Thesis (doctoral)--Swedish University of Agricultural Sciences, 2007. / Thesis documentation sheet inserted. Includes appendix of four papers and manuscripts, three co-authored with others. Includes bibliographical references. Also issued electronically via World Wide Web in PDF format; online version lacks appendix.

Thesis (M.S.)--Wake Forest University. Dept. of Biology, 2003. / Includes bibliographical references (leaves 44-47).

Submitted by NICÁCIO RIBEIRO NETO null (ribeironeton@gmail.com) on 2016-04-04T19:06:58Z No. of bitstreams: 1 Dissertação Nicácio Ribeiro Neto.pdf: 1805580 bytes, checksum: a788f2400c566e4a72399d99c32d7e1c (MD5) / Approved for entry into archive by Ana Paula Grisoto (grisotoana@reitoria.unesp.br) on 2016-04-06T14:19:24Z (GMT) No. of bitstreams: 1 ribeironeto_n_me_assis.pdf: 1805580 bytes, checksum: a788f2400c566e4a72399d99c32d7e1c (MD5) / Made available in DSpace on 2016-04-06T14:19:24Z (GMT). No. of bitstreams: 1 ribeironeto_n_me_assis.pdf: 1805580 bytes, checksum: a788f2400c566e4a72399d99c32d7e1c (MD5) Previous issue date: 2016-03-14 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / A presente dissertação foi desenvolvida em uma parcela pemanente na Estação Ecológica de Assis (EEcA), Estado de São Paulo, onde a vegetação predominante é cerradão (savana florestada). Os objetivos foram realizar um levantamento florístico dos indivíduos arbóreos da parcela, confeccionar uma chave de identificação para as famílias desses indivíduos, realizar analises fitossociológicas gerais nesse componente e também verificar estatisticamente se ao longo de três medições realizadas nos anos de 2002, 2004 e 2010 espécies típicas de cerrado estão sendo substituídas paulatinamente por espécies típicas de floresta, uma vez que em sua instauração, em 1959, a EEcA possuía predomínio de vegetações savanicas mais esparças, mas a supressão de incêndios naturais e antropizados, devido ao senso comum de que esses são prejudiciais à conservação, modificou essa vegetação. A parcela possui 10,24 hectares, disposta em um quadrado de 320 x 320 m, a chave de identificação é dicotômicas e elaboradas com caracteres vegetativos, as análises fitossociológicas gerais foram realizadas com o auxílio do Programa R e para a verificar se ocorreram ou não variações nas proporções entre espécies de cerrado e florestais foi aplicado o teste de qui-quadrado. Os dados foram obtidos no banco de dados do projeto temático “Diversidade, dinâmica e conservação de florestas no Estado de São Paulo: 40 hectares de parcelas permantentes”, dados esses levantados em três medições ocorridas nos anos de 2002, 2004 e 2010. Foram encontrados na parcela 128 espécies de árvores, distribuídas em 47 famílias e 93 gêneros. As famílias de maior riqueza espécifica foram Myrtaceae (19 espécies), Fabaceae (15) e Lauraceae (6), e os gêneros mais ricos foram Myrcia (7 espécies), Eugenia (4), Guapira (4) e Qualea (4), foi encontrada grande similaridade florística entre a área e estudos realizados em floresta estacional semidecidual, a espécie de maior VIr e VCr nas três medições foi Copaifera langsdorffii e a hipótese de que espécies típicas de cerrado estão sendo substituídas por espécies florestais não pôde ser confirmada. / The present thesis was developed in a permanent portion on the Ecological Station of Assis (EEca), São Paulo State, where the prevailing vegetation is the cerradão (forested savannah). The objective were to analyze the arboreal components of the portion and generate a identification key for each family of the area, analyze the phytosociological characteristics and also verify if there were a gradual replacement of the vegetation from different analysis on the years of 2002, 2004, 2010, since its establishment in 1959, the EEcA had a prevalence of scattered savanic vegetation, but with the suppression of natural and anthropogenic fires, with the common thought that they were harmful for the environment conservation the predominant vegetation ended up changing. The contingent has 10,24 hectare, in a block with 320 x 320 m, the identification key was dichotomous, the general phytosociological analysis were performed with the aid of the Programa R and to verify if there were any variation in the proportion between the species the portion we applied the Chi-square. The data were obtained from the database of the tematic Project “Diversidade, dinâmica e conservação de florestas no Estado de São Paulo: 40 hectares de parcelas permantentes”, this data were collected in the years of 2002, 2004, 2010.. There were 128 arboreal species found in the area, distributed in 47 families and 93 genus. The richest families were Myrtaceae (19 species), Fabaceae (15) and Lauraceae (6), the richest genus found were Myrcia (7 species), Eugenia (4), Guapira (4) and Qualea (4), there were found great similarity between the studies realized in the deciduous stacional forest, the species with the greatest Vlr and VCr on the three measures was Copaifera langsdorffii and the thesis of the vegetal replacement of the area can not be confirmed. / FAPESP: 2014/12502-3

