http://chameleon.polytechnic.edu.na/wiki/ Fri, 18 Jun 2010 04:00:04 +0100 FeedCreator 1.7.2-ppt DokuWiki http://chameleon.polytechnic.edu.na/wiki/lib/images/favicon.ico http://chameleon.polytechnic.edu.na/wiki/ http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera&rev=1221208328 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Fri, 12 Sep 2008 09:32:08 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera2&rev=1237214546 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Below is a typical mature tree, that could be over 100 years old. Patrick Rickert holds a 2m pole and Luke Claassen is measuring the stem circumference. back to home page? Mon, 16 Mar 2009 15:42:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera_2&rev=1188573386 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Fri, 31 Aug 2007 16:16:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera_q10&rev=1221220251 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Fri, 12 Sep 2008 12:50:51 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera_q11&rev=1221554609 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Tue, 16 Sep 2008 09:43:29 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=acacia_mellifera_q3&rev=1221214858 Acacia mellifera is a fascinating species which in fact is divided into two subspecies: subsp. mellifera and subsp. detinens. The “problem” one is subsp. detinens. In Namibia subsp mellifera is found only near the Kunene River and does not form thickets. More information will be added to this page, as time permits. Fri, 12 Sep 2008 11:20:58 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=biodiversity&rev=1188573386 Lichens seem to prefer the smooth bark of Acacia mellifera to other species with rough barks such as Acacia erioloba. There seem to be more species and a greater abundance of lichens than on other similar sized trees. Lichens are only found on the larger individuals, almost exclusively on the better shaded south side of the trunk. Fri, 31 Aug 2007 16:16:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=birds&rev=1188573386 Cape Penduline tits seem to prefer nesting in 2m to 3m Acacia mellifera shrubs, about 30cm from the top near the centre. The thorny branches make it impossible for humans to get to them under normal circumstances, although mongooses and Gabar Goshawks might! Fri, 31 Aug 2007 16:16:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=browsing&rev=1218540333 Browsing of gulliver by hares on Argo Rust’s farm, Sonnleiten. back to Question 3 Tue, 12 Aug 2008 12:25:33 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=bush_encroachment&rev=1221219728 Everyone seems to have their own view of what bush encroachment is, and when it is a problem? Actually, it is a process, and in most cases should be termed “thickening” since the bushes are already in the area and are just increasing in density and cover, whereas bush encroachment implies moving into the area. One could say bush encroachment is the increase in density and cover of bushes to such an extent that grass production is significantly decreased. Some farmers like to have bush thicke… Fri, 12 Sep 2008 12:42:08 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=bush_seedlings&rev=1221137190 It is difficult to know exactly if what you see is a seedling or a young gulliver. However, if it is only half a centimetre in diameter you could probably treat it as a seedling, although it might be six year old. Once its lateral roots have developed, it is likely to “behave” differently, and probably becomes more fire resistant. back to question 5 Thu, 11 Sep 2008 13:46:30 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=cold_dry_season&rev=1221468613 Loosely speaking, this season starts in May and ends around July, although cold fronts bring cold spells until September. Go back to Question 1 Mon, 15 Sep 2008 09:50:13 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=cold_dry_season_q1&rev=1221222368 Loosely speaking, this season starts in May and ends around July, although cold fronts bring cold spells until September. Go back to Question 1 Fri, 12 Sep 2008 13:26:08 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=dave_joubert&rev=1189086966 Send an eMail to Dave Joubert. Back to start Thu, 06 Sep 2007 14:56:06 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=de-stocking&rev=1217935752 De-stocking refers to the reduction of animal numbers that are allocated to graze a certain area over a certain period. Tue, 05 Aug 2008 12:29:12 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=decision_tree&rev=1269870856 Our decision tree outlines, without any detail, the decisions and how they are reached. [Decision Tree] The decisions on the left are decisions to be taken at critical times (during exceptional rainfall years), the decisions on the bottom right are decisions taken to treat the symptoms (ie. in areas where you already have a problem) and the decisions on the upper right refer to ongoing good management decisions that will minimise the risk of a bush encroachment event in future. Mon, 29 Mar 2010 14:54:16 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=dichrostachys_cinerea&rev=1222683212 back to Decision 21 An adult D.cineria tree. Stumps