Download An evaluation of Israeli forestry trees and shrubs as potential forage

1
An evaluation of Israeli forestry trees and shrubs as potential forage plants for bees
2
Tamar Keasar(1) and Avi Shmida(2)
3
4
(1) Department of Science Education - Biology, University of Haifa – Oranim, Tivon
5
36006, and Dept. Life Sciences, Achva College, Mobile Post Shikmim 79800,
6
Israel.
7
8
(2) Department of Evolution, Systematics and Ecology and Center for the Study of
Rationality, Hebrew University, Jerusalem 91904, Israel.
9
10
Corresponding author: Dr. Tamar Keasar, phone: 972-52-871-8860, fax: 972-4-953-
11
9608; e-mail: [email protected]
12
Key words: forestry; honeybee; nectariferous plant; nectar production.
13
1
14
ABSTRACT
15
Loss and fragmentation of foraging habitats limit honeybee populations in Israel.
16
This problem can be alleviated by the planting of bee forage plants in forests, parks, and
17
along roadsides. To provide recommendations for such planting, we combined a
18
literature survey and qualitative evaluations of experts to compile a list of 266 local wild
19
plant species that have high food potential for bees. We also quantitatively evaluated the
20
food potential of 32 species of trees and shrubs planted by the Israeli Forestry Service.
21
We recorded the following parameters of each species: main flowering season; flower
22
morphology; type of food reward; number of flowers per plant; nectar standing crop;
23
hourly nectar production rate; type of insect visitors; and frequency of insect visits. We
24
ranked the surveyed species according to their potential importance as food plants,
25
assigning high ranks to species that (a) bloom between July and February (the period of
26
dearth in flowering natural vegetation), (b) produce large amounts of nectar, (c) are
27
highly attractive to honeybees. Of the species surveyed, Amygdalus communis,
28
Eucalyptus camaldulensis, Ceratonia siliqua, and Ziziphus spina-christi best combined
29
these benefits. A regression model indicated that nectar production rates, but not the other
30
plant parameters measured, significantly explain differences among species in insect
31
visitation rates. Our study highlights the importance of diversified forestry planting to
32
address agricultural, conservation, and recreational needs.
33
2
34
35
INTRODUCTION
Populations of honeybees and other pollinating insects have been decreasing
36
worldwide in recent years, limiting the reproduction of food crops and wild plants (Allen-
37
Wardell et al., 1998). A major reason for these population declines is loss and
38
fragmentation of natural and agricultural foraging habitats for bees, along with their flora
39
(Kremen et al., 2002; Goulson, 2003). Food limitation for honeybees may be particularly
40
severe in Israel, because colonies are kept at high densities (95,000 colonies at 6,100
41
forage points on less than 7,000 km2, Israel Honey Board, 2008).
42
The planting of forage plants for bees in non-agricultural and open areas can help
43
sustain honeybee populations, and thus improve honey production and pollination
44
services. Such planting is already in practice in field margins and small gardens in some
45
countries (Carvell et al., 2006; Comba et al., 1999; Dag et al., 1998). Recent work has
46
aimed at identifying the plant species that are most attractive to pollinators for such
47
planting (Pontin et al., 2006). Designing forest areas for apiculture has been suggested in
48
the US, especially for small privately owned plots (Hill and Webster, 1995).
49
The Israeli Forestry Service (Keren Kayemet Leisrael, KKL) is in charge of
50
public planting of trees and shrubs in forests, parks, and along roadsides in Israel.
51
Planting is designed to answer a combination of needs, such as prevention of soil erosion
52
and desertification, stabilization of sand dunes, and formation of recreation sites
53
(http://www.kkl.org.il/kkl/english/main_subject/forest_and_places/fgeneral/kkl%20affore
54
station%20work.htm). Enhancement of foraging areas for honeybees may also be
55
achieved in planted forests, and requires the use of pollinator-friendly plant species. The
56
present work aims to form recommendations for trees and shrub species that are suitable
3
57
as food plants for bees, and that also meet additional forestry needs in Israel. This aim is
58
compatible with current KKL policy to diversify the species used in forestry (Ginsberg,
59
2006).
