Spatial Resource Partitioning Research Articles

Habitat use by triplefin species (Tripterygiidae) on rocky reefs in New Zealand

Habitat use and nesting sites of 12 triplefin species (Tripterygiidae) were investigated at 26 coastal and offshore rocky reef locations in north‐eastern New Zealand. Within these locations, 17 broad‐scale habitats and 14 fine‐scale habitats were surveyed using visual transects. In terms of broad‐scale habitat use, four species, Notoclinops segmentatus, Forsterygion lapillum, Forsterygion varium and Ruanoho whero showed a high similarity in distribution, irrespective of depth or habitat characteristics. The distributions of Bellapiscis lesleyae, Cryptichthys jojettae and Ruanoho decemdigitatus were relatively similar, being primarily confined to shallow habitats providing a high degree of shelter. Forsterygion flavonigrum, Forsterygion malcolmi and Notoclinops caerulepunctus were all predominantly found beyond 10 m, irrespective of habitat characteristics. Despite the majority of species using several distinct fine‐scale habitats, a high degree of variation was apparent between species, with the majority of species showing extremely low overlap of fine‐scale habitats used. Differences in fine‐scale habitat use were not apparent when comparing the nesting sites of species. All nests were found in fine‐scale habitats, presumably affording a high degree of shelter from predation and physical disturbance. Interspecific partitioning of spatial resources probably occurs by depth and microhabitat in this species assemblage in north‐eastern New Zealand.

The relative importance of spatial aggregation and resource partitioning on the coexistence of mycophagous insects

The relative importance of spatial aggregation and resource partitioning on coexistence was investigated for mycophagous insects in central Japan. The effects of spatial aggregation and resource partitioning were separated by a randomization procedure. From 124 patches of macrosporophores belonging to 37 species, 3275 individuals belonging to 14 families of Diptera and 11 individuals to Lepidoptera emerged. Since the level of identification varied among insect taxa, the analysis was made in three ways; 1) for all taxa to assess the stability of the whole community, 2) for drosophilid species to assess their persistence in the community, and 3) for species of Drosophila and Mycodrosophila to assess their persistence against congeneric and heterogeneric species. Both spatial aggregation and resource partitioning functioned for the stability of whole mycophagous insect community, and spatial aggregation played a more important role than resource partitioning. On the other hand, only spatial aggregation functioned for the persistence of drosophilid species in the community. According to the analysis on species of Drosophila and Mycodrosophila against congeneric and heterogeneric species, the relative importance of resource partitioning was smaller for the coexistence of within‐genus species pairs than for that of between‐genus species pairs. These results suggest that the relative importance of these two mechanisms depends on the phylogenetic and guild diversity of community.

HABITAT PREFERENCE OF TWO BURYING BEETLES (COLEOPTERA: SILPHIDAE: NICROPHORUS) LIVING AMONG SEABIRDS

Abstract We investigated habitat preference of two Silphidae species (Nicrophorus investigator Zetterstedt and N. defodiens Mannerheim) occurring on a seabird island located off the southeastern shore of Newfoundland, Canada. Pitfall traps were placed in the nesting burrows of two seabird species: Atlantic Puffin (Fratercula arctica) located in grassland habitat and Leach's Storm-Petrel (Oceanodroma leucorhoa) occurring in both forest and open meadow habitat. Nicrophorus investigator was primarily found in petrel burrows located in open meadow habitat, whereas N. defodiens occurred exclusively in petrel burrows located in forested habitat. Only a few specimens of N. investigator were collected from puffin burrows. These results show a spatial partitioning of resources between the two beetle species and suggest petrel burrows provide more abundant food sources than puffin burrows for burying beetles breeding on the island.

ESS Analysis of Mechanistic Models for Territoriality: the Value of Scent Marks in Spatial Resource Partitioning

In this paper elements of game theory are used to analyse a spatially explicit home range model for interacting wolf packs. The model consists of a system of nonlinear partial differential equations whose parameters reflect the movement behavior of individuals within each pack and whose solutions describe the patterns of space-use by each pack. By modifying the behavioral parameters, packs adjust their patterns of movement so as to maximize their reproductive output. This involves a tradeoff between maximizing prey intake and minimizing conflict with neighbors. Evolutionarily stable choices of the behavioral parameters yields territories that are immune to invasion by groups with alternate behaviors.