Large areas within alpine and subalpine tundra have been x disturbed by mining during this century. The most promising method for retarding deterioration of these areas is revegetation with native species through both seeding and transplants. One natural process of revegetation which occurs on portions of many existing disturbances seems to be the establishment of a few species that expand with time to form matts of plants. At the McLaren Mine, located at 3000 m elevation in the Beartooth Mountains, Montana, active succession is occurring and is dominated by Carex species. Seed viability and successional patterns studies were conducted on the mine. The objectives included: 1) determinations of seed viability on the spoils, 2) determine to what extent the Carex communities enhanced seedling survival, 3) to quantify the vegetation characteristics within the Carex communities and adjacent mine spoil, and 4) determine the effect that Carex communities have on microenvironmental factors. Greenhouse tests were used to determine seed viability in soil samples taken from the mine. Paired observations in field studies were used to compare vegetational and microenvironmental differences between Carex communities and adjacent bare areas. Statistical analyses of the data collected showed that there was an adequate source of viable seeds of various species in the spoils to encourage natural revegetation if they could become established. Seedling mortality was reduced in Carex communities, apparently by decreasing soil disruption caused by frost action. Carex communities altered the microenvironment by reducing soil temperatures, wind speed, and radiation flux, and by providing a richer source of nitrogen and potassium than did the bare areas. Carex communities did not alter ?oil pH, phosphorus or soil water. Measurement of microenvironmental factors varied between the center and edge locations within the Carex communities. Species diversity and percent litter cover increased with increase in community size.

No description available.

One of the human activities impacting biodiversity is the cutting of old-growth forests. In response to the controversy surrounding the cutting of old-growth in the coastal rainforest of BC, the Ministries of the Environment and Forests have produced biodiversity guidelines that are to be applied when manipulating stands in the provincial forest. This study augments these guidelines by investigating the diversity differences between second-growth and old-growth forests in relation to site quality. We demonstrate how standlevel plant diversity differs between 40-year-old and old-growth stands in the Very Wet Coastal Western Hemlock subzone (CWHvm) on Vancouver Island. This information is intended to provide foresters with an understanding of the effects of age, disturbance and site quality on stand-level plant diversity, thereby allowing for informed professional management decisions.

The forest floor represents the uppermost organic and organicenriched mineral soil horizons. They have been formed by the deposition of organic material and the subsequent biologically mediated decomposition. The forest floor influences rooting-zone temperature, aeration, moisture, and nutrient conditions, and hence, forest productivity. Considering the importance of the forest floor, and the fact that it is exposed to disturbance (being the surface layer), we need to assess the potential impacts our logging practices may have. Clearcutting, one of the contentious silvicultural practices used in British Columbia, is imputed to most adversely affect ecosystems and sustainability. We assessed the long-term impact of clearcutting on the forest floor by documenting changes in the thickness, chemical and biotic properties of the humus form across a chronosequence of forest stands. The study was located in the largest and most representative portion of the coastal rainforest the Very Wet Maritime Coastal Western Hemlock (CWHvm) subzone.