of D.cineria accessed by herbicide. Mon, 29 Sep 2008 11:13:32 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=dss&rev=1257242636 A Decision Support System for Bush Encroachment by Acacia Mellifera in the Highland Savanna Start NB! Use the DSS for each part of the farm (e.g. per camp). Each part of the farm might be in a different state, or condition, and different decisions might be appropriate. Tue, 03 Nov 2009 11:03:56 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=dss_paper&rev=1188573386 The development of a Decision Support System for Semi-Arid Rangeland Management in Central Namibia with Emphasis on Bush Thickening. Introduction * What a DSS is? Get definition/explanation from Davis et al. (1989). From Starfield and Louw (1986) or Starfield and Bleloch (19xx) – emphasise the range of sophistication and power. Make it clear what we mean by DSS (or expert system) * Its uses and use, generally and specifically for rangeland management). * Its perceived value. * DSS a… Fri, 31 Aug 2007 16:16:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=fire&rev=1221554543 Although the use of fire has often been advocated for controlling mature bushes in conjunction with browsers, this research has mostly focussed on other species such as Acacia karroo (e.g. Trollope, 1974; Trollope, 1980). This has has not been shown to be very successful with mature Acacia mellifera bushes in Namibia. Far more success is likely when young plants have still not yet developed their lateral root systems. Tue, 16 Sep 2008 09:42:23 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=fungal_dieback&rev=1221731515 Extensive Fungal dieback of Swarthaak on Neudam Farm It is likely that thickets showing such extensive dieback will not recover and in fact enhance the soil fertility, create a seed bed, as well as protect young perennial grasses from grazing. Back to Question 10 Thu, 18 Sep 2008 10:51:55 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=germination&rev=1221215271 Acacia mellifera tends to grow very slowly in their first years. Six year old plants that germinated in 2001 would be misidentified by many people as first year seedlings! Go back to Question 3 (Click on the image to enlarge.) Fri, 12 Sep 2008 11:27:51 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=home&rev=1257168397 Welcome to the Chameleon Bush Encroachment Wiki: a decision tool for farmers. It is an ongoing process to develop this Decision Support System, and thus there may be pages under construction at any time. We greatly encourage you to communicate with us, providing your suggestions for improvement, viewpoints etc. Mon, 02 Nov 2009 14:26:37 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=hot_dry_season&rev=1221468485 The hot dry season can also be wet, 2006’s “hot dry season” was particularly wet! Back to Question 1 Mon, 15 Sep 2008 09:48:05 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=hot_dry_season_q1&rev=1221216607 The hot dry season can also be wet, 2006’s “hot dry season” was particularly wet! Back to Question 1 Fri, 12 Sep 2008 11:50:07 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=hot_dry_season_que1&rev=1221222291 The hot dry season can also be wet, 2006’s “hot dry season” was particularly wet! Back to Question 1 Fri, 12 Sep 2008 13:24:51 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=hot_wet_season&rev=1221468660 The hot wet season of 2007 was particularly dry in the Highland Savanna, with most rain falling in the hot dry season in 2006! Back to Question 1 Mon, 15 Sep 2008 09:51:00 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=hot_wet_season_q1&rev=1221222506 The hot wet season of 2007 was particularly dry in the Highland Savanna, with most rain falling in the hot dry season in 2006! Back to Question 1 Fri, 12 Sep 2008 13:28:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=joubert_rothauge_and_smit_in_prep&rev=1237215598 Citation The correct citation for this reference is * Joubert, D.F., Rothauge, A. and Smit, G.N. 2008. A conceptual model of vegetation dynamics in the semiarid Highland savanna of Namibia, with particular reference to bush thickening by Acacia mellifera. J Arid Environ. 72: 2201-2210. Chameleon Wiki Home Mon, 16 Mar 2009 15:59:58 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=monitoring&rev=1221210447 We intend to introduce a monitoring advice section to our Decision Support System soon. back to Decision 2 Fri, 12 Sep 2008 10:07:27 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=more_info&rev=1191942224 The Decision Support System (DSS) is not intended to be a definitive work on how to manage bush encroachment. The DSS was in fact developed for the Highland Savanna vegetation type of the Khomas Region, and is largely based on a conceptual model for savanna dynamics in this region, developed by Dave Joubert and Axel Rothauge (Joubert & Rothauge, 2001) and later (Joubert, Rothouge and Smit, in prep.). The model in turn was largely based on research done on the population dynamics of Acacia mellif… Tue, 09 Oct 2007 16:03:44 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=moribund_q12&rev=1221731761 Moribund refers to the physical dying back of the grass as opposed to growth. The figure below shows