Temporal and spatial partitioning of water resources among eight woody species in a Hawaiian dry forest.

Lowland dry forests are unique in Hawaii for their high diversity of tree species compared with wet forests. We characterized spatial and temporal partitioning of soil water resources among seven indigenous and one invasive dry forest species to determine whether the degree of partitioning was consistent with the relatively high species richness in these forests. Patterns of water utilization were inferred from stable hydrogen isotope ratios (δD) of soil and xylem water, zones of soil water depletion, plant water status, leaf phenology, and spatial patterns of species distribution. Soil water δD values ranged from -20‰ near the surface to -48‰ at 130 cm depth. Metrosideros polymorpha, an evergreen species, and Reynoldsia sandwicensis, a drought-deciduous species, had xylem sap δD values of about -52‰, and appeared to obtain their water largely from deeper soil layers. The remaining six species had xylem δD values ranging from -33 to -42‰, and apparently obtained water from shallower soil layers. Xylem water δD values were negatively correlated with minimum annual leaf water potential and positively correlated with leaf solute content, an integrated measure of leaf water deficit. Seasonal patterns of leaf production ranged from dry season deciduous at one extreme to evergreen with near constant leaf expansion rates at the other. Species tapping water more actively from deeper soil layers tended to exhibit larger seasonality of leaf production than species relying on shallower soil water sources. Individuals of Myoporum sandwicense were more spatially isolated than would be expected by chance. Even though this species apparently extracted water primarily from shallow soil layers, as indicated by its xylem δD values, its nearly constant growth rates across all seasons may have been the result of a larger volume of soil water available per individual. The two dominant species, Diospyros sandwicensis and Nestegis sandwicensis, exhibited low leaf water potentials during the dry season and apparently drew water mostly from the upper portion of the soil profile, which may have allowed them to exploit light precipitation events more effectively than the more deeply rooted species. Character displacement in spatial and temporal patterns of soil water uptake was consistent with the relatively high diversity of woody species in Hawaiian dry forests.

Spatial and dietary overlap in the Georges Bank groundfish community

Patterns in spatial and trophic resource partitioning in the fish community of the Georges Bank region are identified, accounting for size-based changes in diets. During autumn and spring, this community is divided into geographic assemblages of species that have high spatial overlap. Similarity in spatial distribution is primarily related to similarity in depth preferences, and seasonal differences in species composition within assemblages are related to migrations. There is also important trophic structure within the Georges Bank community separating predators based upon prey size and location in the water column. Ontogenetic changes in diets are an important feature of the trophic structure in this system, particularly in the major piscivores. Seasonal changes in trophic structure reflect both predator and prey migrations. Dietary overlap among predator types is independent of either spatial overlap or depth preferences. There is spatial segregation within trophic guilds, and this spatial partitioning reduces the potential for exploitative competition within this community. Given the observed spatial patterns in trophic structure, the geographic assemblages on Georges Bank may be considered ecologically distinct functional units within this ecosystem.

Species diversity in a mycophagous insect community: the case of spatial aggregation vs. resource partitioning

Summary 1. Previous work has suggested that species diversity in resource‐limited insect communities on patchy resources is maintained by spatial aggregation, not by resource partitioning. The most comprehensive test of this claim to date was by Shorrocks & Sevenster (1995), but some of their datasets included only a few resource types, which reduces the likelihood of finding a strong effect of resource partitioning. Also, methods of analysis have since been refined, e.g. to account for patch size. 2. We collected 733 mushroom samples belonging to 66 taxa in a Dutch woodland area. From these mushrooms, 38,891 insects were reared, belonging to 60 taxa of Diptera and Hymenoptera. Drosophilid species and their parasitoids were identified to the species level; other taxa to the family level. We argue that the community is resource limited. 3. Generally, the insects have fairly narrow diets, including only a few of the available mushroom species. The degree of niche overlap varies widely in this community. 4. Within single resource types, co‐existence can be explained by intra‐specific aggregation over patches alone, in accordance with previous studies. 5. This conclusion remains unchanged for the mycophagous community as a whole: intra‐specific aggregation of competitors is a sufficient and necessary mechanism for co‐existence in this diverse community, while resource partitioning does not contribute detectably to species diversity. This is the first time that this pattern has been demonstrated in a dataset involving such a large number of resource types. 6. Our conclusions are strongly supported by data manipulations in which we removed or intensified the effect of resource partitioning and spatial aggregation. 7. We argue that this community may be close to saturation, but we emphasize that saturation is a gradual phenomenon in patchy systems. 8. Since differential use of resource types does not reduce competitive interactions among the insects, it seems unlikely that inter‐specific competition constitutes the selective pressure favouring specialization.