The objective of this study was to describe the impacts of the density of Chromolaena odorata (chromolaena) on species composition in coastal grasslands and to investigate serial changes in the vegetation following the implementation of a burning programme. The thesis deals with key ecological concepts and issues, so a comprehensive literature review is included. Chromolaena invades coastal grasslands that are not burnt regularly (i.e. biennially). Grasslands that were not burnt for 30 years were seral to secondary forest. The successional pathway from open grassland to closed canopy forest varied according to soil type. Coastal grasslands on Glenrosa soils were characterised by savanna at an intermediate stage between the grassland and forest states. Shading ended the persistence of savanna species (e.g. Combretum molle, Dichrostachys cinerea and Heteropyxis natalensis) in forest, whereas forest precursors (e.g. Canthium inerme, Maytenus undata and Protorhus longifolia) only established where fire was absent. Chromolaena infestations were characterised by multi-stemmed adult plants of variable height (i.e. 1-3 m), depending on soil type. Regic sands did not support stratified woody vegetation and chromolaena infestations were self-supporting, reaching a maximum height of 1.5 m. Glenrosa soils supported tree communities and chromolaena reached more than 3 m in places. The density of chromolaena affected species composition in grasslands with moderate to dense stands (> 5 adult plants m ¯² or >50000 shrubs ha ¯¹). Chromolaena stands became monospecific when the number of adult plants exceeded 7 m ¯². Succession to forest also ceased once chromolaena became thicket-forming. Fire-induced mortality of the chromolaena depended on grass fuel loads. Grass cover of 30% (c. 1 000 kg ha ¯¹) was required to achieve 80% mortality of the parent infestation after the initial burn. Dense infestations could only be killed by running head-fires from adjacent grasslands into thickets. Under conditions where head-fires could not be used, infestations were slashed and burnt at the height of the dry season (July to August) to achieve an 80% kill rate. Seedlings were killed (99%) by annual burning in sparse (≤ 10000 shrubs ha ¯¹) to moderate < 50 000 shrubs ha ¯¹) infestations. The suppression of chromolaena and other alien species, establishing on bare ground after clearing dense infestations, required chemical control until grass cover was sufficient (i.e. 1 000 kg ha ¯¹) to effect uniform burning. Certain secondary alien invaders (e.g. Lantana camara, Psidium guajava and Solanum mauritianum) persisted by coppicing profusely after fire and herbicides need to be integrated into burning programmes when these species occur. Grasslands on regic sands (e.g. Ischaemum fasciculatum, Panicum dregeanum and Themeda triandra) were more resilient to the modifying effects of woody vegetation, than grasslands on Glenrosa soils. Grasslands on Glenrosa soils did not revert to an open state but persisted as ruderal savanna grassland (e.g. Eragrostis curvula, Hyparrhenia tamba and Cymbopogon validus) once fire-resistant tree species (e.g. Combretum molle and Heteropyxis natalensis) had established. Depending the objectives for land management and the vegetation's condition, coastal grasslands can be rehabilitated and managed in multiple states, i.e. grassland, savanna or forest communities. A state-and-transition model based on the empirical data recorded in the study is presented and shows chromolaena altering vegetation states from open grassland to chromolaena dominated thicket. The model illustrates chromolaena thickets as the dominant phase of a moist coastal forest/savanna succession, irrespective of soil type, in absence of appropriate land management practices (e.g. control burning and integrated control of alien vegetation). This model should aid in planning strategies for the control of chromolaena in subtropical grasslands in South Africa. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2000.

Thesis (MScFor)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Several studies have shown that stands of invasive alien plants in the natural forest environment can facilitate the rehabilitation and recovery of such forests and challenged the general and global perception that such invasive species threaten the biodiversity and functioning of natural vegetation systems. The aim of this study was to develop an understanding of the dynamics of the spread and establishment of natural forest species in a large stand of the invasive alien plant species Acacia mearnsii (Black wattle) along the Buffeljagsrivier, Western Cape, South Africa. Several patches of Moist forest, Dry forest and Riparian forest occur along the Buffeljagsrivier, above the Buffeljagsrivier dam. The stand of Black wattle consists of 90 ha for a distance of 3.12 km. The main objective was pursued through four specific objectives: (i) to map and assess the patterns in the distribution, size and species composition of the natural forest clusters within the Black wattle stand; (ii) to determine the relationship between natural forest clusters establishing within the Black wattle stand and the neighboring