Long‐term change and implications for the management of wood‐pastures: experience over 40 years from Denny Wood, New Forest
Long‐term change and implications for the management of wood‐pastures: experience over 40 years from Denny Wood, New Forest
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森林牧场管理的长期变化和影响：新森林丹尼伍德 40 多年的经验
DOI：
10.1093/forestry/76.1.19
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发表时间：
2003
期刊：
影响因子：
2.8
通讯作者：
G. Peterken
中科院分区：
文献类型：
--
作者：
E. P. Mountford;G. Peterken
丹尼木材，一个古老的森林牧场在新的森林，长期的变化记录在两个永久性的样带。其中一个位于森林的未封闭部分，对所有大型食草动物（小马，鹿，牛）开放。另一个是在一个封闭的部分，这是围栏对牲畜（但不是鹿）从1870年至1960年12月，之后小马重新获得访问。样带内乔木、灌木、幼苗和维管地面植被的记录主要在1959-1964年和1996-2001年进行。未封闭样带变化很大。在1959年，它包括封闭的山毛榉-橡树林，有丰富的冬青林下和小块剪股颖草坪或蕨草，由中等数量的大型食草动物放牧。40年后，这里变成了一片开阔的橡树山毛榉帕克兰，几乎没有下层植物。物种丰富的草坪和蕨类植物已经广泛传播，大型食草动物也变得越来越多。橡树比山毛榉存活得好得多：较大的山毛榉在1976年遭受了干旱，中等的山毛榉则被灰松鼠松鼠（Sciurus carolinensis）剥皮。许多山毛榉在1981年的一次安全/打捞行动中被切割和移走。冬青的减少主要是由于小马和鹿的浏览和剥皮。树木和灌木幼苗变得更加丰富，但浏览有效地阻止了再生。1959年，封闭样带还包括封闭的山毛榉-橡树-冬青林。然而，林分更密集，地面植被更严重的阴影，物种贫乏和稀疏比未封闭样带。在接下来的40年里，主要由于1976年干旱和后来的风暴造成了大量山毛榉和橡树的损失，造成了巨大的差距。林隙以下主要发育等级低、种类少的蕨草草地和林分，但大部分地区仍为郁闭的高林，地面植被很少。没有枯死的树木被清除，枯木数量仍然居高不下。冬青减少了很多，主要是由于鹿和小马的浏览和剥皮。放牧几乎完全阻止了树木的再生。放牧的木材牧场的影响进行了讨论。长期排除牲畜与鹿的数量减少允许大量的树木再生冬青，但随之而来的密集，封闭的立场有一个贫困的地面植物群。适度数量的牲畜（包括小马和牛）和鹿保持了一些草地空地，但允许冬青蔓延。大量的牲畜（主要是小马）和鹿减少了冬青，在树冠打开的地方，有助于恢复草本植物丰富的地面植被，这得益于放牧草皮的连续性和蕨类植物为放牧敏感植物提供的避难所。尽管如此，主要由小马进行的大量放牧阻止了树木的再生长达数十年，即使是在大开口中，尽管存在可能的保护功能，即多刺灌木丛，倒下的树木和蕨类植物。再生的普遍失败，安德伍德和灌木丛的减少，加速死亡率和旧林的分解，以及灰松鼠对幼树的破坏，代表了新森林牧场历史上的一个脆弱点。
Long-term changes in Denny Wood, an ancient wood-pasture in the New Forest, were recorded on two permanent transects. One was located in an unenclosed part of the wood, which remained open to all large herbivores (ponies,deer, cattle). The other was in an enclosed part, which was fenced against livestock (but not deer) from 1870 to ∼1960, after which ponies regained access. Records of trees, shrubs, seedlings and vascular ground vegetation within the transects were made mainly during 1959-1964 and 1996-2001. The unenclosed transect changed greatly. In 1959 it comprised closed beech-oak Fagus sylvatica-Quercus robur forest with abundant holly Ilex aquifolium understorey and small patches of Agrostis lawn or Pteridium aquilinum grazed by moderate numbers of large herbivores. Forty years later this had become an open oak-beech parkland with little understorey. Species-rich lawns and stands of Pteridium had spread extensively, and large herbivores had become far more numerous. Oak survived much better than beech: the larger beech suffered particularly from drought in 1976 and the medium beech from debarking by grey squirrels Sciurus carolinensis. Many beech were cut and removed in a safety/salvage operation in 1981. Holly was reduced mainly by browsing and debarking by ponies and deer. Tree and shrub seedlings became more abundant, but browsing effectively prevented regeneration. The enclosed transect also comprised closed beech-oak-holly forest in 1959. However, the stand was denser and the ground vegetation was more heavily shaded, species-poor and sparser than on the unenclosed transect. Substantial gaps were created during the next 40 years due mainly to the loss of large beech and oak after drought in 1976 and later storms. Rank, species-poor grassland and stands of Pteridium developed mainly below gaps, but many parts remained as closed high forest with little ground vegetation. No dead trees were removed and dead wood volumes remained consistently high. Holly was much reduced, principally due to browsing and debarking by deer and ponies. Grazing almost completely prevented tree regeneration. The implications for grazing of wood-pastures are discussed. Prolonged exclusion of livestock with reduced deer numbers allowed abundant regeneration of trees with holly, but the ensuing dense, closed stand had an impoverished ground flora. Moderate numbers of livestock (both ponies and cattle) and deer kept some grassy glades, but allowed holly to spread. High numbers of livestock (mainly ponies) with deer reduced holly and, where the canopy opened, helped restore herb-rich ground vegetation, aided by the continuity of grazed turf and refuges provided by Pteridium for grazing-sensitive plants. Nevertheless, heavy grazing mainly by ponies prevented tree regeneration for many decades, even in large openings and despite the presence of possible protective features, i.e. spiny bushes, fallen trees, and stands of Pteridium. The widespread failure of regeneration, reduction in underwood and scrub, accelerating mortality and break up of old-growth stands, and damage to young trees by grey squirrels, represents a vulnerable point in the history of New Forest wood-pastures.