A population is never constant, but changes over time, and a connection is often found in population changes between predator and prey. A population increase in one can affect the other species positively or negatively. An increase in wood voles (Clehtrinomys glareolus) and field voles (Microtus agrestis) provides more food for the red fox (Vulpes vulpes), which in turn gets a better chance to reproduce. When the fox then increases in number, the vole decreases because the fox hunts and eats more food. Cycles are formed in the ups and downs of the populations which are followed. The purpose of this study is to see if a large vole population increases the fox's reproductive success in subsequent years and if a cycle interval with displacement between voles and foxes exists with a clear interval. Grimsö Research Station has contributed its data on the populations from the year 1973 until the year 2023. Lotka-Volterra's equations for predator-prey interactions were used and to see if a clear cycle interval between the populations existed. The result shows that the Lotka-Volterra equation does not give any clear shifts between the peaks and valleys of the populations as we thought before the test. In contrast, an autocorrelation analysis shows that the fox appears to follow the typical pattern of population cycles while the vole does not. A cross-correlation strengthens the result as the result is highest at a minimal time shift. A non-parametric correlation analysis finally shows that the correlation is strongly positive but not significant. / En population är aldrig konstant utan förändras över tid och ofta återfinns ett samband i populationsförändringar mellan predator och bytesdjur. En populationsökning hos den ena kan påverka den andra arten positivt eller negativt. En ökning av skogssork (Clehtrionomys glareolus) och åkersork (Microtus agrestis) ger mer mat åt rödräven (Vulpes vulpes) som i sin tur får bättre chans att reproducera sig. När räven då ökar i antal så minskar sorken eftersom räven jagar och äter mer mat. Det bildas då cykler i populationernas upp- och nedgångar som följs åt. Syftet med denna studie är att se om en stor sorkpopulation ökar rävens reproduktionsframgång efterföljande år samt om ett cykelintervall med förskjutning mellan sork och räv finns med tydligt intervall. Grimsö Forskningsstation har bidragit med data på populationerna från år 1973 fram till år 2023. Lotka-Volterras ekvationer för predator-prey interaktioner användes för att se om ett tydligt cykelintervall mellan populationerna fanns. Resultatet visar på att Lotka-Volterras ekvation inte ger några tydliga förskjutningar mellan populationernas toppar och dalar som vi trodde inför testet. Däremot visar en autokorrelationsanalys att räven ser ut att följa det typiska mönstret för populationscykler medan sorken inte gör det. En korskorrelation stärker resultatet då resultatet är högst vid minimal tidsförskjutning. En icke-parametrisk korrelationsanalys visar slutligen att korrelationen är starkt positiv men att den inte är signifikant.

In the following essay, I examine the ecocritical aspects of the writings of Thomas Tidholm, Swedish poet and children’s author. I argue for the existence of “green threads” that permeate the authorship, and analyse them through three thematic chapters where several of Tidholm’s texts, for children and adults, are juxtaposed in order to expand, contrast and deepen one another. The themes are: approaching the other, language and humanity and parts and unity. In my analysis I show that Tidholm continues to return to these themes throughout many different texts, exploring the difficulties and possibilities in human relationships to each otherand to nature. I conclude that even though Tidholm questions whether we truly can come close to, communicate with and fully understand others (humans or otherwise), he seems to hold the conviction that it is vitally important that we try. While the essay belongs in the field of ecocriticism, my working approach has been that of ordinary language philosophy as defined by literary scholar Toril Moi, following the works of Wittgenstein, Austin and Cavell. Thus, the essay is written in a spirit of acklowledgement rather than scepticism – my aim has been to bring out important aspects of the texts and show that, when read together, those aspects are enhanced. I find this especially important since the readerships of poetry and picture books do not always overlap. Furthermore, I suggest that Thomas Tidholm can be seen as a contemporary thinker whose ideas question and seek alternatives to the individualism of capitalist modern society. Keywords: ecocritisism, Thomas Tidholm, nature, environment, language