Making use of trees on Shabbos:
The Sages decreed against making any use of a tree on Shabbos due to worry that if this were to be allowed one may come to climb the tree and remove fruits, leaves, or branches from it. This decree applies equally to all trees, even to those which are barren and have no leaves or branches.
The decree against making use of trees includes the following prohibited actions:
- Climbing a tree.
- Hanging on a tree branch.
- Leaning on a tree.
- Placing or removing objects from a tree or its branch.
- Tying items to a tree or its branch.
One may not climb on a tree on Shabbos whether the tree is dry or damp.
Climbing up a tree before Shabbos: One may not climb a tree from before Shabbos in order to remain on it throughout Shabbos. If one climbed the tree from before Shabbos, and remained on it into Shabbos he may descend from it on Shabbos. [See footnote if he must descend immediately upon remembering]. This applies even if one ascended the tree before Shabbos with intent to remain there on Shabbos, and had prior knowledge that being on the tree on Shabbos is forbidden. It certainly applies if one ascended without prior knowledge of the prohibition involved in remaining there on Shabbos.
If one climbed up a tree on Shabbos may he climb down:  If one climbed up a tree on Shabbos unknowing of the prohibition involved, it is permitted for him to descend on Shabbos. If however one climbed the tree despite his knowledge of the prohibition, it is forbidden for him to descend from the tree on Shabbos, and he must rather remain there throughout Shabbos. 
B. Hanging on a tree:
One may not hang on a tree.
C. Leaning on a tree:
Ruling of Admur in SH”A: (One may not lean on a frail tree on Shabbos if doing so will cause it to shake. One may lean on a sturdy tree that will not shake as a result of one’s leaning.)
Final ruling of Ketzos Hashulchan: The Ketzos Hashulchan rules that practically, even for those which follow the rulings of Admur, it is forbidden to lean on any tree, whether sturdy or weak, to the point that if the tree were to be removed the person would fall. However it is permitted to slightly lean on a [strong] tree in a way that even if the tree were to fall one would remain standing.
D. Touching a tree:
It is permitted to touch a tree so long as one does not cause it to shake in the process.
E. Making use of a tree for one’s objects:
One may not use a tree for any purpose. Thus it is forbidden to:
- Place an item on it.
- Remove an item from it.
- Tie an animal to it.
If one’s Tallis got stuck on a tree may one remove it?
F. May one place an item on a tree before Shabbos having it remain there into Shabbos?
It is permitted to place a candle on a tree from before Shabbos with intent that it remains there into Shabbos being that the candle is Muktzah. It is however forbidden to place a candle on a tree from before Yom Tov with intent that it remain there into Yom Tov, as on Yom Tov a candle is not Muktzah.
[Thus as a general rule all non-Muktzah items are forbidden to be placed on a tree from before Shabbos with intent that they remain there on Shabbos due to suspicion that one may come to take them down. The same applies on Yom Tov.]
It is forbidden to leave non-Muktzah objects on a tree over Shabbos. It is permitted to leave Muktzah items on a tree over Shabbos.
G. Making use of items which are attached to a tree:
It is forbidden to make use of items which are in direct contact with a tree. Those items which are in contact with an item that is in direct contact with a tree one may make use of that item so long as that doing so will not inevitably cause the tree or its branches to shake.
- Example 1-Climbing a ladder:
One may not climb a ladder which is leaning on a tree, although one may climb the ladder if it is leaning on a nail which is attached to the tree. Furthermore one may even initially lean this ladder on the nail on Shabbos.
- Example 2-Using a basket:
One may make use of a basket which is hanging on a nail which is knocked into the tree if doing so will not inevitably cause the tree or its branches to shake. Thus one may remove an item from within a widely opened basket [or enter an item into it]. However a narrowly opened basket which will cause the tree to shake upon removing, or entering an item into it, may not be used. In all cases one may not remove the basket from the nail as by doing so he is making use of the nail. If the basket is hanging directly on the tree, such as on a branch, it is forbidden in use in all cases and hence one may not remove items from it or insert items into it.
