Strukturális komplexitás és términtázati szervezettség dinamikai következményei: Brachypodium pinnatum erdőssztyepprét kompozíciós koordináltsága, degradációja és regenerációja = Dynamic consequences of structural complexity and spatial organization: coordination, degradation and regeneration of Brachypodium pinnatum grassland

A téridő szerkezetek funkcionális következményeit információstatisztikai modellekkel teszteltük 34 db változatos diverzitású és dinamikai státuszú Brachypodium pinnatum erdőssztyepprét eltérő táji, tájhasználati és vegetációs szomszédossági körülmények között előforduló állományaiban. A términtázati jellemzők és a cönológiai állapotteres módszer jelezték a természetes és az enyhén leromlott állományok közötti különbségeket, amelyeket a fajszám és a Shannon diverzitás változása még nem mutatott. A természetes állományok térben és időben koordináltnak bizonyultak. A degradált, kisebb strukturális komplexitású és nagyobb térbeli heterogenitású állományokban viszont jelentősek voltak az éves szerkezeti változások. Az állományok eltérő szerkezetéhez eltérő időbeli viselkedések, pl. a degradált gyepek kisebb időbeli koordináltsága, az extrém időjárási jelenségekkel ill. a fluktuációval szembeni kisebb rezisztencia képessége társult. Az eltérő természetességi állapotú gyepek cönológiai állapotteres pozíciója és időbeli mintázata közötti eltérések szignifikánsak voltak, ezért a megfelelő referencia állapotok feltárása után a cönológiai állapotteres módszer hatékony eszköz a gyeptársulások dinamikai állapotának és állapottranszformációjának monitorozásában. Kimutattuk, hogy a vegetáció mikrostruktúrájának jellemzése hasznos a vegetáció-talaj kutatásokban is, mert nem érzékeny a biogeográfiai különbségekre, de igen érzékeny a vegetáció dinamikai állapotában meglévő kicsi különbségekre. | Vegetation dynamics is a spatiotemporal phenomenon; still relatively few studies consider dynamic processes as a function of within-stand spatial complexity. We focused on the effects of fine-scale patterns on vegetation dynamics and analysed temporal behaviour of 18 natural vs. 16 slightly degraded stands of Brachypodium grassland as a function of their spatial organization. We found that the information theory measures and the coenostate-space methodology sensitively differentiated between natural and slightly degraded stands, which differences remained unexplored by species richness and Shannon diversity. The fine-scale structure and spatial organization of natural vs. degraded stands were clearly different, which significantly affected plant community dynamics: higher interannual variability of the multispecies coexistence patterns and interactions among species combinations were detected in the degraded stands indicating their higher vulnerability compared to natural ones. As temporal change was successfully captured by the coenostate-space approach after defining the natural spatiotemporal variation range of natural stands as a reference, the method was recommended for monitoring the effectiveness of conservation treatments. Fine-scale structural characterisation of vegetation was also useful in studies of vegetation-soil relationships, because it was not sensitive to biogeographic differences, but was more sensitive to minor differences in vegetation dynamic status

A foundation for synthesising programming language semantics

Programming or scripting languages used in real-world systems are seldom designed with a formal semantics in mind from the outset. Therefore, the first step for developing well-founded analysis tools for these systems is to reverse-engineer a formal semantics. This can take months or years of effort. Could we automate this process, at least partially? Though desirable, automatically reverse-engineering semantics rules from an implementation is very challenging, as found by Krishnamurthi, Lerner and Elberty. They propose automatically learning desugaring translation rules, mapping the language whose semantics we seek to a simplified, core version, whose semantics are much easier to write. The present thesis contains an analysis of their challenge, as well as the first steps towards a solution. Scaling methods with the size of the language is very difficult due to state space explosion, so this thesis proposes an incremental approach to learning the translation rules. I present a formalisation that both clarifies the informal description of the challenge by Krishnamurthi et al, and re-formulates the problem, shifting the focus to the conditions for incremental learning. The central definition of the new formalisation is the desugaring extension problem, i.e. extending a set of established translation rules by synthesising new ones. In a synthesis algorithm, the choice of search space is important and non-trivial, as it needs to strike a good balance between expressiveness and efficiency. The rest of the thesis focuses on defining search spaces for translation rules via typing rules. Two prerequisites are required for comparing search spaces. The first is a series of benchmarks, a set of source and target languages equipped with intended translation rules between them. The second is an enumerative synthesis algorithm for efficiently enumerating typed programs. I show how algebraic enumeration techniques can be applied to enumerating well-typed translation rules, and discuss the properties expected from a type system for ensuring that typed programs be efficiently enumerable. The thesis presents and empirically evaluates two search spaces. A baseline search space yields the first practical solution to the challenge. The second search space is based on a natural heuristic for translation rules, limiting the usage of variables so that they are used exactly once. I present a linear type system designed to efficiently enumerate translation rules, where this heuristic is enforced. Through informal analysis and empirical comparison to the baseline, I then show that using linear types can speed up the synthesis of translation rules by an order of magnitude

Unimodal Relationships of Understory Alpha and Beta Diversity along Chronosequence in Coppiced and Unmanaged Beech Forests

Patterns of diversity across spatial scales in forest successions are being overlooked, despite their importance for developing sustainable management practices. Here, we tested the recently proposed U-shaped biodiversity model of forest succession. A chronosequence of 11 stands spanning from 5 to 400 years since the last disturbance was used. Understory species presence was recorded along 200 m long transects of 20 × 20 cm quadrates. Alpha diversity (species richness, Shannon and Simpson diversity indices) and three types of beta diversity indices were assessed at multiple scales. Beta diversity was expressed by a) spatial compositional variability (number and diversity of species combinations), b) pairwise spatial turnover (between plots Sorensen, Jaccard, and Bray–Curtis dissimilarity), and c) spatial variability coefficients (CV% of alpha diversity measures). Our results supported the U-shaped model for both alpha and beta diversity. The strongest differences appeared between active and abandoned coppices. The maximum beta diversity emerged at characteristic scales of 2 m in young coppices and 10 m in later successional stages. We conclude that traditional coppice management maintains high structural diversity and heterogeneity in the understory. The similarly high beta diversities in active coppices and old-growth forests suggest the presence of microhabitats for specialist species of high conservation value