Partage des ressources spatiales et tropiques au sein d’un peuplement de lézards insectivores des Jbilets centrales (Maroc occidental)

Spatial and trophic resource partitioning among seven sympatric insectivorous lizard species was investigated in arid area in the central Jbilet mountains (Western Morocco) during spring 1995. Two foraging guilds are apparent : a specialist sit-and-wait (Agama impalearis, Tarentola mauritanica et Saurodaclylus brosseti) and a generalist one (Eumeces algeriensis, Chalcides polylepis, Acanthodaclylus erythrurus and Mesalina simoni). The studied lizard species differentiate from each other in substrate use relatively to their respective adaptive morphological traits. A impalearis and T. mauritanica occur mainly in rocky areas, K algeriensis and M. simoni appear mostly on rocky and pebbly-bare ground substrates, A. erythrurus and C. polylepis are found on sandy-pebbly substrates while S. brosseti occurs in pebbly soils. By contrast, there were large overlaps in the taxonomic composition of their diets which are numerically dominated by Formicidae, Isoptera, Coleoptera and Araneidae with different proportions according to lizard species. However, important prey-size differences between species allowed to reduce trophic overlap. A selectivity analysis of lizard diet revealed patterns of prey selection based on criteria inherent either to predator (foraging behaviour, morphological constraints) or prey (size, abundance and activity). Results suggest that spatial and trophic segregation along with taxonomic divergence make possible the coexistence of these lizard species.

Partitioning of soil water among canopy trees in a seasonally dry tropical forest.

Little is known about partitioning of soil water resources in species-rich, seasonally dry tropical forests. We assessed spatial and temporal patterns of soil water utilization in several canopy tree species on Barro Colorado Island, Panama, during the 1997 dry season. Stable hydrogen isotope composition (δD) of xylem and soil water, soil volumetric water content (θv), and sap flow were measured concurrently. Evaporative fractionation near the soil surface caused soil water δD to decrease from about -15‰ at 0.1 m to -50 to -55‰ at 1.2 m depth. Groundwater sampled at the sources of nearby springs during this period yielded an average δD value of -60‰. θv increased sharply and nearly linearly with depth to 0.7 m, then increased more slowly between 0.7 and 1.05 m. Based on xylem δD values, water uptake in some individual plants appeared to be restricted largely to the upper 20 cm of the soil profile where θv dropped below 20% during the dry season. In contrast, other individuals appeared to have access to water at depths greater than 1 m where θv remained above 45% throughout the dry season. The depths of water sources for trees with intermediate xylem δD values were less certain because variation in soil water δD between 20 and 70 cm was relatively small. Xylem water δD was also strongly dependent on tree size (diameter at breast height), with smaller trees appearing to preferentially tap deeper sources of soil water than larger trees. This relationship appeared to be species independent. Trees able to exploit progressively deeper sources of soil water during the dry season, as indicated by increasingly negative xylem δD values, were also able to maintain constant or even increase rates of water use. Seasonal courses of water use and soil water partitioning were associated with leaf phenology. Species with the smallest seasonal variability in leaf fall were also able to tap increasingly deep sources of soil water as the dry season progressed. Comparison of xylem, soil, and groundwater δD values thus pointed to spatial and temporal partitioning of water resources among several tropical forest canopy tree species during the dry season.

Differential water resource use by herbaceous and woody plant life-forms in a shortgrass steppe community.