H. Making use of tree roots:
Roots of trees which protrude from the ground are permitted to be used in their area that is within three Tefach from the ground. However the area of a root that is above three Tefach from the ground is considered like a tree and is forbidden to be used. Roots which do not reach three Tefach from the ground are considered like the ground itself and are entirely permitted to be used. If the roots reach above three Tefach from ground from one direction while in other directions they are equal to ground then if in 2 areas they are equal to ground, one measures the three Tefach from that area of ground for the entire root. If however only one area is equal to ground then the entire root is forbidden in being used.
Moving the roots with one’s hands: In all cases it is forbidden to move the roots of a tree with one’s hands due to the Muktzah prohibition.
I. Making use of branches of a tree:
Grow below three Tefach from the ground: All branches which grow on the bark within three Tefach from the ground are allowed to be used.
Grow above three Tefach from the ground: All branches which grow on the bark above three Tefach from the ground are prohibited from being used. However if the branch bends downwards towards the ground then the area of the branch which reaches within three Tefach from the ground may be used, while the area of the branch which extends above three Tefach from the ground is forbidden to be used.
- Moving the branches with one’s hands: In all cases it is forbidden to move branches with one’s hands due to the Muktzah prohibition.
J. Making use of the trunk of a tree:
The trunks of all trees may be used up to three Tefach from the ground.
K. Entering into a pit on Shabbos:
It is permitted to descend into a pit, and ascend from a pit on Shabbos. This allowance applies irrelevant to the measurement of depth of the pit.
 As the Sages decided to make a guardrail for their decree, and hence forbid all trees from their use. [ibid]
 As sitting on the tree on Shabbos is itself considered making use of the tree, which is forbidden to be done. [ibid]
 Seemingly he must descend immediately upon remembering as it is forbidden to remain on the tree on Shabbos, as explained above. However it requires further analysis why this was omitted from Admur, and on the contrary Admur gives no implication that one must descend at all. Perhaps the reason is because going down from the tree is also a prohibition and hence whether he decides to remain on the tree or descend he is doing a prohibition, and it is just that he is allowed to descend. However this matter requires further analysis as remaining on the tree is seemingly a continuous prohibition while descending is a onetime action, hence why should it not be required for him to descend?
 There is a dispute regarding this matter brought in Admur: The first [Stam] opinion rules it is permitted to descend on Shabbos if one ascended before Shabbos, even if one did so with prior knowledge of the prohibition.
Other opinions however rule that in a case that one ascended Bemeizid before Shabbos with intent to remain there on Shabbos, [meaning he ascended with prior knowledge of the prohibition], then if he in truth remains on the tree into Shabbos, in such a case the Sages fined him to need to remain on the tree until the end of Shabbos. According to this opinion it was only permitted to descend from a tree which one ascended before Shabbos if one intended to descend before Shabbos, and inadvertently remained into Shabbos.
Practically, the final ruling is that regarding Rabbinical matters one is to follow the lenient opinion. [ibid]
 This applies according to all as explained in the previous footnote.
 As although by climbing down the tree he is making use of it, nevertheless this was not prohibited as either way he will be making use of the tree, as if we require him to remain on the tree until after Shabbos, then he has made use of sitting on the tree on Shabbos. [ibid] And making use of a tree on Shabbos by sitting on it is likewise forbidden, therefore the Sages allowed him to descend even though he is making use of the tree by doing so. [336/3]
 This is due to a fine of the Sages. [ibid]
 336/1 and 21
Ruling of M”A and its explanation: The M”A 336/15 writes “to lean on a tree for a healthy is allowed while for a weak is not allowed” It is unclear from the M”A if the term healthy and weak refers to the tree or the person. Meaning is he ruling that if the tree is week it is forbidden to lean on it, or is he ruling that if a person is week he may not lean on it”. Admur [as well as Chayeh Adam] here rules like the former option, that if the tree is week it is forbidden due to it shaking while if the tree is healthy it is permitted. Admur [and Chayeh Adam] makes no differentiation regarding a healthy or week person, hence showing he understood the M”A to be referring to the tree and not to the person. However the Machatzis Hashekel [end of 336] and Peri Megadim A”A 336/15 learn like the latter that if the person is week it is forbidden while if the person is healthy it is permitted.