natural forest patches as potential seed sources for the developing forest clusters; (iii) to determine the subsequent spread of natural forest species from the developing forest clusters into the rest of the Black wattle stand; and (iv) to synthesize the information on the dynamics of the spread and establishment of natural forest species into the Black wattle stand as a basis for developing general guidelines for the conversion of invasive alien plant stands in the forest environment towards regrowing natural forest. In total, 329 clusters of natural forest species were GPS recorded and mapped (Arc-GIS) in three zones (Proximal, Intermediate and Distant in relation to the forest patches) within the Black wattle stand: 266 small clusters (one to three reproductively mature trees), 36 medium sized clusters (four to nine trees) and 27 large clusters (more than 10 trees). Large clusters were abundant in the zone close to the natural forest patches and the number of small clusters increased with increasing distance from the forest patches. A total of 28 species of 20 families were recorded. Natural forest species are therefore able to establish within a Black wattle stand. The relationship between natural forest clusters establishing within the Black wattle stand and the natural forest patches as potential seed sources was studied by sampling the stand composition along transects through the stands. A total of 55 rectangular plots (20 m x 10 m, 200 m2) were sampled across forest patches and forest clusters. Hierarchical clustering analysis, using number of stems of a species per plot, identified three main groups and 10 sub-groups. All the sampled forest clusters were included in four of the five Riparian forest sub-groups. Most Moist and Dry forest species were absent from the forest clusters. The three main forest types differed in their general characteristics and site conditions, and this was supported by the ordination analyses: aspect, slope and canopy closure. The developing forest clusters within the Black wattle stand related more to the Riparian forest in terms of similar very gentle south-westerly slope and mean stem diameter. This suggested Riparian forest to be the primary seed source of the establishing forest clusters within the Black wattle stand. However, the large-sized stems of common species were not significantly different between Riparian forest patches and forest clusters, suggesting that large-sized stems in the forest clusters could be part of remnant forest patches, which could act as local seed sources. Detailed evaluation of species importance values and stem diameter distributions showed that some important Moist and Dry forest species are present in the forest clusters. The conclusion was that every type of forest patch contributes to a greater or lesser degree to the development of forest clusters within the Black wattle stand. Seven large clusters were selected to sample the regeneration of natural forest species within 18 m from the forest cluster boundary. Two species lists were generated; one of species from adjacent natural forest patches, and another from 59 forest clusters of all sizes sampled throughout the wattle stand. The results indicated that (1) Mature trees of well-established forest clusters were the main seed sources for the cluster expansion in all directions; (2) Three different patterns were observed in terms of the distance of expansion of regeneration from the clusters: a decrease in regeneration with increasing distance from the cluster margin; increasing regeneration with increasing distance from the cluster; and no distinct pattern with a lack of regeneration of the dominant species of a forest cluster. The 40 species recorded within the Buffeljagsrivier site include a wide range of fruit and seed characteristics. Four main groups of woody species were identified, based on their presence/absence in forest patches and forest clusters. The presence/absence of most species can be explained in terms of their fruit/seed characteristics and dispersal mechanisms. The majority of recorded woody species were most likely dispersed by birds and mammal, particularly Rameron pigeons and baboons. In conclusion, a conceptual framework was developed to guide the rehabilitation of stands of light demanding invasive stands in the forest environment. Several topics for further research were identified. / AFRIKAANSE OPSOMMING: Verskeie studies het gewys dat opstande van uitheemse indringerplante in die woudomgewing kan die rehabilitasie en herstel van sulke woude fasiliteer, en daag die algemene en globale persepsie uit dat sulke indringerplantspecies die biodiversiteit en funksionering van natuurlike plantegroeisisteme bedreig. Die doel van hierdie studie was om ‘n beter begrip te ontwikkel van die dinamika vir die verspreiding en vestiging van inheemse woudspesies binne ‘n omvangryke opstand van die uitheemse indringerplant, Acacia mearnsii (swartwattel), langs die Buffeljagsrivier, Wes-Kaap, Suid Afrika. Verskeie kolle (‘patches’) van Vogtige, Droë- en Oewerwoud kom langs die Buffeljagsrivier voor. Die swartwattel opstand van ongeveer 90 ha groei langs die Buffeljagsrivier oor ‘n afstand van 3.12 km, tussen