Results

11.3.1 Bird Feeding Guild Abundance, Species Richness, and Diversity in Forest Classes

A total of 13,721 individuals of 128 species were included in the analysis; 11 species were excluded because they were raptors and fully aerials, or omnivores. For all feeding guilds, the observed, rarefied, and estimated species richness did not differ significantly among forest classes (Table 11.2). For bark insectivores (BI), observed species richness was significantly higher in > 15-year-old forests on flat areas than in >15-year-old forests on hills; estimated species richness was higher in >15-year – old forests on flat areas compared to 3- to 8-year-old forests (Table 11.2).

Table 11.1 Description of biophysical variables grouped into three sets of variables: vegetation structure, landscape structure, and spatial structure of sampling sites

Set of variables

Description

Code

Vegetation set

Stand age

Age after abandonment following slash-and-burn shifting cultivation

AGE

Total species richness

Total number of woody plant species per plot, including adults and saplings

SPPT

Species richness for adults

Number of woody plant species >5 cm dbh [diameter at breast (1.3 m) height] per plot

SPPa

Species richness for saplings

Number of woody plant species 1-5 cm dbh [diameter at breast (1.3 m) height] per plot

SPPs

Abundance of adult individuals

Number of individuals of adults per plot

ABUNa

Abundance of sapling individuals

Number of individuals of saplings per plot

ABUNs

Total basal area

Basal area (m2/ha) of all woody plants per plot, including adults and saplings

ABT

Total basal area for adults

Basal area(m2/ha) of all woody plants for adults per plot

ABa

Total basal area for saplings

Basal area (m2/ha) of all woody plants for saplings per plot

ABs

Mean height of adults

Mean canopy height (m) for adults per plot

Ha

Mean height of saplings

Mean canopy height (m) for saplings per plot

Hs

Total density

Total number of individuals per hectare

TD

Density for adults

Number of adults per hectare

Da

Density for saplings

Number of of saplings per hectare

Ds

Simpson diversity index

Computed for all woody plants, including adults and saplings

SIMP

Shannon diversity index Landscape structure set

Computed for all woody plants, including adults and saplings

SHAN

Proportional abundance of each patch type

High values indicate dominance of certain successional patch type

PLAND

Patch density

High values indicate higher number of small patches per area unit

PD

Edge density at the class level

High values indicate higher edge density per successional class

ED

Overall shape complexity Patch isolation

High values indicate more irregular patch shape

SHAPE

ENN

Edge contrast Spatial structure set

High values indicate higher landscape fragmentation

TECI

PCNM vectors

Represents a spectral decomposition of the spatial relationships among the sampling plots and provides a better representation of the spatial structure present in the sampling data than simple geographic coordinates

PCNM

Table 11.2 Changes in bird feeding guild species richness (observed and estimated) and diversity for all feeding guilds and for bark insectivores only: rarefaction for all guilds, 1,169 individuals; rarefaction for bark insectivores, 64 individuals. Different letters (a-b) indicate significant differences according to Tukey’s post hoc test (P < 0.05)

Jointly feeding guilds Only bark insectivores

Successional

class

Total number of samples

Total

number

of

individuals

Observed number of species

95 % Cl (Mao Tau)

Number

of

species

(rarefied)

95 % СІ

(Мао

Tau)

Estimated number of species

95 % Cl (Chao 1)

Total number of individuals

Observed number of species

95 % Cl (Mao Tau)

Number

of

species

(rarefied)

95 %

Cl (Mao Tau)

Estimated number of species

95 % Cl (Chao 1)

3-8 year

46

1,461

93a

82.96-

103.04

95.08a

91-97

94.23-

90.07-

111.02

39

6“b

2.76-9.24

7.63a

6-8

6.38a

6.12-9.73

9-15 year

77

2,531

90“

80.36-99.64

92.52а

88-97

99.22-

96.11-

113.94

84

9ab

6.26-11.74

8.90a

7-11

9 42“b

9.12-12.96

>15 year on flat

87

2,934

98“

89.54-

106.46

91.93“

86-97

99.03-

96.84-

111.05

162

10b

8.13-11.87

8.73a

7-11

10.95b

10.72-

13.74

>15 year on hills

64

2,138

91“

81.05-

100.95

92.93а

89-96

96.31-

93.38-

110.58

119

T

3.87-10.13

6.39 a

5-8

8.45a

8.38-9.49

Results

Conditional

 

Conditional

Results

 

Spatial set

 

Landscape set

 

Vegetation set

 

a No. individuals/1.1 ha

 

b No. Species/plot

 

Results

Fig. 11.2 Amount of variance explained by each set of variables (marginal effect), and the conditional effect explained by all sets of variables for (a) number of individuals and (b) number of species. Unexplained variance is not depicted