We conducted a study to test the predictions of Walter's two-layer model in the shortgrass steppe of northeastern Colorado. The model suggests that grasses and woody plants use water resources from different layers of the soil profile. Four plant removal treatments were applied in the spring of 1996 within a plant community codominated by Atriplex canescens (a C4 shrub) and Bouteloua gracilis (a C4 grass). During the subsequent growing season, soil water content was monitored to a depth of 180 cm. In addition, stem and leaf tissue of Atriplex, Bouteloua and the streamside tree Populus sargentii were collected monthly during the growing seasons of 1995 and 1996 for analysis of the δ18O value of plant stem water (for comparison with potential water sources) and the δ13C value of leaves (as an indicator of plant water status). Selective removal of shrubs did not significantly increase water storage at any depth in the measured soil profile. Selective removal of the herbaceous understory (mainly grasses) increased water storage in the top 60 cm of the soil. Some of this water gradually percolated to lower layers, where it was utilized by the shrubs. Based on stem water δ18O values, grasses were exclusively using spring and summer rain extracted from the uppermost soil layers. In contrast, trees were exclusively using groundwater, and the consistent δ13C values of tree leaves over the course of the summer indicated no seasonal changes in gas exchange and therefore minimal water stress in this life-form. Based on anecdotal rooting-depth information and initial measurements of stem water δ18O, shrubs may have also had access to groundwater. However, their overall δ18O values indicated that they mainly used water from spring and summer precipitation events, extracted from subsurface soil layers. These findings indicate that the diversity of life-forms found in this shortgrass steppe community may be a function of the spatial partitioning of soil water resources, and their differential use by grasses, shrubs, and trees. Consequently, our findings support the two-layer model in a broad sense, but indicate a relatively flexible strategy of water acquisition by shrubs.

Trophic structure of three streams with contrasting riparian vegetation and geomorphology

The relative influence of riparian vegetation and geomorphology on trophic structure was examined at three streams in adjacent catchments of the French Massif Central mountains. The study sites differed mainly by the degree of anthropogenic alteration of riparian and watershed vegetation, and by valley geomorphology. Fishes, benthic macroinvertebrates (grouped into functional feeding groups: FFG), macrophytes and periphyton were sampled seasonally between July 1991 and April 1992. At the riffle-pool (10 0 m) scale, instream morphological units appear to control the spatial partitioning of trophic resources and their consumers. For example, depositional zones supported a specialized trophic structure based on coarse organic matter consumption, whereas in erosional zones (subdivided into lotic and lentic units) periphyton and fine organic matter were the main food source. At the reach-segment scale (10 1 to 10 2 m), valley morphology was the primary factor controlling the stream ecosystem, but anthropogenic alteration of riparian vegetation seems to override geomorphological controls on the trophic structure. For example, the open-canopied Triouzoune Creek (gentle plateau valley), characterized by scrapers (>60% by density) and a greater epilithic algal biomass, had a autotrophic-based structure. At this site, 20 % of total fish biomass was represented by brown trout (Salmo trutta) dominated by fish 50% by density) and fish communities dominated by brown trout with high densities of age 1+ individuals. Overall, the results emphasize the importance of riparian vegetation on the trophic structure of streams, especially when anthropogenic alteration of riparian vegetation is severe. We conclude that there is a need to better integrate riparian vegetation is severe. We conclude that there is a need to better integrate riparian vegetation into European stream management practices in order to maintain the vitality of these systems over the long-term.

THE ROLE OF COMPLEMENTARITY AND COMPETITION IN ECOSYSTEM RESPONSES TO VARIATION IN PLANT DIVERSITY

To investigate how plant diversity affects ecosystem-level processes such as primary production and nutrient cycling, I established an experimental plant diversity gradient in serpentine grassland using four functional groups of plants: early season annual forbs (E), late season annual forbs (L), perennial bunchgrasses (P), and nitrogen fixers (N). These groups differ in growth form, phenology, and other traits relevant to nutrient cycling (e.g., rooting depth, litter C:N ratio). Two or three species of each type were planted in single-group treatments, and in two-, three-, and four-way combinations, giving a range of richness from zero to nine species. I tested the hypothesis that, because of complementary resource use, increasing functional group diversity will lead to higher net primary production. At the scale of this experiment (α-diversity and yearly production), more diverse treatments were not necessarily the most productive. Live plant biomass varied more within than among levels of diversity. In most two-, three-, and four-way mixtures of functional groups, overall productivity did not differ significantly from the average of the yields of component one-group treatments. This pattern apparently resulted from competition: early season annuals and late season annuals reduced the biomass of perennial bunchgrasses (the most productive group in monoculture) below levels expected from monoculture yields. Relative Yield Totals (RYT) indicated complementary resource use in the EL and LP two-way and ELPN four-way mixtures. In the EL mixture, complementarity appeared to result from temporal rather than spatial partitioning of resources. Because of shifts in root:shoot ratio in mixtures, however, only the LP treatment had consistently significant RYT >1 when assessing total (roots plus shoots) productivity and nitrogen yield. These results show that (1) composition (the identity of the species present) can be at least as important as richness (the number of species present) in effects on ecosystem processes; (2) competition during critical parts of the growing season may prevent absolute increases in net primary production with increasing diversity, despite complementary resource use at other times of the year; and (3) shifts in belowground allocation in species mixtures can have significant effects on estimates of productivity and resource use as species diversity changes.