die dam en die woudkolle aan die stroom-op kant van die swartwattelopstand. Die hoofdoel is nagevolg deur vier spesifieke doelwitte: (i) om die groepies (‘clusters’) vestigende inheemse houtagtige plantsoorte binne die swartwattelbos te karteer en die patrone in hul verspreiding, grootte en spesies samestelling binne die swartwattelopstand te evalueer; (ii) om die verwantskap tussen natuurlike woudgroepies wat binne die swartwattelopstand vestig en die aangrensende woudkolle as potensiële saadbronne vir die ontwikkelende woudgroepies te bepaal; (iii) om die daaropvolgende verspreiding van inheemse woudspesies vanaf die ontwikkelende woudgroepies binne die res van die swartwattelopstand te bepaal; en (iv) om die inligting oor die dinamika van die verspreiding en vestiging van die woudspesies binne-in die swartwattelopstand saam te vat as ‘n basis vir die ontwikkeling van algemene riglyne vir die omskepping van uitheemse indringerplantopstande in die woudomgewing na hergroeiende inheemse woud. In totaal is 329 groepies van inheemse woudspesies aangeteken (via GPS) en gekarteer (Arc-GIS) in drie sones (nabygeleë, intermediêre en afgeleë) binne die swartwattel opstand: 266 klein groepies (een tot drie voortplantingsvolwasse bome), 36 medium-grootte groepies (vier tot nege bome) en 27 groot groepies (10 of meer bome). Groot groepies was volop in die sone naby aan die woudkolle en die aantal klein groepies het toegeneem met toenemende afstand vanaf die woudkolle. ‘n Totaal van 28 species van 20 families is aangeteken, en spesies soos Canthium inerme, Celtis africana, Gymnosporia buxifolia, Rapanea melanophloeos en Vepris lanceolata was algemeen binne die swartwattelopstand. Dit is daarom moontlik vir inheemse woudspesies om binne die swartwattelopstand te vestig. Die verhouding tussen inheemse woudgroepies wat binne die swartwattelopstand vestig en die woudkolle as potensiële saadbronne is bestudeer deur die opstandsamestelling langs transekte deur die opstande te bemonster. ‘n Totaal van 55 reghoekige persele (20 x 10 m, 200 m2) is opgemeet: nege in Droeëwoudkolle, 17 in Vogtige woudkolle, 20 in Oewerwoudkolle, en nege in die woudgroepies binne the swartwattelopstand. Hiërargiese Groeperingsanalise, gebaseer op aantal stamme van ‘n spesies per plot, het drie hoofgroepe en 10 sub-groepe ge-identifiseer: Vogtige woud met drie sub-groepe, Oewerwoud met vyf sub-groepe, en Droeëwoud met twee sub-groepe. Al die gemete woudgroepies is in vier van die Oewerwoud sub-groepe ingesluit. Die meeste Vogtige en Droeëwoud spesies was afwesig van die woudgroepies. Die hoof woudtipes (Droog, Vogtig, Oewer) verskil in hul algemene eienskappe en groeiplektoestande, en dis ondersteun deur die ordinasie-analises: aspek, helling en kroonsluiting. Die ontwikkelende woudgroepies binne die swartwattelopstand was nouer verbonde met Oewerwoud in terme van soortglyke baie geleidelike suid-westelike helling en gemiddelde stamdeursneë. Dit veronderstel dat Oewerwoud is die primêre saadbron van die vestigende woudgroepies binne die swartwattelopstand. Baie inheemse woudspesies kom egter oor die verskillende groepe en sub-groepe voor, met goeie verjonging oor die gemeenskappe. Die stamdeursneë van goter stamme van algemene spesies was niebeduidend verskillend tussen die Oewerwoudkolle en die woudgroepies, en dit veronderstel dat die groter stamme in die woudgroepies kan deel wees van oorblywende woudkolle, wat as plaaslike saadbronne kan dien. Gedetaileerde ontleding van spesies belangrikheidswaardes en stamdeursneëklasverdelings het getoon dat sommige belangrike Vogtige en Droeëwoud spesies is wel teenwoordig in die woudgroepies. Die gevolgtrekking was dat elke tipe woudkol in a mindere of meerdere mate bydra tot die ontwikkeling van die woudgroepies binne die swartwattelopstand. Sewe groot woudgroepies is geselekteer om die woudverjonging binne 18 m vanaf die woudgroepierand te bemonster. Twee spesieslyste is saamgestel; een van spesies van die aangrensende woudkolle, en een van spesies van 59 woudgroepies van alle groottes wat deur die hele swartwattelopstand aangeteken is. Die resultate het aangetoon dat (1) volwasse bome van goed-gevestigde woudgroepies was die hoof saadbronne vir die uitbreiding van die woudgroepies in all rigtings; (2) drie verskillende patrone is waargeneem in terme van die afstand van uitbreiding van verjonging weg vanaf die woudgroepies: ‘n afname in verjonging met toenemende afstand vanaf die groepierand; toenemende verjonging met toenemende afstand vanaf die woudgroepie; en geen beduidende patroon met ‘n gebrek aan verjonging van die dominante spesies van die woudgroepie. Die 40 spesies wat binne die Buffeljagsrivierstudiegebied aangeteken is het ‘n wye reeks vrug- en saadeienskappe ingesluit. Vier hoofgroepe van houtagtige spesies is geïdentifiseer, gebaseer op hul aan- of afwesigheid in die woudgroepies and woudkolle: spesies algemeen in die woudkolle en teenwoordig in die woudgroepies; spesies spesifiek to bepaalde woudkolle en teenwoordig in die woudgroepies; spesies teenwoordig in die woudkolle maar afwesig van die woudgroepies; en spesies afwesig van die woudkolle maar teenwoordig in die woudgroepies. Die aan- of afwesigheid van die meeste