Question on Admur: The Igleiy Tal [brought in Ketzos Hashulchan 142 footnote 10] and Biur Halacha [336 “Umutar”] takes issue with the explanation of Admur and Chayeh Adam being that to lean on a tree is prohibited due to Tzedadin [using the sides of a tree] and hence what relevance is there whether the tree will shake or not, either way it is forbidden in use. They thus conclude that it is forbidden to lean even on a strong tree. The Ketzos Hashulchan [142 footnote 10] concludes based on these questions, that even Admur himself did not conclusively rule like the former option ,and hence placed the ruling in parentheses. He thus concludes to be stringent.
 The parentheses are in the original and were entered by Admur. The Sheiris Yehuda writes that all laws that were placed by Admur in parentheses were done so because they were in need of final review. Thus as will be explained next the Ketzos Hashulchan 142 footnote 10 rules not to follow this ruling.
Other Opinions: As rules Admur so also rules Chayeh Adam. However the PM”G; Machatzis Hashekel; M”B and Igleiy Tal ibid rule it is forbidden to lean on any tree unless one he is merely touching it. The Ketzos Hashulchan ibid defines this as leaning slightly in a way that one would still remain standing even if the tree were to fall.
 142 footnote 10
 Meaning that they should not follow the ruling of Admur in parentheses, as maters placed in parentheses are not considered a final Halachic ruling of Admur, and hence one is allowed to rule like other Poskim. [Ketzos Hashulchan ibid]
 However on a weak tree it would remain forbidden due to causing it to shake, as explained in Admur and other Poskim. [so rules also Kaf Hachaim 336/90]
 The Ketzos Hashulchan defines the ruling of the Igleiy Tal and M”B that touching is not literal
 Kaf Hachaim 336/90
 The Kaf Hachaim ibid suspects for both explanations and is hence stringent to require both the person and the tree to be healthy.
 As a tree is Muktzah and hence may not be moved. [ibid]
 As upon taking the item down one is using the tree, which is forbidden. If however the item were to remain on the tree until after Shabbos no prohibition would be done. Hence this case is not similar to a person who has climbed a tree from before Shabbos, as in such a case even making him remain on the tree involves a prohibition of using the tree, and hence there is no Halachic advantage of making the person remain there rather than descend. [ibid]
 Sheivet Haleivi 7/44
 277/7; 514/16
 As since a candle is Muktzah there is no worry that one may come to take it down from the tree on Shabbos. ibid]
 Hence we suspect one may come to take it down on Yom Tov and by doing so one makes use of the tree which is forbidden to be done whether on Shabbos or Yom Tov. [ibid]
 Ketzos Hashulchan 142 footnote 11 in name of Iglei Tal.
 As only the use of the side of the tree was decreed against, while the use of “the sides of the side” were permitted. [Ibid]
 As if one causes it to shake he has made use of the tree itself which is forbidden. [ibid]
 As by doing so one is making use of the side of the tree which he is using as support. [ibid]
 As the nail is considered the side while the ladder is the side of the side which is allowed to be used. [ibid]
 This ruling of Admur is based on Michaber 336/13
Question on above ruling and Other Opinions: Tzaruch Iyun as for why it is allowed to lean a ladder onto a nail, is this not considered making use of the nail which is “sides”, and it is forbidden to make use of sides on Shabbos? The M”B [336/60;62 in name of Achronim, Upashut] and Kaf Hachaim 336/85 both take issue with this ruling based on this question and conclude to reinterpret the ruling of the Michaber to rather read as follows “It is permitted to place a ladder on a nail on Erev Shabbos in order to climb on it on Shabbos”. However on Shabbos itself it is forbidden to place a ladder onto the nail. SSH”K 16/16 practically rules like their opinion that it is forbidden to place the ladder on the nail on Shabbos.
Question on “Other Opinions”: However it is very difficult to enter this explanation into either the wording of Admur or the Michaber and it is literally requiring rewriting their words. Admur writes “It is permitted to place the ladder on the nail and climb up” According to the new explanation why did he not just simply state “However if the ladder is leaning on a nail of the tree it is permitted to climb up” as is the wording of the first case in which he writes “if the ladder is leaning on the tree itself it is forbidden to climb it on Shabbos”. If anything the change of wording in the second case to “It is permitted to place a ladder on the nail” negates the explanation given above and hence is the reason why Admur wrote it this way so there be no misunderstanding in the Michaber. In the Michaber as well it is difficult to enter this explanation as he simply rules “it is forbidden to place the ladder on the tree itself while onto a nail is permitted”. The Michaber here is not even discussing the idea of climbing the tree but simply of placing the ladder. Hence it appears that according to the Michaber and Admur, as well as all the other Poskim such as the Taz, M”A, Aruch Hashulchan which did not edit anything into the Michaber, it is clear they rule one may place the ladder onto the actual nail.
