puna mat, bunch-grass formation, moor bunch-grasslands, and the vege-tation of rocks and stone fields Floristically, the moist and dry puna are closely related Evergreen shrubs are more common in the dry puna (Weber-bauer, 1936; Wilcox et al., 1987) In the desert

puna, vegetation cover is lower and is dominated

by shrubs Examples of vegetation changes because of human impact are the elimination of

Polylepis forests (Simpson, 1979) in much of the puna and proliferation of Opuntia floccosa Salm-Dyck (Molina and Little, 1981)

Regarding the use of the puna, indigenous culture developed highly productive and sus-tainable agriculture based on efficient soil and water management and the integration of crops and livestock (Tapia Nunex and Flores Ochoa, 1984) However, the growing human population has increased the demand for land and food Traditional production systems have broken down or been forgotten, and puna resources are being degraded by grazing herds of domestic llamas, alpacas, goats, and sheep, as well as by people gathering wood for fuel Introduced and invasive species, as well as uncontrolled fires, also cause environmental problems (Tapia Nunex and Flores Ochoa, 1984)

Grazing has traditionally been viewed as having a negative impact on the subsequent rate

of energy capture and primary production within grazing systems through a series of direct and indirect effects on plant growth (Heitschmidt and Stuth, 1991) Direct effects of grazing are those associated with alterations in plant physiology and morphology resulting from defoliation and trampling (Caldwell, 1984) Grazing also indirectly influences plant

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154 Land Use Change and Mountain Biodiversity

performance by altering microclimate, soil

properties, and plant competitive interactions

(Woodmansee and Adamsen, 1983)

The value of grasslands to agricultural

interests commonly depends on the quality and

quantity of forage produced This is reflected

indirectly in the capacity of the range to

duce livestock (carrying capacity) Forage

pro-duction can be expressed in terms of range

con-ditions; in general, the more the forage

produced on a given site, the better the range

conditions (Humphrey, 1962) On the other

hand, there is often a general relationship

between range conditions and stages in

second-ary plant succession Thus, in general, the better

the conditions, the more advanced the

succes-sional stage To assist in determining the range

condition class for a range site, plant species

are grouped as decreasers, increasers, or

invad-ers, based primarily on the response to grazing

intensity (Humphrey, 1962; Lacey and Taylor,

2003) Decreasers are highly productive, palat-able plants that grow under low grazing inten-sity These plants decrease in relative abun-dance under continued intensive grazing

Increasers are less productive and less palatable plants that also grow in the original climax community They tend to “increase” and take the place of the decreasers that weaken or die due to heavy grazing, drought, or other range disturbances Invaders are native or introduced plants that are rare in the climax plant commu-nity They invade a site as the decreasers and increasers are reduced by grazing or other dis-turbances A relationship between the grazing intensity, range conditions, and the relative pro-portion of decreasers, increasers, and invaders for a hypothetical grassland site is shown in Figure 11.1 Botanical composition and species diversity have been reported to change with the degree of utilization in degraded grasslands

FIGURE 11.1 Relationship between intensity of grazing, range condition, and percentage of decreasers,

increasers, and invaders (Modified from Stoddart et al, 1975.)

Excellent

80

60

40

20

100 80

Grazing intensity

60 40 20

Good

Increa sers

Invaders

Decr easers

Fair

Range condition classes

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Grazing Intensity, Plant Diversity and Rangeland Conditions in the Southeastern Andes 155

(Flórez et al., 1985) For example, high-quality

grasses that are preferred by grazing animals

tend to disappear, whereas the growth of

annu-als that have thorns and that contain tannins

tends to increase in the course of degradation

(Belsky, 1992)

Based on the information given in the

pre-ceding text, my hypothesis was that the grazing

system of Andean pastoralists in the puna (3950

to 5000 m asl) is characterized by moderate

grazing intensity and intermediate frequency of

disturbance that favor high plant diversity The

main objective of this study was to relate

grass-land species diversity to different rangegrass-land

conditions and the main environmental and

socioeconomic factors

STUDY AREA AND METHODS

S TUDY A REA

The study area of approximately 9786 ha was

the peasant community of Palccoyo, District of

Checacupe, Province of Canchis in the

Depart-ment of Cusco, Peru (14°03 S, 71°21 W)

Pal-ccoyo is located approximately 128 km from

the city of Cusco Elevation ranges from 3950

to 5000 m, and the main village is at 4100 m

Topography consists of both gentle and rugged

mountainous terrain Palccoyo is in the upper

land of the Vilcanota valley, located on the

southeastern cordillera of the Andes in the dry

puna belt, as classified by Troll (1968)