60
Our immediate goal was to provide information about the foraging value of a
61
number of specific trees and shrubs for honeybees. We addressed this goal both
62
qualitatively and quantitatively. The qualitative approach consisted of compiling a list of
63
local plant species that are attractive to insects, based on a literature survey, personal
64
information, and consultations with experts. For the quantitative evaluation, we sampled
65
32 species, in use or under testing by the Israeli Forestry Service, for food value and
66
insect visit rates. We selected only trees and bushes for the quantitative evaluation, while
67
the qualitative list additionally covers herbaceous species. We considered both local and
68
introduced species in the quantitative evaluation, while the qualitative list includes local
69
species only.
70
More generally, we sought to identify which plant/flower traits most affect
71
pollinator attraction in an interspecific comparison. These traits should be measured in
72
the evaluation of further potential plant species. For this purpose we recorded several
73
floral and plant parameters, which were previously shown to influence pollinator
74
attraction to plants within species: The number of flowers per plant (Brody and Mitchell,
75
1997; Goulson et al., 1998), nectar standing crops (Hodges, 1995; Pappers et al., 1999),
76
nectar production rates (Delph and Lively, 1992; Mitchell, 1993), and parameters of
77
floral morphology (Conner and Rush, 1996; Galen and Stanton, 1989). We tested the
78
contribution of these parameters to the variability in visit rates among the plant species of
79
our survey.
4
80
81
METHODS
82
Qualitative evaluation
83
A list of local bee forage plants was compiled based on data by Dag et al. (1993, 1998),
84
Fahn (1948), Gindel (1951), Lupo & Eisikowitch (1987), Reves (2004), and Zohary
85
(1947). It was updated based on consultations with researchers from the Israeli
86
Agricultural Research Organization (Arnon Dag, Haim Efrat, Sima Kagan, Yossi
87
Slabezki), Tel Aviv University (Dan Eisikowitch) and Haifa University (Ofrit Shavit).
88
We also consulted with the following beekeepers: Tomer Erez (Klil), Shalom Israeli
89
(Ayelet Hashachar), Yehuda Kendel (Kfar Pines), Pini Nahmani (Yokneam), Shmuel Nir
90
(Eilon), Noga Reuven (Manot), Hagai Schitzer (Gamla), Ya'akov Stam (Kfar Kish), Uri
91
Surkin (Ein Harod Meuchad), Dan Weil (Yad Mordechai Pollination Services) and Eitan
92
Zion (Yad Mordechai Apiary). The updating process allowed us to reduce an initial list of
93
562 potential honeybee forage plants to 266 species. Data on the plants’ distribution and
94
abundance in Israel and on their phenology were obtained from our Ecological Data-Base
95
of the Israeli Flora (Shmida and Ritman, 1985).
96
97
Quantitative evaluation
98
Selection of plant species
99
The surveyed plant species are a subset of the assemblage of trees and shrubs that
100
are grown in KKL’s nurseries for wide-scale planting in forests, open areas, roadsides
101
and parks, or for experimental planting and evaluation. We surveyed species that were
102
considered attractive for bees, based on qualitative preliminary observations by our team
5
103
and by the staff of KKL, the Shaham agricultural extension service, and the Volcani
104
Center Dept. of Horticulture. We biased the survey toward plants that bloom in summer,
105
autumn, and winter (July – February), since this is the period of dearth in floral food
106
resources in Israel. The food potential of several Eucalyptus species for bees was
107
assessed by a different research team (Eisikowitch and Dag, 2003). We therefore
108
restricted our survey of Eucalyptus sp. to four common species that were sampled in
109
autumn. On each day of the survey, 2-3 individuals of one species were observed. Most
110
species were studied for two days (totaling 4-6 individuals), but some of the species were
111
observed more intensively (see Table 2). Most observations were carried out in KKL
112
nurseries, forests, and parks in Israel’s coastal plain and Negev desert. Repeated
113
observations were conducted at different locations and flowering seasons to reduce local
114
effects. The survey species, numbers, and months of observation are detailed in Table 2.