Explanation: As a possible explanation of why there is no prohibition involved in placing the ladder onto the nail, perhaps one can answer that placing a ladder onto the nail is not considered doing an actual use with the nail which is the Tzdedain, as the actual use is when he climbs onto the ladder. Meaning the same way there is no prohibition in touching a tree as by doing so he has not done any use of the tree, so too there is no prohibition in leaning a ladder on a tree as until he climbs the tree he has done absolutely no use of the tree, as the ladders only purpose and use is for climbing. This understanding can find support in the wording of the Michaber. He writes “One may not lean a ladder onto a tree as when one climbs it he us using the sides”. The Michaber clearly writes that the prohibition is the climbing and not the actual leaning of the ladder. Meaning that only the climbing in the ladder is considered using the Tzedadin while the leaning is not. However according to this it remains to be understood why the Michaber wrote in the first place it is forbidden to lean the ladder on the tree if the prohibition is only the leaning? Perhaps this is the inference in the change of wording of Admur from the wording of the Michaber, Admur, unlike the Michaber, does not mention it is forbidden to lean the ladder on the tree on Shabbos, he rather simply states it is forbidden to climb a ladder that is leaning directly on a tree. Perhaps this change of wording is emphasizing the exact point brought above, that placing the ladder onto the tree is permitted as it has done no use, while only climbing is forbidden. [Note of Author: All this I have written not because I Chas Veshalom feel I understand the Shulchan Aruch better than the M”B and Kaf Hachaim but simply to defend the simple straightforward meaning of the Michaber and Admur, as well as all the other Poskim which never felt a need to explain or edit their words. What does however require further study is why Admur rules that removing the basket from the nail is considered using the side of the tree, as what actual use has been done by removing the basket. Vetzaruch Iyun.]
 As the nail is considered the side while the basket is the side of the side which is allowed to be used. [ibid]
 As if one causes it to shake he has made use of the tree itself which is forbidden.
 Ketzos Hashulchan 142/7
 And the nail is considered the side of the tree which is forbidden in use. [ibid]
 As the basket is considered the side of the tree which is forbidden in use. [ibid]
 336/5-6 and 8
Explanation of case: All parts of a tree which are within three Tefach from the ground are permitted in use just like the ground itself. At times trees grow roots which protrude above the ground. Sometimes these roots are very tall, and extend as high up as 24 cm. The question thus is asked what status do these roots have, are they considered like ground or like the tree. Hence Admur explains that the entire area of the root which is within three Tefach from the ground is permitted in use, while those areas of the root which are above three Tefach from the ground are forbidden in use.
 As is common by old trees. [ibid]
 24 cm.
 As the entire area within three Tefach from the ground was never prohibited in use by the Sages. [336/6 regarding the trunk of a tree and so applies likewise to the root, as on the contrary the main Halacha of the Michaber 336/2 is going on the root and not the trunk or branches, and it is only added that it also applies to the branches.]
 As although by such roots the suspicion that one may come to remove a branch and the like is inapplicable, nevertheless the Sages did not make a differentiation in their decrees. [ibid]
 It requires further analyses as to the exact understanding of this Halacha in terms of the exact positioning of the root.
 24 cm.
 24 cm.
 Now although the root of the branch grows above three Tefach from the ground which is a forbidden area of use, and this area of the branch too was once within this area of growth and hence forbidden, nevertheless upon it growing further and bending downwards it became permitted, as it is now considered like ground. As all which is less than three Tefach to the ground is considered like ground. [ibid]
 As the entire area within three Tefach from the ground was never prohibited by the Sages. [ibid]
 We do not decree that one may come to consciously remove earth from the pit upon his decent or ascent (and fix for himself steps and hence be liable for building) as a person is more careful to avoid doing these actions then he is in regards to avoiding removing leaves, fruits and branches off a tree. [ibid]