Accord-ing to Holdridge’s classification, the life zones

present in Palccoyo are:

1 Subtropical mountain–humid forest:

Elevation ranges from 3950 to 4050

m, precipitation ranges from 500 to

1000 mm per year, and the average monthly temperature ranges from 13

to 15ºC Vegetation is composed of perennial grasses, forbs, some shrubs, and tree remains of Escallo-nia resinosa and Escallonia myr-tilloides Agriculture (cultivation and pastoralism) is the main activity

2 Very humid paramo–subtropical

sub-Andean: Elevation ranges from 4050

to 4550 m, precipitation ranges from

500 to 1000 mm per year, and the average monthly temperature ranges from 6 to 12ºC Vegetation is com-posed of bunchgrass formation, and pastoralism is the main activity

3 Pluvial tundra–subtropical Andean: Elevation ranges from 4550 to 4900

m, precipitation is above 500 mm per year, and the average monthly tem-perature ranges from 1.5 to 3ºC Veg-etation is composed of bunchgrass formation; tufted grasses are also important components Pastoralism

is the main activity

4 Subtropical nival: Elevation is above

4900 m, precipitation is above 500

mm per year, and the average monthly temperature is below 1.5°C Vegetation is almost absent, with the exception of several lichens and mosses Alpaca herders do not use this zone for grazing in the Palccoyo area

L IVESTOCK H OLDING

The population of the Palccoyo peasant com-munity is 834 inhabitants (INEI, 1993), distrib-uted in 161 families, with 5.2 persons per fam-ily, of which 3.3 are children Livestock breeding is the main activity, but people also grow potatoes (more than 15 native varieties), native varieties of tubers (oca, olluco, and añu), and edible roots to feed themselves, to exchange, and to sell any surplus (Bustamante Becerra, 1993) Family-owned flocks consist of alpacas, sheep, llamas, horses, and some cattle Families of the Palccoyo community (45 in total) were classified into three socioeconomic levels (high, medium, and low), according to the number of livestock owned Livestock pos-session varied considerably within the commu-nity (Table 11.1) Families of a high or medium level have on an average four species of live-stock: alpacas, sheep, llamas, and horses; very few at the high level also own cattle Families

of a low level usually have three species: alpacas, sheep, and horses Livestock posses-sion in the Palccoyo community showed a clear differentiation between the three levels, mainly depending on the tenure of bofedales, which are

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essential for the feeding of alpacas and sheep

during the dry season

Grazing system, and the spatial and

chro-nological arrangement, were determined by

sur-veying 15 families of high, medium, and low

socioeconomic levels (45 families in total), and

subsequent in situ visual checking (Bustamante

Becerra, 1993)

S PATIAL AND C HRONOLOGICAL

A RRANGEMENT OF THE N ATURAL

The two main spatial arrangements in Palccoyo

are the grasslands of the low part (altitudinal

range from 4000 to 4250 m) and high part (from

4400 to 4800 m) of the community Both parts

are mainly natural dry grasslands and bofedales

The grasslands of these parts are better defined

in four classes (Table 11.2), as follows:

1 Natural grasslands of low parts are

located close to the small settlements and main village of the community, and are characterized by the small size of crop plots combined with a rotational pattern of crops and natu-ral grasslands Undesirable species, such as Astragalus garbancillo,

A s t r a g a l u s u n i o l o i d e s, a n d

Oenothera multicaulis, are indicators

of overgrazing and are common in several of these grasslands

2 Bofedales of low parts are located in

the middle of the low parts and also close to the small settlements and main village Good conditions and plant cover characterize these sites

3 Natural grasslands of high parts are located far from the village, on the steep slopes of the mountains, and are placed on the high parts of the community Here, shelters and cor-rals can be found, with herders (pas-toralists) also remaining during pasturing, close to their grazing ani-mals

4 Bofedales of high parts are located

at the foot of mountains of the high parts Corrals and shelters are close

to bofedales and, generally, on the gentle slopes of the mountains, whose peaks are often covered by snow

G RAZING S YSTEMS

The grazing system is continuous, with sea-sonal rotation of the grasslands of Palccoyo The local people’s knowledge of the puna envi-ronment allows for spatial and chronological arrangements throughout the year The first period of pasturing starts in December and lasts until the end of May During this season, live-stock grazing occurs in range sites of the low part, where the grasslands are in good condi-tion Plant cover is as good a parameter of rangeland conditions as plant vigor and forage species composition (Bustamante Becerra, 1993) The second period of pasturing starts in June, when livestock are transferred from the grasslands of the lower to the higher parts The livestock stays there for 6 months (until November) This is when the bofedales are of significant importance as they sustain grazing during the critical dry season