115
116
Plant and flower morphology
117
We counted the total number of flowers of surveyed individuals whenever
118
possible, and estimated the number of flowers by counting a sector of the plant in
119
individuals that were too large for complete counting. We recorded the following
120
parameters of floral morphology in ten flowers from each of three individuals per
121
species: total length of the flower (from the base of the tube to the tip of the corolla);
122
length of the tube; and maximal diameter of the corolla.
123
124
Nectar measurements
6
125
When sampling three individuals of a species, we determined nectar standing
126
crops for ten flowers per plant on each sampling day. When sampling two individuals, we
127
measured nectar standing crops from 16 flowers per plant. Thus, nectar measurements are
128
based on 30-32 flowers per sampling day. We used 1-µl or 5-µl micropipettes to measure
129
nectar volumes, and Bellingham-Stanley hand-held refractometers to measure sugar (w/w
130
%) concentrations. Sugar concentrations could be measured only for nectar standing
131
crops that exceeded 1/3 µl. We bagged ten sampled, depleted flowers (3-5 per plant) with
132
bridal-veil netting (Wyatt et al., 1992), and harvested them again after 24 h. The nectar
133
that accumulated in the sampled flowers represents the plant’s 24 h nectar production.
134
We divided the produced nectar volume by the covering time to obtain hourly per-flower
135
nectar production rates. We calculated mean per-plant nectar production rates for each
136
species by multiplying the mean per-flower production rate by the mean number of
137
flowers per plant. The logarithm of this rate was defined as the species’ nectar score.
138
139
140
Insect visits
We observed each plant for insect visits for 10 minutes on each observation day.
141
The observation unit was a patch of flowers on the plant that allowed convenient
142
recording of visits. A visit was defined as a touch of the corolla, the stigma, or the stamen
143
by an insect. We did not record numbers of arrivals to the patch, which generally
144
correlate with the number of visits (Bar-Shai, 1995). Observations were conducted during
145
peak pollinator activity (typically between 10-12 am). We classified the pollinators into
146
the following functional groups: honeybees, large bees (larger than honeybees), small
147
bees (smaller than honeybees), flies, butterflies, and beetles. We noted nectar-extraction
7
148
behavior and loading of pollen sacs. Accordingly, we classified the visitors’ food reward
149
as pollen, nectar, or both. We recorded the number of flowers observed per individual
150
(usually 100), and calculated the 60-minute visit rate per flower.
151
Insect visit rates may vary widely between dates and locations because of
152
differences in weather conditions, proximity to honeybee colonies, or composition of the
153
surrounding plant community. To partially correct for these confounds, we used
154
Rosmarinus officinalis as a reference species. Immediately after recording insect visits to
155
a survey species, we counted visits to nearby R. officinalis shrubs using the same
156
protocol. R. officinalis was selected as a reference because it is abundant, has a long
157
flowering season (August – April) and is frequently visited by honeybees. R. officinalis
158
did not grow in all the survey sites, and some of the survey species were observed outside
159
its flowering season. The reference observations could thus only be obtained for some of
160
the survey plants (see Table 5).
161
162
163
Regression model
We tested which floral and plant parameters best predicted insect visitation rate
164
on a between-species basis, and thus should be measured in future evaluations of
165
additional plant species. We defined the mean per-species visit rates as the dependent
166
variable in a regression model. Mean per-species nectar standing crops, nectar production
167
rates per flower, number of flowers, nectar score, flower length, tube length, and corolla
168
diameter were treated as independent variables.