Spatial and trophic partitioning in cryptic fish communities of shallow subtidal reefs in False Bay, South Africa

Thirty-nine species of cryptic fishes belonging to 16 families were captured on shallow reefs (0-20 m) in False Bay, South Africa using the ichthyocide rotenone. Five samples were collected in each of four depth zones (0-5, 6-10, 11-15 and 16-20 m). The area from which fish were collected in each sample was measured to give an estimate of density. The overall density of cryptic fishes in the area was 3.41 fish m-2, with the families Congrogadidae and Clinidae being numerically dominant, representing 27.9% and 22.3% of the total sample respectively. The Clinidae were by far the most diverse group, being represented by 17 species, while no other family was represented by more than three species. Multivariate analysis of numerical density revealed that partitioning of spatial resources did occur, with the shallowest samples (0-5 m) forming a group discrete from the deeper samples (6-20 m). Further analysis indicated that the amount of algal cover present was the most important factor influencing community structure, although the abundance of algae is in turn related to depth. The shallowest samples were dominated by members of the families Clinidae, Gobiesocidae and Bythitidae, while the Cheilodactylidae, Tripterygiidae and Ariidae were more important components of deeper water communities (6–20 m). Analysis of percentage volume of prey items in the diets of 21 species revealed that only two species shared diets that were more than 50% similar, and that partitioning of trophic resources was considerable.

Spatial and temporal soil moisture resource partitioning by trees and grasses in a temperate savanna, Arizona, USA.

Stable isotope analysis was used to determine sources of water used by coexisting trees and grasses in a temperate savanna dominated by Quercus emoryi Torr. We predicted that (1) tree seedlings and bunchgrasses utilize shallow sources of soil water, (2) mature savanna trees use deeper sources of water, and (3) trees switch from shallow to deep water sources within 1 year of germination. We found that Q. emoryi trees, saplings, and seedlings (about 2 months, 1 year, and 2 years old), and the dominant bunchgrass [Trachypogon montufari (H.B.K.) Nees.] utilized seasonally available moisture from different depths within the soil profile depending on size/age relationships. Sapling and mature Q. emoryi acquired water from >50 cm deep, 2-month-old seedlings utilized water from <15 cm, and 1- and 2-year-old seedlings and grasses used water from between 20 cm and 35 cm. This suggests that very young seedlings are decoupled from grasses in this system, which may facilitate germination and early establishment of Q. emoryi within extant stands of native grasses. The potential for subsequent interaction between Q. emoryi and native grasses was evidenced by similar patterns of soil water use by 1- and 2-year-old seedlings and grasses. Q. emoryi seedlings did not switch from shallow to deep sources of soil water within 2 years of germination: water use by these seedlings apparently becomes independent of water use by grasses after 2 years of age. Finally, older trees (saplings, mature trees) use water from deeper soil layers than grasses, which may facilitate the stable coexistence of mature trees and grasses. Potential shifts in the seasonality of precipitation may alter interactions between woody plants and grasses within temperate savannas characterized by bimodal precipitation regimes: reductions in summer precipitation or soil moisture may be particularly detrimental to warm-season grasses and seedlings of Q. emoryi.