spesies kan verduidelik word in terme van hul vrug/saadeienskappe en verspreidingsmeganismes. Die meerderheid van aangetekende houtagtige spesies was meeswaarskynlik deur voëls en soogdiere versprei, veral Geelbekbosduiwe en Bobbejane. Ten slotte, ‘n konsepsuele raamwerk is ontwikkel om die rehabilitasie van opstande van ligafhanklike indringerspesies in die woudomgewing te rig. Verskeie onderwerpe vir verdere navorsing is geïdentifiseer. / RESUME: Plusieurs études ont montré que les peuplements de plantes exotiques envahissantes dans le milieu de forêt naturelle peuvent favoriser la réhabilitation de ces forêts contestant par-là, la perception générale et globale que ces espèces envahissantes menacent la biodiversité et le fonctionnement des systèmes de végétation naturelle. L’objective de cet étude était de mieux comprendre le dynamisme d’établissement et de propagation dans une forêt naturelle des espèces forestières au sein d’un large peuplement de l'espèce de plantes exotiques envahissantes Acacia mearnsii (acacia noir) le long de Buffeljagsrivier, Western Cape, en Afrique du Sud afin d’élaborer des axes directives de réhabilitation relative aux recouvrements d’espèces invasive. La forêt de Buffeljagsrivier s’étale sur un gradient de petites parcelles de forêt allant de forêt sèche, humide et marécageux. Au milieu de ces parcelles de Buffeljagsrivier, on circonscrit un peuplement d’acacia noir estimé à 90 ha sur une distance de 3,12 km. L’objective principal s’est poursuit à travers quatre sous objectives à savoir: (i) cartographier et évaluer les formes d’ invasions dans la distribution, la taille et la composition des recouvrements des espèces de forêt naturelle à l’intérieur du recouvrement d’acacia noir servant comme preuve possible de l’existence et établissement des espèces de forêt naturelle sous un recouvrement d'une espèces invasive; (ii) de déterminer la relation entre les recouvrements de forêt naturelle s’établissant á l’intérieur du peuplement d’acacia noir et ceux de la forêt naturelle avoisinante humide, sèche et marécageuse pouvant être considéré comme sources potentiel de semences conduisant au développement des premiers recouvrement cités; (iii) de déterminer l’étalement subséquent des espèces de la forêt naturelle à partir des recouvrements d’ acacia noir se développant à l’intérieur du reste du peuplement de l’Acacia noir; (iv) Synthétiser les informations sur la dynamique de la propagation et l'établissement d'espèces forestières naturelles dans l’acacia noir comme une base pour l'élaboration des lignes directrices générales pour la conversion de peuplements de plantes exotiques envahissantes se trouvant dans l'environnement de la forêt vers des repousses des forêts naturelles. Au total, 329 recouvrements d'espèces forestières naturelles ont été GPS enregistrées et cartographiées (Arc -GIS) dans trois zones (Proximale, Intermédiaire et Eloignée par rapport aux parcelles de forêt avoisinantes) dans le peuplement de l'acacia noir: 266 petits recouvrements avaient un à trois arbres matures, 36 recouvrements de taille moyenne avaient quatre à neuf arbres matures et 27 larges recouvrements avaient plus de 10 arbres matures. La visualisation de la carte a révélé que les larges recouvrements de forêt mature étaient abondant dans la zone proche des parcelles de forêt naturelle avoisinantes et que de petits recouvrements de jeunes arbres de forêt naturelles croissaient en nombre à mesure que la distance depuis les parcelles de forêts naturelles adjacentes s’élargissait. Un total de 28 espèces appartenant à 20 familles a été répertorié. Deux familles, Rubiaceae suivit de Anacardiaceae ont dominé l’echantillon. Les espèces forestières naturelles sont donc en mesure de s’établir dans un peuplement d'acacia noir. L’échantillon qui a servi à l’évaluation des sources de semences pour le développement des recouvrements de forêt naturelle à travers l’investigation de la relation entre les recouvrements de forêt naturels qui s’établissent à l’intérieur du peuplement d’acacia noir et les parcelles de forêt avoisinantes humide, sèche et marécageuse était constitué de 55 placettes rectangulaires de 200m2 le long de layons à travers le site d’étude. Une analyse hiérarchique des recouvrements réalisée sur la composition des espèces de l’échantillon a révèle que la forêt marécageuse concentre les espèces les plus fréquentes des recouvrements de forêts, et que la majorité des espèces présentes sur les parcelles des forêts sèches et humides étaient absente dans l’ensemble des recouvrements des forêts de l’acaci noir. Les trois principaux types de forêts différaient dans leurs caractéristiques générales et les conditions du site, et cela a été appuyé par l’analyse d’ordinants à partir de trois facteurs environnementaux, la pente, l’angle d’inclinaison par rapport au soleil, et la fermeture de la canopée. Les recouvrements de foret en développement au sein de l'acacia noir se sont trouvés davantage liés à la forêt marécageuse en termes de pente plate orientée sud-ouest et en diamètre moyen des arbres. Ces résultats ont désigné la forêt marécageuse comme la première source potentielle de semences permettant l’établissement des recouvrements de