TABLE 11.1

Number of grazing animals per socioeconomic level in Palccoyo

Socioeconomic

Level

Number of

Number of Grazing Animals

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METHODS

In the study area, seven range sites were

iden-tified and measured from visual interpretation

(texture and tonality) of an aerial photograph

(scale 1:25,000) and a map (Sicuani, sheet,

scale 1:100,000) both of 1975 (Oficina de

Catastro Rural, 1976) and subsequent

field-work, to produce the range site map The range

site is defined as a large area of natural

grass-lands with similar environmental characteristics

and used as rangeland (Flórez et al., 1992;

Young, 1997; Pamo et al., 1991)

To understand the grasslands of the

Pal-ccoyo community better, three altitudinal

classes and two soil humidity classes were

iden-tified Altitudinal classes of grasslands were

upland (above 4500 ma sl), midland (4250 to

4500 m asl), and lowland (below 4250 m asl)

Soil humidity classes were humid (i.e.,

bofedales) and dry grasslands According to

these criteria (altitude, soil humidity), seven

range sites were identified, as shown in Table

11.3

The following abiotic parameters were sampled during the survey at each range site: soil texture, depth, humidity, altitude, and slope Soil texture was recorded by the “fell” method, using the soil texture triangle and soil depth fol-lowing the procedures proposed in the Soil Sur-vey Manual (Soil SurSur-vey Division Staff, 1993) Species composition was measured using the nearest-point sampling method (Owensby, 1973) Point samples were recorded along a 100-m transect at 1-m intervals (100 point/transect) Plant species names and fea-tures such as bare ground and the presence of rock, litter, and moss were recorded at each point Plant cover for each species was calculated

as the percentage of direct hits per transect Therefore, each transect will always have 100 registers (points) Seven sites in the study area were sampled, each with three transects These samplings were repeated at three different dates: November 1992, January 1993, and May 1993

To determine the range condition (or vege-tation condition) at each range site, four rating criteria were used in the site-potential approach,

TABLE 11.2

Range conditions, range site extension, and estimated carrying capacity (CC) according

to the range condition and actual stocking rate (SR) of the Palccoyo community range sites

Site

Altitude (m)

Range Condition

CC OU/ha/yr

CC

Note: Range site CC is estimated as follows = (CC × range sites), where CC is expressed as OU/ha/yr, and range sites

as ha Total CC is estimated as the grand total of the seven range site CCs OU, ovine unit

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based on Humphrey (1962) and Flórez et al

(1992): (1) Composition of desirable species,

(2) Forage species, (3) Plant vigor, and (4)

Ero-sion (Table 11.4) Range condition was

calcu-lated as 0.5 (1) + 0.2 (2) + 0.1 (3) + 0.2 (4)

1 Composition of desirable species is

the most important of the various cri-teria employed The total plant cover, within reach of livestock, was subdi-vided by forage value based on desir-able (decreasers), less desirdesir-able (increasers), and undesirable (invad-ers) species These classes were determined from specialized litera-ture on grassland species palatability for alpacas and sheep in the Andean region (Contreras, 1967; Antezana, 1972; Peña, 1970; Montufar, 1983;

La Torre, 1963; Sanches, 1966;

Farfan, 1981; Reiner and Bryant, 1986; Bryant and Farfan, 1984;

Reiner, 1985) Composition of desir-able species was determined by reg-istering the percentage of desirable species

2 Forage species is usually identified

as the percentage of ground surface covered by the current year’s growth

of desirable and less desirable spe-cies

3 Plant vigor of two key forage species

is a useful indicator of range condi-tions Vigor is determined by com-paring the heights of ten plants from

the area being rated with ten of the same species identified as vigorous and flourishing, located in ungrazed areas

4 Erosion is an indirect measure of vegetal cover and was determined by registering bare soil, rock, and pave-ment on the transect on each range site sampled