a moribund grass. back to Question 12 A moribund perennial grass. Thu, 18 Sep 2008 10:56:01 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=parent_trees&rev=1190207585 The picture below taken at Claratal, west of Windhoek, shows same aged offspring of a central parent tree (that is dying). In fact there is another generation, germinated in 2001, but they are too small to see (0.5cm stem diameter, and perhaps 10cm high). Most seeds germinate very close to parent trees. Wed, 19 Sep 2007 14:13:05 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=perennial_grass_q12&rev=1221731670 Perennial grass refers to grasses that grows continuosly throught the year to the next and new materials are ussually from the same old parent plant instead of from new seeds. Go back to Question 12 An area dominated by perennial grasses. Thu, 18 Sep 2008 10:54:30 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=privileged_trees&rev=1221475198 This tree is growing on the side of the road, and thus, despite the poor rainfall of the previous season, still has lots of pods on it. This is what we call a “privileged” tree back to Question 2. [ ] Mon, 15 Sep 2008 11:39:58 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seasons&rev=1221472861 We differentiate between three seasons: * Hot Dry Season * Cold Dry Season * Hot Wet Season Please see the respective page for more information. Go back to Question 3 Mon, 15 Sep 2008 11:01:01 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seasons_q1&rev=1221221222 We differentiate between three seasons: * Hot Dry Season * Cold Dry Season * Hot Wet Season Please see the respective page for more information. Go back to Question 1 Fri, 12 Sep 2008 13:07:02 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seed_production&rev=1221208007 This tree will probably produce a large crop of viable mature seeds at the end of the year (November to December) judging by the number of young healthy developing pods. back to Question 2 (Click on the image to enlarge.) Fri, 12 Sep 2008 09:26:47 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seed_production_dec1&rev=1221223572 This tree will probably produce a large crop of viable mature seeds at the end of the year (November to December) judging by the number of young healthy developing pods. back to Decision 1 (Click on the image to enlarge.) Fri, 12 Sep 2008 13:46:12 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seed_production_q2&rev=1221223266 This tree will probably produce a large crop of viable mature seeds at the end of the year (November to December) judging by the number of young healthy developing pods. back to Decision 1 (Click on the image to enlarge.) Fri, 12 Sep 2008 13:41:06 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seedlings&rev=1257258558 It is difficult to know exactly if what you see is a seedling or a young sapling. This is a healthy seedling. However, if the sapling is only half a centimetre in diameter you could probably treat it as a seedling, although it might be six years old already. Once its lateral roots have developed, it is likely to “behave” differently, and probably becomes more fire resistant. back to question 5 Tue, 03 Nov 2009 15:29:18 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seedlings2&rev=1188573386 It is difficult to know exactly if what you see is a seedling or a young gulliver. This is a healthy seedling. However, if the gulliver is only half a centimetre in diameter you could probably treat it as a seedling, although it might be six year old. Once its lateral roots have developed, it is likely to “behave” differently, and probably becomes more fire resistant. back to question 3 Fri, 31 Aug 2007 16:16:26 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seeds&rev=1221216029 Viable seeds of Acacia mellifera are smooth, disc-like and large, without any shrivelling or deformities present. Joubert (in prep.) found very low bruchid infestations in 2000, when an exceptional rainfall produced a huge seed set.Viable seeds are seen on pebbles. These will germinate if not eaten. Fri, 12 Sep 2008 11:40:29 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=seedsq3&rev=1221141372 Viable seeds of Acacia mellifera are smooth, disc-like and large, without any shrivelling or deformities present. Joubert (in prep.) found very low bruchid infestations in 2000, when an exceptional rainfall produced a huge seed set.Viable seeds are seen on pebbles. These will germinate if not eaten. Thu, 11 Sep 2008 14:56:12 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=symptoms&rev=1218703670 Treating of symptoms is usually the least desirable option. Prevention is better and cheaper than cure! However, we realise that many farmers do already have a huge problem and therefore this is an important part of our DSS. Go back to Question 9 Go back to Question 5 Thu, 14 Aug 2008 09:47:50 +0100 http://chameleon.polytechnic.edu.na/wiki/doku.php?id=symptoms_que5&rev=1221218227 Treating of symptoms is usually the least desirable option. Prevention is better and cheaper than cure! However, we realise that many farmers do already have a huge problem and therefore this is an important part of our DSS. Go back to Question 5 Fri, 12 Sep 2008 12:17:07 +0100