forêt à l’intérieur des peuplements d’acacia noir. Cependant, les souches d’arbres de grande taille des espèces communes entre les parcelles de forêts marécageuses et les recouvrements de forêt dans l’acaci noir n'étaient pas significativement différents, suggérant ainsi que ces arbres de grande taille trouves dans les recouvrements de foret pourraient faire parties des parcelles de forêt subsistantes de la dernière turbulence. Elles pourraient constituer des sources locales de semences. Par ailleurs, une évaluation détaillée des valeurs d'importance des espèces et des distributions des diamètres des souches d’arbres a montré que certaines espèces importantes de forêts humides et sèches sont présentes dans les recouvrements de foret. Finalement l’on conclue que chaque type de parcelles de forêt contribue plus ou moins à l’établissement des recouvrements de forêt dans le peuplement de l'acacia noir. Sept grands recouvrements de foret ont été sélectionnés pour étudier la régénération des espèces forestières naturelles sur un rayon de 18 m depuis la limite du recouvrement de foret. Deux listes d'espèces ont été générées, l'une des espèces de parcelles de forêt naturelle adjacentes, et une autre venant des 59 recouvrements de foret, toutes tailles confondues le long de l'acacia noir. Les résultats ont indiqué que (1) Les recouvrements de forêts, lorsque bien matures et bien établies devenaient les principales sources de semences pour leur expansion sur toutes les directions; (2) Trois allures différentes ont été observées en fonction de la distance de l'expansion de la régénération autour des recouvrements: une diminution de la régénération avec l'augmentation de la distance; une croissance de la régénération avec une distance croissante depuis les revcouvrements de foret, et pas d’allure particulaire voire une absence de régénération de certaines especes pourtant dominant dans les recouvrements de foret. Les 40 espèces recensées sur le site deBuffeljagsrivier comprennent un large éventail de caractéristiques de fruits et de graines. Quatre principaux groupes d'espèces ligneuses ont été identifiées, en fonction de leur présence / absence dans des parcelles de forêt et les recouvrements de forêt. De façon générale, la présence / absence de la plupart des espèces a pu être expliquée en termes de caractéristiques de leur fruits/graines et les mécanismes de dispersion. La majorité des espèces ligneuses enregistrées sont susceptibles d’être dispersées par les oiseaux et les mammifères, en particulier les pigeons rameron et les babouins vues sur le terrain. En conclusion, un cadre conceptuel a été élaboré pour guider la réhabilitation de peuplements envahissants de lumière en milieu forestier. Plusieurs sujets pour des recherches plus poussées ont été identifiés.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / We performed this study in a fragment of Caatinga under anthropic influence in the county of Poço Verde, Sergipe state, Brazil, with the following objectives: (i) to assess the temporal dynamics of the structure, floristic composition, and ecological groups of woody vegetation after four years with the hypothesis of reducing of the floristic and structural complexity with return of succession stage; (ii) to quantify the stocks aboveground of biomass and carbon, to assess the temporal dynamics of these stocks after four years, and to analyze the relationship of biomass with abundance and richness, all these in the woody vegetation, with the hypothesis of temporal reduction of stocks and positive correlations between biomassabundance and biomass-richness; and (iii) to analyze the structure, floristic composition, and stocks of biomass and carbon of herbaceous vegetation, seeking to relate the results to the anthropic pressure of fragment. Compared with a previous study (2011 - t0), the current data (2015 - t1) were obtained from 30 plots of 20 x 20 m, measuring individuals with circumference at breast height ≥ 6 cm. The species were classified according to ecological group through a subjective criterion, the biomass was estimated using allometric equations and the carbon stock with the following relationship: carbonstock = biomass*0.47. Significant temporal differences were tested (α<0.05) for richness, density, basal area and biomass stock (paired t test), for value of importance and ecological groups (x² of McNemar), and for Shannon-Wiener diversity - H' (t test of Hutcheson). The relationship of biomass with the abundance and richness were assessed by regression analysis. For herbaceous vegetation were used 30 subplots of 1 x 1 m within the plots of 20 x 20 m. The floristic composition was complemented around these subplots and biomass estimated by collecting and weighing the plants present in the subplots and then multiplied by 0.47 to estimate the carbon stock. We showed an increase of density (0.79%) and basal area (4.82%). The biomass stock was estimated at 52.79 t.ha-1 at t0 and 54.93 t.ha-1 at t1 (0.53 t.ha.year-1) and the carbon at 24.81 t.ha-1 at t0 and 25.82 t.ha-1 at t1 (0.25 t.ha.year-1). Changes in the floristic composition and structure were minimal and the H’ decreased from 3.33 to 3.30 nats.ind-1 keeping the plant community