169
170
RESULTS
8
171
172
Qualitative survey
Table 1 lists 266 species from the native floral that were proposed as bee forage
173
plants in the qualitative survey, out of an initial list of 562 potential plants. The table also
174
reports these species’ main food reward, and scores for their distribution and abundance
175
in Israel. The seasonal distribution of blooming peaks of the potential forage species is
176
shown in Fig. 1. The seasonal frequency of species at peak bloom is also plotted for the
177
whole flora of Israel, for the sake of comparison. The plots show that the period between
178
July and February is characterized by a low number of flowering local species in general,
179
and bee forage plants in particular. This period comprises a dry season between July and
180
November, and a rainy, cold one between December and February. These seasons of
181
floral dearth are therefore difficult for honeybee survival, and forage plants that flower
182
during the dearth period should be particularly useful. We therefore biased our
183
quantitative survey towards the subset of forage plants in Table 1 that bloom outside
184
spring. With this consideration in mind, we also included non-native species in the
185
quantitative evaluation. We relied on the information of Table 1 to focus on species that
186
are widespread in Israel, and attractive to insects. These considerations further aided in
187
the selection of species for the quantitative survey.
188
189
190
Quantitative evaluation
The species that were included in the quantitative survey are listed in Table 2.
191
Species that were studied during the period of floral dearth are shaded in the Table.
192
Table 3 lists the plants’ growth form, cultivation status, height (measured for only part of
193
the species), number of flowers per plant, and the parameters of floral morphology.
9
194
Column 2 of Table 4 provides a classification of the survey species according to their
195
main food reward to pollinators (nectar (N), pollen (P), or both (N+P)). This
196
classification is based on qualitative observations of pollinator behavior, and does not
197
express the amount of nectar and pollen produced per plant. A quantitative assessment of
198
a plant’s food potential should take into account its average size (i.e., number of flowers,
199
Table 3) and the quantity of food reward produced per flower (Table 4). In the present
200
study, we quantified per-flower nectar production, but not per-flower pollen yields. The
201
product of the mean number of flowers per plant and the mean per-flower nectar
202
production rate provides an estimate of per-plant nectar production rates (Table 4,
203
column 6). We observed large variations in per-plant production rates both within and
204
among species. To facilitate among-species comparisons, we defined a plant’s “nectar
205
score” as the base-10 logarithm of its mean per-plant production rate (Table 4, column 7).
206
Nectar scores for our survey species ranged between 1.5 and 4.5, i.e., across three orders
207
of magnitude of per-plant nectar production rates. The species with the highest nectar
208
scores (above 4.0) appear shaded in Table 4. These species have large numbers of flowers
209
per plant, high nectar production rates per flower, or both. Table 5 lists the main
210
pollinator groups for each of the studied species, mean visit rates, and, when available,
211
insect visitation rates relative to visits to R. officinalis.
212
Mean per-flower nectar production rates significantly explained the variation in
213
insect visit rates among the survey species (P=0.001). The remaining parameters included
214
in the regression model (nectar standing crop, number of flowers, nectar score, flower
215
length, tube length, and corolla diameter) had no significant effects. The complete
216
regression model was statistically significant (R2= 0.52, P=0.027).
10
217
218
219
DISCUSSION
Our qualitative and quantitative surveys focused mainly on several criteria for the
220
selection of bee forage plants in forestry: blooming season, type of food reward, amount
221
of food reward, and insect attraction. None of the 32 species that were studied
222
quantitatively ranked highest according to all criteria (Tables 2, 4, 5). Nevertheless, the
223
trees Amygdalus communis, Ziziphus spina-christi, and Eucalyptus camaldulensis shared
224
the following desirable traits: blooming during the period of floral dearth, production of
225
both nectar and pollen, high nectar scores, and high rates of visits by honeybees
226
(compared with R. officinalis). These species therefore seem the most promising for
227
pollinator-friendly forestry. Ceratonia siliqua should also be considered, due to its
228
favorable flowering season, low water requirements, and large number of flowers. Plants
229
that bloom in spring (e.g., Styrax officinalis, Cercis siliquastrum) should receive lower
230
priority in planting as bee forage plants.
231
Two of the surveyed shrubs, Myrtus communis and Leucophyllum frutescens,
232
produce pollen as their only (M. communis) or main (L. frutescens) food reward, and
233
therefore received low nectar scores. We recommend their planting as pollen sources, in
234
combination with other plants that can serve as sources for nectar. We further recommend
235
the subshrub Rosmarinus officinale var. Blue Lagoon, which is native to the western
236
Mediterranean but is well adapted to the local ecosystem. This chamaephyte blooms
237
during the summer, produces both nectar and pollen, and is frequently visited by
238
honeybees.