Species Diversity and Small-Scale Disturbance in an Old-Growth Temperate Forest: A Consideration of Gap Partitioning Concepts

The importance of spatial partitioning of gap resources in the maintenance of tree species diversity was studied in an Appalachian old-growth forest. We established three 1-ha plots, subdivided into contiguous 10 x 10 m subplots, in a mesic cove forest with a disturbance regime characterized by small canopy gaps ( 1.37 m tall and ≤ 10 cm DBH) based on: (1) species per unit area, and (2) species per individual were plotted for each of the canopy cover classes and for all subplots combined. The species-area curve for gaps was steeper than the all-subplots curve that represented the entire gradient from gap centers to the shaded understory. By contrast, all of the species-individuals curves were similar. Sorrenson's indices showed that only gap subplots, particularly those associated with large gaps, had highly self-similar species composition. Furthermore, the relative abundance of most species was similar between gaps and the shaded understory. However, intolerant species often had higher relative abundance in gaps, especially in gaps ≥0.04 ha in size. We concluded that gap partitioning hypotheses applied to some intolerants, but not to tolerants. The density hypothesis, a null model attributing species richness levels to stem density levels, largely explained the richness patterns in our study forest.

Effects of Zebra Mussel (Dreissena polymorpha) Colonization on Water Quality Parameters in Saginaw Bay, Lake Huron

A large-scale study of Saginaw Bay was initiated in 1990 and continued through 1993 to examine the effects of the zebra mussel colonization which began in summer/fall 1991. Saginaw Bay responded quickly to the zebra mussel colonization, as fall 1991 values of chlorophyll were similar to 1992 and 1993 values. In inner Saginaw Bay, where most zebra mussels were found, chlorophyll, kPAR, and total phosphorus values decreased, and Secchi disk depth increased during the study period, regardless of the presence or absence of zebra mussels at a specific station. At outer bay control stations no significant differences were found for chlorophyll, kPAR, and Secchi disk values. In order to examine longer-term trends, water quality data from 1979–1980 (STORET) were combined with our 1990 data (pre-zebra mussel period) and compared to values from the post zebra mussel period (fall 1991, all 1992 and 1993). At stations with high densities of zebra mussels, chlorophyll and total P decreased by 66% and 48%, respectively, and Secchi disk values increased 88%. At outer bay control stations no significant differences were found for chlorophyll or Secchi disk. When parameters were averaged throughout inner Saginaw Bay, zebra mussels caused a 59% and 43% decrease in chlorophyll and in total phosphorus and a 60% increase in Secchi disk transparency. Although zebra mussels significantly altered water quality parameters in the pelagic region of Saginaw Bay, they did not necessarily change system trophic state; rather they altered the spatial partitioning of resources.

Resource partitioning in a Mediterranean lizard community

Abstract Some aspects of community ecology in a lizard assemblage composed of three sympatric and diurnal species (Algyroides fitzingeri, Podarcis tiliguerta, Chalcides ocellatus) were studied in a Mediterranean habitat of central Sardinia. The three lizards were characterized by significantly different mean body size. There was no spatial overlap between the smallest species (A. fitzingeri) and the largest one (C. ocellatus), while there was a certain amount of overlap between P. tiliguerta and each of the other two lizards. The three species preyed on a wide variety of invertebrates, but mainly on insects. Food niche breadth was higher in P. tiliguerta, and this could be related to the higher microhabitat heterogeneity of this lizard in the study area. Food niche overlap was high between Chalcides ocellatus and Podarcis tiliguerta, but low between Algyroides fitzingeri and C. ocellatus. Although further data are required before any firm conclusion can be drawn, the results of this investigation seem to indicate that (i) interspecific competition among the three lizards is rather limited, due both to food and spatial resource partitioning, and (ii) the lizard community is organized through the ecological needs of each species.

Foraging and dietary strategies of two sublittoral cottids, Jordania zonope and Artedius harringtoni

The longfin sculpin, Jordania zonope Starks, 1895, and the scalyhead sculpin, Artedius harringtoni (Starks, 1896), arecommon subtidal cottids in the San Juan Archipelago, Washington, but little of their autecology has been investigated. Comparisons of distribution, microhabitat density, foraging behaviour and diet were conducted for the two species. Even though the two species occurred close together, microhabitat use differed between them, as did foraging strategies. Jordania zonope had a broader foraging range and tended to take bites out of prey items, whereas A. harringtoni had a more limited foraging range and tended to swallow prey whole. Partitioning of spatial and nutritional resources as well as morphological differences supported the hypothesis that J. zonope and A. harringtoni minimize interspecific competition in spite of microhabitat overlap and often side‐by‐side feeding.