The checklist of species composition, pal-atability of grassland species, and results of the four criteria for range conditions for the study area is given in Bustamante Becerra (1993) The three assessments of range conditions correspond to the beginning of the wet season (November), the peak of the wet season (Janu-ary), and the beginning of the dry season (May) The land use factor of grasslands is defined

as the relationship between the stocking rate

(SR) and carrying capacity (CC) of the grass-land Stocking rate is the number of specific kinds and classes of animals grazing on a unit

of land for a specified period (Society for Range Management, 1989) Both SR and CC are expressed as ovine units per hectare per year (OU/ha/a) One OU is defined as a sheep of 35

kg in the Andean region (Leon Velorie and Izquierdo Cadena, 1993; Flórez et al., 1992)

CC is the maximum stocking rate possible that does not damage range conditions and main-tains or improves vegetation or related resources This may vary from year to year in the same area because of fluctuating forage

pro-TABLE 11.3

Identification of the seven range sites according to altitudinal and classes humidity

(below 4250 m)

(4250–4500 m)

(above 4500 m)

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duction In the Andean region, according to

Flórez et al (1992), range sites with excellent

conditions have a carrying capacity of 4

OU/ha/a, good conditions have 3 OU/ha/a, fair

conditions have 1.5 OU/ha/a, poor conditions

have 0.5 OU/ha/a, and very poor conditions

have 0.25 OU/ha/a

Nomenclature of plant species follows

McBride (1936) and Tovar (1960, 1965, 1972)

Species identification was confirmed at the

Her-barium of the San Antonio Abad University in

Cusco, Peru, based on collected samples

(Bus-tamante Becerra, 1993) Species-relative

abun-dance and Shannon species diversity index [H′

= sum of pi·lnpi] (Magurran, 1988; Whittaker,

1972) were determined by calculating the

fre-quency of each plant species (pi = proportion

of points along each transect at which species

i was recorded) H’ measures how many

differ-ent species are in an ecological system and how

many of each species are present Plant species

richness (S = number of species sampled per

transect) and evenness of species abundance

(Pielou’s J index = H′/ln S where ln in S=H′

max, or the maximum possible diversity when

all species are represented by the same number

of individuals) were also calculated for each

transect

Spatial distribution of plant species was

analyzed by correspondence analysis (CA)

(Hill and Gauch, 1980; Pielou, 1984) to

deter-mine clustering (assemblage) of species and

samples along ordination gradients, represented

as ordination axes Variables amounting to 21

(seven range sites assessed at three different

dates) and 62 cases (species) were analyzed

One measure of the importance of the

ordina-tion axis is the eigenvalue (λ) of CA, which is

equal to the (maximized) dispersion of species

scores in the ordination axis (ter Braak, 1995)

Values above 0.5 often denote a good separation

of the species along the axis The first five

ordi-nation axes were correlated (using Spearman

rank order correlations at p-level < 0.05) with

environmental variables (altitude, slope, soil

depth, and texture) Afterwards, a multiple

lin-ear regression analysis between axis and

envi-ronmental variables that presented significant

correlation (p-level < 0.05) was carried out to

determine how environmental variables explain

the spatial distribution of plant species along a

defined ordination axis The relationship between indicators of plant diversity (Shannon diversity, species richness, and evenness) and range condition (of seven range sites) was ana-lyzed by Spearman rank order correlations at p-level < 0.05

RESULTS AND DISCUSSION

P LANT C OMPOSITION

The most important families in the Palccoyo area were Poaceae (24.19% of the total spe-cies), Asteraceae (17.74%), Gentianaceae (9.68%), and Cyperaceae (8.06%) The remain-ing families represented 40.33% of the total (Bustamante Becerra, 1993) The number of species and the percentage of herbaceous spe-cies, graminoids, and Gramineae species are listed in Table 11.5 The bofedales range sites showed a greater number of graminoid species than semiarid range sites, whereas semiarid range sites showed a greater number of Gramineae species than bofedales range sites

P LANT C OVER

The highest value of vegetation cover corre-sponded to a range site with greater moisture

— bofedales (Occojuque, 100%, Table 11.6), and the lowest values represented a range site located in a semiarid area (Antakarana, 73%)

The study area, as a whole, had a high vegeta-tion cover (92%) during the wet season

R ANGE C ONDITION

Soil conditions and plant cover of seven range sites are shown in Table 11.7 The best range sites are the bofedale sites (Occojuque and Huayllapampa) because of their good edaphic characteristics for the development of natural grasslands (loamy soil texture, immense depth, and slight inclination) Bofedales located in the highest parts are humid throughout the year because of seepage of groundwater, precipita-tion in the wet season, and melting snow in the dry season

The sites with lower range values, such as Antakarana and Juque, lack water sources that would allow for better range conditions