at the same succession stage. None of parameters evaluated differed significantly between the two surveys (p>0.05), indicating that the community is stable over time. The abundance and richness were not correlated with the biomass (p>0.05). For herbaceous vegetation we found 80 species and 34 families. The families of most species richness were Asteraceae, Malvaceae and Poaceae (seven species each). In the area of subplots were found a density of 32.46 ind/m², basal area of 41.6 m².ha-1 and a carbon stock of 108.45 kg.ha-1 in the biomass of 230.76 kg.ha-1. We found H' of 2.42 nats.ind-1 and the Pielou evenness of 0.67. The results show that the studied plant community has not suffered reducing of floristic and structural complexity, with a maintain in the time of their stock of biomass, locally contributing to carbon storage. Moreover, without the influence of parameters abundance and richness, biomass stocks may remain unchanged in the event of reductions in these parameters. The human disturbance recorded caused moderate influence on herbaceous vegetation, but we suggest that the intensity of these have not been sufficient to set up degradation. The studied plant community tolerate current levels of human disturbance, enabling the use of its resources through a planned management, an alternative for conservation. / O presente estudo foi conduzido em um fragmento de Caatinga antropizado no município de Poço Verde, Sergipe, com os seguintes objetivos: (i) avaliar a dinâmica temporal da estrutura, da composição florística e dos grupos ecológicos da vegetação lenhosa após quatro anos com a hipótese de redução da complexidade florística e estrutural com retrocesso do estágio sucessional; (ii) quantificar os estoques aéreos de biomassa e de carbono, avaliar a dinâmica temporal destes estoques após quatro anos e analisar a relação da biomassa com a abundância e riqueza, todos estes na vegetação lenhosa, com as hipóteses de redução temporal dos estoques e de correlações positivas entre biomassa-abundância e biomassa-riqueza; e (iii) analisar a estrutura, a composição florística e os estoques de biomassa e carbono do componente herbáceo, buscando-se relacionar os resultados com a antropização do fragmento. Comparados com um estudo anterior (2011 - t0), os dados atuais (2015 - t1) foram obtidos através 30 parcelas de 20 x 20 m, medindo indivíduos com circunferência à altura do peito ≥ 6 cm. As espécies foram classificadas quanto ao grupo ecológico através de um critério subjetivo, a biomassa foi estimada através de equações alométricas e o estoque de carbono com a seguinte relação: est.carbono = biomassa*0,47. Diferenças temporais significativas (α<0,05) foram testadas para a riqueza, densidade, área basal e estoque de biomassa (teste t pareado), para valor de importância e grupos ecológicos (x² de McNemar) e para diversidade Shannon-Wiener - H' (teste t de Hutcheson). As relações da biomassa com a abundância e a riqueza foram avaliadas por análises de regressão. Para as herbáceas foram utilizadas 30 subparcelas de 1 x 1 m dentro das parcelas de 20 x 20 m. Coletas adicionais de espécies vegetais férteis foram realizadas no entorno das subparcelas e a biomassa foi estimada através de coleta e pesagem das plantas nas subparcelas e a seguir multiplicada por 0,47 para estimar o estoque de carbono. Para a avaliação temporal da vegetação lenhosa, constatou-se um aumento de densidade (0,74%) e área basal (4,82%). O estoque de biomassa foi estimado em 52,79 Mg.ha-1 em t0 e 54,93 Mg.ha-1 em t1 (0,53 Mg.ha.ano-1) e o de carbono em 24,81 Mg.ha- 1 em t0 e 25,82 Mg.ha-1 em t1 (0,25 Mg.ha.ano-1). Alterações na composição florística e estrutura foram mínimas e o índice de H’ diminuiu de 3,33 para 3,30 nats.ind-1 e a comunidade manteve-se em mesmo estágio sucessional. Nenhum dos parâmetros avaliados diferiu significativamente entre os dois levantamentos (p>0,05), apontando que a comunidade se encontra estável no tempo. A biomassa não foi correlacionada com a abundância e a riqueza (p>0,05). Para a vegetação herbácea foram encontradas 80 espécies e 34 famílias. As famílias de maior riqueza foram Asteraceae, Malvaceae e Poaceae (sete espécies cada). Na área das subparcelas foi encontrada uma densidade de 32,46 ind/m², uma área basal de 41,6 m².ha-1 e um estoque de carbono de 108,45 kg.ha-1 numa biomassa de 230,76 kg.ha-1. Foi encontrado um índice de H’ de 2,42 nats.ind-1 e uma equabilidade de Pielou de 0,67. Os resultados apontam que a comunidade vegetal estudada não sofreu redução temporal de sua complexidade florística e estrutural, com uma manutenção temporal de seu estoque de biomassa, contribuindo localmente para o armazenamento de carbono. Além disso, sem influência da abundância e da riqueza, os estoques de biomassa podem manter-se inalterados diante de reduções nestes parâmetros. Considerando-se ainda que os impactos antrópicos registrados causaram moderada influência na vegetação herbácea, acredita-se que a intensidade destes não tenham sido suficientes para configurar uma degradação. A comunidade vegetal estudada tolera os atuais níveis de antropização, viabilizando o uso de seus recursos através de um manejo planejado, uma alternativa para a conservação.