11
239
Our regression analysis indicates that nectar production rates significantly explain
240
differences among species in insect attraction. We therefore suggest that nectar
241
production rates be determined for additional potential forage plant species in the future.
242
Other plant traits account for the variability in pollinator attraction among individuals
243
within a species. These include plant size (Robertson and McNair, 1995; Goulson et al.,
244
1998), variability in nectar standing crops (Keasar et al., 2008), and flower size (Conner
245
and Rush, 1996). However, these traits did not significantly contribute to the variability
246
in insect visits among species in our study.
247
Our measurements include several confounding effects. The most important ones
248
are climactic differences between seasons and sampling sites, which may have affected
249
both the plants’ nectar production patterns and the insects’ foraging activity (Wyatt et al.,
250
1992). In addition, the composition of the plant community surrounding the survey plants
251
varied among sampling days, and likely affected the pollinators’ attraction to the focal
252
plants (e.g., Moeller, 2004). These confounds cannot be eliminated completely, but can
253
be reduced by increasing sample sizes in future evaluations.
254
The Society for the Protection of Nature in Israel (SPNI), co-founded by Azaria
255
Alon, has been involved in campaigns to increase the use of local tree species in public
256
forestry. KKL’s forestry policy has changed significantly in recent years, from focusing
257
on planting of conifer stands to diversified forestry that emphasizes local tree species
258
(Ginsberg, 2006,
259
http://www.kkl.org.il/kkl/english/main_subject/forest_and_places/fprofession/kkl-
260
tree%20data%20(website).mht). Diversification of forest composition in Israel promotes
261
diversity of forest arthropods (Levanoni, 2005) and birds (Shochat and Tsurim, 2004).
12
262
Additional potential advantages of diversified planting may include reduced impacts of
263
plant diseases and pests, and a wider range of possibilities for recreation. We conclude
264
that multiple organisms in forest ecosystems, including bees, are likely to benefit from
265
diversified planting of trees and shrubs.
266
13
267
ACKNOWLEDGMENTS
268
Adi Sadeh assisted with field work. Yossi Slabezki commented on the manuscript. The
269
study was funded by KKL. Data analysis and writing were supported by the research
270
group on Evolution and Game Theory at the Institute of Advanced Studies, The Hebrew
271
University.
272
273
274
REFERENCES
275
Allen-Wardell, G., Bernhardt, P., Bitner, R., Burquez, A., Buchmann, S., Cane, J., Cox,
276
A.P., Dalton, V., Feinsinger, P., Ingram, M., Inouye, D., Jones, C.E., Kennedy, K.,
277
Kevan, P., Koopowitz, H., Medellin, R., Medellin-Morales, S., Nabhan, G.P., Pavlik, B.,
278
Tepedino, V., Torchio, P., Walker, S. 1998. The potential consequences of pollinator
279
declines on the conservation of biodiversity and stability of food crop yields. Cons. Biol.
280
12: 8-17.
281
Bar-Shai, N. 1995. Fruit set in relation to tree size and pollination in the Almond. M.Sc.
282
Thesis, Dep. of Evolution, Systematics, and Ecology, The Hebrew University of
283
Jerusalem (in Hebrew with English summary).
284
Brody, A.K., Mitchell, R.J. 1997. Effects of experimental manipulation of inflorescence
285
size on pollination and pre-dispersal seed predation in the hummingbird-pollinated plant
286
Ipomopsis aggregata. Oecologia 110: 86-93.
287
Carvell, C., Westrich, P., Meek, W.R., Pywell, R.F., Nowakowski, M. 2006. Assessing
288
the value of annual and perennial forage mixtures for bumblebees by direct observation
289
and pollen analysis. Apidologie 37: 326-340.