Reply to Shorrocks and Rosewell

Previous articleNext article No AccessNotes and CommentsReply to Shorrocks and RosewellRichard F. GreenRichard F. Green Search for more articles by this author PDFPDF PLUS Add to favoritesDownload CitationTrack CitationsPermissionsReprints Share onFacebookTwitterLinkedInRedditEmail SectionsMoreDetailsFiguresReferencesCited by The American Naturalist Volume 131, Number 5May, 1988 Published for The American Society of Naturalists Article DOIhttps://doi.org/10.1086/284820 Views: 2Total views on this site Citations: 8Citations are reported from Crossref Copyright 1988 The University of ChicagoPDF download Crossref reports the following articles citing this article:Kazuo H. Takahashi The effect of travel time on oviposition behavior and spatial egg aggregation: experiments with Drosophila, Entomologia Experimentalis et Applicata 124, no.33 (Sep 2007): 241–248.https://doi.org/10.1111/j.1570-7458.2007.00583.xHideyuki Mitsui, Kazuo H. Takahashi, Masahito T. Kimura Spatial distributions and clutch sizes of Drosophila species ovipositing on cherry fruits of different stages, Population Ecology 48, no.33 (Apr 2006): 233–237.https://doi.org/10.1007/s10144-006-0260-5Stephen Hartley, Bryan Shorrocks A general framework for the aggregation model of coexistence, Journal of Animal Ecology 71, no.44 (Jul 2002): 651–662.https://doi.org/10.1046/j.1365-2656.2002.00628.xBregje Wertheim, Jan G. Sevenster, Irene E. M. Eijs, Jacques J. M. Van Alphen Species diversity in a mycophagous insect community: the case of spatial aggregation vs. resource partitioning, Journal of Animal Ecology 69, no.22 (Mar 2000): 335–351.https://doi.org/10.1046/j.1365-2656.2000.00396.xTadhg O'Connell, Thomas Bolger Intraspecific aggregation, `probability niches' and the diversity of soil microarthropod assemblages, Applied Soil Ecology 9, no.1-31-3 (Sep 1998): 63–67.https://doi.org/10.1016/S0929-1393(98)00055-9 Stephen B. Heard and Lynne C. Remer Clutch‐Size Behavior and Coexistence in Ephemeral‐Patch Competition Models Heard & Remer, The American Naturalist 150, no.66 (Jul 2015): 744–770.https://doi.org/10.1086/286092H. T. Band Aggregated oviposition byChymomyza amoena (Diptera: Drosophilidae), Experientia 45, no.99 (Sep 1989): 893–895.https://doi.org/10.1007/BF01954067WADE B. WORTHEN Predator-mediated coexistence in laboratory communities of mycophagous Drosophila (Diptera: Drosophilidae), Ecological Entomology 14, no.11 (Feb 1989): 117–126.https://doi.org/10.1111/j.1365-2311.1989.tb00761.x

Field water relations of three temperate vines.

A two year comparative field water relations study was conducted in central Maryland on three sympatric temperate lianas, Lonicera japonica, Vitis vulpina and Parthenocissus quinquefolia. Seasonal physiological activity was longer by approximately 9 weeks in the evergreen L. japonica, while peak rates of stem elongation were 4-10 fold higher in the two deciduous species. There were marked differences in vascular anatomy and water use patterns among the three species, however all three evidenced varying degrees of stomatal closure in response to decreasing soil water availability and increasing atmospheric evaporative demand. The range of leaf water potentials measured in these species was quite narrow in comparison to other temperate woody species. Two of the species showed no alterations in their tissue water release properties in response to decreased soil water availability, while V. vulpina showed a limited capacity in this regard. Most significant among the species differences in water relations were the conservative water use patterns of P. quinquefolia, and the midday maxima of transpirational water loss measured in L. japonica compared to the morning peaks in traspiration for the two deciduous species. The differences found in anatomy, leaf phenology, climbing mechanics, water relations and canopy development among these three sympatric vines implies a spatial and temporal partitioning of light and water resources and emphasizes the diversity of morphological-physiological suites of characters present among species co-occurring in the same macrohabitat.