Another important factor determining range

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TABLE 11.4

Classification of vegetation conditions utilized to classify Andean natural grasslands,

using four criteria

1 Composition of Desirable Species

Percentage

Score (0.5) = [(Percentage of Desirable Species)]

2 Forage Species

Percentage

Score (0.2) = [(Percentage of Forage Species)]

3 Plant Vigor

Percentage

Score (0.1) = [(Percentage of Plant Vigor)]

4 Erosion

Percentage

Score (0.2) = [(100-%]

5 Range Condition

Total score = 0.5 (1) + 0.2 (2) + 0.1 (3) + 0.2 (4)

Source: From Flórez et al (1992)

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condition of a site is the proximity to small

settlements and the main village, as animals

frequently consume the grass at these places,

contributing to the process of vegetation

degra-dation at these range sites

Range conditions at the beginning and peak

wet season were good (63 and 65 points,

respectively) but range conditions at the

begin-ning of the dry season were significantly lower

(p < 0.01) and declined to almost fair conditions

(56 points) This decrease of the range

condi-tion in the dry season is well known in the

Andean region (Molinillo and Monasterio,

1997; Bryant and Farfan, 1984; Tapia Nunez

and Flores Ochoa, 1984) Therefore, bofedales

become important in the dry season when the range condition of semiarid grasslands degrades

C ARRYING C APACITY AND A CTUAL

L AND U SE

According to Table 11.2, the livestock number for Palccoyo was 18,326 OU in total With a total grassland area dedicated to animal food production of 6,682.5 ha, the resulting stocking rate was 2.74 OU/ha/a Dry or semiarid range sites represented 94.15% of the total grasslands, whereas bofedales represented 5.82%

TABLE 11.5

Some characteristics of plant composition found in the Palccoyo community, using seven range sites

TABLE 11.6

Plant cover found in the Palccoyo community

Beginning

of Wet Season

Peak

of Wet Season

End

Note: Using seven range sites measured at the beginning of the wet season (November 1992), in the middle of the wet

season (January 1993), and at the beginning of the dry season (May 1993).

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The total carrying capacity of the Palccoyo

community, on the other hand, was only

10,932.3 OU/ha/a or 1.64 OU/ha/a The land

use factor (expressed as the relationship of

stocking rate and carrying capacity) of

Pal-ccoyo was therefore not appropriate, because

the stocking rate (2.74 OU/ha/a) is much greater

than the carrying capacity (1.64 OU/ha/a) This

relationship implies a future degradation of

grassland ecosystems by overgrazing because

of overstocking

The situation of overstocking was even

worse due to the seasonally uneven distribution

of the livestock The fact that livestock remains

on lowland grasslands of the community during

the favorable wet season while the uplands

remain without livestock resulted in

undergraz-ing of natural high-elevation grasslands This

situation (undergrazing) is reverted in the dry

season with an additional reduction of range

conditions of the grasslands by the movement

of livestock from lowland to upland grasslands

of the community, thus causing an even stronger

decrease in carrying capacity than with a

con-stant stocking rate throughout the year

R ELATIONSHIP BETWEEN S PATIAL

D ISTRIBUTION OF P LANT S PECIES AND

M ICROENVIRONMENTAL V ARIABLES

The results of spatial distribution of species by correspondence analysis (CA) showed that the first two CA ordination axes, 1 and 2, denoted good separation (λ) of the species along their axes, λ1= 0.72 and λ2= 0.58, respectively On the other hand, correlation analysis between ordination axes and environmental variables showed that the axes 1, 2, and 5 are correlated (p-level < 0.05) as follows: axis 1 showed sig-nificant correlation with soil texture (0.8882) and depth (0.5072), axis 2 with slope (0.7399) and soil depth (0.4993), and axis 5 with altitude (0.6487)

Therefore, spatial distributions of grassland species in the puna are significantly related to environmental gradients Similar results have been found by Cingolani et al (2003) in a mountain in central Argentina, where topo-graphic and edaphic parameters were related to species distributions; Adler and Morales (1999) demonstrated in a site at northwestern Argen-tina that environmental variables explained

TABLE 11.7

Soil conditions and plant cover found in the Palccoyo community at the seven study range sites

Altitude (masl)

Soil Texture

Soil Depth (cm)

Slope (cm)

Plant Cover (November)

Plant Cover (January)

Plant Cover (May)

Plant Cover (Average)

loam

Note: Plant cover was measured at three different dates: beginning of the wet season (November 1992), peak of the wet season

(January 1993), and beginning of the dry season (May 1993).

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