14
290
Comba, L., Corbet, S.A., Hunt, L., Warren, B. 1999. Flowers, nectar and insect visits:
291
evaluating British plant species for pollinator-friendly gardens. Ann. Bot. 83: 369-383.
292
Conner, J.K., Rush, S. 1996. Effects of flower size and number on pollinator visitation to
293
wild radish, Raphanus raphanistrum. Oecologia 105: 609-516.
294
Dag, A., Regev, A., Bar Yossef, Y. 1998. The economic values of planted bee forage
295
plants. Ecology & Environment 4: 234-235 (in Hebrew).
296
Dag, A., Rotem, T., Sela, N. 1993. Finding pollen sources for bee colonies. Hassade 63:
297
1286-1289 (in Hebrew).
298
Delph, L.F., Lively, C.M. 1992. Pollinator visitation, floral display, and nectar production
299
of the sexual morphs of a gynodioecious shrub. Oikos 63: 161-170.
300
Eisikowitch, D. Dag, A. 2003. Examination of trees as nectariferous plants. Report to the
301
Israeli Tree Improvement Fund, JNF-KKL, Forest Department.
302
Fahn, A. 1948. The nectaries of honey plants in the land of Israel: their structure, and the
303
effects of ecological factors on nectar secretion. Published by the Hebrew Apiculturists’
304
Society, Rehovot (in Hebrew).
305
Galen, C. Stanton, M.L. 2006. Bumble bee pollination and floral morphology: factors
306
influencing pollen dispersal in the Alpine Sky Pilot, Polemonium viscosum
307
(Polemoniaceae). Amer. J. Bot. 76: 419-426.
308
Gindel, Y. 1951. The Eucalyptus in Israel. 1. A study of its acclimation during 1935-
309
1951. Publication no. 42 of the Agricultural Research Station, Rehovot, Israel (in
310
Hebrew).
311
Ginsberg, P. 2006. Restoring biodiversity to pine afforestations in Israel. J. Nature Cons.
312
14: 207-216.
15
313
Goulson, D. 2003. Conserving wild bees for crop pollination. Food, Agriculture &
314
Environment 1: 142-144.
315
Goulson, D., Stout, J.C., Hawson, S.A., Allen, J.A. 1998. Floral display size in comfey,
316
Symphytum officinale L (Boraginaceae): relationships with visitation by three bumblebee
317
species and subsequent seed set. Oecologia 113: 502-508.
318
Hill, D.B., Webster, T.C. 1995. Apiculture and forestry (bees and trees). Agroforestry
319
Systems 29: 313-320.
320
Israel Honey Board, 2005 apiculture statistics. Available:
321
http://www.honey.org.il/info/gidul/gidul-dvorim.htm
322
Hodges, S.A. 1995. The influence of nectar production on Hawkmoth behavior, self-
323
pollination, and seed production in Mirabilis multiflora (Nyctaginaceae). Amer. J. Bot.
324
82: 197-204.
325
Lupo, A., Eisikowitch, D. 1987. Eucalyptus erythrocorys: a honey and pollen plant.
326
Hassade 77: 2363-2367 (in Hebrew).
327
Keasar, T., Sadeh, A., Shmida, A. 2008. Variability in nectar production and standing
328
crop, and their relation to pollinator visits in a Mediterranean shrub. Arthropod-Plant
329
Interactions 2: 117-123.
330
Kremen, C., Williams, N.M., Thorp, R.W. 2002. Crop pollination from native bees at
331
risk from agricultural intensification. PNAS 99: 16812-16816.
332
Levanony, T. 2005. Species diversity in pine plantations and natural maquis in the Judean
333
Foothills. M.Sc. Thesis, Tel Aviv University (in Hebrew with English summary).
334
Mitchell, R.J. 1993. Adaptive significance of Ipomopsis aggregata nectar production:
335
observation and experiment in the field. Evolution 47: 25-35.
16
336
Moeller, D.B. 2004. Facilitative interactions among plants via shared pollinators.
337
Ecology 85: 3289-3301.
