Demographic vital rates and population growth: rethinking the relationship in a harvested elk population

Understanding the nature of the relationship between demographic vital rates and the rate of population change (λ) is important for determining effective strategies for population management and conservation. We examined the relative impacts of various demographic vital rates on λ within the range of temporal vital rate variability observed in a harvested population to test the hypotheses that adult survival rates in ungulates are relatively invariant when compared to other vital rates and that variability in calf survival has a greater influence on rates of population change than adult survival. Vital rates were estimated for an elk (_Cervus elaphus_) population at Fort Riley, Kansas from October 2003 – February 2007. The magnitude of adult survival rates were similar to other harvested populations and models including a negative relationship between survival and age received the highest levels of support. Prime-age adult survival had the highest stage-specific elasticity values, indicating a high contribution of these matrix elements to λ. Life-stage simulation analysis indicated that variation in calf survival had the highest correlation with variation in λ (r^2^ = 0.61). Our results suggest that adult survival rates in harvested populations may experience increased levels of variability, but that calf survival rates have the greatest relative influence on λ due to the wider range of variability observed for this vital rate

The White Waterlily of Iowa

Most of the known species of waterlily (Nymphaea Sm.) are extremely variable. The student feels obliged to recognize certain extreme forms as species. These are often restricted geographically. But where their habitats are connected by continuous land areas, the intermediate country is usually populated by a series of waterlilies which grade insensibly from one extreme to the other. The commoner white waterlilies of North America illustrate these conditions

Spore Formation in Lycogala exiguum Morg.

On the 5th of October, 1907, young aethalia of a Lycogala were collected in a grove four miles southwest of Grinnell, Iowa, killed in chromo-acetic acid and carried through into paraffin. Sections have shown some interesting stages in the development of spores. Since this process has hitherto been described in only two species of saprophytic myxomycetes, it seemed desirable to record the observation. Whether the organism in question is Lycogala exiguum or L. epidendrum cannot be certainly determined. Its small size and the fact that only four or five aethalia were found indicate the former species

Mosses and Liverworts of Iowa

In 1945 I published three papers on the Atracheata (Bryophytes) of Iowa in The Bryologist, vol. 48:I. The species and the counties from which they were known, with the herbaria in which specimens could be seen. II. Names that have been published but were not recognized in my list, and why not. III. Papers on the subject, with notes about the authors. Since that time several additional species have been collected in the State, many new county records have been made, some misidentifications are to be corrected, and some changes in names must be made. As I am not likely to see additional collections from Iowa, it seems right to present a corrected list at this time

The Banana Floatingheart (Nymphoides aquaticum)

It is well known that Nymphaea mexicana Zucc. and Nymphoides aquaticum (Walt.) produce brood bodies, hibernating bodies or organs of vegetative propagation. In both species the bodies consist of a cluster of fleshy roots more or less resembling a hand or a small bunch of bananas

Homology of Tissues of Ferns

In comparing two or more organisms our standpoint may be developmental, morphological or physiological. Or, we may strike a middle ground in what is called the morpho-physiological point of view

Secotium agaricoides, a Stalked Puffball

Last autumn a considerable number of specimens of that odd fungus, Secotium agaricoides, were brought to our laboratory. It seems desirable to record the following observations

A Manual of the Gymnosperms ( Ever-Greens ) of Iowa, Both Native and Cultivated

Trees or shrubs with needle-shaped or scale-like lvs, or with broad 2-lobed fork-veined lvs. The pollen falls directly upon the ovule or young seed; there is therefore no stigma or ovary. Wood close grained, without ducts (pores); soft woods. Stam. fl. Cone-like or catkin-like, short-lived. Seeds various, with fleshy endospern. Cambium in stems and roots, forming rings of wood

The Fir Forests of Iowa

The occurrence of balsam fir (Abics balsamea) m Allamakee County was recorded by Macbride. He noted it as Not rare. A fine grove on the hill above Yellow River, near Myron. In Winneshiek County it was recorded by Shimek. He considered it Not rare, along rocky slopes and above ledges along the upper course of the Upper Iowa River. Most abundant near Kendallville and Bluffton. Several visits to these areas in the last five years enable us to report on present conditions and on certain other species of this region

Ferns and Liverworts of Grinnell and Vicinity

The flora of the high prairie is peculiarly devoid of mosses and ferns. Excessive insolation and evaporation are prime causes of this. Though the necessary protection for mosses might be afforded by the tall grasses, the ground is too closely occupied, and moisture throughout much of the year is too scant