338
Pappers, S.M., de Jong, T.J., Klinkhamer, P.G.L., Meelis, E. 1999. Effects of nectar
339
content on the number of bumblebee approaches and the length of visitation sequences in
340
Echium vulgare (Boraginaceae). Oikos 87: 580-586.
341
Pontin, D.R., Wade, M.R., Kehrli, P., Wratten S.D. 2006. Attractiveness of single and
342
multiple species flower patches to beneficial insects in agroecosystems. Ann. Appl. Biol.
343
148: 39-47.
344
Reves, Y. 2004. A guide to Eucalyptus species growing in Israel. Novell Publishers (in
345
Hebrew).
346
Shmida, A., Ritman, S. 1985. The Israel Plant Data-Base: A unified approach to
347
ecology, phytosociology, floristics, teaching, and conservation. In: The Role of Data in
348
Scientific Progress, P.S. Glaeser (ed.), Elsevier Pub., pp. 91-95.
349
Shochat, E., Tsurim, I. 2004. Winter bird communities in the northern Negev: species
350
dispersal patterns, habitat use and implications for habitat conservation. Biodiv. Cons. 13:
351
1571-1590.
352
Wyatt, R., Broyles, S.B., Derda, G.S. 1992. Environmental influences on nectar
353
production in milkweeds (Ascelapias syriaca and A. exaltata). Amer. J. Bot. 79: 636-642.
354
Zohary, M. 1947. The honey plants of the land of Israel. Publication of the Agricultural
355
Research Station, Rehovot, Israel (in Hebrew).
356
17
357
TABLES
358
Table 1: A list of potential local bee forage plants, based on published literature and
359
qualitative evaluations by experts. Pollination system: Z – zoophilous, W – wind;
360
Attractivity score: + mildly attractive to bees, ++ - moderately attractive, +++ - highly
361
attractive; Food reward: P: pollen, N: nectar, B: both pollen and nectar, NP: more nectar
362
than pollen, PN: more pollen than nectar, L: very little nectar and pollen; Area score:
363
estimate area occupied by the plants, scaled from 1 (least abundant) to 5 (most abundant);
364
Peak blooming month: the main blooming period of the species; Total blooming months:
365
range of blooming period throughout the plant’s area of distribution; Climactic region: D:
366
Desert (70-250 mm rain annually), H: Hermon subalpine, M: Mediterranean, O:
367
orographic (montane) belt, on Mt. Hermon above 1300 m, T: transition between
368
Mediterranean and desert, X: Extreme desert (1-70 mm rain annually); Cultivated / Feral
369
(in addition to occurrence as a wild plant): C: cultivated, F: feral, O: left over after
370
cultivation but not feral.
371
Table 2: A List of surveyed species, and the months in which they were surveyed, during
372
2000-2002. Numbers denote survey days within a month. 2-3 individuals per species
373
were studied on each day of the survey. Species that were surveyed between October and
374
February, the period of floral dearth, are shaded.
375
376
Table 3: Data on plant and flower morphology of the survey species. Growth form: C:
377
chamaephyte (up to 0.5 m), S: shrub (0.5-2 m), T2: tree of 2-4 m height, T4: tree of 4-8
378
m height, T8: tree above 8 m, V: vine; Cultivated / Feral: C: cultivated, F: feral, O: left
18
379
over after cultivation but not feral, W: wild; NR: flower length is not relevant when the
380
flower tube is rather wide and does not restrict insect foraging.
381
Table 4: Reward parameters of survey species. Main food reward collected by visitors: N:
382
nectar, P: pollen, N+P: nectar and pollen; NSC: nectar standing crop; NP: nectar
383
production; NP / plant: mean NP per flower × mean number of flowers; Nectar score: log
384
(NP/plant).
385
386
Table 5: Insect visits to survey species. Main visitors: HB: honeybee, LB: large bees, SB:
387
small bees, F: flies;
388
389
FIGURE LEGENDS
390
Fig. 1: The number of species at peak bloom throughout the year. Dashed: local potential
391
bee forage plants, listed in Table 1; Solid: all species of the Israeli flora.
19